Biodegradable compositions and articles of manufacture

Abstract

Biodegradable or reusable compositions and articles of manufacture having eco-friendly sustainable properties are described. The biodegradable compositions can be effectively used to produce bioplastic resins or reinforce polymers, without the use of plasticizers or thermoplastic additives, using organic, sustainable, renewable and / or recyclable material sources. The bioplastic resins are amenable to use in durable goods, computer parts, food and beverage containers, food and healthcare / cosmetic packaging, medical devices, automotive materials, and any other related applications that are currently made from petroleum-based plastic materials.

Description

68800-437150BIODEGRADABLE COMPOSITIONS AND ARTICLES OF MANUFACTURECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Serial No. 63 / 761,483, filed on February 21, 2025, the entire disclosure of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates generally to biodegradable compositions and articles of manufacture having eco-friendly sustainable properties.BACKGROUND AND SUMMARY

[0003] Petroleum-based polymer resins, such as polyethylene phthalate, polyethylene, polypropylene, polyethylene terephthalate, epoxy resins, nylon, polyolefin, and plasticized polyvinyl chloride (PVC), are used extensively for a wide range of applications, such as packaging materials, computer parts, automotive parts, home appliances, toys, and the like. However, such petroleum-based resins are not compostable or biodegradable, thereby increasing the possibility of causing environmental harm. For instance, use of petroleum-based resins have been implicated in harmful greenhouse gas emission, pollution, landfill overflow, and oceanic contamination.

[0004] Global annual petroleum-based polymer resin production exceeded 700 billion pounds in 2020. Plastics currently available in the marketplace are typically still petroleum-based, which require large amounts of processing energy and cost to produce. Moreover, petroleum is derived from non-renewable crude oil, which is often in limited supply and in high demand. Worse yet, petroleum-based plastic products are typically not biodegradable or bio-compostable, which creates a tremendous environmental problem globally, including by causing disposal issues once the product has been used.

[0005] Moreover, Printed Circuit Boards (PCBs) are a vital part of the electronics industry and demands for new devices rise every year. With this increase in demand, the amount of materials dedicated to, and wasted by, the production of PCBs has become worrying to environmental specialists. The environmental consequences are further realized when the precious metals within the PCBs are reclaimed through burning68800-437150or treating the PCBs with harsh chemicals. Such environmental concerns can relate to the structure of current PCBs, i.e., a laminate backbone and supplementary fibers being made of primarily synthetic materials such as petroleum-based epoxy resin and electronics-grade fiberglass (E-Glass), respectively. The longevity and inertness of synthetic materials means that more energy and effort must be spent to dispose of PCBs containing synthetic materials after use. Due to its biodegradability, thermal plasticity and relatively good mechanical properties, thermoplastic poly(lactic acid) (PLA) has shown promise for applications in packaging, disposable items, agriculture, electronics and automobiles. However, conventional linear PLA homopolymer has glass transition and melt temperatures of about 55 °C and 175 °C, respectively, and its poor heat stability and flammability have limited its applications. Biodegradable, flame retardant-containing thermoset PLA resins and methacrylated star-shaped PLA resins have been developed that have a higher glass transition temperature and greater tensile strength than thermoplastic PLA.

[0006] While biodegradable PCBs have been developed in the past, they typically fall short in key performance areas compared to epoxy / fiberglass-based composites, i.e., mechanical performance for strength and flexibility, electrical performance for effective interference elimination, and flammability ratings in order to meet FR4 or V-0 standards. These limitations affect the ability to print circuits on the boards.

[0007] Similarly, the demand for sustainable alternatives in food packaging has been steadily increasing due to a combination of factors that have raised awareness and shifted consumer preferences towards environmentally friendly options. This shift is driven by a surge in scientific collaboration to develop or find alternatives to traditional food packaging materials due to concerns over waste, carbon footprint, and the sustainability of fossil fuels. The food industry has recognized the importance of sustainable packaging to address the challenges of ecological impact, waste management, and consumer preferences for ready-to-eat foods with enhanced shelf life. Sustainable food packaging has been identified as a crucial element in promoting sustainable food consumption and preserving the environment within a circular economy context. As a result, development of the next generation of sustainable food packaging solutions is highly desired.

[0008] Furthermore, the concept of eco-sustainable consumption has provided a recent trend in the food sector in which consumers demand environmentally friendly packaging options. This trend is further supported by the understanding that resource68800-437150consumption and pollution generated by packaging products can be reduced through the adoption of sustainable packaging options, such as recyclable materials or packaging made from environmentally friendly sources. In response to the foregoing demands, industries are exploring the use of biodegradable materials and biopolymers to demonstrate sustainable food packaging solutions. The focus is not only on sustainability, but also on ensuring the quality, safety, and efficiency of the packaging to meet consumer expectations and regulatory standards.

[0009] Natural fibers are growing in popularity for usage in the plastics industry for their relatively high strength, low density, and superior sustainability. In particular, hemp has emerged as a desirable natural fiber due to its high crop yield. This property makes hemp ideal for high volume production, requiring less cultivated land and providing additional benefits such as rapid carbon sequestration and soil reclamation. Additionally, hemp cultivation enhances bio-content in various industries, including textiles, construction, healthcare, and energy production. Studies conducted to date with hemp, while proving the viability of polymer-hemp combinations, tend to rely on complex processes that would be difficult to apply in industrial production. For example, the use of fiber in woven mat form or using melt mixing to combine materials adds extensive and costly processing, thereby masking the benefits of hemp as a low-cost, eco-friendly property modifier. Any additional preprocessing of hemp, other than harvesting, retting, and drying, increases cost and energy demands. The ability to use hemp in its most natural condition is a desirable feature that emphasizes sustainability and promotes biodegradability.

[0010] Cellulosic fibers derived from natural sources such as cotton display impressive mechanical properties in tension and stiffness. These fibers can be incorporated into a mixture of plastic(s) and molded into a part with enhanced capabilities. The resultant fibers, which are stronger than the surrounding plastic or matrix material, can reinforce the structure by distributing force along their length, held together by the polymer matrix and thereby forming fiber-reinforced plastic (FRP) composites. Medium density fiberboard and oriented strand board are common materials that function in a similar way, i.e., waste wood strands are held together by a phenolic resin glue. For instance, recent studies using FTIR and x-ray diffraction analysis of common dryer lint have confirmed the emission spectrum of lint to be similar to that of pure cellulose. Importantly, the crystalline structure of lint fibers can be retained throughout multiple washing and drying cycles. The ability of lint to retain its mechanical68800-437150properties can be utilized to create fiber-reinforced plastic (FRP) composites thereby simultaneously establishing a useful way to reuse this common source of municipal solid waste.

[0011] To date, there have been no sustainable bioplastic compositions developed that i) can be economically scaled for mass production of bioplastic resins, ii) are economically feasible, and iii) can be used to produce and replace a wide range of petroleum-based resins and plastic products used today in the global market. Therefore, there is a need to provide economically feasible, compostable and biodegradable or reusable bioplastic compositions and resins having eco-friendly properties, and scalable methods of manufacturing such bioplastic compositions and resins globally.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:

[0013] Figure 1 shows particle size distribution of the hemp fiber powder used in combination with UHMWPE powder;

[0014] Figure 2 shows mold platen temperature and pressure profiles during compression molding cycles for combinations of UHMWPE powder and hemp fiber powder;

[0015] Figures 3A-3B show photographic views of typical testing blocks after compressive strength testing failure for combinations of UHMWPE powder-hemp fiber powder (Figure 3A) and combinations of UHMWPE powder-hemp fiber powder-PE wax (Figure 3B);

[0016] Figure 4 shows the effect on ultimate tensile strength by adding hemp fiber powder and PE-waxto UHMWPE powder;

[0017] Figures 5A-5B show graphical views of representative tensile stress-strain curves indicating tensile yield points for combinations of UHMWPE powder-hemp fiber powder (Figure 5A) and combinations of UHMWPE powder-hemp fiber powder-PE wax (Figure 5B);

[0018] Figure 6 shows the effect on tensile modulus of adding hemp fiber powder and PE-wax to UHMWPE powder;

[0019] Figure 7 shows the effect upon elongation to break of adding hemp fiber powder and PE-waxto UHMWPE powder;68800-437150

[0020] Figure 8 shows the effect upon compressive strength of adding hemp fiber powder and PE-waxto LIHMWPE powder; and

[0021] Figure 9 shows the effect upon surface hardness of adding hemp fiber powder and PE-wax to LIHMWPE powder;

[0022] Figure 10 shows tensile bars for PLA and PLA-PHB composites produced using an injection molding machine based on ASTM D638 standard;

[0023] Figure 11 shows a stress-strain comparison of PLA and PLA-PHB composites;

[0024] Figure 12 shows stress-strain curves for PLA-PHB composites comprising various hemp fiber contents;

[0025] Figure 13 shows stress-strain behavior of composites comprising 10% hemp fibers and 5% plasticizers;

[0026] Figure 14 shows stress-strain behavior of composites comprising 20% hemp fibers and 10% plasticizers;

[0027] Figure 15 shows stress-strain behavior of composites comprising 30% hemp fibers and 15% plasticizers; and

[0028] Figure 16 shows a comparison of oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) for different compositions, including PLA-PHB as the matrix.

[0029] Figure 17 shows a diagram of synthesis setup for DMMP-M4sPLA.

[0030] Figure 18 shows a diagram of DMMP-M4sPLA synthesis methodology.DETAILED DESCRIPTION

[0031] Before the present disclosure is further described, it is to be understood that this disclosure is not limited to particular embodiments described, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

[0032] Embodiments described herein can be understood more readily by reference to the following detailed description, examples, and figures. The compositions, components, and methods described herein, however, are not limited to the specific embodiments presented in the detailed description, examples, and figures. It should be recognized that these embodiments are merely illustrative of the principles of the present68800-437150disclosure. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the subject matter disclosed herein.

[0033] All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. In addition, unless expressly stated to the contrary, use of the term “a” is intended to include “at least one” or “one or more.” For example, “a device” is intended to include “at least one device” or “one or more devices.”

[0034] Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0035] Any composition disclosed herein may comprise, consist of, or consist essentially of any element, component and / or ingredient disclosed herein or any combination of two or more of the elements, components or ingredients disclosed herein.

[0036] Any method disclosed herein may comprise, consist of, or consist essentially of any method step disclosed herein or any combination of two or more of the method steps disclosed herein.

[0037] The transitional phrase “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, un-recited elements, components, ingredients and / or method steps.

[0038] The transitional phrase “consisting of” excludes any element, component, ingredient, and / or method step not specified in the claim.

[0039] The transitional phrase “consisting essentially of” limits the scope of a claim to the specified elements, components, ingredients and / or steps, as well as those that do not materially affect the basic and novel characteristic(s) of the claimed invention.68800-437150

[0040] Unless specified otherwise, all molecular weights referred to herein are weight average molecular weights and all viscosities were measured at 25 °C with neat (not diluted) polymers.

[0041] As used herein, the term "about" refers to the cited value being within the errors arising from the standard deviation found in their respective testing measurements, and if those errors cannot be determined, then "about" may refer to, for example, within 5%, 4%, 3%, 2%, or 1% of the cited value.

[0042] Examples of methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other reference materials mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control.

[0044] The terms “bioplastic” and “bioplastics,” as used herein, include plastic materials produced, at least in part, from renewable biomass sources. Unlike traditional plastics derived from petroleum, bioplastics are obtained from renewable resources, and some are biodegradable.

[0045] The terms “polymer,” “poly,” and the like include not only polymers comprising two monomer residues and polymerization of two different monomers together, but also include (co)polymers comprising more than two monomer residues and polymerizing together more than two or more other monomers. For example, a polymer as disclosed herein includes a terpolymer, a tetrapolymer, polymers comprising more than four different monomers, as well as polymers comprising, consisting of, or consisting essentially of two different monomer residues. Additionally, a “polymer” as disclosed herein may also include a homopolymer, which is a polymer comprising a single type of monomer unit.

[0046] Unless specified differently, the polymers of the present disclosure may be linear, branched, crosslinked, structured, synthetic, semi-synthetic, natural, organic, inorganic, and / or functionally modified. A polymer of the present disclosure can be in the form of a solution, a dry powder, a liquid, or a dispersion, for example.68800-437150

[0047] Furthermore, the disclosure encompasses any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the disclosure and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

[0048] In an illustrative aspect, a bioplastic composition comprising a combination of i) a natural fiber and ii) a resin is provided.

[0049] In an embodiment, the composition is processed by compression. In an embodiment, the composition is processed by extrusion molding. In an embodiment, the composition is processed by injection molding. In an embodiment, the composition is processed by rotational molding. In an embodiment, the composition is processed by thermoforming.

[0050] In an embodiment, the natural fiber is presented for the combination in a chopped form. In an embodiment, the natural fiber is presented for the combination in a ground form. In an embodiment, the natural fiber is presented for the combination in a powdered form.

[0051] In an embodiment, the natural fiber comprises hemp. In an embodiment, the natural fiber comprises hemp fiber powder. In an embodiment, the hemp fiber powder comprises a mesh size under 45 microns. In an embodiment, the hemp fiber powder is dried prior to the combination. In an embodiment, the hemp fiber powder is dried at a temperature of at least 80° C for a duration of at least 6 hours.

[0052] In an embodiment, tensile strength of the bioplastic composition is inversely proportional over the range of hemp fiber powder in the combination. In an embodiment, the hemp fiber powder is present in the combination at between 20-60% weight percent. In an embodiment, the hemp fiber powder is present in the combination at between 30-60% weight percent. In an embodiment, the hemp fiber powder provides an increase in biodegradability of the bioplastic composition.

[0053] In an embodiment, the resin comprises a polyethylene (PE). In an embodiment, the resin comprises a high molecular weight polyethylene (HMWPE). In an embodiment, the resin comprises an ultra-high molecular weight polyethylene (LIHMWPE). UHMWPE is an extremely long-chain grade of polyethylene with average molecular weights of several million AM Us. It features a low coefficient of friction as well68800-437150as exceptional toughness and wear resistance. UHMWPE can be crosslinked with polyethylene wax (PE-wax) to improve stability and durability; additionally, it can be combined with reinforcing fibers to make it further attractive to industry.

[0054] In an embodiment, the resin is presented for the combination as a powder. In an embodiment, the powder is present in the combination at between 20-90% weight percent. In an embodiment, the powder is present in the combination at between 30-80% weight percent. In an embodiment, the powder is present in the combination at between 40-80% weight percent. In an embodiment, the powder is present in the combination at between 36-76% weight percent.

[0055] In an embodiment, the bioplastic composition further comprises a polyethylene wax (PE-wax). Without being bound by any theory, PE-wax can be combined with UHMWPE in order to address UHMWPE's high viscosity during melting. PE-wax can act as a lubricant between UHMWPE chains, reducing rigidity in the overall structure, and improving flow without additional heat. This modification can maximize fiber-matrix contact and enhances mechanical properties, including tensile strength and modulus, through co-crystallization. Prior to use, the PE-wax in pellet form can be ground into a powder using a high-speed, multi-functional grinder and sieved (e.g., with a 200 mesh sieve).

[0056] In an embodiment, the PE-wax is presented for the combination as a powder. In an embodiment, the PE-wax is present in the combination at between 1-5% weight percent. In an embodiment, the PE-wax is present in the combination at between 2-4% weight percent. In an embodiment, the PE-wax is present in the combination at between 3-4% weight percent.

[0057] In an embodiment, the PE-wax provides an increase in tensile modulus of the bioplastic composition. In an embodiment, the PE-wax provides an increase in compressive strength performance of the bioplastic composition.

[0058] In an illustrative aspect, a printed circuit board (PCB) is provided. The PCB comprises a fiber-based material and a polymer, wherein the fiber-based material comprises hemp. For example, hemp can be utilized to provide desirable mechanical and electrical properties required by safety standards. In some embodiments, hemp fibers can be used as near to their raw form as possible to reduce the processing required for large scale manufacturing. The resulting completely biodegradable PCB does not require intervention to degrade (e.g., soaking in water, chemical treatment, or burning / melting).68800-437150

[0059] In an aspect, a printed circuit board (PCB) is provided that provides a significant advantage over previous biodegradable PCBs. The PCB comprises a fiberbased material and a polymer where the resulting bioplastic composition can directly replace synthetic epoxy / fiberglass-based composites to produce PCBs that meet mechanical performance standards for strength and flexibility, electrical performance standards for effective interference elimination, and flammability ratings in order to meet FR4 or V-0 standards.

[0060] In an embodiment, the hemp comprises one or more fibers derived from hemp waste. In some instances, hemp can be used in the form of unretted hemp fibers. Retting is a process that softens and separates the fibers of plants, such as hemp, from the surrounding cellular tissues and gummy substances. It involves the action of bacteria and moisture to partially rot the fibers, making them easier to extract from the stem. Thus, using hemp in its unretted form reduces the processing (and related cost) required for large scale manufacturing.

[0061] In an embodiment, the polymer is biodegradable. In an embodiment, the polymer is a resin. In an embodiment, the polymer is DMMP-M4sPLA.

[0062] In an embodiment, the polymer is an end-functionalized homopolymer. In an embodiment, the end-functionalized homopolymer comprises a pentaerythritol core. In an embodiment, the end-functionalized homopolymer comprises L-Lactic acid chains. In an embodiment, the end-functionalized homopolymer comprises a combination of methacrylate and dimethyl methylphosphonate end groups.

[0063] In an embodiment, the polymer is a poly(lactic acid) (PLA) resin. In an embodiment, the PLA resin is a thermoset PLA resin. In an embodiment, the hemp and the PLA resin are present as a laminate.

[0064] In an embodiment, the polymer is a liquid phenolic resin. In an embodiment, the liquid phenolic resin is present as a fiber reinforced plastic (FRP) composite.

[0065] In an embodiment, the polymer is a lignin-phenolic formaldehyde resole resin. In an embodiment, the lignin-phenolic formaldehyde resole resin comprises 40% lignin. In an embodiment, the lignin-phenolic formaldehyde resole resin comprises a 1.8:1 formaldehyde-phenol ratio.

[0066] In an illustrative aspect, a food packaging material is provided comprising the bioplastic composition of any one of the embodiments described herein.

[0067] In an illustrative aspect, a food packaging material comprising a fiber-based material, a polymeric blend, and a biodegradable plasticizer is provided.68800-437150

[0068] In an embodiment, the fiber-based material comprises hemp. In an embodiment, the hemp comprises one or more unretted hemp fibers.

[0069] In an embodiment, the polymeric blend comprises poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB). In an embodiment, the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC), D-limonene, or a combination thereof. In an embodiment, the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC). In an embodiment, the biodegradable plasticizer comprises D-limonene. In an embodiment, i) the polymeric blend comprises poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB); and the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC), D-limonene, ora combination thereof.

[0070] In an embodiment, the food packaging material is biodegradable.

[0071] In alternative embodiments, the fiber-based material comprises lint. In alternative embodiments, the natural fiber comprises lint. In some embodiments, the lint is sourced from a location selected from the group consisting of a laundromat, a home, a hotel, a gym, or any combination thereof.

[0072] The foregoing may be better understood by reference to the following examples, which are intended for illustrative purposes and are not intended to limit the scope of the disclosure or its application in any way.EXAMPLESExample 1Bioplastic CompositionsMaterial Preparation

[0073] Field-retted hemp fiber powder was sourced from Hemp Traders (Los Angeles, CA). A sieve shaking machine (D-4325, Dual Manufacturing Co. Inc., Chicago, IL) was used to analyze the size distribution of hemp powder particles. The particle sizes ranged from visible fibers over 2.6 mm in length to powders with a mesh size under 45 microns. The particle size distribution of hemp fiber powder used is presented in Figure 1.

[0074] The hemp fiber powder was then dried in an electric oven (NJ70X2462, Brosites Industries Inc., Greenwich, CT) at 80°C for 6 hours to avoid formation of voids in the final composite material due to the evolution of water vapor during molding. Ultra-high molecular weight polyethylene (UHMWPE) powderwas used with mesh size of 20068800-437150m, molecular weight of 5,000,000 AMU (Magerial Science, McKee, KY). UHMWPE is an extremely long-chain grade of polyethylene with average molecular weights of several million AMU’s. It features a low coefficient of friction as well as exceptional toughness and wear resistance. Numerous applications exist in the automotive, biomedical, and manufacturing areas. This versatile material can be crosslinked with polyethylene wax (PE-wax) to improve stability and durability. Additionally, it can be combined with reinforcing fibers to make it further attractive to industry.

[0075] UHMWPE's high viscosity during melting poses a challenge for thoroughly wetting hemp fibers, as poor wetting can result in internal voidsand limit contact between fiber and matrix phases, leading to compromised mechanical properties. Increasing the melt temperature to reduce viscosity risks degrading natural fibers such as hemp, which start to break down above 150°C. To address this, low molecular weight polyethylene wax (PE-wax) has been introduced, acting as a lubricant between UHMWPE chains, reducing rigidity in the overall structure, and improving flow without additional heat. This modification helps maximize fiber-matrix contact and enhances mechanical properties, including tensile strength and modulus, through co-crystallization. However, if PE-wax does not fully integrate into the UHMWPE matrix, it remains as a free-floating component, causing embrittlement and reducing the composite's mechanical strength.

[0076] Following the same approach, here a polyethylene wax additive (Polywax 2000, TALAS, Brooklyn, NY) was used. The PE-wax, in pellet form, was ground into a powder using a high-speed, multi-functional grinder (Model A11 Basic, IKA Works, Inc., Wilmington, NC) and sieved to 200 mesh. To reduce the risk of clumping or sintering of the wax, grinding was performed in increments of 1.0 minute with 2.0 minutes of idle time between increments.

[0077] In the instant example, eight compositions of UHMWPE, hemp fiber powder, and PE-wax were evaluated, with four containing PE-wax and four without. The component powders were weighed and blended in an electric mixer at room temperature for 2 minutes until a cohesive powdered mixture was obtained. Hemp content varied from 0 to 60% w / w, and PE-wax compositions were 5.0, 3.2, 4.8, and 4.0% w / w, replacing UHMWPE in the respective combinations. These combinations were labeled So, S20, S40, and S60(without PE-wax) and Sow, S20w, S40w, and S60w(with PE-wax) as shown in Table 1.68800-437150Table 1. Summary of UHMWPE compositionsCompression Molding and Mechanical Testing

[0078] The mold used to manufacture tensile pieces has three cavities, each in the shape of an ASTM D638-14 Type I “dog-bone.” The mold was constructed from 7075 aluminum having a mass of 11 .2 kg and, when closed, measures 229 mm in length, 210 mm in width, and 89 mm in height. Mold cavities were sprayed with an even layer of oilbased mold release (Pure EZE #45712N, Slide Products Inc., Wheeling, IL) and filled with the required amount of charge powder based on the density of the combination. Half of the charge material was loaded, and then the mold was shaken to disperse the material evenly. The material was then packed manually with a wooden tamping tool, and the process was repeated once more to fill the mold completely.

[0079] When processing UHMWPE, it is important that there are two distinct regimes: the melt region and the recrystallization region. The compression molding time / temperature / pressure cycle for UHMWPE powder-hemp fiber powder combinations is displayed in Figure 2. The press (Autofour / 30, Wabash MPI Carver, Wabash, IN) platen pressure was manually controlled during the cycle; therefore, between changes in platen pressure, the pressure was momentarily lowered to near zero. For the melt region, the charged mold is placed in pre-heated platens and compressed to 8.0 MPa. The mold is then allowed to heat to 176°C over the course of 20 minutes at which time it is held for a 10 minutes soak time to ensure that all material is saturated evenly. Following this, the mold is cooled over the course of 10 minutes to the recrystallization temperature of 121 °C initiating the recrystallization. The mold is68800-437150released from the pressure and is then at once re-pressurized to 17.25 MPa to ensure compaction and a tight crystalline structure. The pressure is maintained at a temperature of 121 °C for 15 minutes, and then cooled to 20°C over a period of 10 minutes by circulating cooling water through the machine’s platen cooling channels. The mold is then removed from the press; the samples were demolded; and flash was carefully removed using a razorblade. Two molding cycles were run to fabricate a total of six specimens for each combination listed in Table 1. All resulting test data represent averages obtained from five of the specimens. For each cycle, all specimens are considered to have a nearly identical temperature molding history.

[0080] After molding, samples were placed in an environment test chamber at 23°C and 50% relative humidity for 40 hours before testing according to ASTM D618-13 for conditioning plastic test pieces. Tensile pulls (Model EZ 50, Lloyd Instruments Ltd., Bognor Regis, UK) produced data for ultimate tensile strength (UTS), tensile modulus, and elongation at break in accordance with ASTM D638-14 specifications; the stressstrain results underwent toe compensation to remove the effects of slack take-up during the initial portion of the stress-strain curve.

[0081] Separately, the compression and hardness test samples were molded as one rectangular block, and both test specimen types were carefully fabricated from the single block. The 4140-steel mold shaped one 76x51 x13 mm thick block with filleted corners (material combinations of Table 1 and the molding cycle from Figure 2 were also employed to produce the rectangular blocks). The two filleted ends were trimmed with a bandsaw and set aside to be used as the hardness test pieces with a final size of 51x13x13 mm. The 51x50x13 mm center block piece remained to be formed into compressive strength test samples. The block was cut in 13-mm strips, and finally, each strip was cut in half to make six 25x13x13 mm test specimens, as specified by ASTM D695-15. As in the tensile testing, prior to these tests, the specimens were conditioned at 23°C and 50% humidity for 40 hours.

[0082] The tensile machine was run in compression mode for the compressive strength tests. A piece of mild steel round stock was used as the base, and a similar piece was threaded into the machine’s load cell to function as the upper compressive platen. All tests followed the ASTM D695-15 procedure, with an extension rate of 1.3 mm / min. Note that compressive failures differ from the typical tensile failure of a complete break; thus, in the case of compression, there may not be a decisive finish to68800-437150the test. In the baseline cases of Soand Sow, the failure point is unclear as the UHMWPE tends to continually compress into a flat disk. For this reason, the compressive stress values are taken at a linear deformation of 60% for the Soand Sowsamples exclusively. On the other hand, for all compositions containing hemp, a clear compressive failure was encountered and is displayed, qualitatively, in Figures 3A-3B and in the collected testing data.

[0083] The Shore type D procedure of ASTM D2240-15 was employed for surface hardness testing data. Measurements were taken with a digital durometer (Model HARDMATIC HH-334, Mitutoyo America Corporation, Aurora, IL) and recorded at the highest reading — indicative of the “skin” (surface) layer. Five readings were obtained from each sample, spaced at least 6 mm apart and at more than 2.5 mm from any edge. The readings were then averaged to report the Shore type D hardness (HD) of each combination.

[0084] The eight compositions prepared in the instant example displayed unique characteristics. Test results for ultimate tensile strength (UTS), tensile yield strength, tensile modulus, elongation, compressive strength, and Shore type D hardness are presented in Figures 4-9. Data bars and labels display the average value of each of the five individual runs; to indicate the uncertainty in the measurements, at the top of each bar graph the error range spans the highest and lowest values. The UHMWPE to PE-wax ratio is displayed within the data bars identifying the compositions that were modified with wax.Tensile Properties of UHMWPE-Hemp Combinations

[0085] As seen in Figure 4, the hemp fiber powder produces the typical filler effect when compared to the pure resin’s (So) ultimate tensile strength of 35.7 MPa. With the addition of 5% w / w PE-wax (Sow), the UTS decreases by 6%; this suggests that the PE-wax did not properly bond with the UHMWPE. As the hemp powder content increases, tensile strength decreases dramatically for all compositions. This is consistent with the hemp powder acting as filler as it displaces volume rather than providing reinforcement. For S20, the UTS decreases by 13% with the PE-wax (S20w). For S40, the effect of adding PE-wax on tensile strength is negligible, but not negative. This demonstrates that the PE-wax is more effective at a higher hemp concentration; for S60w, tensile strength68800-437150increases by 77% compared to S60. Without being bound by any theory, PE-wax appears to promote wetting of hemp fibers when hemp content is high.

[0086] The ultimate tensile strength is a useful metric to evaluate the maximum strength of a material, but in actual applications it is imperative to also consider the tensile yield point. All values represent the proportional limit tensile yield strength. Accordingly, Figures 5A-5B present the stress-strains curves for the runs that best typified each combination in Table 1. Here, the tensile yield points (labeled on the stressstrain curve for each combination) of both Soand Soware 10.0 MPa. For S20, the yield point is 7.7 MPa which drops to 5.3 MPa with the addition of wax (S20w), consistent with the UTS behavior with the addition of PE-wax. The yield points of both S40and S60samples increase from 4.6 to 5.4 MPa and from 0.5 to 1.6 MPa, respectively; this is also consistent with the increase seen in UTS for these compositions. Although generally the tensile yield decreases as hemp fiber content increases and the PE-wax mixtures trend similarly as with the UTS results, for the 40% w / w composites, the data indicate approximately a 50% reduction in tensile yield strength compared to a 70% decrease in UTS. This suggests that UHMWPE powder-hemp fiber powder combinations can find more structural design applications up to, and including, 40% w / w hemp, while 60% w / w compositions could be used in frangible applications. The tensile yield strength is especially relevant as design safety factors reduce any allowable tensile strength below the yield and, thus, certainly well below UTS.

[0087] The effect upon the tensile modulus of including the same modifiers to UHMWPE is available in Figure 6; overall with fiber, combinations are stiffer, as anticipated. Sodisplays an elastic modulus of 0.71 GPa which increases to 0.98 GPa with the PE-wax (Sow). Interestingly, S20and S40have an identical elastic modulus — 1.02 GPa; when PE-wax is added, the moduli increase to 1.46 GPa. For the S60sample, the tensile modulus decreases dramatically, but for S60w, the modulus levels out to near the Sowvalue.

[0088] Increasing both hemp fiber powder and PE-wax content has a detrimental effect on elongation as expected (Figure 7). The Sobaseline yields an elongation of 488% which decreases 9% with the addition of wax (Sow) as the material combination stiffens. The presence of 20% w / w hemp fiber powder (S20) in the matrix results in an 83% decrease in elongation compared to the neat value. Clearly, the hemp particles interfere with the polymer-to-polymer contact within the matrix, causing a deterioration68800-437150in ductility. Although the S40and S40wsamples had null difference in UTS, the addition of wax to S40inhibits elongation, reducing the value by 54%. On the other hand, the PE-wax somewhat improves the elongation in the S60wsample compared to S60; this 21% increase in elongation is paired with the substantial increases in UTS, tensile yield strength, and tensile modulus. This demonstrates the value of PE-wax as an effective property modifier in compositions with higher hemp content.Compressive Strength Test Results

[0089] The UHMWPE powder compositions without hemp fiber powder performed well under compression, as apparent from Figure 8. Values for the Soand Sowsamples are given at 60% deformation as the pieces never had a clear failure point. The compression tests most clearly demonstrated the benefit of the PE-wax, as all compression values increased when it was added. This increase is more drastic for compositions with lower hemp fiber powder content. As is seen for most mechanical properties in the instant example, hemp fiber powder has a negative effect on the compressive strength as its content increases. In Figure 8, compressive strength increases from 29.3 to 43.1 MPa for pure UHMWPE (So) when PE-wax is utilized (Sow). This is consistent with the stiffening effect of PE-wax. The greatest benefit occurs in the S20wsample, nearly doubling the compressive strength compared with S20. However, this extent of benefit disappears for higher hemp concentrations; possibly the hemp fibers compress more easily than the UHMWPE, negating the effects of the PE-wax.

[0090] The Soand Sowsamples lacked a clear failure in the data but seen in Figures 3A-3B, the failure mode was a combination of barreling and shearing; as an elastomeric material, this is the expected result. The most common failure mode for compositions containing hemp was a shear failure that took either the shape of an “X” or “Y,” or a corner- to-corner crack. These samples have an observable failure point qualitatively and in the data; therefore, it was not necessary to select a common percent deformation point for terminating each test. In the case of the “X” or“Y” faults, an initial wedge-shaped crack appears which is driven down into the lower part of the block until additional crack(s) appear, creating the “X” or “Y” patterns. Internal stresses from barreling cause crack formation and propagation in the samples, leading to an eventual shear failure mode for the piece. In the S20wsample (shown in Figure 3B), two opposing wedge-shaped cracks developed creating a failure appearing as a backwards “N.” In the case68800-437150of the corner-to-corner crack failures, once a crack appeared, the piece would shear until, in most cases, the two halves separated.Hardness Testing Performance

[0091] The hardness of the pure UHMWPE (So) measured 58.1 HD. The values, present in Figure 9, steadily decrease with hemp. The S20wand S40wcombinations both show approximately 2% lower values. Mostly, the hardness is only slightly reduced by PE-wax; this may be caused by the relatively softer, free-floating PE-wax particles with the largest effect in the S60wcase with a 28% hardness decrement. The increase in data uncertainty with increasing hemp percentage is likely due to the inconsistent structure of the randomly oriented hemp powder within the matrix. The compositions were mixed in powder form in a blender whereas melt mixing or fabricating pellets, in a ram extrusion machine, prior to compression molding may be preferable. These processes infuse additives into the resin more effectively, but the positive property effects of using such methods would likely be small and not cost-effective due to added processing.

[0092] The plastics industry needs sustainable solutions to counter the mass consumption of petroleum-based polymers. Natural fibers, hemp in particular, can be evaluated as one possible answer to this problem. Hemp grows rapidly, and its fibers are particularly strong, lightweight, inexpensive, and biodegradable. These factors make hemp ideal for use in plastics, such as UHMWPE, as filler in the polymer matrix replacing a portion of the petroleum-based component. Usage of these methods with a bio-based polymer would even further bolster the biodegradability and other “green” effects of the hemp filler. Processing such combinations by compression molding allows the powdered charge material to be loaded easily and uniformly, cutting down on processing time and complexity.

[0093] The results of this effort identify an average decrement in mechanical properties with increasing hemp powder content. Ultimate tensile strength decreases from 35.7 to 1.6 MPa from the pure Sosample to the S60sample, although the S60wsample yielded a UTS of 7.1 MPa. The tensile modulus tends to increase with more hemp fiber powder and PE-wax up to S60where the tensile modulus decreases compared to the S40sample. Compressive strength also is lower as hemp fiber powder increases, but the use of PE-wax has a positive effect on this metric for all compositions,68800-437150near doubling to 18.3 MPa for 20% w / w hemp. UHMWPE hardness is negatively affected when incorporating hemp powder and PE-wax.

[0094] Overall, the mechanical properties of the combinations exhibit trends commonly found when fillers are mixed with a polymeric matrix, i.e., the addition of hemp fiber powder i) significantly reduces the ultimate and yield tensile strengths as well as the elongation at break, the effect increasing with more hemp (notably, PE-wax improves performance at 40% and 60% w / w hemp, compared to the no wax condition), ii) increases the tensile modulus for 20% and 40% w / w hemp fiber powder, and PE-wax improves the tensile modulus at all hemp concentrations; iii) reduces compressive strength as hemp fiber powder content increases (notably, PE-wax raises the performance at all hemp levels, nearly doubling the 20% w / w hemp strength), and iv) lowers shore type D hardness values steadily with increasing hemp fiber powder content (with a 60% loss in hardness, from the pure UHMWPE baseline to the 60% w / w hemp sample).

[0095] At the same time, increased bio-content makes a more sustainable and biodegradable product while adding a natural coloring. Hemp also has inherent damping properties which it passes on to its composites. Utilizing hemp fiber in its powdered form as opposed to woven mat form substantially lowers the cost of processing by omitting the weaving and layering traditionally required for hemp-based FRPs. Additionally, the UHMWPE powder-hemp fiber powder combinations have tensile yield strengths that are within a range usable in numerous engineered applications. For example, reviewing their compressive stress-strain curves, the S60and S60wsamples exhibited average compressive yield strengths of 0.07 and 0.2 MPa, respectively, substantially lower than the compressive strengths but yet competitive with commercially available low-density polyurethane foam in packaging materials.

[0096] In the instant example, a complex relationship was observed relating hemp fiber powder, PE-wax, and UHMWPE powder content to mechanical properties of the resulting material. The decrease in most mechanical properties with the addition of PE-wax can likely be attributed to the incomplete coupling of PE-wax with the polymer matrix. Future studies might employ an alternative melt mixing method where shear is used to more thoroughly combine in the additives. This may provide a more homogeneous material, but also adds manufacturing time and costs as UHMWPE must be processed with specialized machinery due to its exceptionally low melt flow rates. In general, the data presented here successfully demonstrate the potential of hemp fiber68800-437150powder as a filler material in IIHMWPE combinations, highlighting the advantages and some challenges of integrating natural fibers into a synthetic polymer matrix.Example 2Food Packaging MaterialsMaterials and Methods

[0097] The primary hemp raw material utilized in the instant example, which evaluates the potential of the composition of PLA-PHB polymer combinations with hemp fibers and biodegradable plasticizers, comprises unretted hemp bast fibers procured from industrial hemp plants and obtained from "Hemp Traders" company (Los Angeles, CA 90021). These fibers are in their raw state and have not undergone degumming or lignin removal processes. PLA 3052D in pellet form was purchased from JAMPLAST (Mount Vernon, IN 47620). PHB polymer in powder form was purchased from Material Science Company (KY 40447, US). Two types of plasticizers were used for these experiments, including Acetyl Tributyl Citrate 98% from Fisher Scientific, and D-limonene from MilliporeSigma Company, both in liquid form. Whereas the biodegradable plasticizers, Acetyl Tributyl Citrate (ATBC) and D-limonene, offer desirable properties in terms of tensile properties, oxygen barrier, and water vapor barrier, PLA-PHB combinations contribute to the composite's structural integrity and mechanical properties (with PLA offering high transparency and PHB enhancing crystallinity), and hemp provides additional stiffness and sustainability to the composite.Preparation of Biodegradable Pellets

[0098] To prepare versatile, biodegradable “green” pellets suitable for various food packaging applications that are amenable to large-scale industrial production, it is necessary to powderize polymers and fibers, prior to injection molding, ensuring uniform mixing of fibers, polymers, and plasticizers. In so doing, the instant example provides a formal departure from conventional laboratory techniques such as solution casting. For the experiments in the instant example, hemp fibers were thoroughly washed until the water from the sieves ran clear, indicating the absence of dust or impurities. Subsequently, the fibers were left at room temperature for 48 hours. Afterward, the fibers were dried in an oven (Brosites Industries, INC) at 80°C for 16 hours. The dried fibers were then pulverized into a fine powder using liquid nitrogen to make them brittle,68800-437150followed by milling with an AKA milling machine (A 11 basic Analytical Mills). T o sterilize the hemp fibers, the fine hemp powder was kept in an oven at 160°C for 2 hours after milling. Polymers were also pulverized from pellet form to powder form using a High-Speed Multi-functional Grinder machine. This machine was also utilized for mixing the materials to produce different compositions for the experiments. Table 2 illustrates the various compositions and percentages of fiber, polymer, and plasticizer used in the instant example.Table 2. Composition and Percentage of Materials Used""""

[0099] As explained previously, combining PLA with more crystalline biobased polymers, such as polyhydroxybutyrate (PHB), has shown promise in overcoming possible limitations of PLA. Studies reveal that PLA-PHB combinations, particularly in a ratio of 75:25, exhibit improved mechanical properties and enhanced crystallinity. This ratio was utilized for compositions in the instant example. To maintain consistency, a standard ratio was employed for all compositions in the instant example. This testing aims to evaluate the effects of adding PHB, hemp fiber, and different percentages of plasticizer, respectively. The production of pellets from these compositions utilized a Davis-Standard Single Screw Extrusion Machine. The machine is equipped with three band heaters on the barrel, one band heater on the adapter, and one on the die to ensure68800-437150consistent heat during the extrusion process. The extruding portion of the die used for this experiment has a diameter of 0.14 inches.

[0100] Due to the potential clogging issue caused by high percentages of hemp fibers, the breaking plate of the extrusion machine was removed to prevent damage to the rupture disk. Temperature ranges of 300-315°F were applied for compositions including hemp fibers. For experiments without hemp fibers, a temperature of 295-310°F was utilized. The mixed materials were fed into the machine, and the filament produced using the extrusion machine was pelletized using a Maag Group pelletizer machine.

[0101] The pellets were dried in an oven (Brosites Industries, INC) at 40-45°C for 24 hours before being fed into the injection molding machine. An Arburg 250-75-220D injection molding machine was used for these experiments. The temperature applied to the barrel was in the range of 165-185°C for different heating zone. The injection molding mold included a cavity for producing ASTM D638 Type I dog-bone samples, which are used for measuring tensile properties. Figure 1 illustrates some of the tensile bars that have been produced using different compositions with an injection molding machine.

[0102] Priorto testing, all samples were conditioned in a Temperature & Humidity Chamber (ESPEC BTL-433) at 23°C and 50% humidity for 40 hours. The LLOYD-AMETEK EZ50 testing machine was utilized to measure the tensile properties of the composites, including ultimate tensile strength, elastic modulus, and elongation at break. An ESPEC BTL-433 extensometer was employed to accurately measure and monitor specimen elongation (strain) during tensile testing, and the extension rate of the machine was set to 5 mm / s.Measurement of Permeation Properties

[0103] To evaluate the permeation properties of each composite, including Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVTR), composite sheets were manufactured using a Carver Auto Series compression molding machine. The mold used had dimensions of 8 x 6 x 1.5 inches.

[0104] The production process commenced with drying the pellets in an oven at 40-45°C for 24 hours, followed by pulverizing them into a fine powder. Mold release spray was applied inside the mold to prevent sample adhesion. Subsequently, the mold was preheated in the compression molding machine. Initially, low pressure (700 lbs of force) was applied to the mold at a temperature of 350°C for 15 minutes. The applied force was then increased to 4500 lbs and maintained at the same temperature for an68800-437150additional 10 minutes. Thereafter, while maintaining constant force, the temperature was gradually reduced, initiating the cooling process over the next 15 minutes. Finally, the molds were extracted from the machine, and the samples were separated.

[0105] For OTR and WVTR measurements, all samples were forwarded to the Center for Flexible Packaging at Clemson University (Clemson, SC). Mocon equipment was employed for testing. Oxygen Transmission Rate Testing followed ASTM D3985-02 standards, conducted at 0% humidity and a test temperature of 23°C. Water Vapor Transmission Rate Testing adhered to ASTM F1249-01 standards, performed at 90% humidity and a test temperature of 38°C.

[0106] In the instant example, ASTM D638 Type I dogbone samples were fabricated for tensile testing to assess the mechanical properties of the composites, including ultimate tensile strength, elongation at break, and elastic modulus. Additionally, the research investigates the impact of PHB, hemp fibers, and two types of biodegradable plasticizers on the permeation properties of PLA, aiming to develop biodegradable composites suitable for food packaging applications. The subsequent tables and graphs illustrate the findings and resulting analyses.Mechanical Properties: Impact of Polyhydroxybutyrate (PHB) on Polylactic acid (PLA)

[0107] In the instant example, the effect of incorporating polyhydroxybutyrate (PHB) into polylactic acid (PLA) composites is examined. Previous studies have shown that combining PHB with PLA can alter the mechanical properties of the resulting materials. For consistency, a standard combination ratio of 75:25 (PLA) was employed across all compositions in this investigation. Table 3 presents the results of mechanical property testing for PLA versus PLA-PHB composite.Table 3. Tensile properties of PI_A and PLA-PHB composites68800-437150

[0108] The incorporation of polyhydroxybutyrate (PHB) into PLA composites resulted in notable changes in mechanical properties compared to pure PLA. Specifically, the mean elastic modulus of PLA-PHB composites (2.75 GPa) showed a slight increase compared to pure PLA (2.33 GPa), indicating enhanced stiffness with PHB addition. Conversely, the mean ultimate tensile strength of PLA-PHB composites (48.99 MPa) was slightly lower than that of pure PLA (50.19 MPa), suggesting a marginal reduction in strength. Importantly, the elongation at break significantly improved from 2.40% in pure PLA to 7.99% in PLA-PHB composites, indicating enhanced ductility and flexibility. These findings suggest that PHB incorporation can effectively modify the mechanical properties of PLA, offering potential advantages in applications requiring improved flexibility without compromising overall strength. The observed variations were within acceptable limits, as indicated by the low coefficients of variation and consistent correlation coefficients across samples for both materials. In addition to numerical data, stress-strain curves were generated to compare the mechanical behavior of PLA and PLA-PHB composites under tensile loading conditions (Figure 11).

[0109] While PLA exhibited a higher ultimate tensile strength (UTS) compared to PLA-PHB composites, approximately 50 MPa versus 49 MPa, respectively, the curve for PLA-PHB showed a more gradual decrease in stress post-UTS, indicating enhanced ductility and toughness. PLA-PHB composites demonstrated an elongation at break of approximately 8%, significantly higher than the 2.5% observed for pure PLA. These curves visually illustrate how the incorporation of PHB modifies the mechanical properties of PLA, highlighting PHB's role in improving flexibility while marginally reducing ultimate strength.Impact of Hemp Fiber Addition on PLA-PHB Composite Properties

[0110] The incorporation of hemp fibers into PLA-PHB composites presents a promising approach to enhancing the sustainability of biopolymer-based products. This analysis aims to highlight the potential benefits and limitations of using hemp fibers in biopolymer composites, contributing to the development of more sustainable materials for various applications, including food packaging. To evaluate the impact of hemp fibers, tensile tests were conducted on PLA-PHB composites incorporating different percentages of hemp fibers, including 10%, 20%, and 30%. The addition of hemp fibers was hypothesized to enhance the composite's stiffness and lower the ductility of the product while improving its sustainability, making it more suitable for environmental68800-437150applications. The following section presents detailed results and discussions on these mechanical properties, supported by tables and stress-strain curves, to provide a comprehensive understanding of how hemp fibers alter the performance of PLA-PHB composites. In the next section, the effect of adding a plasticizer to this composition, with regard to enhancing the flexibility of the product, will be discussed. Table 4 illustrates the mechanical properties for each of the compositions.Table 4. Tensile properties of PLA-PHB composites"" "

[0111] The addition of hemp fibers significantly influenced composite performance, as evidenced by changes in elastic modulus, ultimate tensile strength (UTS), and elongation at break. The elastic modulus increased progressively with the addition of hemp fibers: from 2.75 GPa for pure PLA-PHB to 3.16 GPa (10% hemp), 4.94 GPa (20% hemp), and 5.14 GPa (30% hemp). This increase indicates enhanced stiffness and rigidity in the composites, attributed to the intrinsic high stiffness of hemp fibers. The trend suggests that higher percentages of hemp fibers contribute to a stiffer composite. Conversely, the UTS exhibited a decreasing trend with the addition of hemp fibers. This reduction is typical in fiber-reinforced composites, as the stress transfer efficiency between the matrix and fibers can decrease with higher fiber loadings, potentially leading to lower overall strength. Part of this reduction could also be due to degrading fibers during the drying process or the sterilizing process, where the fibers were exposed to 160°C for two hours, causing the fibers to act more as fillers rather than reinforcing elements. However, it was noteworthy that the reductions are relatively moderate, indicating that even with 30% hemp fibers, the composites still maintain reasonable strength levels suitable for various applications.

[0112] Elongation at break showed a decreasing trend as hemp fiber content increased: from 7.99% for pure PLA-PHB to 1 .96% (30% hemp). This decrease suggests68800-437150reduced ductility with increasing fiber content, which is expected due to the inherent brittleness of fibers compared to the matrix material. Despite the reduction, the composites maintained sufficient elongation at break for practical applications, particularly at lower hemp fiber loadings.

[0113] To further illustrate the mechanical behavior of the PLA-PHB composites with varying percentages of hemp fibers, stress-strain curves were generated for each composition (Figure 12). These curves provide a visual representation of the relationship between stress and strain, highlighting key differences in mechanical performance across the different fiber contents.

[0114] As observed, the initial linear portion of each curve corresponds to the elastic region, where the material deforms elastically, and the slope represents the elastic modulus. The slope of the curve increases with higher hemp fiber content, confirming the increase in stiffness previously discussed.

[0115] The area under each stress-strain curve represents the toughness of the material, indicating its ability to absorb energy before fracturing. The composites with lower hemp content have larger areas under the curve, suggesting better toughness compared to those with higher hemp content.Effect of Plasticizer Addition on PLA-PHB Composites with Varied Hemp Fiber Concentrations

[0116] The impact of plasticizer addition, specifically Acetyl Tributyl Citrate (ATBC) and D-limonene, on the mechanical properties of PLA-PHB composites with varying hemp fiber concentrations was investigated. Plasticizers are known to enhance the flexibility and processability of polymers, potentially affecting their mechanical behavior. Here, we analyze the elastic modulus, ultimate tensile strength (UTS), and elongation at break of the composites to understand the influence of plasticizer content (Table 5).68800-437150Table 5. Tensile properties of PLA-PHB composites

[0117] As explained previously, an increase in hemp fiber concentration led to a higher elastic modulus. This trend is attributed to the high stiffness of hemp fibers, which reinforce the polymer matrix and enhance its structural integrity. However, the addition of plasticizers, resulted in a notable reduction in the elastic modulus across all fiber loadings. The introduction of ATBC plasticizer effectively reduced the elastic modulus in all compositions. This decrease can be explained by the plasticizer’s ability to disrupt the polymer chain interactions, thereby increasing the free volume and reducing the overall stiffness of the composite. Similar to ATBC, D-limonene plasticizer contributed to lowering the elastic modulus. Its molecular structure and compatibility with the polymer matrix facilitated better dispersion, resulting in a more flexible composite structure.

[0118] While the addition of hemp fibers moderately reduces the ultimate tensile strength (UTS) and ductility of the composite, the incorporation of plasticizers, as expected, had a notable impact on further reducing the UTS. While ATBC plasticizer increased elongation at break, it concurrently reduced UTS. This trade-off is common in plasticized composites, where increased ductility often comes at the expense of tensile strength due to reduced intermolecular forces within the polymer matrix. Similarly, D- limonene plasticizer enhanced elongation at break but slightly decreased UTS. Its plasticizing effect facilitated better polymer chain mobility, which can reduce the stress transfer efficiency between fibers and the matrix, thereby lowering UTS.68800-437150

[0119] On the other hand, both ATBC and D-limonene significantly increased elongation at break across all hemp fiber concentrations. This improvement underscores their role in enhancing the composite's flexibility and toughness, making the material more resilient to deformation and less prone to brittle failure. Overall, from the data, D-limonene generally results in higher elastic modulus and UTS values compared to ATBC, especially at higher hemp fiber content. For instance, in the 20% and 30% hemp composites, D-limonene significantly outperforms ATBC in both modulus and tensile strength. This suggests that D-limonene is more effective at maintaining the structural integrity and strength of the composite even with higher fiber content. On the other hand, ATBC tends to significantly increase elongation at break, particularly noticeable in the 20% hemp composite, where the mean elongation at break reaches 14.38%, compared to 4.56% for D-limonene. This indicates that ATBC is better at enhancing the flexibility of the composites.

[0120] Therefore, the choice between ATBC and D-limonene should be guided by the specific application requirements. For instance, for applications demanding higher strength and stiffness, D-limonene may be preferable. Alternatively, for applications where flexibility and ductility are more critical, ATBC may be the better option.

[0121] Figures 13-15 illustrate the stress-strain curves for each percentage of hemp fibers with both plasticizers. The figures illustrate that adding hemp fibers to the PLA-PHB matrix increases stiffness but reduces ductility. Incorporating ATBC as a plasticizer decreases stiffness and ultimate tensile strength (UTS) but significantly increases elongation at break by enhancing polymer chain mobility. In contrast, D-limonene maintains stiffness and UTS better than ATBC while moderately increasing elongation at break, striking a balance between flexibility and mechanical strength in the composites.Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVTR) Testing

[0122] The oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) are critical parameters in evaluating the suitability of materials for food packaging applications. These metrics determine the permeability of packaging materials to oxygen and water vapor, respectively, which are essential in preserving the quality and extending the shelf life of food products. Low OTR and WVTR values are68800-437150desirable as they indicate better barrier properties, protecting the food from oxidation and moisture loss or gain, which can lead to spoilage and reduced nutritional value. For food packaging materials, maintaining the integrity of the product by preventing oxygen and moisture ingress is crucial. Oxygen can lead to the oxidation of fats and oils, causing rancidity, off-flavors, and loss of nutritional quality. Similarly, moisture control is vital to prevent microbial growth, maintain texture, and prevent caking or sogginess in products like powders and crisps. Therefore, assessing the OTR and WVTR of packaging materials ensures they provide the necessary protection to maintain the quality and safety of food products over their intended shelf life. In the following sections, we will present and discuss the OTR and WVTR results for the various PLA-PHB composite formulations. These results will highlight the impact of hemp fibers and plasticizers on the barrier properties of the composites and their potential effectiveness as food packaging materials. Table 6 illustrates the OTR and WVTR results for PLA, PLA-PHB, and the composite of PLA-PHB with different percentages of hemp fibers and plasticizers.Table 6. OTR and WVTR results for PLA, PLA-PHB and its composites" "68800-437150

[0123] Table 6 demonstrates that incorporating PHB into PLA significantly enhances the barrier properties of PLA, and the addition of hemp fibers without plasticizers further amplifies these improvements. Figure 16 provides a detailed visual comparison, clearly illustrating the magnitude of these enhancements. The figure highlights the distinct performance differences, making it evident how each modification contributes to the overall barrier properties of the composite material.

[0124] Pure PLA has a high oxygen transmission rate. This indicates moderate permeability to oxygen, which limits its effectiveness as an oxygen barrier in food packaging applications. The semi-crystalline structure and inherent permeability of PLA to gases contribute to this result. The water vapor transmission rate of pure PLA falls within the "High" barrier grade. This reflects good resistance to water vapor permeation, making it relatively effective in preventing moisture ingress, which is important for maintaining the quality of food products.

[0125] Incorporating PHB into PLA significantly improved the barrier properties. The PLA-PHB combination serves as a foundational material for biocomposites due to its inherent balance between flexibility and barrier properties. Incorporating PHB into PLA significantly enhances the oxygen barrier properties, reducing the OTR. This improvement is due to PHB's higher crystallinity and better compatibility with PLA, which restricts oxygen permeability. Furthermore, the addition of PHB also improves the water vapor barrier properties. This indicates a strong resistance to water vapor transmission, enhancing the potential shelf life and quality preservation of packaged foods.Effect of Adding Hemp Fibers

[0126] When hemp fibers are introduced into the PLA-PHB matrix, a significant improvement in oxygen barrier properties is observed, particularly at moderate fiber concentrations. The results show that adding 10% hemp fibers to the PLA-PHB combination reduces the OTR, which can be attributed to the increased tortuosity in the diffusion path for oxygen molecules. This is consistent with the understanding that the fibrous structure of hemp creates a more complex pathway for gases, thereby hindering their transmission through the material. However, the results also highlight that the addition of hemp fibers decreases the WVTR, particularly at higher concentrations. This trend can be attributed to the hydrophilic nature of hemp fibers, which likely absorb water vapor during the testing process. As the fiber content increases, the composite's capacity to absorb moisture also rises, leading to a reduction in the amount of water68800-437150vapor that can permeate through the material. This absorption creates a "moisture sink" effect, where the fibers trap water molecules, effectively lowering the WVTR. Additionally, the fibers may create a more tortuous path for water vapor diffusion, further inhibiting its transmission. Thus, while hemp fibers generally increase moisture permeability in hydrophilic environments, in this case, their ability to absorb water vapor directly leads to a decreased WVTR, reflecting the complex interactions between fiber content and barrier properties in biocomposite materials.Impact of Plasticizers (e.g., ATBC and D-limonene)

[0127] The addition of plasticizers, such as ATBC and D-limonene, introduces a complex interplay between enhancing flexibility and maintaining barrier properties. The results from the instant example provide clear evidence of these effects:

[0128] The results indicate that adding ATBC plasticizer to the PLA-PHB-hemp composite increases both OTR and WVTR, especially at higher concentrations. This suggests that while ATBC improves the flexibility and processability of the composite, it does so at the cost of creating a more open matrix structure, which allows gases and moisture to permeate more easily. For instance, with 10% hemp and 5% ATBC, the OTR increases, indicating a reduction in the composite’s ability to block oxygen. This trend continues as the concentration of ATBC increases, confirming that ATBC, while beneficial for processing, may not be ideal when barrier properties are paramount.

[0129] Conversely, the results show that D-limonene plasticizers has a less pronounced negative effect on barrier properties compared to ATBC. In some cases, D-limonene even appears to enhance the oxygen barrier, as seen in the slight decrease in OTR with 10% hemp and 5% D-limonene compared to ATBC. This suggests that D-limonene interacts more favorably with the polymer matrix, potentially tightening the structure and thereby reducing permeability. The WVTR, however, increases with D-limonene, though not as dramatically as with ATBC, indicating that while D-limonene is a better choice for maintaining oxygen barrier properties, it still requires careful consideration when moisture resistance is a critical factor.Synergistic Effects and Optimization

[0130] The interaction between hemp fibers and plasticizers plays a critical role in determining the final properties of the PLA-PHB composite. The results suggest that a balanced approach is necessary to optimize both oxygen and moisture barrier68800-437150properties. On the other hand, higher fiber concentrations or excessive plasticizer content lead to diminishing returns, as seen with 30% hemp and 15% ATBC, where the OTR increases significantly. This suggests that overloading the composite with fibers or plasticizers can disrupt the matrix, creating pathways for gas and moisture transmission, thereby compromising the barrier properties.

[0131] These results highlight the significant influence of PHB, hemp fibers, and plasticizers on the barrier properties of PLA-based biocomposite films. PHB enhances both oxygen and water vapor barrier performance, while hemp fibers introduce additional tortuosity, significantly reducing oxygen permeability. The choice of plasticizer further refines the film's mechanical and barrier properties, illustrating the potential for tailored packaging solutions in sustainable food packaging applications. These findings suggest that combining PLA with PHB, hemp fibers, and appropriate plasticizers can produce biocomposites with enhanced barrier properties suitable for food packaging. Considering the promising mechanical and barrier properties observed for the PLA-PHB-hemp fiber composite in the instant example, and the fact that the PLA-PHB combination is biodegradable within two months, this hybrid composite holds significant potential for use in the food packaging industry as an environmentally friendly product.

[0132] In the instant example, integrating hemp fibers into PLA-PHB composites was shown to enhance stiffness while moderately reducing ultimate tensile strength (UTS) and ductility, aligning with composite material science expectations with respect to mechanical properties. These adjustments allow for tailored mechanical properties in biodegradable composites, catering to specific application needs. Further modification with plasticizers such as ATBC and D-limonene alters these properties. ATBC notably enhances ductility while reducing stiffness and UTS, suitable for applications prioritizing flexibility. Conversely, D-limonene maintains a balanced blend of strength and flexibility, ideal for applications requiring both properties. Thus, the choice of plasticizer should be guided by specific mechanical requirements. These findings highlight ATBC and D-limonene's potential as effective plasticizers for PLA-PHB composites, offering customized mechanical properties for diverse applications. Understanding these effects is crucial for optimizing composite formulations to meet performance criteria in industrial and commercial settings. In conclusion, the selection between ATBC and D-limonene should be based on the mechanical demands of the intended application.

[0133] Furthermore, the instant example explored the oxygen and water vapor transmission rates (OTR and WVTR) of PLA-based biocomposite films incorporating68800-437150polyhydroxybutyrate (PHB), hemp fibers, and natural plasticizers (D-limonene and ATBC). Results demonstrate these components significant impact on barrier properties crucial for food packaging. Incorporating PHB into PLA substantially enhances barrier properties, reducing OTR and WVTR compared to pure PLA due to PHB's increased crystallinity. The addition of hemp fibers to PLA-PHB films further decreases both oxygen and water vapor transmission. Natural plasticizers like D-limonene and ATBC improve film flexibility and modify polymer matrix properties. While both plasticizers maintain the OTR and WVTR properties of the composite in the high barrier category, D-limonene exhibits superior performance. Optimizing PLA-based biocomposite film composition with PHB, hemp fibers, and natural plasticizers presents promising avenues for sustainable food packaging solutions.Example 3Synthesis of DMMP-M4sPLAMaterials and Methods

[0134] The instant example provides synthesis of DMMP-M4sPLA, which was completed using 90% L-lactic acid solution in water derived from fermenting sugar beets (Thermo Fisher Scientific, Spain), VoxtarTM M4098% renewable-based pentaerythritol (Perstorp, Sweeden), 98% tin(ll) oxalate powder (Sigma-Aldrich, USA), 99% hydroquinone (Sigma-Aldrich, USA), Methacrylic anhydride, 94%, stab, with ca 0.2% 2,4-dimethyl-6-tert-butylphenol (Thermo Fisher Scientific, USA), 98% dimethyl Methylphosphonate (Sigma-Aldrich, USA), 95% sodium methoxide (Sigma-Aldrich, USA), and 98% tert-Butyl Peroxybenzoate (Thermo Fisher Scientific, Belgium).Formation of 4sPLA Oligomers

[0135] In the instant example, 4sPLA oligomers were synthesized from two starting conditions: 1) purified L-lactic acid. 2) purified L-lactide. The 4sPLA synthesis procedure was kept constant for both starting conditions and conducted using the same reactor set up, as seen in Figure 17. The mass of pure lactic acid was determined by subtracting the mass of the water collected from the original mass of the L-lactic acid solution. At 120°C and a stir speed of 200 rpm, PENTA was added to the three-neck flask until a molar ratio of 1:20 PENTA to L-lactic acid was achieved. Once the PENTA was completely dissolved into solution, 1 % w / w of tin(ll) oxalate powder, with respect to68800-437150total solution mass, was added to the three-neck flask. The temperature within the three-neck flask was ramped at a rate of 20°C an hour until reaching the holding temperature of 160°C. As with the L-lactic acid purification stage, the 4sPLA oligomerization was optimized via examining the FTIR spectra every half hour for 12 hours.Grafting DMMP onto 4sPLA Oligomers

[0136] Before beginning the DMMP grafting process, the temperature of the three-neck flask was lowered to 90°C and the stirring rate was reduced to 150 rpm. DMMP was added dropwise into the three-neck flask until achieving a 1:1 molar ratio of DMMP to PENTA. 2% w / w sodium methoxide, with respect to DMMP, was added to the three-neck flask. The temperature of the three-neck flask was raised to 110°C over the course of an hour and then held for 3-5 hours.Grafting Methacrylate Groups onto DMMP-M4sPLA Oligomers

[0137] Before beginning the MAAH grafting process, the temperature of the three-neck flask was lowered to 100°C. 0.2%w / w of hydroquinone, with respect to the total solution mass, was added to the three-neck flask and allowed to fully dissolve. MAAH was added dropwise to the three-neck flask until a 3:1 molar ratio of MAAH to PENTA was achieved. To push the grafting to completion, it is recommended to use at least a 15% molar excess of MAAH. The temperature of the three-neck flask was raised to 120°C over the course of an hour and was never allowed to achieve a temperature higher than 125°C. Due to the exothermic nature of the MAAH grafting, it was vital to have the temperature controlled over the course of the reaction. The MAAH grafting was carried out over the course of 3-5 hours before excess MAAH removal began. Unreacted MAAH was removed from the three-neck flask via vacuum distillation at a consistent temperature of 120°C and an increased stir rate of 300 rpm. MAAH removal continued until condensation stopped and resin crystals began forming on the walls of the-three neck flask. Once all excess MAAH was removed from the DMMP-M4sPLA resin, the resin was poured from the three-neck flask into temperature-resistant silicone casting molds for cooling. After cooling, the uncured resin was granulized and stored in a cold and dry environment for future use.Priming and Curing DMMP-M4sPLA Resin68800-437150

[0138] The granulated DMMP-M4sPLA resin was added to room temperature chloroform until a 1 :2 weight ratio of resin to chloroform was achieved. 1-2% w / w of the cure initiator, tert-Butyl Peroxybenzoate, was added to the loosened DMMP-M4sPLA resin and allowed to mix at a stir speed of 150 rpm for 30 minutes. The primed DMMP-M4sPLA resin was allowed to rest in silicone casting molds at room temperature within a fume hood until all chloroform was evaporated. After evaporation was completed, the resin-filled silicone molds were placed within a vacuum at 130°C. The temperature was ramped to 170°C and held at that temperature for an hour to ensure cure completion. The cured DMMP-M4sPLA specimens were slowly cooled within the vacuum oven to preserve dimensional stability and reduce internal stresses. The cured DMMP-M4sPLA was removed from the cooled silicone molds and prepared for conditioning. A diagram of DMMP-M4sPLA synthesis methodology is shown in Figure 18.

[0139] Further, resins with varying characteristics can be formulated with modifications of the methods of the instant example. For instance, a resin comprising a core of PENTA and arms of L-Lactic Acid with methacrylate and DMMP end groups can be formulated. The use of L-Lactide as the starting point can provide a resin with fewer impurities, including residual L-lactic acid, L-lactic acid oligomers, and meso-lactide. Further, an average chain length of 2-3 L-Lactic Acid units can be utilized for a molar ratio of PENTA to L-Lactic acid of 1:8 - 1:12. Finally, a tailored amount of flame retardant for a shorter arm length and higher PENTA content can be used for a molar ratio of DMMP to PENTA of 1:1 - 1:2.

[0140] While the present invention is described above in connection with representative or illustrative embodiments, these embodiments are not intended to be exhaustive or to limit the scope of the invention. Rather, the invention is intended to cover all alternatives, modifications and equivalents included within its spirit and scope, as defined by the appended claims.

Claims

68800-417105WHAT IS CLAIMED IS:

1. A bioplastic composition comprising a combination of i) a natural fiber and ii) a resin.

2. The bioplastic composition of claim 1, wherein the composition is processed by compression.

3. The bioplastic composition of claim 1, wherein the composition is processed by extrusion molding.

4. The bioplastic composition of claim 1, wherein the composition is processed by injection molding.

5. The bioplastic composition of claim 1, wherein the compositionprocessed by rotational molding.

6. The bioplastic composition of claim 1, wherein the composition is processed by thermoforming.

7. The bioplastic composition of claim 1, wherein the natural fiber is presented for the combination in a chopped form.

8. The bioplastic composition of claim 1, wherein the natural fiber is presented for the combination in a ground form.

9. The bioplastic composition of claim 1, wherein the natural fiber is presented for the combination in a powdered form.

10. The bioplastic composition of claim 1 , wherein the natural fiber comprises hemp.

11. The bioplastic compositionclaim 1 , wherein the natural fiber comprises hemp fiber powder.

12. The bioplastic composition of claim 11, wherein the hemp fiber powder comprises a mesh size under 45 microns13. The bioplastic composition of claim 11, wherein the hemp fiber powder is dried prior to the combination.

14. The bioplastic composition of claim 11, wherein tensile strength of the bioplastic composition is inversely proportional over the range of hemp fiber powder in the combination.

15. The bioplastic composition of claim 11, wherein the hemp fiber powder provides an increase in biodegradability of the bioplastic composition.68800-41710516. The bioplastic composition of claim 1, wherein the resin comprises a polyethylene (PE).

17. The bioplastic composition of claim 1, wherein the resin comprises a high molecular weight polyethylene (HMWPE).

18. The bioplastic composition of claim 1, wherein the resin comprises an ultra-high molecular weight polyethylene (IIHMWPE).

19. The bioplastic composition of claim 1, wherein the bioplastic composition further comprises a polyethylene wax (PE-wax).

20. The bioplastic composition of claim 19, wherein the PE -wax is presented for the combination as a powder.

21. The bioplastic composition of claim 20, wherein the PE -wax is present in the combination at between 1-5% weight percent.

22. The bioplastic composition of claim 20, wherein the PE -wax is present in the combination at between 2-4% weight percent.

23. The bioplastic composition of claim 20, wherein the PE -wax is present in the combination at between 3-4% weight percent.

24. The bioplastic composition of claim 19, wherein the PE-wax provides an increase in tensile modulus of the bioplastic composition.

25. The bioplastic composition of claim 19, wherein the PE-wax provides an increase in compressive strength performance of the bioplastic composition.

26. A printed circuit board (PCB) comprising a fiber-based material and a polymer, wherein the fiber-based material comprises hemp.

27. The PCB of claim 26, wherein the hemp comprises one or more fibers derived from hemp waste.

28. The PCB of claim 26, wherein the polymer is biodegradable.

29. The PCB of claim 26, wherein the polymer is DMMP-M4sPLA.

30. The PCB of claim 26, wherein the polymer is an end-functionalized homopolymer.

31. The PCB of claim 30, wherein the end-functionalized homopolymer comprises a pentaerythritol core, one or more L-Lactic acid chains, and a combination of methacrylate and dimethyl methylphosphonate end groups.

32. The PCB of claim 26, wherein the polymer is a poly(lactic acid) (PLA) resin.68800-41710533. The PCB of claim 32, wherein the PLA resin is a thermoset PLA resin.

34. The PCB of claim 32, wherein the hemp and the PLA resin are present as a laminate35. The PCB of claim 26, wherein the polymer is a liquid phenolic resin.

36. The PCB of claim 35, wherein the liquid phenolic resin is present as a fiber reinforced plastic (FRP) composite.

37. The PCB of claim 26, wherein the polymer is a lignin-phenolic formaldehyde resole resin.

38. The PCB of claim 37, wherein the lignin-phenolic formaldehyde resole resin comprises 40% lignin.

39. The PCB of claim 37, wherein the lignin-phenolic formaldehyde resole resin comprises a 1.8:1 formaldehyde-phenol ratio.

40. A food packaging material comprising the bioplastic composition of any one of claims 1 to 25.

41. A food packaging material comprising a fiber-based material, a polymeric blend, and a biodegradable plasticizer.

42. The food packaging material of claim 41, wherein the fiber-based material comprises hemp.

43. The food packaging material of claim 42, wherein the hemp comprises one or more unretted hemp fibers.

44. The food packaging material of claim 41, wherein the polymeric blend comprises poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB).

45. The food packaging material of claim 41 , wherein the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC), D-limonene, or a combination thereof.

46. The food packaging material of claim 41 , wherein the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC).

47. The food packaging material of claim 41 , wherein the biodegradable plasticizer comprises D-limonene.

48. The food packaging material of claim 41, wherein i) the polymeric blend comprises poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB); and the biodegradable plasticizer comprises Acetyl Tributyl Citrate (ATBC), D-limonene, or a combination thereof.68800-41710549. The food packaging material of claim 41, wherein the food packaging material is biodegradable.

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