Biodegradable / compostable netting, including forage wrap, and related products and methods

Abstract

A compostable / biodegradable netting has: a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS); in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

Description

BIODEGRADABLE / COMPOSTABLE NETTING, INCLUDING FORAGE WRAP, AND RELATED PRODUCTS AND METHODSTECHNICAL FIELD

[0001] This document relates to biodegradable and / or compostable netting, including forage wrap, and related products and methods.BACKGROUND

[0002] The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.

[0003] Plastic bale wrap is used throughout North America to secure bales. The plastic wrap takes hundreds of years to degrade and poses an environmental concern.SUMMARY

[0004] A biodegradable netting is disclosed comprising: a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PL A) and polybutylene succinate (PBS); in which: the blend is structured to substantially degrade after placement in soil for at least six months, for example after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0005] A method is also disclosed comprising: heating and blending biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS) to form a blend; extruding the blend into a web structure; in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0006] A method is also disclosed comprising: wrapping a forage bale with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS); in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; the web structure is structured to have sufficient strength to be fed through a forage baler machine to be applied to a forage bale and to secure the forage bale; and the web structure is structured to have sufficient strength to act as a structural retainer for a forage bale, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0007] A method is also disclosed comprising: wrapping or securing a loose food item with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS);in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, for example after placement for at least 12 months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for the loose food item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0008] Various features of the product may include one or more of: a. Able to be processed within a commercial scale manufacturing facility to make the net wrap product (criteria was 3 parts: melt flow index 1-6, and in some cases, 2-5; ability to stamp out a tensile bar with clean cuts and no cracks out of an extruded sheet of material; thirdly to be able to stamp out a series of bars and conduct tensile-elongation testing at room temperature and at elevated temperatures. Beyond this the process to have it successfully run is proprietary to the manufacturer (temperature at various stages of production, speed of production line, time lapse to stretch laterally / longitudinally, and pressure applied)) b. Able to be run through a commercial scale mechanical baler (criteria were strength and stretch without breaking) c. Able to maintain structural integrity for an extended period of time on the bale during storage in the outside environment without significant degradation resulting from sun, temperature, moisture or soil contact. A key outcome that is desired is to maintain structural integrity (ability to be loaded / transported to animal feeding areas) beyond 12 months which our research indicated 18 months but could be longer / shorter depending upon the geography and consequent environment). d. Able to degrade in soil within a short period of time. Our research indicates it is visually gone within 6 months. e. Able to disintegrate in a composting facility within the timeframe required by standardized testing. f. Meet Eco Toxicity requirements by standardized testing.

[0009] In various embodiments, there may be included anyone or more of the following features: The blend comprises between 50-90% PBS and between 10-50% PLA by weight. The blend comprises between 65-85% PBS and 15-35% PLA by weight, for example, the blend may comprise 75% PBS and 25% PLA by weight. The PBS comprises BioPBS™. The BioPBS™ comprises one or both FZ91PB™ or FZ91PM™. The PBS is derived from one or more of sugarcane, cassava and com. The PLA comprises 6752D™. The PLA is derived from one or more of com, cassava, sugarcane or sugar beet pulp. The web structure is structured to have sufficient properties to stamp out a tensile bar with clean cuts and no cracks out of an extruded sheet of material. The web structure is structured to have sufficient properties to be able to stamp out a series of bars and conduct tensile-elongation testing at room temperature and at elevated temperatures. The blend is selected to provide the web structure with a breaking strength of between 100 and 200 MPa. The blend is selected to provide the web structure with a breaking strength of at least 100 MPa after twelve months of exposure on a forage bale in the field. The web structure is structured to have sufficient strength to be fed through a forage baler machine to be applied to a forage bale and to secure theforage bale. A forage bale is wrapped and secured by the biodegradable netting. A food product is wrapped and secured by the biodegradable netting. Drying pellets of the biopolymers prior to heating and blending.

[0010] The foregoing summary is not intended to summarize each potential embodiment or every aspect of the subject matter of the present disclosure. These and other aspects of the device and method are set out in the claims. BRIEF DESCRIPTION OF THE FIGURES

[0011] Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which: Fig. 1 is plan view of a biodegradable netting. Fig. 2 is a side view of a baler that is producing a bale wrapped in biodegradable netting. Fig. 3 is a bag of biodegradable netting containing loose food items. Fig. 4 is a graph that illustrates short-term (control, unexposed) and long-term maximum extension of all commercial and biopolymer fdaments after lab (water immersion, UV and soil tests) and field exposure. Fig. 5 is a graph that illustrates short-term (control, unexposed) and long-term maximum extension of all commercial and biopolymer filaments after lab (water immersion, UV and soil tests) and field exposure. Fig. 6 is an image of bio-based PBS that has been molded into various products. Fig. 7 is an image of which illustrates the difference in the rate of change in film shape from fossil-based PBS and bio-based PBS after degradation in soil. Fig. 8 is an image illustrating a field test of the degradation of PBS and PBSA in soil. Fig. 9 is a graph that illustrates a disintegration test of 100 200 pm thickness sheets of PBS, PBSA and PLA. Filled triangle: PBS(MCC). Filled circle: PBSA(MCC). Filled square: PLA. Fig. 10 is a schematic view of the biodegradation process. Figs. 11-12 are graphs that illustrate DSC diagrams of a) PCS (Fig. 11) and (b) PLA (Fig. 12) -: Heating (10°C / min). — : Cooling (10°C / min). Fig. 13 is a graph that illustrates the relation between the solution viscosity IV and the tensile elongation at break. Fig. 14 is a graph that illustrates the relation between intrinsic viscosity and shelf life. Fig. 15 is a graph that illustrates the relation between the storage temperature and the estimate shelf life. DETAILED DESCRIPTION

[0012] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. In this document, various acronyms are used to chemical names, including but not limited to: LLDPE - Linear low density polyethylene, PBAT - Poly(butylene adipate-co-butylene terephthalate), PBS - Polybutylene succinate, PBSA - Poly(butylene succinate-co-butylene adipate), PBT - Poly butylene terephthalate, PCL - Poly(caprolactone), PE - Polyethylene, PES - Polyethylene succinate, PET - Polyethylene terephthalate, PHB - Poly (3 -hydroxybutylate), PHB / V - Poly(3-hydroxybutylate-co-3-hydroxyvalerate), PLA - Poly(lactic acid), PP - Polypropylene, PS - Polystyrene, and PVA - Polyvinyl alcohol, PVC - Polyvinyl chloride.

[0013] Plastic is a versatile and widely used synthetic polymer material in various industries due to its exceptional properties, including durability, flexibility, and ease of production. Its versatility is evident in applications ranging from packaging materials, consumer goods, and construction materials to medical devices and automotive components. Plastics can be tailored to meet specific requirements through various manufacturing processes, such as injection molding, extrusion, and thermoforming, allowing for the production of intricate and customized products. Moreover, plastic use has contributed to advancements in sectors like healthcare, where sterileand lightweight plastic materials are crucial for medical equipment and packaging. However, the extensive use of plastics has raised concerns about environmental sustainability, as they persist in the environment for long periods and contribute to pollution and resource depletion. As a result, efforts are underway to promote responsible plastic use, reduce single-use plastics, and develop eco-friendly alternatives to mitigate the environmental impact associated with plastic consumption.

[0014] Plastic presents complex challenges in terms of disposal due to its durability and resistance to decomposition. Traditional plastic disposal methods, such as landfilling and incineration, have significant environmental drawbacks. Landfilling leads to long-term plastic accumulation in the environment, contributing to soil and water pollution, while incineration can release harmful emissions and greenhouse gases. Efforts to address plastic disposal have focused on recycling, which involves collecting and reprocessing plastic waste to create new products. However, recycling rates remain relatively low globally due to challenges in sorting, contamination, and limited market demand for recycled materials. Additionally, plastic recycling often results in downcycling, where the quality and value of the plastic degrade with each recycling cycle. Emerging solutions for plastic disposal include innovative technologies like chemical recycling, which breaks down plastics into their original chemical components for reuse, and biodegradable plastics designed to naturally decompose under specific conditions. These approaches hold promise in reducing the environmental impact of plastic disposal. However, comprehensive strategies that involve reducing plastic production, promoting sustainable alternatives, and improving waste management infrastructure are essential to address the plastic disposal crisis effectively.

[0015] Twine, plastic wrap and net wrap are used in the agricultural sector for bundling straw or silage into bales (circular or rectangular bundles) for consolidation, storage and transport. There are both synthetic and natural fibre-based baler twine available in the market. Typical baler twine is made from synthetic polymers such as polypropylene, while natural fiber twines are made from sisal mainly imported from Asia or South America. Sisal twines have some limitations such as poor mechanical performance, low durability (propensity for fraying), poor quality, and high cost which has severely limited its market uptake. Sisal twine has also been shown to be only partially digestible in ruminants.

[0016] Net wrap is a polymer-based netting used for baling and has been an alternative to twine since the early 1980s. The market share of net wrap over twine has increased significantly since that time and is becoming the preferred choice for farmers due to its lower operating, storage and handling cost. However, most of the net wrap products available today in the market are polypropylene and polyethylene based which have some potential challenges in terms of poor degradability and risks to livestock health. As a result, there is a significant need to develop a bale net wrap which is degradable at end of life but has effective performance characteristics during baling operations.

[0017] Biodegradable polymers, also known as biopolymers or bio-based plastics, are a class of materials that possess the unique property of undergoing natural degradation processes when exposed to environmental conditions. These polymers are typically derived from renewable resources such as plant starches, vegetable oils, ormicrobial fermentation products, in contrast to traditional plastics derived from fossil fuels. The key advantage of biodegradable polymers lies in their reduced environmental impact. When disposed of in appropriate conditions, such as composting facilities or natural environments, microorganisms break down these materials into simpler compounds like carbon dioxide, water, and organic matter, leaving minimal to no harmful residues. This characteristic makes biodegradable polymers an attractive option for single-use items, packaging materials, and agricultural applications, where reducing plastic waste and pollution are paramount concerns. However, the rate and effectiveness of biodegradation can vary significantly based on polymer composition, environmental conditions, and disposal methods, necessitating careful consideration of these factors in their practical applications and proper waste management strategies.

[0018] Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, classified according to the monomers used and the structure of the biopolymer formed: polynucleotides, polypeptides, and polysaccharides. The polynucleotides, RNA and DNA, are long polymers of nucleotides. Polypeptides include proteins and shorter polymers of amino acids; some major examples include collagen, actin, and fibrin. Polysaccharides are linear or branched chains of sugar carbohydrates; examples include starch, cellulose, and alginate. Other examples of biopolymers include natural rubbers (polymers of isoprene), suberin and lignin (complex polyphenolic polymers), cutin and cutan (complex polymers of long -chain fatty acids), melanin, and polyhydroxyalkanoates (PHAs). In this document, biopolymers may refer to natural polymers produced by the cells of living organisms, or whose starting monomers or precursors are produced by the cells of living organisms, for example from biomass.

[0019] Biomass is a term used in several contexts: in the context of ecology, it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how biomass is defined, e.g., only from plants, or from plants and algae, or from plants and animals. The vast majority of biomass used for bioenergy comes from plants. Bioenergy is a type of renewable energy with potential to assist with climate change mitigation. Biomass sources for energy include various items. Wood and wood processing waste are one example - firewood, wood pellets, and wood chips, lumber and furniture mill sawdust and waste, and black liquor from pulp and paper mills. Agricultural crops and waste materials are another - com, soybeans, sugar cane, switchgrass, woody plants, algae, and crop and food processing residues, mostly to produce biofuels. Biogenic materials in municipal solid waste are another - paper products; cotton and wool products; and food, yard, and wood wastes. Animal manure and human sewage are yet another for producing biogas (renewable natural gas).

[0020] Poly (lactic acid) (PLA) is probably the most popular fully renewable and biodegradable polymer used in various applications, due to its high tensile strength, good heat stability during processing, excellent biocompatibility and excellent gloss and clarity. However, important drawbacks, including brittleness and poor heat resistance, have been reported. To overcome these defects and make the PLA useful even in applications in whichhigh flexibility and toughness are necessary, several studies on PLA blends with other biodegradable polymers, such as with polycaprolactone, poly(butylene succinate) (PBS), polybutylene(succinate-co-adipate), and poly(butylene adipate-co-terephthalate) (PBAT), have been investigated.

[0021] Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a thermoplastic polyester with backbone formula (C3H4O2)n or [-C(CH3)HC(=O)O-]n, formally obtained by condensation of lactic acid C(CH3)(OH)HCOOH with loss of water (hence its name). It can also be prepared by ring-opening polymerization of lactide [-C(CH3)HC(=O)O-]2, the cyclic dimer of the basic repeating unit. PLA has become a popular material due to it being economically produced from renewable resources. In 2021, PLA had the highest consumption volume of any bioplastic of the world, although it is still not a commodity polymer. Its widespread application has been hindered by numerous physical and processing shortcomings. PLA is the most widely used plastic filament material in FDM 3D printing, due to its low melting point, high strength, low thermal expansion, and good layer adhesion, although it possesses poor heat resistance unless annealed.

[0022] The PLA monomer is typically made from fermented plant starch such as from com, cassava, sugarcane or sugar beet pulp. Several industrial routes afford usable (i.e., high molecular weight) PLA. Two main monomers are used: lactic acid, and the cyclic di-ester, lactide. The most common route to PLA is the ring-opening polymerization of lactide with various metal catalysts (typically tin octoate) in solution or as a suspension. The metal-catalyzed reaction tends to cause racemization of the PLA, reducing its stereoregularity compared to the starting material (usually com starch). The direct condensation of lactic acid monomers can also be used to produce PLA. This process needs to be carried out at less than 200 °C; above that temperature, the entropically favored lactide monomer is generated. This reaction generates one equivalent of water for every condensation (esterification) step. The condensation reaction is reversible and subject to equilibrium, so removal of water is required to generate high molecular weight species. Water removal by application of a vacuum or by azeotropic distillation is required to drive the reaction toward polycondensation. Molecular weights of 130 kDa can be obtained this way. Even higher molecular weights can be attained by carefully crystallizing the cmde polymer from the melt. Carboxylic acid and alcohol end groups are thus concentrated in the amorphous region of the solid polymer, and so they can react. Molecular weights of 128-152 kDa are obtainable thus.

[0023] PLA is degraded abiotically by three mechanisms: Hydrolysis: The ester groups of the main chain are cleaved, thus reducing molecular weight. Thermal decomposition: A complex phenomenon leading to the appearance of different compounds such as lighter molecules and linear and cyclic oligomers with different Mw, and lactide. Photodegradation: UV radiation induces degradation. This is a factor mainly where PLA is exposed to sunlight in its applications in plasticulture, packaging containers and films. PLA can also be degraded by some bacteria, such as Amycolatopsis and Saccharothrix. A purified protease from Amycolatopsis sp., PLA depolymerase, can also degrade PLA. Enzymes such as pronase and most effectively proteinase K from Tritirachium album degrade PLA. PLA is biodegradable under industrial composting conditions, starting with chemical hydrolysis process, followed by microbial digestion, to ultimately degrade the PLA. Under industrial composting conditions (58 °C (136°F)), PLA can partly (about half) decompose into water and carbon dioxide in 60 days, after which the remainder decomposes much more slowly, with the rate depending on the material's degree of crystallinity. Environments without the necessary conditions will see very slow decomposition akin to that of non-bioplastics, not fully decomposing for hundreds or thousands of years.

[0024] PLA may have suitable properties. PLA may be structured for fiber Melt Spinning. One suitable compound is the Ingeo™ biopolymer 6752D™, a NatureWorks LLC product ™, which is a thermoplastic fibergrade resin derived from annually renewable resources. Available in pellet form, 6752D™ is designed for extrusion into mechanically drawn staple fibers using conventional fiber spinning and drawing equipment. Ingeo biopolymer 6752D™ can be converted into a broad range of undyed products. See Table 1 below for typical properties. There are numerous applications for PLA. Potential applications for Ingeo biopolymer 6752D™ include: • Nonwoven (spun lace wipes) • Multi filament twine • Various bicomponent fibers. Ingeo biopolymer 6752D™ grade will process on conventional extrusion spinning and drawing equipment with thorough cleaning since PLA is not compatible with most polymers. Machine Configuration includes using general-purpose screws with L / D ratios of 24:1 to 30:1 and 3:1 compression ratios are recommended. Screws with mixing sections or shallow metering channels may overheat the melt at high screw speeds. Typical melt spinning temperatures are 220 - 240°C. Like PET, Ingeo biopolymer 6752D™ requires either high filament velocity or drawing and controlled heat setting to control shrinkage. 6752D™ is often combined with 6202D™ in bicomponent fibers. Drying may include in-line drying capabilities are essential to process Ingeo biopolymer 6752D™, which is supplied with a moisture content of less than 0.040% (400 ppm). The recommended moisture content to prevent viscosity degradation and potential loss of properties is < 0.005% (50 ppm). Typical drying conditions are 4-6 hours at 70-80°C [158-176°F] a dew point of -35°C [- 30°F], with an airflow rate of greater than 0.5 cfm / lbs per hour of resin throughput. Drying at higher temperatures may cause the pellets to stick together. To prevent moisture regain, the resin should not be exposed to atmospheric conditions after drying. Table 1 below shows properties of PLA.

[0025] Table 1 : Typical Material and Application Properties of PLA

[0026] Poly(butylene succinate), often abbreviated as PBS, is a biodegradable synthetic polymer belonging to the family of aliphatic polyesters. It is derived from petrochemical or renewable resources, depending on the desired environmental sustainability. PBS is known for its excellent combination of properties, including good processability, mechanical strength, and biodegradability. PBS has high flexibility, excellent impact strength, as well as thermal and chemical resistance. Moreover, many studies on PBS, in the form of fdms and molded objects, have exhibited significant biodegradation within several months in soil, water with activated sludge, and seawater. Its chemical structure comprises repeating units of butylene and succinic acid, which gives PBS its distinctive properties. PBS is commonly used in various applications, particularly in the field of biodegradable plastics. It can be processed through methods such as extrusion, injection molding, and fdm blowing, making it suitable for the production of packaging materials, agricultural films, and disposable products. One of its significant advantages is its ability to degrade in natural environments, such as soil and water, through enzymatic and microbial action, ultimately breaking down into harmless byproducts. PBS is gaining attention as a sustainable alternative to traditional petroleum-based plastics in efforts to reduce plastic waste and environmental impact. However, like other biodegradable polymers, the effectiveness of its biodegradation can be influenced by factors like temperature, moisture, and microbial activity, necessitating careful consideration of disposal conditions and management practices.

[0027] Polybutylene succinate (PBS) (sometimes written polytetramethylene succinate) is a thermoplastic polymer resin of the polyester family. PBS is a biodegradable aliphatic polyester with properties that are comparable to polypropylene. Various forms of it are marketed under the brand names GsPLA™ or BioPBS™ (Mitsubishi Chemical). PBS consists of polymerized units of butylene succinate, with repeating C8H12O4 units. Like otherpolyesters such as polyethylene terephthalate, two main routes exist for the synthesis of PBS: the trans-esterification process (from succinate diesters) and the direct esterification process starting from the diacid. The direct esterification of succinic acid with 1,4-butanediol is the most common way to produce PBS. It consists of a two-step process. First, an excess of the diol is esterified with the diacid to form PBS oligomers with elimination of water.

[0028] 1,4-Butanediol (hereinafter, sometimes simply referred to as “1,4BG”) is a very useful substance used as a raw material of various solvents or derivatives, and in making PBS. Conventionally, a variety of methods for industrially producing 1,4BG by using petroleum or other fossil fuels as a raw material are known. Recently, a method for producing a biomass-derived 1,4BG by using a biomass resource as a raw material has also been developed, in addition to the conventional method of producing 1,4BG by using petroleum or other fossil fuels as a raw material, see for example US patent no. 10487032. For example, there are methods where succinic acid obtained by the fermentation of a sugar is hydrogenated to obtain 1,4BG, and a method where 1,4BG is directly obtained by fermenting a biomass resource such as sugar. When a product comparable to a petrochemical product produced from a fossil fuel such as petroleum is produced from a biomass resource, a refining process on an industrial scale (large- scale process) may be necessary for stably maintaining the production volume or quality. For example, in the case where the biomass resource used as a raw material is a sugar or the like, the target product is obtained by the fermentation thereof with bacteria, but for maintaining the quality equivalent to that of a product obtained by the conventional production process using a fossil fuel such as petroleum, a refinement technique capable of highly removing impurities contained in the raw material or various byproducts generated in the course of fermentation is required.

[0029] The purification process in a production method for 1,4-BG is preferably applied to a biomass- derived l,4BG-containing composition. The biomass material may include a material in which light energy of the sun is converted into a form of starch, cellulose or the like by photonic synthesis of a plant and stored, whether in a plant or in the body of an animal which grows by eating such plants, and a product is obtained by processing a plant body or an animal body and the like. Specifically, wood, paddy straw, rice bran, old rice, com, sugar cane, cassava, sago palm, soy pulp, corncobs, tapioca refuse, bagasse, vegetable oil refuse, potatoes, buckwheat, soybeans, fat, old papers, papermaking residues, fishery product residues, excreta from domestic animals, sewage sludge, food wastes and the like are mentioned. Among them, plant materials such as wood, paddy straw, old rice, com, sugar cane, cassava, sago palm, soy pulp, corncobs, tapioca refuse, bagasse, vegetable oil refuse, potatoes, buckwheat, soybeans, fat, old papers and papermaking residues may be preferable. More preferable materials may be wood, paddy straw, old rice, com, sugar cane, cassava, sago palm, potatoes, fat, old papers, papermaking residues and the like and most preferable materials are com, sugar cane, cassava and sago palm. The biomass materials generally contain nitrogen atom, many alkali metals and alkaline earth metals such as Na, K, Mg and Ca.

[0030] These biomass materials may be induced to carbon sources through a pretreatment / saccharification step and the like, such as chemical treatment using an acid, an alkali or the like, biological treatment using a microorganism and physical treatment, although the method is not particularly limited. The step often includes a stepfor reducing the size through pretreatment for chipping, shaving or mashing the biomass material, and if necessary, further includes a pulverization step using a grinder or a mill. The biomass material which has been thus reduced in size is generally induced to a carbon source through a further pretreatment / saccharification step. Examples of the specific method are: chemical methods such as acid treatment using a strong acid such as sulfuric acid, nitric acid, hydrochloric acid or phosphoric acid, alkali treatment, ammonia freezing steam blasting method, extraction with a solvent, supercritical fluid treatment and treatment with an oxidizing agent; physical methods such as pulverization, steam blasting method, microwave treatment and irradiation with electron beams; and biological treatment such as hydrolysis by treatment with a microorganism or an enzyme. In general, as the carbon source induced from the above biomass materials, following fermentative carbohydrates and the like are used: hexoses such as glucose, mannose, galactose, fructose, sorbose and tagatose; pentoses such as arabinose, xylose, ribose, xylulose and ribulose; di- and polysaccharides such as pentosan, saccharose, starch and cellulose; fat such as butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, monocutinic acid, arachidic acid, eicosenoic acid, arachidonic acid, behenic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, lignoceric acid and selacholeic acid; and polyalcohols such as glycerin, mannitol, xylitol and ribitol. Among them, hexoses, pentoses or disaccharides such as glucose, fructose, xylose or saccharose is preferable and glucose is particularly preferable. Cellulose, which is the main component of papers, is also preferable as the plant-derived carbon source in a broader sense.

[0031] In the method of producing 1,4BG directly from a carbon source such as glucose by a fermentation process, transgenic E. coli, a coryneform bacterium, a yeast, etc. can be used. For example, 1,4BG can be biologically produced in a culture medium for organism fermentation by the method described in JP-T-2010-521182. In addition, a composition containing 1,4BG that is thus biologically produced in a culture medium for fermentation of an organism capable of producing 1,4BG can be obtained, for example, by entirely or at least partially separating and removing bacterial cells and salt contents by any one separation means or two or more separation means of filtration, centrifugal separation and an ion-exchange resin based on U.S. Patent Application Publication No. 2011 / 0003355, and furthermore, a refined raw material l,4BG-containing solution can be obtained from the 1,4BG- containing composition above by at least partially removing water in the composition

[0032] BioPBS™ (bio-based polybutylene succinate) is revolutionary in its two-fold bio properties. Using advanced technology from Mitsubishi Chemical Corporation™, it is both bio-based and biodegradable plastic. Derived from natural resources, such as sugarcane cassava and com, BioPBS™ is compostable into biomass, carbon dioxide and water. The production of PBS from starting materials made from biomass is believed to introduce impurities from the biomass into the end product PBS that may improve the biodegradability of the end product. Such biomass impurities may ultimately be present in the resultant bioplastic made from the BioPBS™, and may provide microorganisms with useful resources required to more quickly and completely compost and decompose a bioplastic, over time. Products made from BioPBS™ can be disposed of along with organic waste. BioPBS™ has no adverse effects on the environment and is naturally compostable, without requiring a specialized composting facility. This advanced material may be used with the same industrial machines currently used for plastics with no additionalinvestment. BioPBS™ can be applied in current extrusion coating machines, blown film extruders, and injection molding machines. BioPBS™ has several advantages including the following: The material may have high Service Temperature, for example applications made by BioPBS™ can withstand up to 100°C. BioPBS™ may be used for hot beverage cups, boxes, and utensils for freshly cooked food. The material may have high performance heat sealability. The material may have at least same level of seal strength as conventional petro-plastic but achieved with lower temperature, for example with the same performance with less cost in waste disposal expense. The material may have good printability without pre-treatment. The material may be compatible with natural fibers. The material may have excellent processability. The material may have mutual compatibility with other biodegradable plastics such as polylactic acid (PLA). Mixing BioPBS™ with other types of biopolymers may meet customer requirements in a greater degree of properties. According to grades and applications, BioPBS™ is registered as food contact approved, and passes the most demanding bio based and compostable requirements.

[0033] Table 2: Properties of BioPBS™0034] Referring to Fig. 1, a biodegradable netting 10 is illustrated. The netting 10 may comprise a web structure 12 formed of filaments 14. The filaments 14 may be arranged in a suitable pattern such as a grid as shown. The web structure 12 may be made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS). The blend may be structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%. The blend may be structured to have a melt flow index of 1-6. The web structure may be structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field. Referring to Fig. 2, in some embodiments the netting 10 may be applied to a forage bale 16, such as a hay bale made in a baler machine 18. The forage bale 16 may be wrapped and secured by the biodegradable netting 10.

[0035] Referring to Fig. 2, a forage bale 16 is wrapped with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS). The web structure is structured to have sufficient strength to be fed through a forage baler machine 18 to be applied to a forage bale 16 and to secure the forage bale 16. Minimum strength ratings may be set by various manufacturers of baler machines, for specific baler machines. In some cases, the web structure should be at least strong enough to withstand 100 pounds or more of tensile force without breaking. The web structure may be structured to have sufficient strength to act as a structural retainer for a forage bale, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0036] Referring to Fig. 3, in some embodiments the netting 10 may be applied to store or transport a food product 20, such as oranges or tomatoes as shown. The food product 20 may be wrapped and secured by the biodegradable netting 10, which may be arranged in a suitable fashion such as in a bag fashion as shown. A loose food item may be wrapped and secured with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS). The web structure may be structured to have sufficient strength to act as a structural retainer for the loose food item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

[0037] The netting 10 may be used in various other applications. For example, the netting 10 may be used in applications where a biodegradable and / or compostable netting is desired. For example, the netting 10 may be used in erosion control to stabilize soil and prevent sediment displacement. Erosion control netting is a geotextile material designed to stabilize soil, reduce erosion, and promote vegetation growth in areas prone to soil displacement due to water, wind, or human activity. Typically made from biodegradable materials like jute or coir, or synthetic polymers such as polypropylene, the netting is laid over exposed soil to anchor it in place, minimizing sediment runoff and protecting against topsoil loss. It is commonly used on slopes, embankments, construction sites, and shorelines, providing a temporary but effective solution until vegetation establishes a natural barrier against erosion. The mesh structure allows water to infiltrate while preventing soil displacement, and its durability varies depending on material composition and environmental conditions. Proper installation involves securing the netting with stakes or pins and overlapping edges to ensure comprehensive coverage and stability. The netting 10 may gradually decompose into the soil once the vegetation has established a root system to stabilize the soil on its own.

[0038] In other cases, the netting 10 may be applied to sod and may be used to secure and reinforce sod during transportation, installation, and establishment. Sod netting is a lightweight mesh material used to reinforce and stabilize sod during transportation, installation, and early growth. Such netting may be integrated into the sod to hold the grass and soil together, reducing the risk of tearing or separation. It provides structural support, especially on slopes or areas prone to erosion, ensuring the sod remains in place until the roots establish firmly in the underlying soil. While biodegradable netting naturally decomposes over time, leaving no environmental impact, synthetic variants may require removal if long-term visibility, environmental contamination or entanglement concerns arise. The netting 10 may provide structural support to prevent tearing or disintegration of the sod. Thenetting 10 may ensure that the sod stays intact while roots establish in the soil. The netting 10 may enhance stability of the sod on slopes or high-traffic areas, reducing the risk of erosion or sod failure. The netting 10 may gradually decompose into the soil once the sod has established a root system of its own.

[0039] The netting 10 may be used as a garden trellis netting, for example to support climbing plants like beans, peas, and cucumbers, encouraging vertical growth and maximizing space efficiency. The netting 10 may provide a lightweight yet sturdy framework for plants to climb. Such netting may feature a grid structure that provides plants with a framework for vertical growth, improving air circulation, light exposure, and ease of harvest. It is widely used for crops like tomatoes, beans, cucumbers, and flowers, promoting healthier plant development by keeping foliage and fruit off the ground, reducing pest exposure and disease risks. Trellis netting is easy to install, often secured to stakes, poles, or existing structures, and can be reused across growing seasons due to its resilience. Its flexibility allows for custom configuration in gardens, greenhouses, and open fields, making it an essential tool for optimizing space and enhancing crop yield. The open mesh of the netting 10 may allow for proper air circulation and sunlight penetration, promoting healthy plant development.

[0040] The netting 10 may be used for applications which do not traditionally demand a compostable or biodegradable netting, for example, the netting 10 may be used as pallet wrap to secure and stabilize goods during transportation while allowing ventilation to prevent moisture buildup. Pallet net wrap is a specialized material used to secure and stabilize palletized goods during transportation and storage. Usually made from durable, stretchable polyethylene or other synthetic materials, the net wrap features an open mesh design that allows for ventilation, making it ideal for perishable items like produce, plants, or dairy products that require airflow to prevent spoilage. The stretchability of the net wrap ensures a tight and secure hold, reducing the risk of load shifting while minimizing material usage compared to traditional shrink wrap. Its lightweight design simplifies application and removal, while its strength ensures reliable performance under demanding conditions. Pallet net wrap is widely used in logistics, agriculture, and industrial sectors, providing an efficient and eco-friendly alternative to solid wraps by reducing plastic waste and ensuring product integrity during transit. Such netting 10 may provide strong containment without restricting airflow, making it ideal for perishable or temperature-sensitive items. The netting 10 may be lightweight and reusable, which may enhance efficiency and reduce packaging waste compared to traditional plastic pallet wraps.

[0041] Referring to Fig. 1, the blend may have a suitable composition. The blend may comprise between 50-90% PBS and between 10-50% PLA by weight, for example about 75% PBS and about 25% PLA by weight. In some cases, the blend comprises between 65-85% PBS and 15-35% PLA by weight. Other ranges may be used. The BioPBS™, if used, may comprise one or both FZ91PB™ or FZ91PM™. The PBS may be derived from one or more of sugarcane, cassava and com, or other types of biomass. The PLA may comprise 6752D™. The PLA may be derived from one or more of com, cassava, sugarcane or sugar beet pulp. In one embodiment, a suitable formula for a bale net wrap is: BioPBS™ FZ91PB™ (75%) x PLA 6752D™ (25%). In another embodiment, a suitable formula for food packaging is: BioPBS FZ91PM (75%) x PLA 6752D (25%).

[0042] The web structure may have suitable properties. The web structure may be structured to have sufficient properties to stamp out a tensile bar with clean cuts and no cracks out of an extruded sheet of material. The web structure may be structured to have sufficient properties to be able to stamp out a series of bars and conduct tensile-elongation testing at room temperature and at elevated temperatures. The blend may have between 400% - 500% elongation in MD (machine direction) and TD (transverse direction). The blend may have an MD Break force (lbs. / 3 strands or filaments) between 20-30 and a TD Break force (lbs. / 3strands or filaments) between 15 and 20. The blend may be selected to provide the web structure with a breaking strength of between 100 and 200 MPa. The blend may be selected to provide the web structure with a breaking strength of at least 100 MPa after twelve months of exposure in the field.

[0043] The netting 10 may be made by a suitable method, such as by heating and blending the biopolymers to form a blend. The blend may be shaped into the netting 10 by a suitable method, such as by extruding the blend into a web structure. In some cases, the method includes drying pellets of the biopolymers prior to heating and blending. BioPBS™ pellet may be dried and packed in aluminum-lined packaging before delivering to customers. In some cases, drying may involve using a temperature 80°C for over 5 hours to moisture content of less than 1,000 ppm (preferable less than 700 ppm) prior to using next time.

[0044] In some embodiments of this disclosure degradable biopolymers are taught as a replacement in manufacturing of twine and net wrap products. There are many biodegradable polymers that have been produced in the literature along with identification of microorganisms and enzymes capable of degrading them. Polylactic acid (PLA) is a commercially available rigid thermoplastic biodegradable polymer with good mechanical properties. It is a cost-effective alternative material that can be used in synthetic polymers applications, and is readily available at scale. However, PLA has its limitations such as brittleness, strong rigidity and short life span which reduce its potential application. Adding flexible and compatible biopolymers to PLA can potentially solve this problem. For example, several researchers have reported that blending Polybutylene Succinate (PBS) with PLA increases the crystallization rate and subsequently improves the mechanical properties. Over the past decade, there has also been an increased focus on research and development of bio-based materials and applications in Alberta. A number of successful studies have been conducted by the applicants in these areas including development of novel biopolymers, development of improved agronomic practices and applications for industrial hemp, and development of natural fibre reinforced plastics for automotive and building products sector. They have also heavily investigated the enzymatic modification of fiber property improvement for materials applications.

[0045] The overall objective of this industry driven project is to develop a high quality and functional baler net wrap product that has controlled degradability in the field at end of life, and has similar mechanical performance / consistency of synthetic counterparts. In this study, a commercial and technical assessment was performed to evaluate the potential market and business case for a degradable bale net wrap product, and to develop proof of concept biopolymer formulations which approaches the functional requirements of current synthetic bale net wrap products yet is shown to degrade over time in ambient outdoor conditions. For the technical assessment, twocommercial biopolymers were used to manufacture and assess a number of biopolymer fdament prototypes (blended and unblended) compared to a number of commercial net wrap products. Both short-term and long-term mechanical properties were assessed using laboratory tests (water immersion, artificial UV weathering and soil box biodegradability) and field exposure trials on actual bales. Both breaking strength and maximum extension were measured on unexposed and exposed filament samples over time. For the commercial assessment, a market survey of existing (commercially available) baling products, a value proposition for farmers to convert to a degradable option, and a preliminary pricing analysis based on the experimental results was performed to determine the business case for a degradable bale net wrap. From these assessments, it was observed that the biopolymer filaments demonstrated degradability over time relative to the commercial net wrap filaments which is a positive outcome for these trials. Furthermore, it can be seen that the level of degradation over time can be altered (tailored) by proper biopolymer selection and blending. Laboratory soil box testing demonstrated that all biopolymer samples were affected by biodegradation. This suggests that burial of biopolymer net wrap may be an effective way for farmers to dispose of their bale net wraps, as opposed to burning or landfilling non-degradable commercial products. This study was also able to show that laboratory exposure tests were capable in simulating degradation of net wrap during the 1-year field trial (sunlight and precipitation at the top of the bale, and soil exposure at the bottom of the bale). This result could help in the accelerated development of agricultural products without costly and time-consuming field work.

[0046] Test results.

[0047] New bale wrapping technology was tested which offers improved environmental sustainability (degradable at end of service life) and good mechanical performance. The overall objectives of the project were the same as initially proposed, however, there were a number of changes to the original test plan based on new information and commercial strategy: - there was a change in product focus from twines to net-wrap bale products. This decision was based on an initial market survey and consultation with an industrial partner which qualitatively indicated increasing preference of net wrap by the farming community. However, it should be noted that the results obtained from the experimental part of this study (screening trials) could be still be applicable to twine-based products. There was also a change in material selection. Natural fibre options (either as twine or hybridized with polymers) were excluded based on feedback from suppliers (natural fibre twines are available but are problematic with strength consistency and breakage). In addition, recent studies by the lab in a separate study showed that natural fibers or hybrids have challenges with significant strength degradation in water environments. As such, the sole focus of the experimental program was on extruded bio-based polymer fibers instead of natural fibre options. Furthermore, only commercially available biopolymers were tested due to the commercial nature of this project (desire to have a potential product commercialized within 5 years). Polymer formulations from the literature were excluded due to lack of material availability at commercial scale and uncertainty in cost. - Finally, there was also a slight modification to the characterization methods proposed in the original proposal. It was determined that abrasion testing was not necessary due to the focus on net wrap products (abrasion is not as significant in net wraps as opposed to twines in baling operations). Furthermore, with this test being a non-standard method, some risk ismitigated by not having to construct and commission a test rig to ultimately perform these tests. Funding allocated to these tests was used to expand the bio-polymer blend trials.

[0048] Biopolymer Materials Tested. Two types of commercial biopolymers were selected for potential blending, extrusion and testing of fdaments: 1) two grades of polylactic acid (PLA) biopolymer from NatureWorks LLC™ (USA), and 2) two grades (FZ91PB™ and FD92PB™) of bio-based polybutylene succinate (BioPBS™) from Mitsubishi Chemical Performance Polymers, Inc.™ (USA). The PLA biopolymer offers good strength properties, while the BioPBS™ offers excellent ductility (i.e., stretch or extension) and toughness. These biopolymers are both advertised as being biodegradable and compostable. Blending of PBS with PLA has been shown to improve the mechanical properties and can provide properties similar to polyolefins.

[0049] In some cases, the netting produced in the disclosed methods is compostable. Compostability refers to the ability of a material to decompose under controlled conditions in a composting environment, resulting in nutrient-rich organic matter without leaving harmful residues. For a material to be deemed compostable, it must meet specific standards, such as breaking down within a certain timeframe under defined conditions of temperature, moisture, and microbial activity. Compostability may be associated with industrial or home composting systems, where the end product can enrich soil and support plant growth. Biodegradability, in contrast with compostability, refers to the natural breakdown of materials by microorganisms, such as bacteria and fungi, into simpler substances like water, carbon dioxide, and biomass, regardless of specific environmental conditions. The key difference between biodegradability and compostability is that compostability ensures beneficial outcomes within a regulated timeframe and environment, while biodegradability is a broader term that does not guarantee the timeframe, conditions, or quality of the end product. Additionally, biodegradable materials may leave microplastics or other residues, whereas compostable materials are designed to decompose completely into non-toxic, soil-friendly matter.

[0050] Commercial Net Wrap Products Tested. For comparison purposes, filaments from a number of commercial net wraps made from synthetic polymers (polyethylene) were also tested in this study. Both new net wrap (packaged / unexposed) obtained directly from suppliers, and net wrap taken from pre-existing straw bales in the field were assessed. Individual filaments were cut from all net wrap samples to test for either short-term or long-term (exposure) testing. The results from the commercial products provide baseline net wrap properties required to ensure proper bale integrity. In terms of field exposed samples, sections of a commercial net wrap were sampled on the top of existing straw bales which were in the field for approximately 1 and 3 years. These bales were located at a ranch near Wainwright, Alberta, Canada.

[0051] Biopolymer Filament Manufacturing. A series of biopolymer filaments were fabricated in the lab using polymer extrusion methods in order to simulate net wrap strands for testing. Prior to extrusion, pellets of both grades of PLA and PBS biopolymers were dried at 70o C for 4 hours in an oven before extrusion. Both PLA and PBS biopolymers were extruded using a laboratory-scale conical co-rotating and intermeshing twin-screw extruder (Plasti-corder Digi-system™, PL 2200, C.W. Brabender Instruments Inc., South Hackensack, NJ). The screws were single flighted and had uniform pitch. The barrel length was 35 cm with a diameter of 31.8 / 20 mm and the extruderscrew had a compression ratio of 3 : 1. A 3 -mm die was used during extrusion. The extruded filaments were collected on a spool using a single station extrusion winding system purchased from Automated Manufacturing Systems™ (USA). Processing conditions for both PLA and BioPBS™ biopolymers were selected based on the literature and the data sheet provided by the respective polymer supplier. Based on these parameters, four virgin biopolymer filaments (two polymer types X two grades each) were successfully extruded for testing. After preliminary weathering tests, the best two performing polymer grades (PLA 6752D™ and BioPBS™ FZ91PB™) were then used to manufacture five blended filaments options for testing. Details of all biopolymer filaments variations developed and tested in this study are shown in Table 2.

[0052] Table 2. List of manufactured PLA, BioPBS™ and blended filamentsFilament Extruded Material / GradePLA Filament 1 PLA6100DPLA Filament 2 PLA 6752DPBS Filament 1 FZ91PBPBS Filament 2 FD92PBBlended Filament 1 PLA50PBS50 (PLA 6752 (50%) and PBS FZ91PB (50%))Blended Filament 2 PLA75PBS25 (PLA 6752 (75%) and PBS FZ91PB (25%))Blended Filament 3 PLA25PBS75 (PLA 6752 (25%) and PBS FZ91PB (75%))Blended Filament 4 PLA60PBS40 (PLA 6752 (60%) and PBS FZ91PB (40%))Blended Filament 5 PLA40PBS60 (PLA 6752 (40%) and PBS FZ91PB (60%))

[0053] Characterization of Biopolymer and Commercial Net Wrap Filaments. The durability of the various biopolymer filaments and filaments from commercial net wrap products was assessed by measuring changes in mechanical properties before and after exposure to a number of environmental conditions (both laboratory and field based). The intent is to quantify the functional life of these filaments when exposed to actual outdoor conditions found in straw bale applications. To determine this degradation, the short-term mechanical properties of unexposed samples (baseline) are compared to the long-term mechanical properties over time of samples exposed to both lab and field conditions. For lab testing, three artificial exposure methods were used: 1) water immersion, 2) accelerated UV weathering, and 3) biodegradation using soil boxes.

[0054] For the field tests, filaments were mounted directly on straw bales in a farm field to replicate actual outdoor service conditions. In addition to mechanical testing, the density of all commercial and extruded biopolymer filaments was determined using pycnometry. A minimum of 10 replicates of each polymer filament were used in all tests, and all error bars in this report represent + / - one standard deviation.

[0055] Mechanical Testing Mechanical properties of both exposed and unexposed filaments were assessed using an Instron testing system. Tests were conducted using the ISO 4167 standard - “Polyolefin agricultural twine”. The tensile breaking force (in N) along with maximum tensile extension (in mm) was recorded for each test sample. The gage length of all test specimens was 250 mm, and the crosshead speed during testing was 25 mm / min. Load was continuously applied until breakage occurred in the polymer filament or until the maximum extension of themachine was reached (350 mm). Prior to testing, the mass and geometry (average diameter and length) of each filament was measured. A minimum of 10 replicates were tested for each filament type. After the test, the effective strength of the filament (in MPa) was calculated by dividing the breaking force by the measured average cross- sectional area of the filament (based on average diameter). Averages and standard deviations for each filament type and test condition was determined from the replicates. The use of strength and elongation allow for direct comparison between lab and commercial filament types of different sizes.

[0056] Water Immersion Tests The water immersion tests were used to expose filament samples to water in order to simulate possible degradation of materials due to hydrolysis which can occur at ground level conditions (pooling water) for both bio-based and synthetic materials. For the water immersion tests, water baths were set up and custom-made test rigs were assembled to hold and expose filaments in place during immersion. The different PLA, BioPBS™ polymer and PLA-BioPBS™ blended filaments along with filaments from the commercial net wrap were subjected to 28 days (4 weeks) of exposure in water at room temperature (2 DC). During exposure, a series of filaments were removed at 7-day intervals, and were tested using the methods outlined herein to evaluate the changes in mechanical properties with exposure time.

[0057] Accelerated Weathering Test. The accelerated weathering tests were used to expose filament samples to outdoor conditions including simulated solar radiation (UV exposure), precipitation (moisture) and temperature in order to simulate possible degradation of materials in above ground situations. These exposure tests were conducted by following the ISO 4892-3 Cycle 2 Standard - “Plastics — Methods of exposure to laboratory light sources — Part 3 : Fluorescent UV lamps”. The specimens were exposed to fluorescent UV lamps under controlled environmental conditions (temperature, humidity and / or water). The accelerated weathering test was conducted by using an Atlas™ UVTest Weatherometer. The different grades of PLA and BioPBS™ extruded filaments along with the commercial net wrap sample was subjected to Test Cycle #2 of the ISO 4892-3 standard for 1,000 hours. During testing, the filament samples were removed at regular intervals (approximately 145-150 hours) and were tested for strength and elongation as outlined herein.

[0058] Biodegradation (Soil Box) Tests. Soil box burial tests are one of the most widely used methods to investigate the biodegradation behavior of biodegradable polymers. The soil box tests were used to expose filament samples to outdoor soil conditions to simulate the potential effects of biodegradation. The various filaments were mounted to test racks which were then buried in soil for 21 weeks. The soil and filaments were contained in a series of plastic storage containers. The soil used was top soil obtained from a farm in Alberta. In a representative soil box test, a single filament would be buried in the top soil, as the clumping, folding, or burying of a relatively large amount of netting in a given parcel of top soil may affect the degradation time negatively. The soil boxes were covered and stored in the lab at 21 °C, and the moisture of soil was maintained at 12-15%. During the exposure test, a series of filaments were removed at 7-week intervals, and were tested for strength and elongation as outlined herein. The samples of filaments were considered to have substantially degraded when the filament structure itself had broken down, and the filaments were either visually imperceptible or broken down into numerous smaller fibers.The fibers may be too small to perform standard strength and elasticity testing. In some cases, any remaining fibers had lost at least 50%, and in some cases 75% or more, up to 100%, of break strength and / or extension strength.

[0059] The Melt Flow Index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer. It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures. Polymer processors usually correlate the value of MFI with the polymer grade that they have to choose for different processes, and most often this value is not accompanied by the units, because it is taken for granted to be g / lOmin. Similarly, the test conditions of MFI measurement are normally expressed in kilograms rather than any other units. The method is described in the similar standards ASTM D1238 and ISO 1133. Melt flow rate is an indirect measure of molecular weight, with high melt flow rate corresponding to low molecular weight. At the same time, melt flow rate is a measure of the ability of the material's melt to flow under pressure. Melt flow rate is inversely proportional to viscosity of the melt at the conditions of the test, though it should be borne in mind that the viscosity for any such material depends on the applied force. Ratios between two melt flow rate values for one material at different gravimetric weights are often used as a measure for the broadness of the molecular weight distribution. Melt flow rate is very commonly used for polyolefins, polyethylene being measured at 190 °C and polypropylene at 230 °C. The plastics engineer should choose a material with a melt index high enough that the molten polymer can be easily formed into the article intended, but low enough that the mechanical strength of the final article will be sufficient for its use.

[0060] Field Trials. Field trials of the various filaments were conducted using a custom designed test rack mounted to actual straw round bales for a one-year period. Filaments tested included the extruded virgin PLA and BioPBS™ filaments, the blended PLA / BioPBS™ filaments, and filaments from the commercial TT net wrap product. The test racks are picture frame like structures which can hold and separate a series of fully extended filaments allowing them to be fully exposed. These test racks were custom made using 22-24 gage galvanized sheet metal. A series of test racks were mounted to a number of actual straw round bales for outdoor testing in a secure field location at a ranch near Wainwright, AB. The location allowed for full exposure to the environment. For each filament variation, six sets of test racks were mounted on each bale: 3 sets of test racks on the top of the bale (for UV and weathering exposure), and another 3 sets of test racks at the bottom of the bale (soil and moisture exposure conditions with no UV). At regular 4-month intervals, individual racks with filaments were removed from both the top and bottom, and were taken to test for changes in filament mechanical properties as outlined herein. The intent of these tests is to measure degradation in filament properties in actual field conditions over time, and to provide a validation to the lab durability tests. These preliminary field tests also provide valuable guidance for any future fieldtesting program of similar bale products.

[0061] Testing of Commercial Net Wraps from Pre-Existing Straw Bales. These first mechanical tests were performed on commercial net wraps samples taken from pre-existing straw bales that were in the field for approximately 1 and 3 years. The breaking force and maximum tensile extension at maximum load for these sampleswas measured. For comparison, the properties are compared to those of new / unexposed net wrap (NW). It was found that the breaking strength of commercial net wrap showed a small decrease when exposed to environment for 1 and 3 years, but this change was not significant. However, there was a significant decrease in tensile extension (stretch) at failure after 3 years. This suggests that the synthetic polymer in the commercial net wrap becomes more brittle due to exposure to sun, wind, and precipitation. However, the net wrap was seen to be still intact on the bale and, as expected, was found not to degrade significantly in field conditions.

[0062] Bio-based Polymer Filament Test Results. Results of Short-term Mechanical Test (Unexposed Samples). The short-term breaking strength of filaments of the various unexposed commercial net wraps along with the extruded PLA, BioPBS™ and blended biopolymer filaments, was measured. All three commercial net wraps showed significantly higher breaking strength than the unblended PLA and PBS biopolymer filaments (two grades of each). Furthermore, PLA filaments were found to be slightly stronger than the PBS filaments. The PLA 6752™ grade was found to be stronger that PLA 6100D™ and amongst BioPBS™ grades, FZ91PB™ was stronger than FD92PB™. By blending the PLA (6752D™) and BioPBS™ (FZ91PB™) biopolymers, there was a noticeable increase in mechanical strength for all blend fractions. This result suggests that blending BioPBS™ with PLA reduces the brittleness of the PLA and imparts flexibility to the blend, allowing strengthening to occur prior to fracture. The blended PLA50PBS50 filament (50% PLA and 50% BioPBS™) showed the highest breaking strength amongst all of the blended biopolymer filaments, and was found to be the optimal blend formulation for the samples tested. This confirms previous observations reported in the literature that for 50wt% PLA / 50wt% PBS, a co- continuous morphology in polymer blend is formed which provides the higher tensile strength. Compared to the commercial net wrap filaments, the short-term (unexposed) breaking strength of the PLA50BPBS50™ blend was found to be 60% of TT net wrap which was a very promising result. The maximum extension of all samples from the mechanical tests was measured. Both grades of BioPBS™ were found have the most ductility (high stretch) whereas the commercial net wrap polymers (polyolefins) and PLA samples were found to have much low ductilities (minimal stretch). It should be noted that the extension of all BioPBS™ filaments and blends with BioPBS™ higher than 50 wt.% reached the limit of the test machine (350 mm) and did not actually fracture (break). This highlights the toughening ability of this biopolymer.

[0063] Long-term Durability Test Results.

[0064] Results from Water Immersion Tests. The change in breaking strength over time of selected commercial net wrap and biopolymer filaments (unblended and blended) when immersed in water for 28 days (4 weeks) was measured. The effect of water immersion for all filaments (except for PLA50PBS50) is not significant. In general, the commercial net wrap (TT) showed no change in strength over time, while most biopolymer formulations showed minimal changes. The PLA50PBS50 filament did show a drop in strength (approximately 30%) over the 4-week period, however, the cause of this reduction is unclear. It was also found that water immersion did not have any significant effect on reducing tensile extension of any of the polymer filament tested.

[0065] Results from Accelerated UV Weathering Tests. The effect of lab-based accelerated UV weathering on selected commercial net wrap and biopolymer filaments (unblended and blended) was measured. The breaking strength of all samples tested decreased with time when exposed to the artificial weathering cycles (UV, spray, temperature and condensation). The breaking strength of the commercial net wrap (TT) was reduced by approximately 60% when exposed to 910 hours of weathering. The degradation (decrease in strength) of the biopolymer blends were initially more significant than that of the commercial net wrap filaments, however, the rate of reduction was seen to flatten over time. The BioPBS™ filaments were most affected by the UV weathering cycles and became brittle over time. It was observed that the unblended BioPBS™ FD92PB™ and BioPBS™ FZ91PB™ filaments were both completely degraded (fragmented) after 308 and 750 hours in the UV weathering machine, and as such, could not be tested for its mechanical properties. Blending of the PLA and BioPBS™ improved the mechanical strength of the filament over time which also corroborates previous observations in the literature. The blended PLA50PBS50 filaments showed the highest retained mechanical properties amongst all the extruded biopolymer filaments tested. Similar to breaking strength, all of the polymer filaments showed a decrease in tensile extension when exposed to UV weathering. The commercial net wrap (TT) and PLA filaments showed a gradual decrease in tensile extension with respect to time during the UV weathering cycles, however, there was large change in tensile extension of the unblended BioPBS™ filaments. Again, the blended PLA50PBS50 filament had the highest retained extension over time of all the biopolymer blends, however, this was lower than that of the commercial net wrap filament.

[0066] Results from Soil Box (Biodegradation) Tests. Changes in the mechanical strength of the various polymer filaments buried in lab-based soil boxes over 21 weeks was measured. The filament properties from the commercial net wrap (TT) did not degrade over time, while all biopolymer filaments (blended and unblended) showed degradation in break strength. It was also observed that the breaking strength of BioPBS™ (blended and unblended) decreased faster than that of the PLA samples. Similar results showing that PBS degrades faster upon composting due to bacterial and soil micro-organism activity have also been reported by other researchers. Both unblended BioPBS™ filaments fully degraded in 14 weeks with only small pieces remaining and attached to the sample holder. The PLA samples did not fully degrade but became extremely brittle and hence could not be tested. After 21 weeks of burial, the PLA-BioPBS™ blended filaments were still intact, however, the strength values were approximately 25-35% of the commercial TT samples (65-75% reduction). In terms of maximum extension (ductility), the commercial net wrap (TT) again did not see any significant changes in properties over time, while all biopolymer filaments (blended and unblended) showed degradation in properties.

[0067] Field Testing of Filaments. Field testing of the various filament options occurred near Wainwright, AB (one year trial). Three sets of samples were extracted and tested over this period: 4 months, 8 months, and 12 months. At each interval, filament racks on both the top of the bale and bottom were removed, and were transported back for mechanical testing. Results of the breaking strength performance over time for the commercial net wrap (TT), unblended PLA grades and unblended BioPBS™ grades were measured, while all blended biopolymer samplewere also measured. Overall, the commercial net wrap filaments (TT) at the bottom of the bale and the unblended biopolymers at the top of the bale only experienced slight reductions in breaking strength over the one-year period. However, both unblended PLA and BioPBS™ fdaments located at the bottom of the bale saw significant degradation. This is most likely due to biodegradation mechanisms as a result of direct exposure to soil conditions. Conversely, the commercial net wrap filament at the top of the bale likely degraded due to exposure to sunlight (UV radiation). For the blended samples, degradation of strength properties can be seen for filaments located at both the top and bottom of the bales. However, most of these blends did manage to retain some mechanical strength after the one-year period (i.e., did not full degrade). Both UV and soil microorganisms have been shown to play a role in the degradation of PLA and PBS polymers. In terms of maximum extension (ductility), the commercial net wrap (TT) again did not see any significant changes in properties over time, while all biopolymer filaments (blended and unblended) showed degradation in properties. The greatest drop in extension for the biopolymer filaments (blended and unblended) occurred at the bottom of the bales suggesting that biodegradation at the soil level has a greater effect that UV exposure (top of the bale). The blended biopolymer filaments at the top of the bale managed to maintain sufficient extension over a majority of the one-year trial which is promising.

[0068] Composting Test Results. The disintegration of a sample product was evaluated in a 3rd party(Normec OWS™) lab using a laboratory-scale composting test simulating industrial composting processes. The test procedure was based on ISO 20200 (2023). Test item sample product, cut into 5 cm x 5 cm pieces, was mixed in a 0.5% concentration with synthetic solid waste and incubated in the dark for 84 days at 58°C at 2°C. The test was performed in triplicate and lasted 12.0 weeks.

[0069] According to the European norm EN 13432 Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging (2000), the American standard ASTM D6400 Standard Specification for Labeling of Plastics Designed to be Aerobically Composted in Municipal or Industrial Facilities (2023) and the international standard ISO 17088 Specifications for compostable plastics (2021) less than 10% of the material may remain present in the > 2 mm fraction after 84 days of composting (= minimum 90% disintegration).

[0070] The test item is mixed with synthetic solid waste and incubated at 58°C at 2°C in the dark. During the test the moisture content is verified and adjusted when needed according to a fixed procedure as prescribed by ISO 20200 (2023) . The maximum test duration during which disintegration should be demonstrated is 12 weeks as prescribed by the European norm EN 13432 Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging (2000), the American standard ASTM D6400 Standard Specification for Labeling of Plastics Designed to be Aerobically Composted in Municipal or Industrial Facilities (2023) and the international standard ISO 17088 Specifications for compostable plastics (2021).

[0071] From the results of this quantitative test, it can be concluded that the disintegration requirement as prescribed by EN 13432 (2000), ASTM D6400 (2023) and ISO 17088 (2021) was reached for sample product.

[0072] At the end of the test the contents from each reactor were sieved by means of a manual sieve over 2 mm in order to recover the not disintegrated residues of the test material in the > 2 mm fraction. The degree of disintegration for the three replicates of each test item does not differ by more than 20% and as such this validity requirement of ISO 20200 (2023) is fulfilled.

[0073] Eco Toxicity Test Results. Eco Toxicity testing was performed at a 3rd party (Normec OWS™) lab. From the results it can be concluded that the sample product fulfills: a. The requirement on volatile solids as defined by EN 13432 (2000), ASTM D6400 b. (2023), CAN / BNQ 0017-088 (2010) and ISO 18606 (2013); c. The requirements on heavy metals as defined by EN 13432 (2000), ASTM D6400 d. (2023) and CAN / BNQ 0017-088 (2010); e. The requirement on fluorine as defined by EN 13432 (2000)

[0074] Summary of Experimental Results. Based on the results in the previous sections, a compilation of maximum breaking strengths and maximum extensions for all test conditions (laboratory and field exposures) and all filament types (commercial and biopolymer) was compiled and is provided in Figs. 4 and 5, respectively. Fig. 4 illustrates short-term (control, unexposed) and long-term maximum extension of all commercial and biopolymer filaments after lab (water immersion, UV and soil tests) and field exposure * BioPBS™ polymer filaments and Blended samples with 50%, 60% and 75% PBS content didn’t break; breaking strength represents strength at 350 mm extension (test machine limit). Fig. 5 illustrates short-term (control, unexposed) and long-term maximum extension of all commercial and biopolymer filaments after lab (water immersion, UV and soil tests) and field exposure * BioPBS™ polymer filaments and Blended samples with 50%, 60% and 75% PBS content didn’t break and reached maximum limit of test machine extension (350 mm). In these figures, the short-term (unexposed) test results are denoted as the “control”. These summary plots provide an effective way to compare overall performance of non-degradable, commercial net wrap filaments with degradable biopolymer options tested in an Alberta context. From these figures, it was observed that the biopolymer filaments demonstrated degradability over time relative to the commercial net wrap filaments which is a positive outcome for these trials. Furthermore, it can be seen that the level of degradation over time can be altered (tailored) by proper biopolymer selection and blending. For example, we were able to achieve approximately 60% of the unexposed strength of commercial net wrap using a range of PLA and BioPBS™ biopolymer blends (range from 25%PLA-75%BioPBS™ to 50%PLA-50%BioPBS™). After 12 months of field exposure, this strength dropped to approximately 25-35% of the strength of commercial net wrap. These lower strength values for the biopolymers necessitate that more biopolymer material (thicker filaments) or more wraps per bale would be required to meet required performance. However, it should be noted that there were no UV additives added to the bio-based blends to reduce the effect of UV degradation, whereas the commercial net wrap filaments did have a UV reducing agent. This suggests that improvement in biopolymer performance could be enhanced by compounding with a biodegradable, non-toxic UV additive (to be examined in future work).

[0075] In terms of the biopolymers tested, the BioPBS™ biopolymers offered improved filament extension (toughness) versus PLA but degraded faster than the PLA during both UV and soil box tests. Blended PLA-PBS samples showed better mechanical properties and degraded slower compared to PBS fdaments alone. Overall, the soil box tests demonstrated that all biopolymer samples were affected by biodegradation. This suggests that burial of biopolymer net wrap may be an effective way for farmers to dispose of their bale net wraps, as opposed to burning or landfilling non-degradable commercial products.

[0076] Another important result from this study was the comparison between laboratory and field-testing methods. From the figures, it can be seen that the lab-based soil box / biodegradation test (21 weeks) did a good job at predicting results from filaments situated at the bottom of bales in the field (1 year trial). Conversely, the lab-based UV weathering tests showed higher degradation rates compared to the field trials for filaments located at the top of the bale (exposed to sunlight). This suggests that a shorter or less intense lab weathering cycle may be needed to better represent 1 year exposure in the field. Finally, the water exposure tests were seen to have a minimal effect over time for all polymers tested (both synthetic and bio-based), and did not represent any mode of field degradation. While water immersion has been shown to have significant effect on lingo-cellulose materials over time (e.g., natural fibers, wood), this test may not be necessary in the future for the class of biopolymers being considered for a degradable net wrap product.

[0077] In the study, a commercial and technical assessment was performed to evaluate the potential market and business case for a degradable bale net wrap product, and to develop a proof-of-concept biopolymer formulation which approaches the functional requirements of current synthetic bale net wrap products yet is shown to degrade over time in ambient outdoor conditions. A summary of findings are as follows: a. A clear market opportunity and value proposition was identified for a degradable bale net wrap product. Key benefits include reduced effort and cost of synthetic twine / net wrap disposal and reduced potential risk to animal health. b. Filaments from several commercial net wrap products and biopolymer formations were successfully tested to assess changes in mechanical strength and extension over time when exposed to both simulated and actual outdoor conditions. c. Biopolymer blends made with commercially available PLA and BioPBS™ were found to provide adequate strength and extension properties necessary to maintain bale integrity yet effectively degraded in outdoor conditions. d. Based on these mechanical properties, a pricing model was developed to estimate the increase in cost per bale of using the blended biopolymer formulations tested. This model was based on a biopolymer net wrap which provides equivalent mid-term performance of current commercial net wraps (made with synthetic, non-degradable polymers).

[0078] Research regarding the aliphatic polyester polymers has a long history. Before the development of PET and PBT, Carothers of DuPont who is famous as the inventor of nylon had performed the research of aliphaticpolyesters and reported polycondensation of the aliphatic polyester in 1929. Later, P.J. Floly successfully increased the molecular weight using an acid chloride as the raw material. However, the aliphatic polyesters were not put into commercial use as the material over a long time because of low heat stability in comparison with aromatic polyesters such as PET and PBT as well as polyamides such as nylon.

[0079] In points of mechanical properties, the aliphatic polyesters have lower strength than the aromatic polyesters, it was needed to increase a degree of polymerization in order to put them into practical use. Meanwhile, the low heat stability of the aliphatic polyesters made it difficult to increase the molecular weight by means of melt polycondensation reaction at high temperatures. For these reasons, it was forced to adopt a manufacturing method by obtaining a polyester having a relatively low molecular weight to some extent, and then connecting the terminals with each other using a chain extender to increase the molecular weight.

[0080] Because the aliphatic polyesters have biodegradability and many of them are crystalline, it has been proposed that they will possibly have a potential capable of being processed into the molded articles such as films, sheets, and fibers, if it could be achieved to increase the molecular weight. There are three methods for the synthesis of aliphatic polyester: the polycondensation of an aliphatic dicarboxylic acid and an aliphatic diol, the homopolycondensation of an aliphatic oxycarboxylic acid, and the ring-opening polymerization of an aliphatic cyclic ester.

[0081] As compared to the melting points of aromatic polyesters, those of aliphatic polyesters are low, and only four types of polyesters having a melting point of higher than 100°C could be made by a combination of oxalic acid or succinic acid with ethylene glycol or 1,4-butanediol. Because the polycondensation using oxalic acid as the raw material is technically difficult for industrial production, polybutylene succinate made of succinic acid and 1,4- butanediol as raw materials, which has highest heat resistance and is advantageous for industrial production, was considered to be the most promising biodegradable polymer.

[0082] Further, Mitsubishi Chemical has hitherto had manufacturing technologies, technical know-how, and manufacturing equipment for polyesters of an aromatic dicarboxylic acid and ethylene glycol or 1,4-butanediol, such as PET and PBT and thus aimed for and succeeded in industrial production of PBS without using chain extenders.

[0083] As the countermeasure regarding climate change, the movement toward carbon neutrality has been activated. Responsive to this, high goals have been created all over the world, and policies thereof have been publicly announced. In Europe, in order to achieve the goals of the Paris Agreement toward realization of the carbon-neutral society, goals were set to make the amount of carbon dioxide emissions substantially zero in 2050, and it has been decided to achieve 55% reduction of carbon dioxide emissions in 2030 from the 1990 level. Also in the USA, after change of government in 2020, goals were created so as to make the amount of carbon dioxide emissions substantially zero in 2050, and in China, goals were declared so as to make the amount of carbon dioxide emissions substantially zero in 2060.

[0084] Meanwhile, in Japan, immediately after inauguration of the Prime Minister Suga in October 2020, he made the declaration of carbon neutrality and declared that in place of the previous goals for 80% reduction in greenhouse gases, it was aimed to achieve 100% reduction, namely to make the amount of carbon dioxide emissions substantially zero. In receiving the declaration of the Prime Minister Suga, in April 2021, Japan raised the goals for CO2 reduction amount in 2030 from 26% to 46% in comparison with the 2013 year.

[0085] Further, the Japanese Government formulated the policy and the road map for achieving high goals toward the carbon-neutral society. Concretely, in May 2019, the Japanese Government formulated the circulation strategy for polymers and established milestones for reduce, reuse, recycle, and biomass plastics, respectively. In July 2020, a mandatory law for charging for plastic shopping bags that had been free of charge so far in supermarkets and convenience stores was enforced. In this law, marine biodegradable polymers or biomass polymers having a degree of biomass of 25% or more were excluded. As for the conversion of biomass into raw materials, the Japanese Government set highly challenged goals for introducing two million tons of bio-based plastics until 2030. Further, a bill regarding the “Plastic Resource Recycling Promotion Law” was passed in June 2021. According to this law, a guideline regarding the design for environment which manufactures should serve was formulated, and retailers and restaurants, etc. were required to reduce the provision of disposable plastic products. This law focused on the “material” as the plastic and was aimed to promote the resource recycling at each stage of a life cycle from the designing and manufacturing stages of plastics until disposal.

[0086] In 2003, Mitsubishi Chemical succeeded in the commercial production of the aliphatic polyester, PBS having an increased molecular weight in terms of a trademark “ GS Pla™” without using a chain extender for the first time in the world. The “GS Pla™” in those days was manufactured for biodegradable applications in batch production using fossil-based succinic acid and 1,4-butanediol as the main raw materials.

[0087] Meanwhile, as described below, since around 2000, Mitsubishi Chemical has attempted to replace chemical raw materials by non-fossil-based resources and started to grapple the development of a group of chemical products satisfying high functionalization simultaneously with CO2 reduction. In the “GS Pla™” business, Mitsubishi Chemical proceeded to perform research and development aiming to launch the bio-based PBS business in which the raw material succinic acid is replaced by succinic acid easily derived from the biomass. However, at the time of commencement of the development, the bio-based succinic acid derived from the biomass resource contained a large quantity of impurities inherent to the biomass resource as the polymer raw material, and thus, PBS having a high molecular weight that could be possible for molding and exhibit sufficient mechanical strength was not produced at all. Even when molded, the resulting molded articles were inferior in designability such as poor color tone and many foreign matters. In order to solve these problems, it was essential to combine biochemistry for biomass conversion and chemical engineering for purification technology of the resulting polyester raw materials, with polymer science for high-molecular-weight polymerization using these raw materials and molding of the resulting polyester. Mitsubishi Chemical accomplished conversion technology into a monomer for polyester with economic rationality and biodegradability control technology by biochemistry, efficient purification process witheconomic rationality by chemical engineering, and molecular weight-increasing technology using bio-based monomers containing specific impurities and molding technology by polymer science. Afterward, Mitsubishi Chemical granted a license of technology to J / V established in 2011 together with Petroleum Authority of Thailand (PTT), designed continuous large-sized full-scale commercial plant (20k Ton / Y) for the first time in the world, and commenced the production of the bio-based PBS (trademark: BioPBS™) made of bio-based succinic acid and fossilbased 1,4-butanediol at PTTMCC Biochem Company Limited since 2017. At the time of 2021, the raw material 1,4- butanediol is derived from petroleum, but Mitsubishi Chemical plans to change it to a bio-based raw material in the near future. When this is realized, the business of all bio-based completely degradable polymers will be operated.

[0088] BioPBS™ is a polymer that is not only biodegradable but also bio-based. Polymers called as a biopolymer or green polymer are needed to be arranged in terms of two points including the viewpoint of biodegradation and whether the raw material is bio-based or fossil-based. BioPBS™, PLA, and PHB are not only bio-based but also biodegradable, and bio polycarbonate (e.g., DURABIO™), bio polyethylene, bio nylon, and bioPET are bio-based but non-biodegradable polymers. Further, PCL and PBAT are fossil-based biodegradable polymers. Almost all of polymers which are currently put into practical use are fossil-based and non-biodegradable polymers.

[0089] Table 3 lists basic physical properties such as thermal properties and mechanical properties of biodegradable polymers and biomass polymers which were put into practical use. PHB and PLA are bio-based polymers and hard-type polymers as in PET, polystyrene, etc., and PCL, PBS, and PBSA are soft-type polymers having physical properties analogous to high density polyethylene (HDPE), low density polyethylene (LDPE), etc. PBAT is a soft biodegradable polymer having a lower elastic modulus. Because there are a few of different types of commercialized biodegradable polymers, for practical implementation of biodegradable polymers, in order to achieve necessary requirement characteristics, these polymers are often blended and used so as to have optimal properties and optimal biodegradation rate through complementary use or blending. PBS and PBSA are biodegradable polymers having heat resistance and mechanical properties close to LDPE. The grades and basic physical properties of BioPBS™ will be described in detail in another chapter.

[0090] Table 3: Properties of biodegradable plastics and biomass plastics.

[0091] The chemical industry has grown so far in a way that provides safety and security to the society, with the objective of providing technologies for pursuing convenience and comfortability of people through high functionalization of products, as well as achieving energy conservation through ruggedization and weight reduction. Meanwhile, it has become an era such that countermeasures against the climate change with an increase inatmospheric CO2 emissions, and the depletion issue of fossil fuels, in recent years, as well as environmental loads on a global scale, such as a waste plastic issue and a recent marine plastic issue must be taken.

[0092] However, since most of the current chemical products have largely depended on petroleum as a fossil resource, the chemical industry is required by society to create technologies that eliminate petroleum as a resource. Among such societal demands, one of the directions of the technical development which the chemical industry should accomplish in the future is to develop products or systems with life cycle assessment for reducing the amount of CO2 emissions, in addition to high functionality and high durability of chemical products to be manufactured. As the chemical process solving the CO2 reduction issue is on a global scale, a process for utilization of a biomass resource or CO2 into a chemical product has been proposed, in addition to accomplishment of an industrial process technology of further energy conservation type. In the polymer industry, an interest in biomass conversion of raw materials is also high, and a large number of researches have been made so far. However, in the polymer manufacture, polymers aiming for conversion of raw material into biomass should be highly versatile polymers that could be mass-produced from that purpose. Further, in general, so far as biomass resources are concerned, in case of Ce sugar, it is a raw material represented by Ce(H2O)e with inferior energy to petroleum resources, and thus, it is important to select the target bio-based polymer. From this viewpoint, the polymer derived from the biomass is desirably a polymer using a raw material relatively easily derived from biomass resources, or a polymer using a raw material with oxygen atoms derived directly from the biomass capable of reducing the energy consumption during manufacture.

[0093] Meanwhile, in general, the biomass raw material is a compound rich in reactivity and is characterized such that impurities are more contained, as compared to fossil resource-derived raw materials. In particular, the polymer raw material is required to be highly purified as compared to general chemical products, and thus, its conversion reactions with high reaction selectivity capable of reducing a load of the purification process of a crude product derived from the biomass are required. Moreover, the versatile polymer is required to be a polymer with high economic rationality because it is a replacement for existing polymers, and thus, in the derivatization reaction from the biomass, it is important that the production process has economic rationality with a reduced number of reaction steps and is of an energy conservation type.

[0094] As a promising candidate for such a polymer raw material, there are exemplified succinic acid and 1,4-butanediol as the raw materials of PBS as taken up in this article and besides, furan derivatives, isosorbide, and ethanol-derived ethylene or ethanediol, a part of which is commercially produced.

[0095] BioPBS™ is a polyester of environmental harmony type developed by Mitsubishi Chemical for the purposes of breaking away from the conventional unidirectional chemical system of production, consumption and exhaustion from fossil resources unevenly distributed on the earth and constructing a cycling-based social system. BioPBS™ is a polyester which using a renewable biomass resource as the chemical raw material, cuts off the depletion issue of fossil resources and diversifies the raw material resources, and which is expected to construct acarbon cycling-based chemical system largely contributing to the CO2 emission reduction by immobilizing CO2 emitted by burning or degradation of used plastics with the growth of plants using solar energy.

[0096] Although this chemical system itself is one proposed from a long time, it is hardly accepted by the current market merely when the chemical raw material is simply replaced from the fossil-based resource by the biobased resource raw material, and it is the actual situation that its market value is low unless it is a technology capable of reducing the costs of plastics or a technology capable of enhancing the functions of plastics by use of the biobased raw material, or a technology in which the manufacture cannot be performed without using the biomass raw material. From that viewpoint, BioPBS™ has characteristic features that it is able to be molded into various molded products, has both practical strength and durability, and has a function such that it is excellent in degradability under soil as compared to the fossil resource-derived PBS. In this way, BioPBS™ aims to achieve the carbon cycling of chemical raw materials and is expected as a polymer capable of achieving both high functionalization and CO2 reduction at the same time, particularly, the function of its biodegradability has got high evaluation in food applications and agricultural multifilm applications.

[0097] PBS has an increased molecular weight exhibits flexible and supple mechanical properties similar to polyethylene and is expected to be adopted for various applications. However, as described above, the difficulty of manufacture of high-molecular-weight PBS having such practical mechanical properties is caused due to the point that in order to reveal practical mechanical properties, the molecular weight is needed to be raised as compared to aromatic polyesters such as PET and the point that the heat stability of PBS is low. In the manufacture of PBS, it is a manufacturing method with economic rationality to adopt a melt polymerization method consisting of a two-stage process of an esterification step of condensation reaction between succinic acid and 1,4-butanediol and a transesterification step under reduced pressure. However, the melt polycondensation reaction of PBS involves such characteristic features that simultaneously with the reaction of raising the molecular weight of PBS, degradation reaction of PBS concurs, for example, tetrahydrofuran and cyclic polyesters are by-produced due to backbiting of polymer terminals, and degradation reaction of PBS such as production of a carboxy group and an olefin group concurs due to thermal degradation in the ester site. In order to control such degradation reaction, a process technology is necessary to produce PBS by lowering the polymerization temperature or shortening the polymerization time. With respect to the method for increasing the molecular weight of PBS, detailed investigations such as an influence of the kind and addition amount of a used polymerization catalyst and reaction rate analysis at the time of polycondensation reaction time were made. Besides, new manufacturing processes such as a polycondensation method and a solid phase polymerization method, in which distillation efficiency of the distillate was enhanced using an organic solvent, were also proposed. However, the PBS manufacturing method with economic rationality was not resulted even when adopting merely these technologies, and before Mitsubishi Chemical commercialized “GS Pla®” and “BioPBS™,” only PBS using a chain extender had been manufactured. In contrast, Mitsubishi Chemical designed the large-sized full-scale commercial plant of not only optimizing a used catalyst and its addition amount but also enhancing the distillation efficiency of a distillate by-produced during the polycondensation reaction and introduced into PTT MCC Biochem Company Limited. Owing to introduction of thiscontinuous production process, Mitsubishi Chemical has successfully accomplished the manufacturing technology of bioPBS having high molecular weight, high practical strength and durability, and excellent designability.

[0098] General scheme of PBS synthesis, (a) Esterification, (b) Transesterification, (c) decompositions during polymerization.

[0099] Table 4 shows the main physical properties of BioPBS™. For comparison, those of PE, PP, PLA, and PS are also shown in this table. “BioPBS™” has two basic grades: FZ Series (PBS) and FD Series (PBSA). The FZ Series have the melting point analogous to PE, but are inferior in transparency. This is closely related to the crystallinity of PBS. The FD Series are the copolymer with adipic acid and the crystallinity is controlled by optimization of a nucleating agent to improve the transparency and the flexibility.

[0100] Table 4: Basic properties of various polymers

[0101] PLA whose market development is energetically carried out is a rigid material and has characteristics significantly different from the flexible PBS. These two types of materials are spread in a different application field from each other and also may be thought to be used as a polymer blend aiming at complementation of mechanical properties and thermal characteristics. Table 5 shows comparison in characteristics between PBS and PLA. In addition, Figs. 6-7 illustrate an example of the morphology in the PBS / PLA blend. Finely dispersed seaisland structure of PBS and PLA with the order of several hundred nm is investigated here. PBS used here is theproduct formerly manufactured in Japan by Mitsubishi Chemical (hereinafter referred to as PBS(MCC)).Furthermore, blending with PBAT is often carried out to improve the film strength.

[0102] Table 5: Comparison of characteristics between PBS and PLA

[0103] PBS and PBSA have relatively good biodegradability. Figs. 8 and 9 show the field test results of the biodegradability carried out in the farm field at Yokohama R&D Center of Mitsubishi Chemical. As indicated in these figures, PBS and PBSA are relatively quickly degraded (precisely disintegrated) even in the environment where PLA or PBAT is not substantially degraded. The reason of this difference can be attributed to the low glass transition temperature and the chemical structure of PBS and PBSA. As the glass transition temperature of PBS and PBSA is not higher than 0°C, the amorphous region is in the rubbery state with high mobility in the usual environment, and in addition, the basic structure of PBA and PBSA is only composed of aliphatic. In general, lowering the molecular weight by the polymer chain scission due to the non-biological hydrolysis and the biological hydrolysis by microorganisms is necessary for the biodegradation and in order to proceed the hydrolysis more rapidly higher mobility of the polymer chains in the amorphous region is preferable. On the other hand, as the amorphous region of PLA is in the glassy state at room temperature due to the glass transition temperature of about 60°C, PLA is disadvantageous for hydrolysis. Meanwhile, it is known that when the temperature rises to about 60°C, PLA is quickly biodegraded. A polymer whose molecular weight is lowered to some level is mineralized into water and carbon dioxide by microorganisms, namely biodegraded. Microorganisms capable of secreting the enzyme degrading the PBS and PBSA are considered to be generally contained in the soil. Furthermore, PBSA is biodegraded faster than PBS due to the lower degree of crystallization and the faster hydrolysis of PBSA. A schematic view of biodegradation process is shown in Fig. 10.

[0104] Thanks to this characteristic feature, each BioPBS™ already acquires the biodegradability certification in various regions as shown in Table 6. Figs. 11-12 show an example of the test results carried out at Normec OWS™ in acquiring the certification. All of the disintegration test, the biodegradability test, the germination test, and the earthworm test demonstrate that BioPBS™ has performances satisfactory in acquiring each certification. Incidentally, as biodegradation rate of the FZ Series is lower than that of the FD Series due to the higher crystallinity, the FZ Series are not able to acquire the “OK compost HOME” certification, but as shown in Fig. 10, if the conditions are met, the FZ Series are also biodegraded in the environment even at ambient circumstances.

[0105] Table 6: Biodegradable certifications of BioPBS™

[0106] BioPBS™ also acquires the certification of food contact certifications in various regions. The FZ Series are certified in Japan, EU, USA, and China, and the FD Series are certified in Japan, EU, and USA. The FZ Series having a higher melting point can be used under higher temperature conditions. Biodegradability test of PBS by OWS. (a) Aerobic biodegradation under 58±2°C. Average biodegradation percentage relative to cellulose was 97.1%. (b) Disintegration of PBS film under 58±2°C. (c) Overview of the growth of cress plants at the end of the test. From top to bottom: PBS compost / reference substrate = 1 / 1 blank compost / reference substrate = 1 / 1 reference substrate, (d) Earthworm, acute toxicity test on compost residuals of PBS.

[0107] As mentioned already, BioPBS™ acquires the food contact certifications in various regions. In addition, PBS has good heat-sealing properties and is frequently used as the sealant for food packaging applications due to these characteristics. A representative example thereof is a paper coating application. Though PE is usually used for the inner surface of the paper cup for the purpose of water resistance and sealant in the joint part, PE must be separated in the recycling process of paper cup. Meanwhile, regarding the PBS coated paper cup PBS is expected to be hydrolyzed under alkaline treatment conditions of the paper recycling process with maintaining the properties of water resistance and high heat sealability. As the result of these PBS properties, the load of waste disposal in the recycling process can be expected to be reduced. Recently Mitsubishi Chemical is jointly carrying out the demonstration experiments with the professional football club in Japan. The PBS coated paper cups provided in the football stadium are collected and composted together with the other food wastes and the obtained composts are used to cultivate the vegetables in the field of the neighborhood. Moreover, utilizing the high heat resistance of PBS compared to PLA, Mitsubishi Chemical prepares some grades for the lid of paper cup, tableware, and straw in combination with the paper cup.

[0108] Since the oxygen barrier property of PBS is low, PBS itself is unsuitable for food packages requiring the storage for a certain period of time, but the case where PBS is used as the sealant of cellulose or paper with excellent gas barrier properties is increasing. Moreover, Mitsubishi Chemical is investigating the multilayered sheet for the total solutions of biodegradable packaging using PBS-based compound as the inner and the outer layer and biodegradable polymer with excellent oxygen barrier property as the middle layer.

[0109] As PBS is a type of polyesters, PBS indicates excellent printability and aroma retaining property like terpene compared to PE. In addition, as the demand to the marine biodegradability and the home compostability is increasing, Mitsubishi Chemical is developing some grades having such functions. In the future, Mitsubishi Chemical is going to expand such highly functionalized products.

[0110] The DSC results of PBS and PLA are shown in Figs. 11 and 12. Since PBS has a relatively fast crystallization rate, it is applicable to almost all of the molding methods (e.g., blown film fabrication, extrusionmolding, sheet molding, injection molding, and vacuum molding) which are used for current plastic materials and can be widely chosen according to the application. Examples of representative molding conditions are shown in Tables 7, 8 and 9.

[0111] Table 7: Example of blown film fabrication conditionsScrew speed (r ) | 4 40Take-up speed j io 10Blow-up ratio | 2.5 2.5Film width I 240 240Film thicknessj 3030

[0112] Table 8: Example of extrusion coating conditions1Semi-malte finish chill roll

[0113] Table 9: Example of injection molding conditionsFZ71

[0114] As for the biodegradable polymer, the hydrolysis gradually proceeds in the hygroscopic state, and the mechanical properties are lowered. Thus, it is important to make an estimate of storability of the products using the biodegradable polymer. Though there are several thoughts about the estimate of storability, an example of the estimate will be given below.

[0115] Fig. 13 schematically shows the relation between the solution viscosity IV and the tensile elongation at break when taking a film as an example. For example, if the performance as the product cannot be satisfied when reaching the arrowed tensile elongation at break, a threshold value Th of IV of the product can be estimated. Meanwhile, assuming that the change of IV with time under a certain temperature and humidity is like Fig. 14, a period until IV reaches Th is an estimated usable period (SL) as the product. The results obtained by these experiments under several conditions are shown in Fig. 15. In this case it is presumed that the product quality is maintained for about 300 days in the environment at 30°C and 50% RH. Actually, as not only the temperature and the humidity change, but also the physical properties adopted as the threshold value and the threshold value thereof vary according to the product form, the situation is very complex. However, this kind of consideration is important in order to image the storage period of the product.

[0116] PBS is completely biodegraded with microorganisms in the natural world. However, because PBS has a high molecular weight, it is thought that PBS is first lowered in the molecular weight and oligomerized due to degradation of the ester linkage with an enzyme, and then degraded into carbon dioxide and water with microorganism. Mizuno et al. performed enzymatic degradation of PBS and PBSA to report that Aspergillus niger- derived lipase degrades PBSA. Further, Maeda et al. report that Aspergillus oryzae-derived cutinase degrades PBS and PBSA.

[0117] Mitsubishi Chemical investigated promotion of the degradation with an enzyme in order to control the biodegradability of PBS. As for the PBS degrading enzyme, it was found that an enzyme that is a kind of Humicola insolens lipase produced from a filamentous fungus Aspergillus strain exhibits very high biodegradability against PBS. When PBS pellets were immersed in an enzyme aqueous solution at 50°C for 6.5 h, the pellets were completely degraded. Dissolution of PBS(MCC) pellets by hydrolysis accelerant. Hydrolysis accelerant: Enzyme provided by Novozymes A / S. (a) Original, (b) After 6.5 h at 50°C.

[0118] In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE ISCLAIMED ARE DEFINED AS FOLLOWS:

1. A biodegradable netting comprising: a web structure formed of fdaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS); in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.2 The biodegradable netting of claim 1 in which the blend comprises between 50-90% PBS and between 10- 50 PLA by weight.3 The biodegradable netting of claim 2 in which the blend comprises 75% PBS and 25% PLA by weight.4 The biodegradable netting of any one of claim 1 - 3 in which the PBS comprises BioPBS™.5 The biodegradable netting of claim 4 in which the BioPBS™ comprises one or both FZ91PB™ orFZ91PM™.6 The biodegradable netting of any one of claim 1 - 5 in which the PBS is derived from one or more of sugarcane, cassava and com.7 The biodegradable netting of any one of claim 1 - 6 in which the PLA comprises 6752D™.8 The biodegradable netting of any one of claim 1 - 7 in which the PLA is derived from one or more of com, cassava, sugarcane or sugar beet pulp.9 The biodegradable netting of any one of claim 1 - 8 in which the web structure is structured to have sufficient properties to stamp out a tensile bar with clean cuts and no cracks out of an extruded sheet of material.

10. The biodegradable netting of any one of claim 1 - 9 in which the web structure is structured to have sufficient properties to be able to stamp out a series of bars and conduct tensile-elongation testing at room temperature and at elevated temperatures.

11. The biodegradable netting of any one of claim 1 - 10 in which the blend is selected to provide the web structure with a breaking strength of between 100 and 200 MPa.

12. The biodegradable netting of any one of claim 1 - 11 in which the blend is selected to provide the web structure with a breaking strength of at least 100 MPa after twelve months of exposure in the field.

13. The biodegradable netting of any one of claim 1 - 13 in which the web structure is structured to have sufficient strength to be fed through a forage baler machine to be applied to a forage bale and to secure the forage bale.

14. A forage bale wrapped and secured by the biodegradable netting of any one of claim 1 - 13.

15. A food product wrapped and secured by the biodegradable netting of any one of claim 1 - 13.

16. A method comprising : heating and blending biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS) to form a blend; extruding the blend into a web structure; in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for a loose item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

17. The method of claim 16 further comprising drying pellets of the biopolymers prior to heating and blending.

18. A method comprising : wrapping a forage bale with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS); in which:the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; the web structure is structured to have sufficient strength to be fed through a forage baler machine to be applied to a forage bale and to secure the forage bale; and the web structure is structured to have sufficient strength to act as a structural retainer for a forage bale, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

19. A method comprising: wrapping or securing a loose food item with a web structure formed of filaments made with a blend of biopolymers of polylactic acid (PLA) and polybutylene succinate (PBS); in which: the blend is structured to substantially degrade after placement in a soil box test for at least six months, where the blend would be buried in top soil, covered, and stored at 21 degrees Celsius while maintaining a moisture content of 12-15%; the blend is structured to have a melt flow index of 1-6; and the web structure is structured to have sufficient strength to act as a structural retainer for the loose food item, without breaking, for at least twelve months, during transportation and ambient exposure in the field.

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