DESC:“LIGNOCELLULOSE REINFORCED THERMOPLASTIC STARCH BASED COMPOSTABLE GRANULATES FOR COMMERCIAL APPLICATIONS”

FIELD OF THE DISCLOSURE
[0001] The present invention relates to a plant-based compostable granulate composition and a method of preparation thereof. More specifically, the invention relates to composition granules for injection moulding and thermoforming process.
BACKGROUND OF THE INVENTION
[0002] Plant-based fibre-polymer composites are being widely used in many engineering fields due to their cost-effectiveness. Various applications of plant-based fibre-polymer composites include (but are not limited to) manufacturing of automotive interiors, packaging material and bulkheads. Plant-based fibres are a viable solution to avoid costly, wasteful and unfriendly disposal methods of non-degradable composites.
[0003] Plant-based fibers, also known as Lignocellulosc fibers, such as, abaca, kenaf, jute and the like, are mainly used as a reinforcing material in various polymer composites. As mentioned earlier, their usage is highly advantageous because of their high availability, abrasion resistance, low density, good mechanical properties and degradability. Although plant-derived fibers are not as strong as synthetic fibers (such as carbon fibres), they have excellent mechanical properties, which is attributed to their stiffness that even exceeds that of E-glass fibers. The non-abrasive behaviour of plant-derived fibers leads to less damage to the composite itself, while the hollow structure of the fibers contributes to the low density of the fibers. Plant-derived fibers can reinforce both thermoplastic and thermoset polymers.
[0004] While the plant-derived fibers are environmentally friendly, the matrix used in the above composites is a non-degradable polymer that does not degrade or at least does not degrade for a very long period of time (800-1000 years). Biodegradable resins are currently available either as a natural or synthetic base. However, these biodegradable resins are cost intensive and are prone to moisture absorption and bacterial attack. Common plant fiber reinforced thermoplastics include polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS) and nylon, while plant fiber reinforced thermosets include epoxies, polyesters, and polyurethanes. Polypropylene (PP) and PVC are known as matrices for most plant-based fiber composites filled with wood flour (from sawmill waste) or wood fiber (from wood product waste). Applications for wood polymer composites (WPC) include furniture, windows and decks. In addition to PP and PVC, wood flour or wood fiber is used with polymeric diphenylmethane diisocyanate (MDI or PMDI) to produce multiple grades of medium density fiber as a wood substitute. These natural or plant-derived compounds are widely used to the extent that they cause environmental problems.
[0005] The commonly used thermoplastic biopolymer for packaging lacks the properties necessary to meet the matrix system requirements for fiber-based composites. In particular, high elongation at break and high machining viscosity are detrimental. Unlike thermoplastics, the development of nature-based resins seems to be easier because suitable starting materials can be provided by triglycerides, epoxidized vegetable oils, polyols and amino lipids.
[0006] However, some of the major disadvantages of biodegradable polymers are their hydrophilic nature, prolonged decomposition rate, and poor mechanical properties in wet environments. Among the biodegradable polyesters, polylactides (i.e. polylactic acid) have received much attention. However, polylactides are expensive. Aliphatic polyesters and hydrophilic natural polymers are thermodynamically immiscible, causing a weak bond between the two components.
[0007] The prior art Chinese patent application CN114106540A discloses a PLA (Polylactic Acid)/wood powder composite wire for FDM (Fused Deposition rapid prototyping) 3D printing and a preparation method thereof. Briefly, the wire comprises 800-950 parts of PLA raw materials, 50-200 parts of wood powder, 1-10 parts of coupling agents, 2-5 parts of toughening agents and 1-5 parts of lubricating agents in parts by weight; the grain size distribution interval of the wood powder is required to be as follows: D90 is less than or equal to 100 µm, D50 is less than or equal to 65µm and less than or equal to 50µm, and D10 is less than or equal to 30µm; the coupling agent is one or more of isobutyl triethoxysilane, tetra-n-propyl zirconate and chromium methacrylate; the toughening agent is one or more of SEBS, POE and PE.
[0008] Another Chinese patent number CN108530854A discloses a kind of straw powder PLA wood and plastic composite preparation method for material, using PLA and straw powder as the main component of composite material, the composite material has the advantages that it can be degradable, while the auxiliary agent added is environmental-friendly so that composite material obtained also has similar properties. A variety of auxiliary agents are also added to enhance the binding force between PLA and straw powder.
[0009] Similarly, the Chinese patent number CN109880331A discloses a kind of preparation methods of graphene PLA wood plastic composite, wherein Eucalyptus is subjected to cutting and grinding, and Eucalyptus powder is passed through 60~100 mesh screens, to remove the larger impurity in Eucalyptus powder and to obtain pure Eucalyptus fine powder. The obtained eucalyptus fine powder is placed in dry air of oven, for forced air drying, followed by adding acetone to dry wood powder along with coupling agent such as silane. This is followed by heat infiltration, to obtain dry the wood powder. Graphene powder and powder are stirred and mixed at high speed, by hot briquetting to obtain wood plastic composite.
[0010] However, none of the prior arts mentioned above provides an end product that is hydrophobic and at the same time possess high strength, stiffness and rigidity. Therefore, there is an unmet need for a plant- based compostable granulate composition that resists degradation and does not get worn off easily when exposed to rough handling and abrasive environments for a prolonged period of time.
OBJECTS OF THE INVENTION
[0011] The principal object of the present invention is to overcome the disadvantages of the prior art.
[0012] An object of the present invention is to provide a plant- based compostable granulate composition and the method of preparation of thereof possessing high strength and rigidity.
[0013] Another object of the present invention is to provide a hydrophobic and anti-bacterial plant- based compostable granulate composition having a long shelf life.
[0014] Another object of the present invention is to provide a biodegradable plant- based compostable granulate composition, thereby preventing damage to the environment.
[0015] Yet another object of the present invention is to provide a cost effective plant- based compostable granulate composition, having economic viability and which can be produced in an industry.
[0016] The foregoing and other objects, features, and advantages of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawings.
SUMMARY OF THE INVENTION
[0017] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope of all its features.
[0018] The present invention relates to plant-based compostable particulate compositions and methods of making the same. In particular, the invention relates to a plant-based compostable granulate composition for injection moulding and thermoforming processes.
[0019] In one aspect of the present invention, a plant- based compostable granulate composition comprising refined wood powder, biodegradable polymers, thermoplastic starch or modified maize starch, filler, additives and processing aids is disclosed. The composition comprises of refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, modified maize or corn starch in 20-30 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts. The modified maize starch consists of 65-75 parts of maize or corn starch and 25-35 parts of plasticizer and wherein the plasticizer is selected form a group comprising water, glycerol, sorbitol, modified vegetable oil, with citric or lactic acid for inducing cross-linking.
[0020] In another aspect of the present invention, a method for preparation of a plant- based granulate composition is disclosed the method comprising; blending maize starch in 65-75 parts and plasticizer in 25-35 parts in a thermomechanical process at 120-150°C for 10-30 minutes followed by extrusion, finally the obtained mixture is pelletized to yield a modified maize starch. The obtained modified maize starch is compounded in 20-30 parts with refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts in extruder to obtain a mixture; and cooled on a conveyor belt and pelletizing the mixture to obtain granules.
[0021] In yet another aspect, of the present invention, a biodegradable article may be manufactured from the plant- based granulate composition, wherein the method comprises adding the plant –based composite granulate composition into an extruder at 130-180°C; and carrying out high speed moulding having a cycle time of 30-60 seconds, at a pressure of 840-870 bars to obtain a biodegradable article.
[0022] Additional aspects and advantages of the present disclosure will become apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. The present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings, description and examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
[0024] Figure 1 illustrates a flow chart representation of method for preparation of plant-based granulates composition.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
[0026] At the outset, for ease of reference, certain terms used in this application and their meanings as used in this context are set forth. To the extent a term used herein is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Further, the present techniques are not limited by the usage of the terms shown below, as all equivalents, synonyms, new developments, and terms or techniques that serve the same or a similar purpose are considered to be within the scope of the present claims.
[0027] The articles “a” and “an” as used herein mean one or more when applied to any feature in embodiments of the present invention described in the specification and claims. The use of “a” and “an” does not limit the meaning to a single feature unless such a limit is specifically stated. The article “the” preceding singular or plural nouns or noun phrases denotes a particular specified feature or particular specified features and may have a singular or plural connotation depending upon the context in which it is used. The adjective “any” means one, some, or all indiscriminately of whatever quantity.
[0028] Increasing depletion of fossil fuels and climate change are putting pressure on increasing the renewable carbon content of plastics. Around 8 billion tons of plastic polymers are produced worldwide. Therefore, the demand for bioplastic is becoming more and more attractive in both academic and industrial fields due to their biodegradability. Bioplastics are highly resistant to chemical and enzymatic reactions. Starch, cellulose, proteins and chitin occur in nature primarily as renewable polymers. Among them, starch has received more attention due to its high productivity from renewable resources.
[0029] In order to make synthetic plastics more environment friendly, biomaterials are blended into biocomposites to create bioplastics that rival synthetic plastics. Natural fibers are also used as fillers to enhance the mechanical and barrier properties of bioplastics. The combination of these materials has resulted in promising biocomposite products that are safe, biodegradable and sustainable. Blending expensive PLA or PBS with starch and natural fibers yields a stable, working product. Starches and natural fibers are known for their abundant, inexpensive, biodegradable and sustainable properties and are widely used to enhance the properties of PLA and PBS. Although starch is not miscible with PLA or PBS, the plasticization of starch improved interfacial bonding to the polymer matrix. The superior properties of the material are preserved and the inferior ones are compensated for each other. Because all the materials used are plant-based, the disposal of plastic waste is compostable, shortening the centuries-long decomposition process to just a few weeks.
[0030] Plant-based or Lignocellulose fibers are the most abundant biomass found in nearly all plant materials, from wood and grass to agricultural and municipal solid waste. The main components of lignocellulose are cellulose, hemicellulose and lignin. However, its composition varies greatly depending on the plant species, growing conditions and plant age.
[0031] Cellulose, which normally constitutes the major organic component (up to 50%) of plants, is a linear polymer of D-glucose linked by ß-glucosidic bonds. Linear cellulose polymers, called elementary fibrils, are held together by hydrogen bonding and van der Waals forces to form microfibrils. Microfibrils are grouped into cellulose fibers and are usually covered with hemicellulose and lignin. Plant cellulose occurs in either crystalline or amorphous form. The former is a highly ordered form and is poorly biodegradable. Hemicellulose contains different sugars (D-xylose, D-glucose, D-mannose, D-galactose, and L-arabinose) depending on its composition. It is a group of complex heteropolysaccharides composed of sugar acids (D-glucuronic acid and D-galacturonic acid) of plant species. Unlike cellulose, hemicellulose has branches with short side chains of different sugars, does not form aggregates and is easily hydrolyzed. The lignin present in the cell wall is an amorphous heteropolymer composed of phenylpropane units (coniferyl alcohol, cynyl alcohol, and coumaryl alcohol) held together by various types of bonds.
[0032] The present invention relates to compostable plant-based particulate compositions and methods of making same. The plant-based particulate compositions as described herein may be advantageously used for production of easy to manufacture, cost-effective, environment- and user friendly cutlery by the process of injection moulding.
[0033] In one embodiment of the present invention, the plant- based compostable granulate composition comprises refined wood powder, biodegradable polymers, thermoplastic starch or modified maize starch, filler, additives and processing aids. In an embodiment, the composition comprises refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, modified maize or corn starch in 20-30 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts. The thermoplastic starch or modified maize starch consists of 65-75 parts of maize or corn starch and 25-35 parts of plasticizer and wherein the plasticizer is selected form a group comprising water, glycerol, sorbitol, modified vegetable oil, with citric or lactic acid for inducing cross-linking.
[0034] Starch is cheaper and more readily available than PLA. Starch-based polymers have poor mechanical and barrier properties, while PLA and PBS have high mechanical and barrier properties despite their high cost and limited availability. Starch in its pure form (native starch) is converted to thermoplastic starch (TPS) in the presence of excess water and plasticizers. However, the biggest drawback of native starch in TPS is its lack of mechanical properties and thermal stability, in addition to its high sensitivity to moisture. Numerous investigations have been conducted to reduce or overcome these negative aspects of TPS by chemically modifying the starch solution or blending it with various biodegradable polymers, polyesters, and fillers.
[0035] The biodegradable polymers of the present invention may be selected from a group comprising globally certified compostable polymers including polylactide (PLA), poly (butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS) and polyhydroxyalkanoates (PHA).
[0036] Plant based nano/micro fillers help improve the mechanical and thermal properties of cellulose composites. Fillers can also be used to adjust the coefficient of thermal expansion (CTE) of cellulosic composites to increase compatibility with other materials used together. Non-limiting examples of fillers include inorganic and organic fillers (e.g., talc, mica, clay, silica, alumina, carbon fiber, carbon black, glass bubbles) and conventional cellulosic materials (e.g., wood flour, etc.) wood fibres, non-wood plant fibres, shavings, newsprint, paper, flax, hemp, straw, rice husks, kenaf, jute, sisal, peanut husks, soybean husks or other cellulosic materials) are included. The amount and type of filler in the fusible composition can be appropriately selected depending on the desired physical properties of the polymer matrix and final composition. Fillers such as calcium carbonate, talc, clay and cellulose fibres are suitable for many applications.
[0037] In addition, fillers such as glass bubbles may be added to the plant-based particulate compositions of the present invention to improve the mechanical, physical, electrical, thermal and dimensional properties. Glass bubbles are finely dispersed, free-flowing powders consisting of thin-walled (0.5-1.5µm) spherical glass particles with an average diameter of 15-65µm. They render polymers with lower density which is directly related to thermal conductivity and insulation properties.
[0038] In an embodiment of the present invention, the plasticizer may be selected form the group consisting of water, glycerol, sorbitol, modified vegetable oil, with citric or lactic acid for inducing cross-linking and filler may be selected from the group consisting of plant based nano or micro fillers, calcium carbonate, silica, mica, talc, glass bubbles and other mineral fillers or a combination thereof. The additives are selected from cellulose, talc, starch and the like.
[0039] In another embodiment of the present invention, a method for preparation of a plant- based compostable granulate composition, is disclosed involving blending of the maize starch in 65-75 parts and plasticizer in 25-35 parts in a thermomechanical process at temperature range of 120-150?. The temperature of the thermomechanical process may preferably at a temperature of 135?. The mixing of the maize starch with plasticizer is followed by extrusion in an extruder; the mixture is then pelletizing to yield a thermoplastic starch or modified maize starch. The obtained thermoplastic starch or modified maize starch is then compounded with refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts in the extruder at temperature range of 120-160°C to obtain a mixture. Subsequently, the mixture is cooled on a conveyor belt and the mixture is pelletized to obtain plant- based compostable granulate composition.
[0040] The plant-based compostable granulate composition of the present invention is advantageously manufactured with the help of extrusion process. Extrusion is a type of metal-forming operation used to create objects of a fixed cross-sectional profile where dies are used to change the shape of the metal piece. The process is carried out by pushing material through a die of the desired cross-section external force which is compressive in nature. The process has a distinct advantage over other manufacturing processes to manufacture very complex cross-sections and to work materials that are brittle, as the extrusion processes uses only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process.
[0041] The extrusion process is widely used to create a complex profile of materials within considerably less time as compared to other metal-forming processes. Furthermore it has a distinct advantage with brittle and ductile materials. The products manufactured by the extrusion process have enhanced mechanical properties such as enhanced and precise finish with increased life cycle of products.
[0042] The extrusion system includes a screw, a barrel, a hopper, a head, and a die. The hopper stores materials for feeding into the extruder. The plastic raw material is plasticized into a uniform melt through the extrusion system, and continuously extruded through the screw, under pressure. The screw is rotated and the raw material is moved by this and pressurized in the barrel.
[0043] The barrel and screw are configured for crushing and softening of plastics, which is then delivered into the moulding system continuously and uniformly.
[0044] Different types of extruder are available in market as per industrial needs and specification. Twin screw extruder is different from a single screw extruder in having two intermeshing and co-rotating screws that are mounted on splined shafts in a closed barrel. Twin screw extruder has a broad diversity of specialized screw designs such as kneading blocks, reverse screw elements, gear mixing elements, etc. The design of the twin screw extruder allows precise and accurate shearing/accurate mixing and therefore the twin extruder has remarkable mixing capability. In addition, it has the capability to handle multiple processing functions in series such as melting, mixing, cooking, venting, cooling, etc. Twin screw extruders can control the process parameters far more efficiently and allows narrower residence time distribution, higher convective heat transfer, lower dispersion of shear rates and strain, and accurate control of temperature profile. Twin screw extruders, are used for bulk polymerisation, processing or compounding.
[0045] Because of the distinct advantage presented above, the present invention discloses a process of manufacturing plant- based compostable granulate composition using a twin screw extruders.
[0046] From the composition derived from the method disclosed herein, various biodegradable products may be manufactured, from example, by injection moulding, which is a commonly used process for mass-production of objects from thermoplastics. In an embodiment, the plant–based composite granulate composition may be moulded into a desired geometrical shape or a product as-desired, such as cutlery such as cups, plates, spoon, forks, glasses, bowls and the like.
[0047] In yet another aspect, of the present invention, a biodegradable article manufactured from the plant- based granulate composition is disclosed, wherein the method comprises adding the plant-based composite granulate composition into an extruder at 130-180°C. The temperature in the extruder may be preferentially be maintained at 150-180°C. This is followed by high speed moulding having a cycle time of 40 seconds, at a pressure of 840-870 bars preferably at 860 bars to obtain a biodegradable article.
[0048] Figure 1 illustrates a flowchart of the process (100) of manufacturing biodegradable articles from plant-based composite granulates. The process starts at step 102, wherein the maize starch is mixed with a plasticizer in a thermomechanical process at 120-150°C for 10-30 minutes. The mixture is subsequently extruded at step 104, via an extruder at 135-155?. The extruded mixture is pelletized in a pelletizing unit at step 106, to yield Thermoplastic starch (TPS), which is collected in a collection bin, at step 108.
[0049] The collected TPS is mixed with biodegradable polymers along with fillers, additives and processing aids introduced via a hooper, whereas the wood powder or wood flour is introduced via a side feeder, at step 110. The resultant mixture is extruded via the extruder at step 112 and is subsequently cooled on a conveyer belt, at step 114, then pelletized via a pelletizing unit at step 116, and is collected in a collection bin at step 118 as a resultant compound.
[0050] The resultant compound is then extruded with an extruder of injection moulding machine at temperature range of 150-170? at step 120. In a preferred embodiment, the extruder is a single screw extruder. Following extrusion, the compound is exposed to high speed injection moulding with a cycle time of around 40 seconds with pressure maintained at 860 bar at step 122. The resultant biodegradable article of interest is then collected in a collection bin at step 124.
[0051] In an alternate embodiment, for the purpose of obtaining biodegradable articles of interest such as water glasses, wine glasses, juice glasses, ice cream cups, single use vegetable trays and sauce cups and the likes, from the plant- based granulate composition of the present invention, thermoforming process can be effectively used. Thermoforming typically uses pressure or the force of a vacuum to stretch thermoplastic material over a mould to create a three-dimensional shape. The process heats a sheet of thermoplastic until it is sufficiently pliable; the heated plastic sheets are removed from the heating equipment and transported to a temperature-controlled and pre-heated die having a mould tool. The mould tool has two parts a male mould and a female mould. The mould tool forms the sheet into a three-dimensional shape/product. The die opening is adjusted according to the granulate flow to avoid the flow marks in the sheet and to obtain a sheet of good smoothness and uniform thickness. To achieve uniform thickness distribution in the article of interest, the mould designated as a female mould utilizes a higher heating time and the mould designated as a male mould uses a shorter heating time. Moreover, the cutting and punching speed is kept at moderate with the temperature inside the mould maintained at around 10-12?, in order to ensure that the articles get instantly cooled when encountering the mould. Silicone spray may be used if the articles are sticking inside the mould.
[0052] The typical process parameter for the thermoforming process used in the present invention is depicted in Table 1.
Table 1: Process Parameters for the Cast Extrusion of the Plant- based Granulate Composition

Temperature profile (0C)
Screw
speed,
(r/min)
Roll
speed
(m/min)

Haul-off
speed
(m/min) Thickness
(µm)

T1 T2 T3 T4 Head (DIE)
T left mid right (0C)

170-180 175-185 175-190 175-190 175-190 175-190 175-190 50-150
1 1.3 500 -800± 5

The plant- based granulate composition of the present invention is biodegradable at recommended conditions that converts it into organic wastes that are degraded by microorganisms into carbon dioxide, water, humus, and soil nutrients. The material is stable up to 6 months if stored in a moisture-free environment. The physical properties of the plant- based granulate composition of the present invention is presented in Table 2.

Table 2: Properties of the Plant- based Granulate Composition Material

ADVANTAGES OF THE PRESENT INVENTION
[0053] Addition of lignocellulose to compostable polymer enhances the strength and stiffness of the product thereby leading to a novel commercially viable product for making single use plastic substitutes which are environment friendly, high biocarbon content and are compostable and biodegradable
[0054] The plant-based granulates cutlery can be used in place of existing single use polyolefin based cutlery. The polyolefin based cutlery is rampantly increasing the environmental hazard as these are only good for single use and are not biodegradable.
[0055] The plant-based granulates of the present invention can compost within 6 months of time in the industrial facility without addition of any special additives
[0056] The plant-based granulates of the present invention are economical and feasible for commercial application
[0057] The plant-based granulates of the present invention is cost-effective and easy to manufacture due the wide availability of the raw material used in the invention including maize starch and lignocellulosic reinforcement both of which are abundant, renewable resources and easily available.
[0058] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

,CLAIMS:
We Claim:

1. A plant-based granulate composition comprising:
refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, modified maize or corn starch in 20-30 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts.
2. The composition as claimed in claim 1, wherein the biodegradable polymers is selected from a group comprising globally certified compostable polymers including polylactide (PLA), poly (butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS) and polyhydroxyalkanoates (PHA).
3. The composition as claimed in claim 1, wherein the refined wood powder comprises an array of plant derived powdered reinforcement for imparting high strength and rigidity to the composition.
4. The composition as claimed in claim 1, wherein the filler is selected from a group comprising plant based nano or micro fillers, calcium carbonate, silica, mica, talc, glass bubbles and other mineral fillers.
5. The composition as per claim 1, wherein the modified maize or corn starch consists of 65-75 parts of maize starch and 25-35 parts of plasticizer and wherein the plasticizer is selected form a group comprising water, glycerol, sorbitol, modified vegetable oil and cross-linking is induced by citric or lactic acid.
6. The additives as claimed in claim 1, wherein the additives are selected from a group consisting of cellulose, talc and starch.
7. The processing aids as claimed in claim 1, wherein the processing aids are selected from a group consisting of plant based anti-slip and mineral based anti-block materials.
8. A method for preparation of a plant- based granulate composition as claimed in claim 1, the method comprising:
a. blending maize starch in 65-75 parts and plasticizer in 25-35 parts in a thermomechanical process at 120-1500C for 10-30 mins followed by extrusion in and pelletizing to yield a modified maize starch ;
b. compounding 20-30 parts of the modified maize starch with refined wood powder in 20-40 parts, biodegradable polymers in 20-40 parts, filler in 20-30 parts and additives and processing aids in 5-10 parts in extruder to obtain a mixture; and
c. cooling the mixture on a conveyor belt and pelletizing the mixture to obtain granules.
9. The method as claimed in claim 9, wherein the extrusion is carried out in an extruder at a temperature range of 120-1600C.
10. A biodegradable article manufactured from the composition prepared by the method as claimed in claim 8, wherein the method comprises
a. adding the plant–based composite granulate composition into a extruder at a temperature range of 130-1800C; and
b. carrying out moulding having a cycle time of 40 seconds, at a pressure of 840-870 bars to obtain a biodegradable article.
11. The extruder as claimed in claim 11 is a single screw extruder.
12. The biodegradable article as claimed in claim 11, wherein the moulding comprises high speed injection moulding or thermoforming.