DESC:TECHNICAL FIELD
The present invention relates to the field of material science, especially to biodegradable polyurethane composite material. In particular to biodegradable polyurethane composite material that can be adopted as an alternative to single use plastics; and a simple, economical single pot method for preparation of said composite material.
BACKGROUND
The conventional petrochemical plastics are cheap, tough, lightweight, resistant to chemical and biological degradation, and easy to process for a variety of goods and applications but are non-biodegradable resulting in serious effects on terrestrial and marine ecosystem. Plastic wastes typically make up 35–55% by volume of the non-biodegradable component of municipal solid wastes sent to landfill. Humongous amounts of plastic litter are discarded and accumulated in oceans via municipal drainage and rivers. The adverse impact of conventional plastics on the environment could be significantly reduced if single-use plastics are reduced. Since durability is not required for single use plastics which are primarily meant for the short-life goods and applications, they can be replaced with biodegradable materials that offer similar advantage and can be degraded effortlessly in the environment after use.
Recently, researchers are conducting intense research to find alternative biodegradable plastics to replace single use plastics. Polyurethane based plastics has attracted wide attention due to its unique properties like light weight, high toughness, and corrosion resistance. The preparation method plays an important role in the properties of polyurethane materials and determines the durability and other mechanical properties. Previously, the synthesis of polyurethane is from unsustainable petroleum products which also cause environmental problems; this triggered the methods which adopts plant-based bio-degradable and sustainable products as raw material.
The Chinese patent CN201410326723 discloses polyurethane composite material and process for preparing the same from a polyurethane composition by a sheet or bulk molding process, wherein the polyurethane composition comprises an organic isocyanate, an organic polyol and hydroxyalkyl (meth)acrylate and other reagents, the preparation is a multistep process. I.S. Ristic et. al., in Materials Chemistry and Physics. 2012, 132, 74–81, disclose about a method of preparation of polyurethanes with different types of diisocyanate and titanium oxide nano particles as fillers. The reaction involves tedious multistep process with large number of reagents rendering the preparation of polyurethane compound to be expensive and not eco-friendly.
The present invention aims to provide biodegradable polyurethane composite material that can be adopted as an alternative to single use plastics and a simple, economical single pot method for preparation of said composite material .
STATEMENT OF INVENTION
The present invention provides biodegradable polyurethane composite material from vegetable oils and an organic material obtained by method comprising steps of-
a) mixing organic material, a diisocyanate and vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2in a solvent to obtain a mixture,
b) heating the mixture at about a temperature ranging from 70°C to 100°C for 6h to 16h,
c) pouring the mixture on a substrate and drying for 8-12 h, and
d) washing the dried mixture with polar solvent to obtain biodegradable polyurethane composite.
The present invention provides a biodegradable polyurethane composite material derived from vegetable oil and an organic material that may be rigid or flexible with high thermal stability.
The present invention provides a single pot method for preparation of biodegradable polyurethane composite material from vegetable oils and an organic material, comprising steps of:
a) mixing organic material, a diisocyanate and vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2in a solvent to obtain a mixture,
b) heating the mixture at about a temperature ranging from 70°C to 100°C for 6h to 16h,
c) pouring the mixture on a substrate and drying for 8-12 h, and
d) washing the dried mixture with polar solvent to obtain biodegradable polyurethane composite.
The invention also provides method for obtaining biodegradable cutlery, bags, water bottle and the like, from the suitable rigid or flexible polyurethane material.
BRIEF DESCRIPTION OF FIGURES
The features of the present invention can be understood in detail with the aid of
appended figures. It is to be noted however, that the appended figures illustrate only
typical embodiments of this invention and are therefore not to be considered limiting of its scope for the invention.
FIGURE 1: shows images of (a) Polyurethane 1(PU1) and (b) Polyurethane 2 (PU2) polymers.
Figure 2: shows (a) FTIR spectra, (b) stress-strain curve, (c) TGA thermograms, and (d) DSC curves of PU1 and PU2.
Figure 3: Weight loss of PU1 and PU2 samples during degradation.
Figure 4: Images of (a) spoon prepared from PU1 and (b) carry bag (c) glass prepared from PU2.
DETAILED DESCRIPTION OF INVENTION
The foregoing description of the embodiments of the invention has been presented for the purpose of illustration. It is not intended to be exhaustive or to limit the invention to the precise form disclosed as many modifications and variations are possible in light of this disclosure for a person skilled in the art in view of the figures and description. It may further be noted that as used herein and in the appended claims, the singular “a” “an” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by person skilled in the art.
The present invention relates to biodegradable polyurethane composite materials; and provides a facile single pot method for preparation of biodegradable polyurethane composite materials.
In an embodiment of present invention, the polyurethane composite material is derived from vegetable oil and organic material.
In an embodiment of present invention, the biodegradable polyurethane composite material from vegetable oils and an organic material is obtained by mixing organic material, a diisocyanate and vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2 in a solvent to obtain a mixture, heating the mixture at about a temperature ranging from 70°C to 100°C for 6h to 16h, pouring the mixture on a substrate and drying for 8-12 h, and washing the dried mixture with polar solvent to obtain the composite.
In still another embodiment of present invention, the vegetable oil is selected from a group comprising castor oil, linseed oil, jojoba oil, soybean oil, jatropha oil, canola oil, olive oil and the like.
In yet another embodiment of present invention, the organic material is selected from Cellulose, waste wood chips, waste rice husk, Glycogen, Chitosan, Hemicellulose and Alginate.
In still another embodiment, the cellulose is extracted from rice straw, wood chips, and jute fibre.
In another embodiment of present invention, the polyurethane composite material is rigid or flexible.
In another embodiment, the biodegradable polyurethane composite materials are thermally stable from 170°C -470°C.
In another embodiment of present invention, the biodegradability of the polyurethane composite material based on weight loss method ranges from 4% to 10% in 60 days.
In another embodiment of invention, the biodegradable polyurethane composite material is synthesized by one pot method with yield ranging from 96% to 98%.
The present invention provides one pot method of preparation of bio-degradable polyurethane composite material, comprising of steps-
a) mixing organic material, a diisocyanate and vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2in a solvent to obtain a mixture,
b) heating the mixture at about a temperature ranging from 70°C to 100°C for 6h to 16h,
c) pouring the mixture on a substrate and drying for 8-12 h, and
d) washing the dried mixture with polar solvent to obtain biodegradable polyurethane composite.
In another embodiment of present invention, the diisocyanate is selected from a group comprising alkyl or aryl groups like for example Diphenylmethane-4-4’-diisocyanate (MDI), Hexamethylene diisocyanate (HMDI), Toluene diisocyanate (TDI), Naphthalene diisocyanate (NDI), and Isophorone diisocyanate (IPDI).
In another embodiment, the alkyl diisocyanates are adopted in the preparation for obtaining flexible biodegradable polyurethane composite materials and aryl diisocyanates are adopted in the preparation of rigid biodegradable polyurethane composite material.
In another embodiment, the solvent is a non-polar solvent with boiling point ranging between 80 °C-120°C, selected from a group comprising polar and nonpolar solvents like for example-Toluene, iso-Butanol, 2-butanol, Ethyl acetate and 1-Propanol.
In another embodiment, the substrate is selected from a group comprising Teflon, Glass and the like.
In an embodiment, the concentration of reagents, including vegetable oil concentrations are varied to tune the rigidity and flexibility of the polyurethane sheet. The amount of vegetable oil to the amount of solvent is maintained at 1:4 to 1:7 ratio, preferably at about 1:5 ratio. It is observed that below 1:4, film formation is not possible because of the poor crosslinking.
In an embodiment of the invention, the polyurethane composite material can be adopted as cost effective biodegradable alternative to single use plastics.
In another embodiment the biodegradable polyurethane composite is adopted by – cutting polyurethane composite into small pieces, heating at temperature between 180?-200? and moulding by compression moulding to a product as per requirement.
In another embodiment, the compression moulded product as sheets are subjected to thermoforming process to develop various cost effective, leak proof products like cutlery, plates, bags, and water bottle.
Experimental:
I. Materials:
The vegetable oils are obtained from commercial sources. Castor oil is purchased from SRL Chemicals. Jatropa Oil (JO) is obtained from Amazon e-commerce platform, Methylene diphenyl diisocyanate (MDI), Hexamethylene diisocyanate (HMDI), and Trimethylamine (TEA) are purchased from Sigma-Aldrich. Toluene is bought from Merck Millipore. Cellulose is extracted from waste rice husks obtained from paddy field of Punjab and used in the reaction. Rice husk is grinded in mixer grinder before using. The waste wood dust is collected from a local shop in Bangalore for using in the reaction. All reagents are of analytical grade and used without further purification.
The polyurethane material prepared from aryl isocyanate is referred to as PU1 and the polyurethane prepared from alkyl isocyanate is referred to as PU2.
II. Methods
A. Extraction of cellulose
Finely chopped 50 gm of rice husks are mixed with 10% w/v NaOH solution and heated at a temperature range of 60-65 °C with occasional stirring. Subsequently, the mixture is filtered and washed several times with distilled water to remove excess NaOH, lignin, and hemicellulose. The obtained neutral pulp is treated with 1% v/v sodium hypochlorite solution maintaining pH 5 of the solution by adding glacial acetic acid. The mixture is heated at 55-60 °C for 10 hours at stirring speed of 350 rpm. Finally, the solid residue of cellulose is washed with distilled water and heated overnight under vacuum at 50 °C.
Synthesis of Vegetable oil derived polyurethanes:
(i) General procedure:
Organic material extracted from various sources is mixed with vegetable oil and a diisocyanate compound in predefined molar ratio in toluene solvent. The reaction is carried out at 70 °C to 90 °C for 8 hours in nitrogen atmosphere. The white coloured viscous liquid is poured on a teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
(ii) Preparation of Polyurethane material with Castor oil(CO):
Example 1:
Cellulose extracted from rice husk and heated with MDI and CO in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8hours in nitrogen atmosphere. The white coloured viscous liquid is poured on to a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.

Example 2:

Cellulose extracted from rice husks and heated with HMDI and CO in the molar ratio of 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8hours in nitrogen atmosphere. The white coloured viscous liquid is poured onto a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.

Example 3:

Cellulose extracted from rice husk and heated with MDI and CO in the molar ratio 1:1.2:2 in Toluene solvent. The reaction is carried out at 80 °C for 8hours in nitrogen atmosphere. The white coloured viscous liquid is poured onto a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.

Example 4:

Cellulose extracted from rice husks and heated with HMDI and CO in the molar ratio 1:1.2:2 in Toluene solvent. The reaction is carried out at 80°C for 8hours in nitrogen atmosphere. The white coloured viscous liquid is poured onto a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.
Example 5:
10 g of grinded rice husk (< 40 micron) is heated with 12 ml of HMDI and 20 ml CO (in the molar ratio 1:1.2:2) in Ethyl acetate solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The white coloured viscous liquid is poured onto a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.
Reactions are carried out with varied castor oil concentrations to tune the rigidity and flexibility of the polyurethane sheets. The details with MDI are tabulated in Table1 and details with HMDI are tabulated with Table 2.

Table 1: Details of reaction with varied molar concentration of castor oil and MDI

Cellulose: MDI:CO Nature of PU film
1:2:0.5 Brittle
1:1.2:1 Flexible
0:2:0.5 Brittle
1:0.6:1 Flexible
1:1.2:2 Flexible
1:2:1.5 Brittle
1:2.5:2 Brittle

Table 2: Details of reaction with varied molar concentration of castor oil and HMDI

Cellulose: HMDI:CO Nature of PU film
1:2:0.5 Flexible
1:1.2:1 Flexible
0:2:0.5 Flexible
1:0.6:1 Flexible
1:1.2:2 Flexible
1:2:1.5 Flexible
1:2.5:2 Flexible

(iii) Preparation of Polyurethane material with Castor oil and wood powder as organic materials
Example 6:
10 g of grinded wood powder (< 40 micron) is heated with 12 g of MDI and 20 ml CO (in the molar ratio 1:1.2:2) in Ethyl acetate solvent. The reaction is carried out at 80°C for 8 hours in nitrogen atmosphere. The white coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol.

(iv) Preparation of Polyurethane material with Jatropha oil (JO):
a) Epoxidation of JO:
30 ml of JO is mixed with formic acid (HCOOH) in toluene solvent and refluxed at 40 °C for 30 min. Then hydrogen peroxide (H2O2) is added dropwise into the solution mixture. The temperature of the solution increased to 80 °C and the reaction is continued further for 7 hours. The pale yellow colour solution is allowed to cool at 25-30 ? before separating the oil and water layer by a separating funnel. Finally, the epoxidized JO is obtained by removing toluene in rotary evaporator.
Ring opening polymerization: The epoxidized JO is treated with methanol, distilled water, and sulfuric acid to obtain free hydroxyl group in the JO. Briefly, methanol, water, and sulfuric acid are mixed well for 15 min at room temperature before adding of epoxidized JO. The solution mixture is refluxed for 45 min at 70 °C. Then the solution is allowed to cool at 20-35 ? and 1% of Na2CO3 solution is added to neutralize the solution. The Jatropa oil(JO) based polyol (JOP) is obtained by washing with distilled water for several times using a separating funnel. The obtained product is dried in a vacuum oven at 60 °C to remove the water before using for preparing of JO based polyurethanes.
Example 7:
Cellulose extracted from rice husk and heated with HMDI and JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 8:
Cellulose extracted from rice husk and heated with MDI and JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 9:
Wood dust is heated with HMDI and JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 10:
Grinded rice husk (< 40 micron) is heated with HMDI and JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 11:
Grinded rice husk (< 40 micron) is heated with MDI and JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 12:
10 g grinded rice husk (< 40 micron) is heated with 12 g MDI and 20 ml JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left over night for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
Example 13:
10 g grinded rice husk (< 40 micron) is heated with 12 ml HMDI and 20 ml JOP in the molar ratio 1:1.2:1 in Toluene solvent. There action is carried out at 80°C for 8 hours in nitrogen atmosphere. The pale yellow coloured viscous liquid is poured onto a Teflon sheet and left overnight for evaporating the solvent. The polyurethane sheet is collected and washed with distilled water and ethanol to remove excess precursors.
(iv). Polyurethane material processing and product development
The polyurethane material sheets are cut into small pieces and moulded by compression moulding. The moulding temperature for polyurethane prepared with aryl isocyanate is (PU1) and with alkyl isocyanate is (PU 2) are 200 °C and 180 °C, respectively. The moulded sheets are used for mechanical and other characterizations. The sheets are subjected to thermoforming process to develop various products like for example spoons, bags, and glass as depicted in Figure 4.
III) Characterization of polyurethane composite materials
The polyurethane composite material is prepared from castor oil as the vegetable oil, cellulose obtained from rice husks as the organic material and the characteristics are analysed. The preparation of the said material is carried out in the presence of a) an aryl isocyanate - Diphenylmethane-4-4’-diisocyanate (MDI) and b) an alkyl isocyanate Hexamethylene diisocyanate (HMDI). The figure 1(a) shows the photograph of rigid polyurethane composite material (PU1) obtained in the presence of Diphenylmethane-4-4’-diisocyanate and figure 1(b) shows the photograph of flexible polyurethane composite material (PU2) obtained in the presence of Hexamethylene diisocyanate.
The formation of the polyurethane is confirmed by the FTIR spectra (Figure 2a). The characteristics peaks for PU1 and PU2 at 1700-1740 cm-1 are due to the stretching frequency of the urethane carbonyl groups (NH-CO-O). The presence of a broad absorbance peak at 3300, and the peak at 1531 cm-1, are assigned to the N-H stretching and bending, respectively. The peaks confirm the existence of secondary amine in the urethane linkage of the PUs. Additionally, the absence of isocyanate (-NCO) absorption peak at 2270 in PU1 indicate that the consumption of all isocyanate groups in the polymerization reaction whereas PU2 shows the low intense peak at the same position, indicating the presence of terminal NCO group in the polymer.
The polyurethane composite material sheets are cut into small pieces and moulded at 180 °C. The compression moulded sheets are adopted for mechanical and other testing. The sheets are subjected to thermoforming process for example to develop plates which could be utilized for food packaging applications. The tensile properties are measured for PU1 and PU2; and details are shown in Figure 2b. From the stress-strain curves, it is clear that the fracture strength and strain are higher for PU2 compared to PU1. The tensile strength and elongation at break of PU2 show 15.23 and 4.90%, respectively. On the other hand, PU1 shows fracture strength at 13.65 MPa and elongation at break of 2.94%. The results clearly indicate the role of HMDI and MDI as a precursor in the PUs. It is observed that the absence of aromatic ring in the PU2 increases the elasticity of the polymer matrix.
Thermal stability:
The thermal stability of the PU1 and PU2 are evaluated by the thermogravimetric analysis (TGA) in Figure 2c. In this study, thermal stability of PU1 and PU2 are compared to pure castor oil derived polyurethane (PU). The pure PU shows the degradation at temperature around 341.2 °C. The degradation temperature of PU1 and PU2 are 469.94 °C and 447 °C with a weight loss of 92% and 97%, respectively. The improvement in thermal stability is attributed to the interaction of cellulose and polymers. Also, the strong interfacial interactions within the layers of PU1 polymer matrix improve the thermal behaviour compared to PU2.
The DSC thermographs of PU1 and PU2 are shown in Figure 2d. The glass transition temperatures (Tg) are measured using DSC techniques in a temperature range from -50 to 250 °C. The graphs show that the Tg of PU1 is higher (22 °C) than Tg(-25 °C) of PU2. Tg of PU1 increases due to increasing of cross-linking density. With increasing the cross linking, chain mobility decreases which results in a higher Tg. The flexibility of PU2 suggests that the cross linking density is lower than PU1. As a result, Tg of PU2 is lower compared to PU1.
Degradation study:
The degradation study of PU1 and PU2 are evaluated by weight loss method. The PU1 and PU2 samples are sterilized by cleaning in ethanol for several times. Then samples are immersed separately in the solution of phosphate-buffered saline (PBS) containing lysozyme enzyme, and sodium azide. The resulting samples are kept in incubator shaker at temperature ranging from about 20°C to about 35°C for 60 days. The samples are taken out from the medium after 30 days, rinsed with distilled water and dried at around 50 °C for two days before measuring the weight loss. The Figure 3 informs about the weight loss, it is confirmed that for PU1 and PU2, around 4% weight of degradation occurs in 60 days. It is observed that the nature of PU films obtained are similar in the presence or in the absence of catalyst. The Figure 4a shows a spoon made from PU1. Figure 4b and 4c show that a carry bag and glass made from PU2.
Thus, the present invention provides a high yielding, simple one-pot synthesis for the preparation of biodegradable polyurethane composite materials comprising vegetable oil and organic material. The polyurethane composite materials can be conveniently adopted as eco-friendly, leak proof, thermally stable alternatives to single use plastics such as cutlery, plates, water bottle/cups, and bags to mitigate environmental pollution.
,CLAIMS:WE CLAIM
1) A biodegradable polyurethane composite comprising polyurethane and organic material; said composite prepared by-
a) mixing an organic material, a diisocyanate and a vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2in a solvent to obtain a mixture,
b) heating the mixture at about a temperature ranging from 70°C to 100°C for 6h to 16h,
c) pouring the mixture on a substrate and drying for 8-12 h, and
d) washing the dried mixture with polar solvent to obtain biodegradable polyurethane composite.
2) The biodegradable polyurethane composite as claimed in claim 1, wherein the organic material is selected from cellulose, waste rice husk, and waste wood chips.
3) The biodegradable polyurethane composite as claimed in claim 1, wherein the composite is flexible or rigid.
4) The biodegradable polyurethane composite as claimed in claim 1, wherein the biodegradability of the composite is 4% weight in 60days.
5) The biodegradable polyurethane composite as claimed in claim 1, wherein the composite exhibit thermal stability ranging between 170? to 470?.
6) A single pot method of preparation of biodegradable polyurethane composite comprising polyurethane and organic material; said method comprising acts of
a) mixing organic material, a diisocyanate and vegetable oil in molar ratio of weight 1:0.6- 2.5: 0.5-2in a solvent to obtain a mixture,
b) heating the mixture at about a temperature ranging from70°C to 100°C for 6h to 16h,
c) pouring the mixture on a substrate and drying for 8-12 h, and
d) washing the dried mixture with polar solvent to obtain biodegradable polyurethane composite.
7) The method as claimed in claim 6, wherein the organic material is selected from cellulose, waste rice husk, and waste wood chips.
8) The method as claimed in claim6, wherein the diisocyanate is selected from a group comprising alkyl and aryl diisocyanate.
9) The method as claimed in claim 6 and 8, wherein the alky diisocyanate is selected from Hexamethylene diisocyanate (HMDI), isophorone diisocyanateand aryl diisocyanate is selected from Diphenylmethane-4-4’-diisocyanate (MDI), Toluene diisocyanate (TDI), and Naphthalene diisocyanate (NDI).
10) The method as claimed in claim 6, wherein the vegetable oil is selected from a group comprising Castor oil, Jatropha oil and the like.
11) The method as claimed in claim 6, wherein the mixture is heated at a temperature of 80°C.
12) The method as claimed in claim 6, wherein the solvent is water, ethanol, toluene, ethyl acetate and a mixture thereof.
13) A moulded product of biodegradable polyurethane composite comprising polyurethane and organic material of claim 1.
14) The moulded product as claimed in claim 13, wherein the product is selected from a group comprising plate, cutlery, bottle, cup and the like.
15) A method of moulding a product of biodegradable polyurethane composite comprising polyurethane and organic material of claim 1, said method comprising acts of –

a) cutting polyurethane composite into small pieces,
b) heating at temperature between 180?-200? and moulding by compression moulding to a product.