A foam precursor composition

Abstract

The invention relates to a foam precursor composition for forming a foam, the composition comprising: a) a polysaccharide material, wherein the dry weight of the polysaccharide material present in the foam precursor composition is at least 20 wt.%, based on the total dry weight of the foam precursor composition, b) biochar, and c) a blowing agent. The invention extends to methods of forming a foam, foams formed from the foam precursor composition and / or methods, and an articles comprising said foams.

Description

[0001] A FOAM PRECURSOR COMPOSITION

[0002] FIELD

[0003]

[0001] The present invention relates to a foam precursor composition, such as an expanded foam precursor composition. The invention also extends to a method of making a foam, such as an expanded foam, a foam formed from the precursor and / or by said method and an article comprising said foam.

[0004] BACKGROUND

[0005]

[0002] Many products require packaging to protect the contents during transport and storage. There are several known materials which are commonly used for packaging, such as cardboard polystyrene and further plastics.

[0006]

[0003] Expanded polystyrene foam is used widely because it’s light, absorbs impact, and provides thermal insulation. However, polystyrene foam has detriments such as requiring petrochemicals make it, taking hundreds of years to degrade, leaching toxic chemicals and it is very difficult to recycle. The fact that polystyrene foam is non-biodegradable means that it is extremely hazardous to the planet and in particular, wildlife.

[0007]

[0004] Therefore, there is a requirement for packaging articles which can sufficiently protect the contents whilst also not negatively affecting the environment after use. For example, packaging which thermally insulative, strong, and lightweight whilst remaining compostable.

[0008]

[0005] It is an object of aspects of the present invention to provide a solution to one or more of the above-mentioned problems.

[0009] SUMMARY OF THE INVENTION

[0010]

[0006] According to a first aspect of the present invention there is provided a foam precursor composition for forming a foam, the composition comprising: a) a polysaccharide material, wherein the dry weight of the polysaccharide material present in the foam precursor composition is at least 20 wt.%, based on the total dry weight of the foam precursor composition, b) biochar, and c) a blowing agent.

[0011]

[0007] According to a second aspect of the present invention there is provided a method of forming a foam, the method comprising the steps of: i) providing a first foam precursor composition according to the first aspect of the present invention at a temperature of below 25°C; ii) mixing the first foam precursor composition at a temperature of at least 30°C to form a second foam precursor composition, wherein the second foam precursor composition is at least partially gelatinised; and iii) heating the second foam precursor composition to a temperature of at least 100°C to form a foam, such as an expanded foam.

[0012]

[0008] According to a third aspect of the present invention there is provided a foam formed from a foam precursor composition according to the first aspect of the present invention.

[0013]

[0009] According to a fourth aspect of the present invention there is provided a foam formed according to the method of the second aspect of the present invention.

[0014]

[0010] According to a fifth aspect of the present invention there is provided an article comprising a foam according to the first, third and / or fourth aspects of the present invention.

[0015] DESCRIPTION OF THE INVENTION

[0016]

[0011] The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0017]

[0012] The foam precursor composition comprises a polysaccharide material. The polysaccharide material may comprise a starch material and / or collagen, for example. The polysaccharide material may comprise a starch material.

[0018]

[0013] As such, the foam precursor composition may comprise: a) a starch material, wherein the dry weight of the polysaccharide material present in the foam precursor composition is at least 20 wt.%, based on the total dry weight of the foam precursor composition, b) biochar, and c) a blowing agent.

[0019]

[0014] Typically, the starch material is a polymeric carbohydrate (polysaccharide) comprising numerous glucose units joined by glycosidic bonds. As used herein, a “glycosidic bond” refers to an ether group which joins a carbohydrate molecule to another molecule, preferably, a further carbohydrate molecule. The term “collagen” as used herein refers to collagen as well as collagen-derived materials and / or collagen derivatives.

[0020]

[0015] The starch material may be selected from cereal starch, root starch, such as tapioca starch, tuber starch, modified starch, potato starch, corn starch, maize starch, or any combination thereof. Suitably, the starch material comprises tapioca starch.

[0021]

[0016] The dry weight of the polysaccharide material present in the foam precursor composition may be at least 20 wt%, such as at least 25 wt%, such as at least 30 wt%, such as at least 35 wt%, such as at least 40 wt.%, such as at least 42 wt.%, such as at least 44 wt.%, such as at least 45 wt.%, based on the total dry weight of the foam precursor composition.

[0017] The dry weight of the polysaccharide material present in the foam precursor composition may be up to 90 wt%, such as up to 80 wt.%, such as up to 78 wt.%, such as up to 76 wt.%, such as up to 75 wt.%, such as up to 74 wt.%, such as up to 70 wt%, such as up to 60 wt%, such as up to 50 wt%, based on the total dry weight of the foam precursor composition.

[0022]

[0018] The dry weight of the polysaccharide material present in the foam precursor composition may be from 20 to 90 wt%, such as from 20 to 80 wt%, such as from 20 to 78 wt%, such as from 20 to 76 wt%, such as from 20 to 74 wt%, such as from 20 to 70 wt%, such as from 20 to 60 wt%, such as from 20 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 25 to 90 wt%, such as from 25 to 80 wt%, such as from 25 to 78 wt%, such as from 25 to 76 wt%, such as from 25 to 74 wt%, such as from 25 to 70 wt%, such as from 25 to 60 wt%, such as from 25 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 30 to 90 wt%, such as from 30 to 80 wt%, such as from 30 to 78 wt%, such as from 30 to 76 wt%, such as from 30 to 74 wt%, such as from 30 to 70 wt%, such as from 30 to 60 wt%, such as from 30 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 35 to 90 wt%, such as from 35 to 80 wt%, such as from 35 to 78 wt%, such as from 35 to 76 wt%, such as from 35 to 74 wt%, such as from 35 to 70 wt%, such as from 35 to 60 wt%, such as from 35 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 40 to 90 wt%, such as from 40 to 80 wt%, such as from 40 to 78 wt%, such as from 40 to 76 wt%, such as from 40 to 74 wt%, such as from 40 to 70 wt%, such as from 40 to 60 wt%, such as from 40 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 42 to 90 wt%, such as from 42 to 80 wt%, such as from 42 to 78 wt%, such as from 42 to 76 wt%, such as from 42 to 74 wt%, such as from 42 to 70 wt%, such as from 42 to 60 wt%, such as from 42 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 44 to 90 wt%, such as from 44 to 80 wt%, such as from 44 to 78 wt%, such as from 44 to 76 wt%, such as from 44 to 74 wt%, such as from 44 to 70 wt%, such as from 44 to 60 wt%, such as from 44 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the polysaccharide material present in the foam precursor composition may be from 45 to 90 wt%, such as from 45 to 80 wt%, such as from 45 to 78 wt%, such as from 45 to 76 wt%, such as from 45 to 74 wt%, such as from 45 to 70 wt%, such as from 45 to 60 wt%, such as from 45 to 50 wt%, based on the total dry weight of the foam precursor composition.

[0019] The dry weight percent of the polysaccharide material present in the foam precursor composition may be from 20 wt.% to 90 wt.%, such as from 20 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0023]

[0020] The dry weight percent of the polysaccharide material present in the foam precursor composition may be at least 40 wt.%, such as from 40 wt.% to 90 wt.%, such as from 40 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0024]

[0021] The dry weight percent of the polysaccharide material present in the foam precursor composition may be at least 50 wt.%, such as from 50 wt.% to 90 wt.%, such as from 50 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0025]

[0022] When the polysaccharide material comprises a starch material, the dry weight of the starch material present in the foam precursor composition may be at least 20 wt%, such as at least 25 wt%, such as at least 30 wt%, such as at least 35 wt%, such as at least 40 wt.%, such as at least 42 wt.%, such as at least 44 wt.%, such as at least 45 wt.%, based on the total dry weight of the foam precursor composition.

[0026]

[0023] When the polysaccharide material comprises a starch material, the dry weight of the starch material present in the foam precursor composition may be up to 90 wt%, such as up to 80 wt.%, such as up to 78 wt.%, such as up to 76 wt.%, such as up to 75 wt.%, such as up to 74 wt.%, such as up to 70 wt%, such as up to 60 wt%, such as up to 50 wt%, based on the total dry weight of the foam precursor composition.

[0027]

[0024] When the polysaccharide material comprises a starch material, the dry weight of the starch material present in the foam precursor composition may be from 20 to 90 wt%, such as from 20 to 80 wt%, such as from 20 to 78 wt%, such as from 20 to 76 wt%, such as from 20 to 74 wt%, such as from 20 to 70 wt%, such as from 20 to 60 wt%, such as from 20 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 25 to 90 wt%, such as from 25 to 80 wt%, such as from 25 to 78 wt%, such as from 25 to 76 wt%, such as from 25 to 74 wt%, such as from 25 to 70 wt%, such as from 25 to 60 wt%, such as from 25 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 30 to 90 wt%, such as from 30 to 80 wt%, such as from 30 to 78 wt%, such as from 30 to 76 wt%, such as from 30 to 74 wt%, such as from 30 to 70 wt%, such as from 30 to 60 wt%, such as from 30 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 35 to 90 wt%, such as from 35 to 80 wt%, such as from 35 to 78 wt%, such as from 35 to 76 wt%, such as from 35 to 74 wt%, such as from 35 to 70 wt%, such as from 35 to 60 wt%, such as from 35 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 40 to 90 wt%, such as from 40 to 80 wt%, such as from 40 to 78 wt%, such as from 40 to 76 wt%, such as from 40 to 74 wt%, such as from 40 to 70 wt%, such as from 40 to 60 wt%, such as from 40 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 42 to 90 wt%, such as from 42 to 80 wt%, such as from 42 to 78 wt%, such as from 42 to 76 wt%, such as from 42 to 74 wt%, such as from 42 to 70 wt%, such as from 42 to 60 wt%, such as from 42 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 44 to 90 wt%, such as from 44 to 80 wt%, such as from 44 to 78 wt%, such as from 44 to 76 wt%, such as from 44 to 74 wt%, such as from 44 to 70 wt%, such as from 44 to 60 wt%, such as from 44 to 50 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the starch material present in the foam precursor composition may be from 45 to 90 wt%, such as from 45 to 80 wt%, such as from 45 to 78 wt%, such as from 45 to 76 wt%, such as from 45 to 74 wt%, such as from 45 to 70 wt%, such as from 45 to 60 wt%, such as from 45 to 50 wt%, based on the total dry weight of the foam precursor composition.

[0028]

[0025] When the polysaccharide material comprises a starch material, the dry weight percent of the starch material present in the foam precursor composition may be from 20 wt.% to 90 wt.%, such as from 20 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0029]

[0026] When the polysaccharide material comprises a starch material, the dry weight percent of the starch material present in the foam precursor composition may be at least 40 wt.%, such as from 40 wt.% to 90 wt.%, such as from 40 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0030]

[0027] When the polysaccharide material comprises a starch material, the dry weight percent of the starch material present in the foam precursor composition may be at least 50 wt.%, such as from 50 wt.% to 90 wt.%, such as from 50 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

[0031]

[0028] The foam precursor composition comprises biochar.

[0032]

[0029] “Biochar” as used herein refers to a carbon-rich, typically granular, material made from organic material and / or biomass that is partially combusted in the presence of limited or no oxygen, such as by pyrolysis or hydrothermal carbonisation, for example. The organic material and / or biomass that is used to form biochar is typically carbonised under high temperatures, typically from about 300-1000°C. The process(es) used to form biochar prevent the carbon present in the biomass being processed from escaping into the environment as greenhouse gases, such as CO2 (such as might happen if the material were burned using conventional combustion) or CH4 (such as might happen if the organic material decomposed). Instead, this carbon is converted into a form that is stable for centuries. Advantageously, each tonne of biochar produced has a greenhouse warming potential of up to -3.6 tonnes CO2 equivalent, meaning it prevents the emission of the equivalent of 3.6 tonnes of CO2 (as either CO2 or methane), and therefore has a positive environmental impact.

[0033]

[0030] It is known to a person skilled in the art that biochar and charcoal are different materials. For example, charcoal is produced at temperatures of ~400°C. In contrast, biochar is produced at higher temperatures from 600-1000°C. The use of higher temperatures to form biochar means that the resultant biochar material contains a more stable form of carbon compared to charcoal. For example, biochar typically has a hydrogen to organic carbon, H / Corg, molar ratio of 0.2 to 0.6, whereas charcoal typically has a H / Corgmolar ratio of greater that 0.6 (wherein a lower H / Corgmolar ratio indicates greater stability of the carbon). The use of higher temperatures to form biochar also means that the resultant biochar material has a larger internal network of pores and channels, resulting in a high surface area. In contrast, charcoal is typically denser and more compact.

[0034]

[0031] The biochar may comprise any suitable biochar, such as biochar formed from any suitable organic material and / or biomass. The biochar may comprise a biochar made from agricultural waste streams or textile waste, for example. The biochar may comprise a biochar formed from waste feedstocks, such as rice husks, wheat straw, woody and other ligninous wastes, spent mycelial substrates, crop waste, manure, other agricultural co-products, vegetable and / or fruit wastes, wood chips and / or combinations thereof. For the avoidance of doubt, in the present context the term “waste feedstock” means organic waste that can be used to produce other materials. The waste feedstock may comprise food waste, biosolids, manure, wood waste, agricultural waste, industrial waste and / or municipal solid waste, for example (on the proviso that said waste feedstock is organic). Advantageously, the foam precursor of the present invention makes use of recyclable material.

[0035]

[0032] In some embodiments, the biochar may comprise a biochar made from waste feedstocks. The use of materials that would otherwise go to waste to form the biochar is advantageous for sustainability.

[0036]

[0033] The biochar may have a particle size of from 100 to 500 pm, such as from 150 to 400 pm, such as from 200 to 300 pm, such as 250 pm. The biochar may have a particle size of up to 500 pm, such as up to 400 pm, such as up to 300 pm, or even up to 250 pm. The biochar may have a particle size of at least 100 pm, such as at least 150 pm, such as at least 200 pm. The biochar may have a particle size of 250 pm.

[0037]

[0034] The dry weight of the biochar present in the foam precursor composition may be at least 10 wt.%, such as at least 12 wt.%, such as at least 14 wt.%, such as at least 15 wt.%, based on the total dry weight of the foam precursor composition.

[0038]

[0035] The dry weight of the biochar present in the foam precursor composition may be up to 80 wt.%, such as up to 70 wt.%, such as up to 68 wt.%, such as up to 66 wt.%, such as up to 64 wt.%, such as up to 62 wt.%, such as up to 60 wt.%, such as up to 58 wt.%, such as up to 56 wt.%, such as up to 54 wt.%, such as up to 52 wt.%, such as up to 50 wt.%, based on the total dry weight of the foam precursor composition.

[0039]

[0036] The dry weight of the biochar present in the foam precursor composition may be from 10 to 80 wt%, such as from 12 to 80 wt%, such as from 14 to 80 wt%, such as from 15 to 80 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 70 wt%, such as from 12 to 70 wt%, such as from 14 to 70 wt%, such as from 15 to 70 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 68 wt%, such as from 12 to 68 wt%, such as from 14 to 68 wt%, such as from 15 to 68 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 66 wt%, such as from 12 to 66 wt%, such as from 14 to 66 wt%, such as from 15 to 66 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 64 wt%, such as from 12 to 64 wt%, such as from 14 to 64 wt%, such as from 15 to 64 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 62 wt%, such as from 12 to 62 wt%, such as from 14 to 62 wt%, such as from 15 to 62 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 60 wt%, such as from 12 to 60 wt%, such as from 14 to 60 wt%, such as from 15 to 60 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 58 wt%, such as from 12 to 58 wt%, such as from 14 to 58 wt%, such as from 15 to 58 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 56 wt%, such as from 12 to 56 wt%, such as from 14 to 56 wt%, such as from 15 to 56 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 54 wt%, such as from 12 to 54 wt%, such as from 14 to 54 wt%, such as from 15 to 54 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 52 wt%, such as from 12 to 52 wt%, such as from 14 to 52 wt%, such as from 15 to 52 wt%, based on the total dry weight of the foam precursor composition. The dry weight of the biochar present in the foam precursor composition may be from 10 to 50 wt%, such as from 12 to 50 wt%, such as from 14 to 50 wt%, such as from 15 to 50 wt%, based on the total dry weight of the foam precursor composition.

[0040]

[0037] The dry weight of the biochar present in the foam precursor composition may be at least 10 wt.%, such as from 10 wt.% to 70 wt.%., such as from 10 wt.% to 60 wt.%. such as from 10 wt.% to 50 wt.%, based on the total dry weight of the foam precursor composition.

[0038] The dry weight of the biochar present in the foam precursor composition may be at least 15 wt.%, such as from 15 wt.% to 70 wt.%., such as from 15 wt.% to 60 wt.%. such as from 15 wt.% to 50 wt.%, based on the total dry weight of the foam precursor composition.

[0041]

[0039] The foam precursor composition may be substantially, essentially or completely free of charcoal. By “substantially free” we mean to refer to foam precursor compositions containing less than 1 wt% charcoal, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.5 wt% charcoal, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.1 wt% charcoal, based on the total dry weight of the foam precursor composition.

[0042]

[0040] The foam precursor composition may comprise any suitable weight ratio of biochar to polysaccharide material, such as starch material. The weight ratio of biochar to polysaccharide material, such as starch material, may be from 1 :5 to 1 :1. For example, the weight ratio of biochar to polysaccharide material, such as starch material, may be 1 :5, 1 :4, 1 :3, 1 :2 or 1 :1 .

[0043]

[0041] In some embodiments, the foam precursor composition may comprise no (i.e., 0 wt%) charcoal, based on the total dry weight of the foam precursor composition.

[0044]

[0042] The foam precursor composition comprises a blowing agent. The blowing agent may comprise any suitable blowing agent. The blowing agent may comprise water, an alcohol, such as methanol, ethanol, butanol, etc., and / or combinations thereof. Preferably, the blowing agent may comprise water.

[0045]

[0043] The blowing agent may comprise water. The blowing agent may comprise at least 50 wt%, such as at least 60 wt%, such as at least 70 wt%, such as at least 80 wt%, such as at least 90 wt%, such as at least 95 wt%, such as at least 99 wt%, or even 100 wt% water based on the total weight of the blowing agent. In some embodiments, the blowing agent may comprise water and one or more further blowing agent(s), such as in the amounts defined herein. In some embodiments, the blowing agent may comprise 100 wt% water based on the total weight of the blowing agent.

[0046]

[0044] The weight of the blowing agent present in the foam precursor composition may be at least 35 wt%, such as at least 40 wt.%, such as at least 42 wt.%, such as at least 44 wt.%, such as at least 45 wt.%, based on the total weight of the foam precursor composition.

[0047]

[0045] The weight of the blowing agent present in the foam precursor composition may be up to 80 wt.%, such as up to 78 wt.%, such as up to 76 wt.%, such as up to 75 wt.%, such as up to 74 wt.%, based on the total weight of the foam precursor composition.

[0048]

[0046] The weight of the blowing agent present in the foam precursor composition may be from 35 to 80 wt%, such as from 35 to 78 wt%, such as from 35 to 76 wt%, such as from 35 to 75 wt%, such as from 35 to 74 wt%, based on the total weight of the foam precursor composition. The weight of the blowing agent present in the foam precursor composition may be from 40 to 80 wt%, such as from 40 to 78 wt%, such as from 40 to 76 wt%, such as from 40 to 75 wt%, such as from 40 to 74 wt%, based on the total weight of the foam precursor composition. The weight of the blowing agent present in the foam precursor composition may be from 42 to 80 wt%, such as from 42 to 78 wt%, such as from 42 to 76 wt%, such as from 42 to 75 wt%, such as from 42 to 74 wt%, based on the total weight of the foam precursor composition. The weight of the blowing agent present in the foam precursor composition may be from 44 to 80 wt%, such as from 44 to 78 wt%, such as from 44 to 76 wt%, such as from 44 to 75 wt%, such as from 44 to 74 wt%, based on the total weight of the foam precursor composition. The weight of the blowing agent present in the foam precursor composition may be from 45 to 80 wt%, such as from 45 to 78 wt%, such as from 45 to 76 wt%, such as from 45 to 75 wt%, such as from 45 to 74 wt%, based on the total weight of the foam precursor composition. The weight of the blowing agent present in the foam precursor composition may be from 35 wt.% to 60 wt.%, such as from 40 wt.% to 50 wt.%, based on the total weight of the foam precursor composition.

[0049]

[0047] The dry ingredients (biochar and polysaccharide material, such as starch material) are typically present in an amount of 50 wt.% of the total weight of the foam precursor composition. In otherwords, the ratio of dry ingredients to blowing agent may typically be 1 :1.

[0050]

[0048] The weight of the polysaccharide material present in the foam precursor composition may be at least 10 wt%, such as at least 12 wt%, such as at least 15 wt%, such as at least 17 wt%, such as at least 20 wt.%, such as at least 21wt.%, such as at least 22 wt.%, such as at least 23 wt.%, based on the total weight of the foam precursor composition.

[0051]

[0049] The weight of the polysaccharide material present in the foam precursor composition may be up to 45 wt%, such as up to 40 wt.%, such as up to 39 wt.%, such as up to 38 wt.%, such as up to 37 wt.%, such as up to 36 wt.%, such as up to 35 wt%, such as up to 30 wt%, such as up to 25 wt%, based on the total weight of the foam precursor composition.

[0052]

[0050] The weight of the polysaccharide material present in the foam precursor composition may be from 10 to 45 wt%, such as from 10 to 40 wt%, such as from 10 to 39 wt%, such as from 10 to 38 wt%, such as from 10 to 37 wt%, such as from 10 to 35 wt%, such as from 10 to 30 wt%, such as from 10 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 12 to 45 wt%, such as from 40 wt%, such as from 12 to 39 wt%, such as from 12 to 38 wt%, such as from 12 to 37 wt%, such as from 12 to 35 wt%, such as from 12 to 30 wt%, such as from 12 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 15 to 45 wt%, such as from 15 to 40 wt%, such as from 15 to 39 wt%, such as from 15 to 38 wt%, such as from 15 to 37 wt%, such as from 15 to 35 wt%, such as from 15 to 30 wt%, such as from 15 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 17 to 45 wt%, such as from 17 to 40 wt%, such as from 17 to 39 wt%, such as from 17 to 38 wt%, such as from 17 to 37 wt%, such as from 17 to 35 wt%, such as from 17 to 30 wt%, such as from 17 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 20 to 45 wt%, such as from 20 to 40 wt%, such as from 20 to 39 wt%, such as from 20 to 38 wt%, such as from 20 to 37 wt%, such as from 20 to 35 wt%, such as from 20 to 30 wt%, such as from 20 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 21 to 45 wt%, such as from 21 to 40 wt%, such as from 21 to 39 wt%, such as from 21 to 38 wt%, such as from 21 to 37 wt%, such as from 21 to 35 wt%, such as from 21 to 30 wt%, such as from 21 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 22 to 45 wt%, such as from 22 to 40 wt%, such as from 22 to 39 wt%, such as from 22 to 38 wt%, such as from 22 to 37 wt%, such as from 22 to 35 wt%, such as from 22 to 30 wt%, such as from 22 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the polysaccharide material present in the foam precursor composition may be from 23 to 45 wt%, such as from 23 to 40 wt%, such as from 23 to 39 wt%, such as from 23 to 38 wt%, such as from 23 to 37 wt%, such as from 23 to 35 wt%, such as from 23 to 30 wt%, based on the total weight of the foam precursor composition.

[0053]

[0051] The weight percent of the polysaccharide material present in the foam precursor composition may be from 10 wt.% to 45 wt.%, such as from 10 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0054]

[0052] The weight percent of the polysaccharide material present in the foam precursor composition may be at least 20 wt.%, such as from 20 wt.% to 45wt.%, such as from 20 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0055]

[0053] The weight percent of the polysaccharide material present in the foam precursor composition may be at least 25 wt.%, such as from 25 wt.% to 45 wt.%, such as from 25 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0056]

[0054] When the polysaccharide material comprises a starch material, the weight of the starch material present in the foam precursor composition may be at least 10 wt%, such as at least 12 wt%, such as at least 15 wt%, such as at least 17 wt%, such as at least 20 wt.%, such as at least 21wt.%, such as at least 22 wt.%, such as at least 23 wt.%, based on the total weight of the foam precursor composition.

[0057]

[0055] When the polysaccharide material comprises a starch material, the weight of the starch material present in the foam precursor composition may be up to 45 wt%, such as up to 40 wt.%, such as up to 39 wt.%, such as up to 38 wt.%, such as up to 37 wt.%, such as up to 36 wt.%, such as up to 35 wt%, such as up to 30 wt%, such as up to 25 wt%, based on the total weight of the foam precursor composition.

[0058]

[0056] When the polysaccharide material comprises a starch material, the weight of the starch material present in the foam precursor composition may be from 10 to 45 wt%, such as from 10 to 40 wt%, such as from 10 to 39 wt%, such as from 10 to 38 wt%, such as from 10 to 37 wt%, such as from 10 to 35 wt%, such as from 10 to 30 wt%, such as from 10 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 12 to 45 wt%, such as from 40 wt%, such as from 12 to 39 wt%, such as from 12 to 38 wt%, such as from 12 to 37 wt%, such as from 12 to 35 wt%, such as from 12 to 30 wt%, such as from 12 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 15 to 45 wt%, such as from 15 to 40 wt%, such as from 15 to 39 wt%, such as from 15 to 38 wt%, such as from 15 to 37 wt%, such as from 15 to 35 wt%, such as from 15 to 30 wt%, such as from 15 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 17 to 45 wt%, such as from 17 to 40 wt%, such as from 17 to 39 wt%, such as from 17 to 38 wt%, such as from 17 to 37 wt%, such as from 17 to 35 wt%, such as from 17 to 30 wt%, such as from 17 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 20 to 45 wt%, such as from 20 to 40 wt%, such as from 20 to 39 wt%, such as from 20 to 38 wt%, such as from 20 to 37 wt%, such as from 20 to 35 wt%, such as from 20 to 30 wt%, such as from 20 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 21 to 45 wt%, such as from 21 to 40 wt%, such as from 21 to 39 wt%, such as from 21 to 38 wt%, such as from 21 to 37 wt%, such as from 21 to 35 wt%, such as from 21 to 30 wt%, such as from 21 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 22 to 45 wt%, such as from 22 to 40 wt%, such as from 22 to 39 wt%, such as from 22 to 38 wt%, such as from 22 to 37 wt%, such as from 22 to 35 wt%, such as from 22 to 30 wt%, such as from 22 to 25 wt%, based on the total weight of the foam precursor composition. The weight of the starch material present in the foam precursor composition may be from 23 to 45 wt%, such as from 23 to 40 wt%, such as from 23 to 39 wt%, such as from 23 to 38 wt%, such as from 23 to 37 wt%, such as from 23 to 35 wt%, such as from 23 to 30 wt%, based on the total weight of the foam precursor composition.

[0059]

[0057] When the polysaccharide material comprises a starch material, the weight of the starch material present in the foam precursor composition may be from 10 wt.% to 45 wt.%, such as from 10 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0058] When the polysaccharide material comprises a starch material, the weight of the starch material present in the foam precursor composition may be at least 20 wt.%, such as from 20 wt.% to 45wt.%, such as from 20 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0060]

[0059] When the polysaccharide material comprises a starch material, the weight of the starch material in the foam precursor composition may be at least 25 wt.%, such as from 25 wt.% to 45 wt.%, such as from 25 wt.% to 40 wt.%, based on the total weight of the foam precursor composition.

[0061]

[0060] The weight of the biochar present in the foam precursor composition may be at least 5 wt.%, such as at least 6 wt.%, such as at least 7 wt.%, such as at least 8 wt.%, based on the total weight of the foam precursor composition.

[0062]

[0061] The weight of the biochar present in the foam precursor composition may be up to 40 wt.%, such as up to 35 wt.%, such as up to 34 wt.%, such as up to 33 wt.%, such as up to 32 wt.%, such as up to 31 wt.%, such as up to 30 wt.%, such as up to 29 wt.%, such as up to 28 wt.%, such as up to 27 wt.%, such as up to 26 wt.%, such as up to 25 wt.%, based on the total weight of the foam precursor composition.

[0063]

[0062] The weight of the biochar present in the foam precursor composition may be from 5 to 40 wt.%, such as from 6 to 40 wt.%, such as from 7 to 40 wt.%, such as from 8 to 40 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 35 wt.%, such as from 6 to 35 wt.%, such as from 7 to 35 wt.%, such as from 8 to 35 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 34 wt.%, such as from 6 to 34 wt.%, such as from 7 to 34 wt.%, such as from 8 to 34 wt.%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 33 wt.%, such as from 6 to 33 wt.%, such as from 7 to 33 wt.%, such as from 8 to 33 wt.%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 32 wt%, such as from 6 to 32 wt%, such as from 7 to 32 wt%, such as from 8 to 32 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 31 wt%, such as from 6 to 31 wt%, such as from 7 to 31 wt%, such as from 8 to 31 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 30 wt%, such as from 6 to 30 wt%, such as from 7 to 30 wt%, such as from 8 to 30 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 29 wt%, such as from 6 to 29 wt%, such as from 7 to 29 wt%, such as from 8 to 29 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 28 wt%, such as from 6 to 28 wt%, such as from 7 to 28 wt%, such as from 8 to 28 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 27 wt%, such as from 6 to 27 wt%, such as from 7 to 27 wt%, such as from 8 to 27 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 26 wt%, such as from 6 to 26 wt%, such as from 7 to 26 wt%, such as from 8 to 26 wt%, based on the total weight of the foam precursor composition. The weight of the biochar present in the foam precursor composition may be from 5 to 25 wt%, such as from 6 to 25 wt%, such as from 7 to 25 wt%, such as from 8 to 25 wt%, based on the total weight of the foam precursor composition.

[0064]

[0063] The weight of the biochar present in the foam precursor composition may be at least 5 wt.%, such as from 5 wt.% to 35 wt.%., such as from 5 wt.% to 30 wt.%. such as from 5 wt.% to 25 wt.%, based on the total weight of the foam precursor composition.

[0065]

[0064] The foam precursor composition may further comprise a salt. The salt may comprise any suitable salt. The salt may comprise a Group 1 metal salt and / or a Group 2 metal salt, for example a Group 1 metal salt. The salt may comprise a Group 1 and / or Group 2 metal fluoride, chloride, bromide and / or iodide salt, for example a Group 1 metal fluoride, chloride, bromide and / or iodide salt. Preferably, the salt may comprise NaCI.

[0066]

[0065] Without being bound by theory, the presence of the salt in the foam precursor composition may advantageously improve the expansion speed of the foam precursor composition, thus providing an improved expanded foam. For example, when water is used as some or all of the blowing agent, the presence of a salt may alter the behaviour of the water by lowering its boiling point, thereby improving the expansion properties of the foam precursor composition to form an improved expanded foam.

[0067]

[0066] When present, the dry weight of the salt present in the foam precursor composition may be at least 1 wt.%, such as at least 1.25 wt.%, such as at least 1.5 wt.%, such as at least 1.75 wt.%, such as at least 2 wt.%, based on the total dry weight of the foam precursor composition.

[0068]

[0067] When present, the dry weight of the salt present in the foam precursor composition may be up to 10 wt.%, such as up to 9.5 wt.%, such as up to 9 wt.%, such as up to 8.5 wt.%, such as up to 8 wt.%, based on the total dry weight of the foam precursor composition.

[0069]

[0068] When present, the dry weight of the salt present in the foam precursor composition may be from 1 to 10 wt%, such as from 1 to 9.5 wt%, such as from 1 to 9 wt%, such as from 1 to 8.5 wt%, such as from 1 to 8 wt%, based on the total dry weight of the foam precursor composition. When present, the dry weight of the salt present in the foam precursor composition may be from 1 .25 to 10 wt%, such as from 1 .25 to 9.5 wt%, such as from 1 .25 to 9 wt%, such as from 1 .25 to 8.5 wt%, such as from 1.25 to 8 wt%, based on the total dry weight of the foam precursor composition. When present, the dry weight of the salt present in the foam precursor composition may be from 1.5 to 10 wt%, such as from 1.5 to 9.5 wt%, such as from 1.5 to 9 wt%, such as from 1.5 to 8.5 wt%, such as from 1.5 to 8 wt%, based on the total dry weight of the foam precursor composition. When present, the dry weight of the salt present in the foam precursor composition may be from 1 .75 to 10 wt%, such as from 1 .75 to 9.5 wt%, such as from 1 .75 to 9 wt%, such as from 1 .75 to 8.5 wt%, such as from 1 .75 to 8 wt%, based on the total dry weight of the foam precursor composition. When present, the dry weight of the salt present in the foam precursor composition may be from 2 to 10 wt%, such as from 2 to 9.5 wt%, such as from 2 to 9 wt%, such as from 2 to 8.5 wt%, such as from 2 to 8 wt%, based on the total dry weight of the foam precursor composition. When present, the dry weight of the salt present in the foam precursor composition may be from 1 wt.% to 10 wt.%., such as from 2 wt.% to 8 wt.%, based on the total dry weight of the foam precursor composition.

[0070]

[0069] The foam precursor may further comprise one or more additives. For example, the foam precursor composition may further comprise one or more materials selected from a plasticizer, nucleating agent, strength adjusting agent, viscosity modifier, adhesion promoter, processing aid, filler, flame retardant agents, anti-fungal agents, mould inhibitors, or any combination thereof.

[0071]

[0070] The foam precursor composition may further comprise a plasticizer. The plasticizer may be any suitable plasticizer. Advantageously, the use of a plasticizer may improve the properties of the final foam, for example by making the material softer and / or more flexible. Suitable plasticizers will be known to the person skilled in the art. Examples of suitable plasticizers include, but are not limited to, polyols, such as glycerol, for example, ortho phthalates, terephthalates, trimellitates, adipates, sebacates, organophosphates, esters, such as 1 ,2- cyclohexane dicarboxylic acid diisononyl ester, alkyl sulphonic acid phenyl ester and triethylene glycol di-2-ethylhexanoate and bis(2-ethylhexyl) cyclohexane-1 ,4-dicarboxylate, for example, and combinations thereof.

[0072]

[0071] In some embodiments, the plasticizer may comprise glycerol.

[0073]

[0072] The plasticizer, when present, may be used in the foam precursor composition in amounts from 1 wt.% to 5 wt.%, such as from 1.5 to 4 wt.%, based on the total weight of the foam precursor composition.

[0074]

[0073] The foam precursor composition may comprise low levels of polyalkylene, such as polyethylene and polypropylene. For example, the foam precursor composition may comprise less than 50, 45, 40, 35, 30, 25, 20, 15, 10 or 5 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition.

[0075]

[0074] The foam precursor composition may be substantially, essentially or completely free of polyalkylene, such as polyethylene and polypropylene. By “substantially free” we mean to refer to foam precursor compositions containing less than 1 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.5 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.1 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition.

[0076]

[0075] The foam precursor composition may comprise 0 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition.

[0077]

[0076] The foam precursor composition may comprise low levels of polyvinyl ester, such as polyvinyl acetate. For example, the foam precursor composition may comprise less than 50, 45, 40, 35, 30, 25, 20, 15, 10 or 5 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition.

[0078]

[0077] The foam precursor composition may be substantially, essentially or completely free of polyvinyl ester, such as polyvinyl acetate. By “substantially free” we mean to refer to foam precursor compositions containing less than 1 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.5 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition. By “completely free” we mean to refer to foam precursor compositions containing less than 0.1 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition, based on the total dry weight of the foam precursor composition.

[0079]

[0078] The foam precursor composition may comprise 0 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition.

[0080]

[0079] According the second aspect of the present invention there is provided a method of forming a foam. Suitable features of the second aspect of the present invention may be as defined herein in relation to the first aspect of the present invention. For the avoidance of doubt, it will be appreciated that the first foam precursor composition of the second aspect of the present invention is equivalent to the foam precursor composition of the first aspect of the present invention.

[0081]

[0080] The first foam precursor composition is mixed at a temperature of at least 30°C, in step ii). For example, the first foam precursor composition may be mixed at a temperature of at least 35°C, such as at least 40°C, such as at least 45°C, such as at least 50°C. Preferably, the first foam precursor composition may be mixed at a temperature of at least 50°C.

[0082]

[0081] The first foam precursor composition may be mixed at a temperature of up to 100°C, in step ii). For example, the first foam precursor composition may be mixed at a temperature of up to 95°C, such as up to 90°C, such as up to 85°C, such as up to 80°C, such as up to 75°C, such as up to 70°C.

[0082] The first foam precursor may be mixed at a temperature of from 30 to 100°C, such as from 30 to 90°C, such as from 30 to 85°C, such as from 30 to 80°C, such as from 30 to 75°C, such as from 30 to 70°C, in step ii). The first foam precursor may be mixed at a temperature of from 35 to 100°C, such as from 35 to 90°C, such as from 35 to 85°C, such as from 35 to 80°C, such as from 35 to 75°C, such as from 35 to 70°C, in step ii). The first foam precursor may be mixed at a temperature of from 40 to 100°C, such as from 40 to 90°C, such as from 40 to 85°C, such as from 40 to 80°C, such as from 40 to 75°C, such as from 40 to 70°C, in step ii). The first foam precursor may be mixed at a temperature of from 45 to 100°C, such as from 45 to 90°C, such as from 45 to 85°C, such as from 45 to 80°C, such as from 45 to 75°C, such as from 45 to 70°C, in step ii). The first foam precursor may be mixed at a temperature of from 50 to 100°C, such as from 50 to 90°C, such as from 50 to 85°C, such as from 50 to 80°C, such as from 50 to 75°C, such as from 50 to 70°C, in step ii). The first foam precursor composition may be mixed at a temperature of from 30 to 100°C, in step ii). For example, the first foam precursor composition may be mixed at a temperature of from 35 to 95°C, such as from 40 to 90°C, or from 45 to 85°C, in step ii). Suitably, the first foam precursor composition may be mixed at a temperature of from 50 to 80°C, in step ii). Suitably, the first foam precursor composition may be mixed at a temperature of from 50 to 60°C, in step ii).

[0083]

[0083] Suitably, by mixing the first foam precursor composition in step ii) at a temperature above room temperature, such as at least 30°C or at least 50°C, for example, the first foam precursor composition becomes at least partially gelatinised to form a second precursor composition. The process of gelatinisation will be well known to a person skilled in the art. Typically, the polysaccharide material, such as starch material, present in the first foam precursor composition is at least partially gelatinised by the process of breaking down the intermolecular bonds of the polysaccharide, such as starch, molecules, causing the thickness of the first foam precursor composition to increase. Suitably, therefore, the second foam precursor composition has a thicker consistency than the first foam precursor composition. The relative thickness of the first and second foam precursor compositions may be determined by any suitable method. For example, the relative thickness of the first and second foam precursor compositions may be determined visually, mechanically, physically and / or experimentally. For example, a person skilled in the art may determine that the second foam precursor composition is at least partially gelatinised by observing an increase in thickness visually and / or physically (such as by stirring the first and second foam precursor compositions, or the like). For example, a person skilled in the art may determine the relative thickness experimentally by measuring the viscosity of each of the first and second foam precursor compositions (wherein the viscosity of the first foam precursor composition is lower than the viscosity of the second foam precursor composition.

[0084]

[0084] Suitably, mixing the first foam precursor composition in step ii) is performed at a temperature below the boiling point of the blowing agent. For example, when the blowing agent is water, mixing the first foam precursor composition in step ii) may be performed at a temperature below 100°C.

[0085]

[0085] The first foam precursor composition may be mixed in step ii) for any suitable time period. For example, the first foam precursor composition may be mixed for a time period of from 2 to 10 minutes, such as from 3 to 5 minutes, in step ii). For example, the first foam precursor composition may be mixed for 2, 3, 4, 5, 6, 7, 8, 9 or 10 minutes, in step ii).

[0086]

[0086] Step ii) is operable to cause the thickness of the first foam precursor composition to increase due to, at least partial, gelatinisation.

[0087]

[0087] In some embodiments, the method may further comprise the step, iia), of increasing the moisture content of the second foam precursor composition prior to step iii). As such, the method may comprise the steps of: i) providing a first foam precursor composition according to the first aspect of the present invention at a temperature of below 25 °C; ii) mixing the first foam precursor composition at a temperature of at least 30°C to form a second foam precursor composition, wherein the second foam precursor composition is at least partially gelatinised; iia) increasing the moisture content of the second foam precursor composition; and iii) heating the second foam precursor composition to a temperature of at least 100°C to form a foam, such as an expanded foam.

[0088]

[0088] The moisture content of the second foam precursor composition may be increased by any suitable method, in step iia). For example, the moisture content of the second foam precursor composition may be increased through exposure to wet steam, such as at a controlled temperature and humidity. In some embodiments, the moisture content of the second foam precursor composition may be increased by exposure to wet steam at a temperature of at least 60°C, such as at least 70°C, such as from 60 to 80°C. Advantageously, increasing the moisture content of the second foam precursor composition may form a substantially fully gelatinised second foam precursor composition.

[0089]

[0089] In some embodiments, the method may further comprise the step, iib), of forming the second foam precursor composition into pellets prior to step iii). By “pellet” in this context is meant a particle, typically created by compressing and / or cutting an original material into smaller parts. As such, the method may comprise the steps of: i) providing a first foam precursor composition according to the first aspect of the present invention at a temperature of below 25 °C; ii) mixing the first foam precursor composition at a temperature of at least 30°C to form a second foam precursor composition, wherein the second foam precursor composition is at least partially gelatinised; iia) optionally increasing the moisture content of the second foam precursor composition; iib) pelletising the second foam precursor composition; and iii) heating the second foam precursor composition to a temperature of at least 100°C to form a foam, such as an expanded foam.

[0090]

[0090] Suitably, the pelletising of the second foam precursor composition comprises extruding the second foam precursor composition and / or passing the second foam precursor composition through a cutting tool.

[0091]

[0091] In some embodiments, the method may further comprise the step, iic), of drying the second foam precursor composition formed in step ii) and / or iia), if the latter step is used, and / or the pellets formed in step iib), if this step is used, prior to step iii). As such, the method may comprise the steps of: i) providing a foam precursor composition according to the first aspect of the present invention at a temperature of below 25 °C; ii) mixing the first foam precursor composition at a temperature of at least 30°C to form a second foam precursor composition, wherein the second foam precursor composition is at least partially gelatinised ; iia) optionally increasing the moisture content of the second foam precursor composition; iib) optionally pelletising the second foam precursor composition to form pellets; iic) drying the second foam precursor composition formed in step ii) and / or iia) and / or the pellets formed in step iib); and iii) heating the second foam precursor composition and / or the pellets to a temperature of at least 100°C to form a foam, such as an expanded foam.

[0092]

[0092] The pellets formed in step iib) may be dried in step iic) such that the moisture content of the pellets is decreased. The moisture content of the pellets after the drying step, step iic), may be up to 20 wt.%, such as up to 15 wt.%, such as up to 12 wt.%, based on the total weight of the pellets. The moisture content of pellets may be decreased by any suitable method. For example, the moisture content of pellets may be decreased by maintaining a sufficient air flow in a controlled humidity environment.

[0093]

[0093] The second foam precursor composition formed in step ii) and / or iia) may be dried by any suitable method, in step iic). For example, step iic) may comprise drying the second foam precursor composition formed in step ii) and / or iia) in a dehydrator. For example, step iic) may comprise exposing the second foam precursor composition formed in step ii) and / or iia) to a suitable temperature. In some embodiments, the second foam precursor composition formed in step ii) and / or iia) may be dried by exposure to a temperature of at least 30°C, such as at least 35°C, such as at least 40°C, such as at least 45°C, such at least 50°C. Preferably, the second foam precursor composition formed in step ii) and / or iia) may be dried by exposure to a temperature of 45 to 55°C, such as 48 to 52°C, such as 50°C.

[0094] The second foam precursor composition formed in step ii) and / or iia) may be dried for any suitable time, in step iic). It will be appreciated by a person skilled in the art that a suitable time period may depend on the moisture-content of the second foam precursor composition prior to the drying step and / or the method used to perform the drying step. Suitably, the second foam precursor composition formed in step ii) and / or iia) may be dried until the water content of the second foam precursor composition may be from 5 wt.% to 25 wt.%. In some embodiments, the second foam precursor composition formed in step ii) and / or iia) may be dried for a time period from 10 hours to 48 hours, in step iic). For example, the second foam precursor composition formed in step ii) and / or iia) may be dried for at least 10 hours, such at least 15 hours, such as at least 20 hours, such as at least 22 hours, in step iic). For example, the second foam precursor composition formed in step ii) and / or iia) may be dried for a time period of up to 48 hours, such as up to 36 hours, such as up to 30 hours, such as up to 25 hours, in step iic). For example, the second foam precursor composition formed in step ii) and / or iia) may be dried for a time period of from 15 hours to 36 hours, such as from 20 hours to 30 hours, such as for 24 hours, in step iic).

[0094]

[0095] The method of the second aspect of the present invention comprises the step iii) of heating the second foam precursor composition to a temperature of at least 100°C to form a foam, such as an expanded foam. For the avoidance of doubt, reference herein to “the second foam precursor composition” in relation to step iii) includes the second foam precursor composition formed in any one or more of steps ii), iia), iib) and iic) and, thus, optionally includes the material on the form of pellets. The second foam precursor composition may be transferred, such as injected, to a mould prior to step iii). The second foam precursor composition may be transferred, such as injected, to a mould prior to step iia) and / or step iic), if present. In some embodiments, the pellets formed in step iib) and / or iic), if present, may be transferred, such as injected, into a mould prior to step iii). Advantageously, the use of a mould may allow for a foam to be formed in a specific shape.

[0095]

[0096] The second foam precursor composition is heated to a temperature of at least 100°C, in step iii). For example, the second foam precursor composition may be heated to a temperature of at least 105°C, such as at least 110°C, in step iii). For example, the second foam precursor composition may be heated to a temperature of up to 200°C, such as up to 175°C, such as up to 150°C, such as up to 130°C, such as up to 125°C, such as up to 120°C, such as up to 115°C, in step iii). The second foam precursor composition may be heated to a temperature from 100 to 200°C, such as from 100 to 175°C, such as from 100 to 150°C, such as from 100 to 130°C, such as from 100 to 125°C, such as from 100 to 120°C, such as from 100 to 115°C, in step iii). The second foam precursor composition may be heated to a temperature from 105 to 200°C, such as from 105 to 175°C, such as from 105 to 150°C, such as from 105 to 130°C, such as from 105 to 125°C, such as from 105 to 120°C, such as from 105 to 115°C, in step iii). The second foam precursor composition may be heated to a temperature from 110 to 200°C, such as from 110 to 175°C, such as from 110 to 150°C, such as from 110 to 130°C, such as from 110 to 125°C, such as from 110 to 120°C, such as from 110 to 115°C, in step iii). The second foam precursor composition may be heated to a temperature of from 100 to 130°C, such as from 105 to 125°C, such as from 110 to 120°C, such as to 115°C, in step iii).

[0096]

[0097] The second foam precursor composition may be heated by any suitable method in step iii). For example, the second foam precursor composition may be heated by microwave radiation, hot air, heat press and / or extrusion methods in step iii). Preferably, the second foam precursor composition may be heated by exposure to microwave radiation in step iii). Advantageously, the use of microwave radiation may allow for the rapid and / or even distribution of heat thus forming a foam with a substantially uniform structure.

[0097]

[0098] When heated by exposure to microwave radiation in step iii), the microwave radiation may be at any suitable power. For example, the second foam precursor composition may be heated by exposure to microwave radiation at a power of at least 600W, such as at least 700W, such as at least 800W.

[0098]

[0099] When heated by exposure to microwave radiation in step iii), the second foam precursor composition may be exposed to the microwave radiation for any suitable time period. For example, the second foam precursor composition may be exposed to microwave radiation for a time period of at least 10 seconds, such as at least 15 seconds, such as at least 20 seconds, such as at least 25 seconds, such as at least 30 seconds, in step iii). For example, the second foam precursor composition may be exposed to microwave radiation for a time period up to 240 seconds, such as up to 210 seconds, such as at up to 180 seconds, such as up to 150 seconds, such as up to 120 seconds, such as up to 90 seconds, in step iii). The second foam precursor composition may be exposed to microwave radiation for a time period from 10 to 240 seconds, such as from 10 to 210 seconds, such as from 10 to 180 seconds, such as from 10 to 150 seconds, such as from 10 to 120 seconds, such as from 10 to 90 seconds. The second foam precursor composition may be exposed to microwave radiation for a time period from 15 to 240 seconds, such as from 15 to 210 seconds, such as from 15 to 180 seconds, such as from 15 to 150 seconds, such as from 15 to 120 seconds, such as from 15 to 90 seconds. The second foam precursor composition may be exposed to microwave radiation for a time period from 20 to 240 seconds, such as from 20 to 210 seconds, such as from 20 to 180 seconds, such as from 20 to 150 seconds, such as from 20 to 120 seconds, such as from 20 to 90 seconds. The second foam precursor composition may be exposed to microwave radiation for a time period from 25 to 240 seconds, such as from 25 to 210 seconds, such as from 25 to 180 seconds, such as from 25 to 150 seconds, such as from 25 to 120 seconds, such as from 25 to 90 seconds. The second foam precursor composition may be exposed to microwave radiation for a time period from 30 to 240 seconds, such as from 30 to 210 seconds, such as from 30 to 180 seconds, such as from 30 to 150 seconds, such as from 30 to 120 seconds, such as from 30 to 90 seconds. The second foam precursor composition may be exposed to microwave radiation for a time period from 15 to 90 seconds, such as 30 to 60 seconds, in step iii).

[0099]

[0100] It will be appreciated by a person skilled in the art that the time period for which the second foam precursor composition is heated may suitably depend upon the amount of first and / or second foam precursor composition, i.e., a larger amount of second foam precursor composition may typically be heated for a longer period of time compared to a smaller amount of first and / or second foam precursor composition.

[0100]

[0101] For example, the second precursor foam composition may be exposed to heat, by any of the methods defined above or otherwise, for any of the time periods defined above per 100 grams (g) of the total weight of the first precursor foam composition. For example, the second precursor foam composition may be heated by exposure to microwave radiation, such as at a power of at least 600W, 700W or 800W, for any of the time periods defined above per 100 grams (g) of the total weight of the first precursor foam composition.

[0101]

[0102] According to the third aspect of the present invention there is provided a foam formed from the foam precursor composition according to the first aspect of the present invention. According to a fourth aspect of the present invention there is provided a foam formed according to the method of the second aspect of the present invention. Suitable features of the third and / or fourth aspects of the present invention may be as defined herein in relation to the first and / or second aspects of the present invention.

[0102]

[0103] The present inventors have surprisingly and advantageously found that foams according to the present invention have improved compressive strength compared to known packaging materials. The foams of the present invention may also have good, or improved, thermal insulation properties, be sufficiently strong for their desired end use and / or be lightweight. The foams of the present invention may also advantageously be compostable and have a positive environmental impact (as described above, each tonne of biochar produced has a greenhouse warming potential of up to -3.6 tonnes CO2 equivalent, meaning it prevents the emission of the equivalent of 3.6 tonnes of CO2).

[0103]

[0104] It is known to a person skilled in the art that a foam a two-phase material having gas cells enclosed by a distinct liquid or solid material. By “foam”, in the context of the present invention, is meant a solid polymeric material which has an open and / or closed cell structure. In a closedcell foam, the gas forms discrete pockets which are completely surrounded by the solid material. In an open-cell foam, gas pockets are connected to each other.

[0104]

[0105] In some embodiments, the foam may be an expanded foam. The term “expanded foam”, and like terms as used herein, will be well known to a person skilled in the art. The foam, such as an expanded foam, may have any suitable structure. For example, the foam, such as an expanded foam, may have a uniform structure. In some embodiments, the foam, such as an expanded foam, may have a closed cell structure. For example, the foam, such as an expanded foam, may have a uniform closed cell structure. By the term “closed cell structure”, and like terms as used herein, is meant foams having a cell structure which comprises at least partially closed cells, and thus, has few, if any, fully open cells within the foam material. “Closed cells”, and like terms as used herein, are cells which are entirely enclosed by its walls and do not interconnect with other cells of the foam. It will be appreciated by a person skilled in the art that a foam may comprise both an open and closed cell structure.

[0105]

[0106] The cells, or gas pockets, of the foam may be any suitable size. Suitably, the cells of the foam are on the microscale or larger. More suitably, the cells of the foam are on the microscale. By the term “microscale”, as used herein, is meant that the cells have an average diameter of at least 0.1 micron (pm) and up to 1 millimetre (mm). The cells of the foam may have an average diameter from 1 pm to 1 mm, such as from 10 pm to 1 mm, such as from 10 pm to 900 pm, such as from 20 pm to 800 pm.

[0106]

[0107] According to a fifth aspect of the present invention there is provided an article comprising a foam according to the first, third and / or fourth aspects of the present invention. Suitable features of the fourth aspect of the present invention may be as defined herein in relation to the first, second and / or third aspects of the present invention.

[0107]

[0108] The article may be any suitable article. Suitable articles formed from foam would be well known to a person skilled in the art. For example, the article may be packing and / or packaging. By “packaging”, and like terms as used herein, is meant an article used to contain another item, such as for shipping from a point of manufacture to a consumer, and for subsequent storage by a consumer. By “packing”, and like terms as used herein, is meant a material used to protect an item during storage and / or shipping. For example, the packing may be used to substantially surround an item during storage and / or shipping. For example, the packaging may be for use in the cold supply chain industry (such as packaging for wine, whiskey and / or refrigerated foods).

[0108]

[0109] For example, the article may be insulation, such as an insulation panel or the insulation material used in a structural insulation panel (which will be well known to a person skilled in the art). For example, the article may be insulation used in insulating seed trays for industrial horticulture. For example, the article may be used in and / or as thermal insulation for construction.

[0109]

[0110] The article may be a modelling foam for applications such as set design, sculpture, product design, and architectural modelling, etc.

[0110]

[0111] As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word "about", even if the term does not expressly appear. Also, the recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1 , 2, 3, 4 when referring to, for example, a number of elements, and can also include 1 .5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges subsumed therein.

[0111]

[0112] Singular encompasses plural and vice versa. For example, although reference is made herein to "a" starch material, “a” blowing agent, “a” salt, and the like, one or more of each of these and any other components can be used.

[0112]

[0113] The terms "comprising", "comprises" and "comprised of’ as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. Additionally, although the present invention has been described in terms of “comprising”, the coating compositions detailed herein may also be described as “consisting essentially of’ or “consisting of’.

[0113]

[0114] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

[0114]

[0115] All of the features contained herein may be combined with any of the above aspects in any combination.

[0115]

[0116] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following examples.

[0116] EXAMPLES

[0117]

[0117] Examples 1-4

[0118]

[0118] Foam precursor compositions were prepared by mixing together starch and biochar in the amounts set out in Table 1 until a uniform mixture was formed. 50 g of water, at a temperature of 100 °C, was poured into the dry mixture and mixed to form a foam precursor composition in the form of a slurry. The slurry was then heated to 60°C for 7 minutes while being stirred continuously. After this time, the slurry was poured into a mould. The mould was placed into a steamer, the atmosphere in the steamer being at a temperature of 71 °C, and exposed to steam for 7 minutes. The mould was then removed from the steamer and placed in a dehydrator at a temperature of 45°C for 24 hours. After this time, the mould was removed from the dehydrator and placed in an 800 W microwave oven for 20 seconds to form an expanded foam. Table 1 - Starch to Biochar Ratio in Examples 1-4

[0119] 1based on the total dry weight of the foam precursor composition

[0120]

[0119] Example 5

[0121]

[0120] The method as set out for examples 1-4 was repeated, expect that 40 g starch was mixed together with 10 g of biochar in the first step (resulting in a biochar loading of 20 wt.%, based on the total dry weight of the foam precursor composition).

[0122]

[0121] The resultant foams were tested in accordance with the following methods.

[0123]

[0122] Test Methods

[0124]

[0123] Compressive strength: the load the sample can withstand before it reaches 10% relative deformation. The compressive strength of the foam was tested using a 250kN hydraulic universal test machine.

[0125]

[0124] Density: The density of the foam was measured by calculating the volume of material and mass of material and dividing the mass of material by the volume of material.

[0126]

[0125] Thermal conductivity: The thermal resistivity of the foam was calculated by use of a heat flow meter and tested using a HFM 446 lambda Eco-Line.

[0127]

[0126] Results

[0128]

[0127] The inventive foams of Examples 1-4 were tested against comparative commercial packaging products and the results are set out in Table 2 below.

[0129] Table 2 - Test Results

[0130] 1Data obtained from Biomimetics (Basel), “Mycelium-Based Composite Graded Materials: Assessing the Effects of Time and Substrate Mixture on Mechanical Properties", 2022 Jun; 7(2): 48

[0131] 2Data obtained from Journal of Bionanoscience, “Mycelium Composites: A Review of Engineering Characteristics and Growth Kinetics", Volume 11 , Number 4, August 2017, pp. 241- 257(17)

[0132] 3Data obtained from https: / / mushroompackaqinq.com / pages / technical-data

[0133] 4Data obtained from Y S Lim et al., 2021 IOP Conf. Ser.: Earth Environ. Sci. 920 012030

[0134] 5Data obtained from Engineered Foam Products, Expanded Polystyrene Flooring Insulation, Technical Datasheet

[0135] 6Data obtained from Pohl, A. and Fontana, M., Nordic Pulp and Paper Research Journal Vol 25 no. 4 / 2010, “The mechanical and thermal properties of corrugated paper honeycomb. Part 2 - Analytical determination"

[0136]

[0128] The results show that the foam formed from the foam precursor according to the present invention has an improved compressive strength compared to known packaging materials.

[0137]

[0129] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0130] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0138]

[0131] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0139]

[0132] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1 . A foam precursor composition for forming a foam, the composition comprising: a) a polysaccharide material, wherein the dry weight of the polysaccharide material present in the foam precursor composition is at least 20 wt.%, based on the total dry weight of the foam precursor composition, b) biochar, and c) a blowing agent.

2. A foam precursor according to claim 1 , wherein the polysaccharide is a starch material.

3. A foam precursor according to any preceding claims, wherein the foam precursor composition further comprises a salt, for example NaCI.

4. A foam precursor composition according to any preceding claim, wherein the dry weight of the biochar present in the foam precursor composition is from 10 wt.% to 70 wt.%, based on the total dry weight of the foam precursor composition.

5. A foam precursor composition according to any one of claims 1 to 4, wherein the dry weight of the polysaccharide material present in the foam precursor composition is from 20 wt.% to 80 wt.%, based on the total dry weight of the foam precursor composition.

6. A foam precursor composition according to any preceding claim, wherein the dry weight of the polysaccharide material present in the foam precursor composition is at least 40 wt.%, based on the total dry weight of the foam precursor composition.

7. A foam precursor composition according to claim 6, wherein the dry weight of the polysaccharide material present in the foam precursor composition is from 45 wt.% to 75 wt.%, based on the total dry weight of the foam precursor composition.

8. A foam precursor composition according to any one of claims 3 to 7, wherein the dry weight of the salt present in the foam precursor composition is from 1 wt.% to 10 wt.%, such as from 2 wt.% to 8 wt.%, based on the total dry weight of the foam precursor composition.

9. A foam precursor composition according to any preceding claim, wherein the weight of the blowing agent present in the foam precursor composition is from 35 wt.% to 60 wt.%,such as from 40 wt.% to 50 wt.%, based on the total weight of the foam precursor composition.

10. A foam precursor composition according to any preceding claim, wherein the weight ratio of biochar to polysaccharide material is between 1 :5 to 1 :1.

11. A foam precursor composition according to any one of claims 2 to 10, wherein the starch material is selected from cereal starch, root starch, such as tapioca starch, tuber starch, modified starch, or any combination thereof.

12. A foam precursor composition according to any preceding claim, wherein the blowing agent comprises water.

13. A foam precursor according to any preceding claim, wherein the composition further comprises one or more materials selected from plasticizer, nucleating agent, strength adjusting agent, viscosity modifier, adhesion promoter, processing aid, filler, flame retardant agents, anti-fungal agents, mould inhibitors, and / or any combination thereof.

14. A foam precursor composition according to any preceding claim, wherein the foam precursor composition further comprises a plasticizer, such as glycerol.

15. A foam precursor composition according to any preceding claim, wherein the foam precursor composition comprises less than 50 wt% polyalkylene, such as polyethylene and polypropylene, based on the total dry weight of the foam precursor composition; and / or wherein the foam precursor composition comprises less than 50 wt% polyvinyl ester, such as polyvinyl acetate, based on the total dry weight of the foam precursor composition.

16. A method of forming a foam, the method comprising the steps of: i) providing a first foam precursor composition according to any one of claims 1 to 15 at a temperature of below 25 °C; ii) mixing the first foam precursor composition at a temperature of at least 30 °C to form a second foam precursor composition, wherein the second foam precursor composition is at least partially gelatinised; and iii) heating the second foam precursor composition by microwave radiation to form a foam, such as an expanded foam.

17. A method according to claim 16, wherein the foam precursor composition is mixed for a time period of at least 2 to 10 minutes, such as 3 to 5 minutes, in step ii).

18. A method according to any of claims 16 or 17, wherein the foam precursor composition is mixed at a temperature of up to 100°C, in step ii).

19. A method according to any of claims 16 to 18, wherein the method further comprises the step, iia), of increasing the moisture content of the second foam precursor composition prior to the heating step iii).

20. A method according to any of claims 16 to 19, wherein the method further comprises the step, iib), of drying the second foam precursor composition prior to the heating step iii).

21. A method according to any of claims 16 to 20, wherein the second foam precursor composition is heated by microwave radiation, hot air, heat press or extrusion methods, for example by exposure to microwave radiation, in step iii).

22. A method according to any of claims 16 to 17, wherein the second foam precursor composition is heated by exposure to microwave radiation at a power of at least 800W in step iii), and / or wherein the second foam precursor composition is heated for a time period of 30 to 60 seconds in step iii).

23. A foam formed from the foam precursor composition according to any one of claims 1 to 15 and / or the method according to any one of claims 16 to 22.

24. An article comprising a foam according to claim 23.

25. An article according to claim 24, wherein the article is packing, packaging or insulation.

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