Biodegradable composite material and preparation method thereof

Abstract

The invention discloses a polylactic acid (PLA) / biomass composite material, which is prepared from polylactic acid (PLA), a biomass material, a compatilizer, a cross-linking agent, a chain extender, an antioxidant and a nucleating agent, wherein the PLA, the biomass material, the compatilizer, the cross-linking agent, the chain extender, the antioxidant and the nucleating agent respectively exist in the PLA / biomass composite material at the concentrations of 30-60% wt / wt, 20-70% wt / wt, 5-20% wt / wt, 0.1-2% wt / wt, 0.1-1% wt / wt, 0.1-1% wt / wt and 1-10% wt / wt.

Description

Technical Field

[0001] The present disclosure relates to a polylactic acid (PLA) / biomass composite material having increased biomass concentration and improved mechanical properties and a method for preparing the same. Background Art

[0002] Manufacturing PLA / biomass composites is a popular carbon reduction method, in which one or more high carbon footprint plastic polymers are replaced by low carbon biomass materials, such as agricultural wastes, such as waste wood, waste bamboo, waste hemp, etc. However, PLA / biomass composites are plagued by deterioration of mechanical properties, which greatly limits their application. For example, when PLA is mixed with bio-based materials in a higher ratio (e.g., ≥50% content), the tensile strength and flexural strength decrease from 60 MPa to 22 MPa and from 94 MPa to 36 MPa, respectively. The reason for this sharp deterioration of mechanical properties is believed to be due to the incompatibility between bio-based materials and plastic polymers. Due to the polarity difference between PLA and biomass, they cannot be effectively mixed or cross-linked, which leads to poor mixing during melt extrusion, resulting in poor dispersion and interface between biomass and PLA polymer chains and biomass, and thus poor mechanical properties. Attempts have been made to use commercially available compatibilizers to improve the dispersion and mixing of PLA and biomass. However, due to the significant difference in functional group density between PLA and biomass materials (>150 times or more), the compatibilizer has a strong tendency to react mainly with the biomass material and form "biomass material-compatibilizer-biomass material" clusters, and ultimately is not evenly dispersed in the composite material, resulting in improved but still unacceptable mechanical properties.

[0003] Therefore, there is a need for an improved PLA / biomass composite material that overcomes at least some of the above-mentioned disadvantages. Summary of the invention

[0004] This article provides a reactive homogenization that can significantly increase the amount of biomass filler from 30% to more than 50%, while providing improved mechanical properties and reducing the high material cost of biodegradable plastics such as PLA. The reactive homogenization is a two-step melt extrusion process. Since PLA is a typical thermoplastic polyester plastic, it carries reactive functional groups at the end of the polymer chain, which can be utilized to form compatible pellets. An octopus-like functional group promoter with a cyclic compound body and multiple epoxy group branches is designed to form network-branched compatible pellets. In the first step, the terminal hydroxyl functional groups of the PLA polymer chain react with an epoxy crosslinker to form compatible pellets. In the second step, the biomass material is combined with the compatible pellets, causing the biomass and the compatible pellets to crosslink, thereby forming a PLA / biomass composite.

[0005] In a first aspect, the present invention provides a polylactic acid (PLA) / biomass composite material, which PLA / biomass composite material comprises: polylactic acid (PLA), biomass material, compatibilizer, cross-linking agent, chain extender, antioxidant and nucleating agent, wherein PLA, biomass material, compatibilizer, cross-linking agent, chain extender, antioxidant and nucleating agent are present in the PLA / biomass composite material at concentrations of 30-60% wt / wt, 20-70% wt / wt, 5-20% wt / wt, 0.1-3% wt / wt, 0.1-2% wt / wt, 0.1-1% wt / wt and 1-10% wt / wt, respectively.

[0006] In certain embodiments, the biomass material is selected from the group consisting of wood, bamboo, corn cobs, and combinations thereof.

[0007] In certain embodiments, the compatibilizer is selected from polylactic acid grafted maleic anhydride (PLA-g-MAH); polybutylene adipate terephthalate grafted maleic anhydride (PBAT-g-MAH); self-synthesized network branched compatible particles represented by chemical structure I or II:

[0008]

[0009] or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0010]

[0011] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

[0012] In certain embodiments, the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol, and combinations thereof.

[0013] In certain embodiments, the chain extender is selected from the group consisting of the following substances and combinations thereof:

[0014]

[0015]

[0016] Where R1 and R 2 are each independently H, CH3 or alkyl; R 3 is an alkyl group, and m, n and p are each independently 1-20.

[0017] In certain embodiments, the antioxidant is selected from the group consisting of the following substances and combinations thereof:

[0018]

[0019] In certain embodiments, the nucleating agent is selected from the group consisting of diphenyl dihydrazide sebacate, montmorillonite, calcium carbonate, and combinations thereof.

[0020] In certain embodiments, the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol, and combinations thereof; the chain extender is selected from the group consisting of the following substances and combinations thereof:

[0021]

[0022]

[0023] Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20;

[0024] The antioxidant is selected from the group consisting of the following substances and combinations thereof:

[0025]

[0026] And the nucleating agent is selected from the group consisting of diphenyl dihydrazide sebacate, montmorillonite, calcium carbonate and combinations thereof.

[0027] In certain embodiments, PLA, biomass material, compatibilizer, crosslinker, chain extender, antioxidant and nucleating agent are present in the PLA / biomass composite at concentrations of 30-60% wt / wt, 21.6-49.5% wt / wt, 8-12% wt / wt, 1.2-2% wt / wt, 0.6-1% wt / wt, 0.5-1% wt / wt and 4-9% wt / wt, respectively.

[0028] In certain embodiments, the compatibilizer is a self-synthesized network-branched compatibilizing particle represented by chemical structure I or II:

[0029]

[0030] or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0031]

[0032] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV;

[0033] Crosslinking agents include tannic acid, gallic acid, 3,4-dihydroxybenzaldehyde and pyrogallol; chain extenders include:

[0034]

[0035] Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20;

[0036] Antioxidants include:

[0037] as well as

[0038] Nucleating agents include diphenyl dihydrazide sebacate, montmorillonite and calcium carbonate.

[0039] In certain embodiments, PLA, biomass material, compatibilizer, crosslinker, chain extender, antioxidant, and nucleating agent are present in the PLA / biomass composite at concentrations of about 50% wt / wt, about 32% wt / wt, about 8% wt / wt, about 1.3% wt / wt, about 1% wt / wt, about 0.7% wt / wt, and about 7% wt / wt, respectively.

[0040] In a second aspect, the present invention provides a method for preparing the PLA / biomass composite material described herein, the method comprising: melt blending PLA, a biomass material, a compatibilizer, a cross-linking agent, a chain extender, an antioxidant, and a nucleating agent; optionally granulating, and optionally drying to form a PLA / biomass composite material.

[0041] In certain embodiments, the biomass material is selected from the group consisting of wood, bamboo, corn cobs, and combinations thereof.

[0042] In certain embodiments, the compatibilizer is selected from polylactic acid grafted maleic anhydride (PLA-g-MAH); polybutylene adipate terephthalate grafted maleic anhydride (PBAT-g-MAH); self-synthesized network branched compatible particles represented by chemical structure I or II:

[0043]

[0044] or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0045]

[0046] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

[0047] In certain embodiments, the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol, and combinations thereof.

[0048] In certain embodiments, the chain extender is selected from the group consisting of the following substances and combinations thereof:

[0049]

[0050] Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is an alkyl group, and m, n and p are each independently 1-20.

[0051] In certain embodiments, the method further comprises: contacting PLA with a compound of Formula V or VI, or a pharmaceutically acceptable salt thereof:

[0052]

[0053] Where: R 5 is independently in each occurrence hydrogen or a moiety of formula IV:

[0054]

[0055] The condition is at least 3 R 5is a moiety of formula IV, thereby forming a compatibilizer, wherein the compatibilizer is a self-synthesized network branched compatibilizing particle represented by chemical structure I or II:

[0056]

[0057] or a pharmaceutically acceptable salt thereof, wherein R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0058]

[0059] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

[0060] In certain embodiments, the method includes melt blending PLA and a compound of Formula V or VI to form a self-synthesized network branched compatible pellets; and melt blending the self-synthesized network branched compatible pellets with PLA, a biomass material, a crosslinking agent, an antioxidant, and a nucleating agent, optionally pelletizing, and optionally drying to form a PLA / biomass composite material.

[0061] In certain embodiments, PLA and a compound of Formula V or VI are melt extruded at 160-190° C. to form a network branched compatible pellet; and the network branched compatible pellet, PLA, biomass material, antioxidant, and nucleating agent are melt extruded at 190-220° C.; optionally pelletized, and optionally dried to form a PLA / biomass composite material.

[0062] In certain embodiments, the crosslinking agent comprises tannic acid, gallic acid, 3,4-dihydroxybenzaldehyde and pyrogallol; the chain extender comprises

[0063]

[0064] Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20;

[0065] Antioxidants include:

[0066] as well as

[0067] Nucleating agents include diphenyl dihydrazide sebacate, montmorillonite and calcium carbonate. DETAILED DESCRIPTION

[0068] In this disclosure, unless the context requires otherwise, the word "comprise" or its grammatical variations shall be understood to mean the inclusion of the stated integer or groups of integers but not the exclusion of any other integer or groups of integers. It should also be noted that in this disclosure, especially in the claims and / or paragraphs, terms such as "comprises" and its grammatical variations may have the meanings ascribed to it in U.S. patent law; for example, they may mean "includes"; and terms such as "consisting essentially of..." and its grammatical variations have the meanings ascribed to it in U.S. patent law, for example, they allow elements not expressly recited, but exclude elements existing in the prior art or affecting the basic or novel characteristics of the invention.

[0069] Furthermore, in the present disclosure and claims, unless the context requires otherwise, the word "include" or its grammatical variations, will be understood to mean the inclusion of a stated integer or groups of integers but not the exclusion of any other integer or groups of integers.

[0070] Unless otherwise expressly stated, the use of the singular in this document includes the plural (and vice versa). In addition, unless otherwise expressly stated, when the term "about" is used before a quantitative value, the present teachings also include the specific quantitative value itself. Unless otherwise indicated or inferred, the term "about" as used in this document refers to a difference of ±10%, ±7%, ±5%, ±3%, ±1% or ±0% from the nominal value.

[0071] In the specification, the term "alkyl" may refer to a linear alkyl group, a branched alkyl group or a cyclic alkyl group. The number of carbon atoms in the alkyl group may be 1 to 50, 1 to 30, 1 to 20, 1 to 10 or 1 to 6.

[0072] The present invention provides a PLA / biomass composite material, which comprises: polylactic acid (PLA), a biomass material, a compatibilizer, a cross-linking agent, a chain extender, an antioxidant and a nucleating agent, wherein the PLA, the biomass material, the compatibilizer, the cross-linking agent, the chain extender, the antioxidant and the nucleating agent are present in the PLA / biomass composite material at a concentration of 30-60% wt / wt, 20-70% wt / wt, 5-20% wt / wt, 0.1-2% wt / wt, 0.1-1% wt / wt, 0.1-1% wt / wt and 1-10% wt / wt, respectively.

[0073] The PLA may have an average molecular weight of 50,000-500,000 amu, 85,000-500,000 amu, 150,000-500,000 amu, 250,000-500,000 amu, 400,000-500,000 amu, 85,000-400,000 amu, 85,000-250,000 amu, 85,000-150,000 amu, 150,000-400,000 amu, or 250,000-400,000 amu. PLA can be present in a concentration of 30-60% wt / wt, 35-60% wt / wt, 40-60% wt / wt, 45-60% wt / wt, 50-60% wt / wt, 55-60% wt / wt, 30-55% wt / wt, 30-50% wt / wt, 30-45% wt / wt, 30-40% wt / wt, 30-35% wt / wt, 35-55% wt / wt, 40-50% wt / wt, 45-50% wt / wt, or 40-45% wt / wt in the PLA / biomass composite. In certain embodiments, PLA can be present in a concentration of about 30% wt / wt, about 40% wt / wt, about 45% wt / wt, about 50% wt / wt, or about 60% wt / wt in the PLA / biomass composite.

[0074] The type of biomass material is not particularly limited and can be any cellulose-containing biomass material. In some embodiments, the biomass material is selected from the group consisting of paper, paper products, paper waste, wood, pressed wood, wood chips, agricultural waste, silage, grass, rice husk, cotton, jute, spinning, flax, bamboo, sisal, straw, corn cob, corn stalks, millet, alfalfa, hay, coconut fiber, cotton, synthetic cellulose, seaweed, algae and their mixtures. In some embodiments, the biomass material is wood, bamboo, corn cob or their mixtures.

[0075] Biomass materials can be used in PLA / biomass composite materials at 20-70%wt / wt, 25-70%wt / wt, 30-70%wt / wt, 35-70% wt / wt, 40-70%wt / wt, 45-70%wt / wt, 50-70%wt / wt, 55-70%wt / wt, 60-70%wt / w t, 65-70%wt / wt, 20-65%wt / wt, 20-60%wt / wt, 20-55%wt / wt, 20-50%wt / wt, 20 -45%wt / wt, 20-40%wt / wt, 20-35%wt / wt, 20-30%wt / wt, 20-25%wt / wt, 25-65% wt / wt, 30-60%wt / wt, 35-55%wt / wt, 40-50%wt / wt, 45-50%wt / wt, 40-45%wt / wt, 21.6-49.5%wt / wt, 21.6-40.8%wt / wt, 21.6-37.3%wt / wt, 21.6-32%wt / wt , 32-49.5%wt / wt, 37.3-49.5%wt / wt, 32-49.5%wt / wt, 37.3-49.5%wt / wt, 40. Concentrations of 8-49.5% wt / wt, 32-40.8% wt / wt, 37.3-40.8% wt / wt or 37.3-40.8% wt / wt are present. In certain embodiments, the biomass material is present in the PLA / biomass composite at a concentration of about 21.6% wt / wt, about 32% wt / wt, about 37.3% wt / wt, about 40.8% wt / wt, or about 49.5% wt / wt.

[0076] The biomass material can have a particle size of 200 mesh, 175 mesh, 150 mesh, 125 mesh, 100 mesh, or 80 mesh. In certain embodiments, the biomass material can have a particle size of 25-200 mesh, 50-200 mesh, 80-200 mesh, 80-175 mesh, 80-150 mesh, 80-125 mesh, 80-100 mesh, 100-200 mesh, 125-200 mesh, 150-200 mesh, 175-200 mesh, 125-175 mesh, 125-150 mesh, or 150-175 mesh.

[0077] The biomass material may optionally be reduced in particle size prior to use in preparing the compositions described herein.

[0078] There are various known methods for controlling the particle size of a material, including reduction by comminution or deagglomeration by grinding and / or screening. Exemplary methods of reducing particles include, but are not limited to, jet milling, hammer milling, compression milling, and tumbling processes (e.g., ball milling). The particle size control parameters of these processes are well understood by those skilled in the art. For example, the particle size reduction achieved in a jet milling process is controlled by adjusting a number of parameters, the main parameters being the grinding pressure and feed rate. In a hammer milling process, the particle size reduction is controlled by the feed rate, hammer speed, and the opening size of the grid / screen at the outlet. In a compression milling process, the particle size reduction is controlled by the feed rate and the amount of compression imparted to the material (e.g., the amount of force applied to the pressure roller).

[0079] The compatibilizer can be selected from the group consisting of poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EGMA), PLA-g-MAH, PBAT-g-MAH, and network branched compatible pellets, wherein the network branched compatible pellets are represented by chemical structure I or II:

[0080]

[0081] or a pharmaceutically acceptable salt thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0082]

[0083] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV. In certain embodiments, R 4 In each case, R is independently a moiety of formula III or a moiety of formula IV. In certain embodiments, 1-5, 1-4, 1-3, 1-2, 2-3, 2-5, 3-5, 3-4, or 4-5 R 4 is a moiety of formula III. In certain embodiments, 2-3, 2-4, or 2-5 R 4 is a part of formula IV. In certain embodiments, the network branched compatible granules are represented by chemical structure I, wherein 1-2 R 4 is a moiety of formula III; and 4-5 R 4 is a part of formula IV. In certain embodiments, the network branched compatible particulate material is represented by chemical structure II, wherein 2-3 R 4 is a moiety of formula III; and 5-6 R 4 is a moiety of formula IV.

[0084] In certain embodiments, the average molecular weight of PBAT-g-MAH is about 120,000 to about 300,000 amu, and the average molecular weight of PLA-g-MAH is about 100,000.

[0085] The PLA / biomass composite may comprise 1, 2, 3, 4, 5 or more compatibilizers.

[0086] The compatibilizer can be present in a concentration of 5-20% wt / wt, 10-20% wt / wt, 15-20% wt / wt, 5-15% wt / wt, 5-10% wt / wt, 5-15% wt / wt, 10-15% wt / wt, 7-12% wt / wt, 8-12% wt / wt, 10-12% wt / wt, 7-10% wt / wt, or 7-8% wt / wt in the PLA / biomass composite. In certain embodiments, the compatibilizer can be present in a concentration of about 7% wt / wt, about 8% wt / wt, about 10% wt / wt, or about 12% wt / wt in the PLA / biomass composite.

[0087] The crosslinking agent can be an epoxidized natural oil, such as epoxidized olive oil, linseed oil, soybean oil, palm oil, peanut oil, coconut oil, algae oil or cod liver oil, NGDE, DGDE, BDE, DE, TA, GA, DB, pyrogallol or mixtures thereof.

[0088] The PLA / biomass composite may comprise 1, 2, 3, 4, 5 or more cross-linking agents.

[0089] The cross-linking agent can be present in the PLA / biomass composite at a concentration of 0.1-3% wt / wt, 0.5-3% wt / wt, 1.0-3% wt / wt, 1.0-2.5% wt / wt, 1.0-2% wt / wt, 1.5-2% wt / wt, 1.0-1.5% wt / wt, 1.2-2% wt / wt, 1.3-2% wt / wt, 1.7-2% wt / wt, 1.8-2% wt / wt, 1.2-1.8% wt / wt, 1.2-1.7% wt / wt, 1.2-1.3% wt / wt, 1.3-1.8% wt / wt or 1.2-1.7% wt / wt. In certain embodiments, the crosslinking agent may be present in the PLA / biomass composite at a concentration of about 1.2% wt / wt, about 1.3% wt / wt, about 1.7% wt / wt, about 1.8% wt / wt, or about 2% wt / wt.

[0090] The chain extender may be a polymeric oligomer containing glycidyl groups incorporated as side chains; epoxy-functional styrene-acrylic polymers such as those sold by BASF under the trade name "JoncrylTM ” epoxy-functional styrene-acrylic polymers sold under the trade name Joncryl TM Exemplary chain extenders sold under the trade name include, but are not limited to, Joncryl TM ADR-4368, Joncryl TM ADR-4368C, Joncryl TM ADR4300 and Joncryl TM ADR4468. Joncryl TM ADR4300 has the following chemical formula:

[0091]

[0092] Joncryl TM ADR-4368C, Joncryl TM ADR4368 and Joncryl TM ADR4468 has the following general chemical formula:

[0093]

[0094] Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is an alkyl group, and m, n and p are each independently 1-20. TM The ADR4368 has the following features: n <3000; PDI>3; EEW=285±15g / mol; T g =55℃.

[0095] The PLA / biomass composite may contain 1, 2, 3 or more chain extenders.

[0096] The chain extender can be present in a concentration of 0.1-2% wt / wt, 0.5-2% wt / wt, 1.0-2% wt / wt, 1.5-2% wt / wt, 1.0-1.5% wt / wt, 1.2-2% wt / wt, 0.1-1.5% wt / wt, 0.1-1% wt / wt, 0.5-1.5% wt / wt, 0.5-1% wt / wt, 0.6-1% wt / wt, or 0.1-0.6% wt / wt in the PLA / biomass composite. In certain embodiments, the chain extender is present in a concentration of about 0.6% wt / wt or about 1% wt / wt in the PLA / biomass composite.

[0097] The antioxidant may be a phenolic antioxidant. Exemplary antioxidants include, but are not limited to, butylated hydroxytoluene, 1010, 1076, 1098, 168 or B 225, etc. In certain embodiments, the antioxidant is selected from the group consisting of:

[0098]

[0099] as well as

[0100] A 1:1 mixture.

[0101] The PLA / biomass composite may contain 1, 2, 3 or more antioxidants.

[0102] Antioxidants can be present in a concentration of 0.1-2% wt / wt, 0.1-1.5% wt / wt, 0.1-1% wt / wt, 0.1-0.5% wt / wt, 0.5-2% wt / wt, 1-2% wt / wt, 1.5-2% wt / wt, 1-1.5% wt / wt, 0.5-1% wt / wt, 0.7-1% wt / wt, or 0.5-0.7% wt / wt in the PLA / biomass composite. In certain embodiments, antioxidants can be present in a concentration of about 0.5% wt / wt, about 0.7% wt / wt, or about 1% wt / wt in the PLA / biomass composite.

[0103] In certain embodiments, the nucleating agent is montmorillonite, calcium carbonate, talc, hydrotalcite, N,N',N"-tricyclohexyl-1,3,5-benzenetricarboxamide, zinc phenylphosphonate, sebacic acid diphenyl dihydrazide (TMC300), adipic acid diphenyl dihydrazide, or a mixture thereof.

[0104] The PLA / biomass composite may contain 1, 2, 3 or more nucleating agents.

[0105] The nucleating agent can be used in PLA / biomass composite materials at 1-10%wt / wt, 2-10%wt / wt, 3-10%wt / wt, 4-10%wt / wt, 5-10%wt / wt, 6-10%wt / wt, 7-10%wt / wt, 8-10%wt / wt, 9-10%wt / wt, 1-9%wt / w t, 1-8%wt / wt, 1-7%wt / wt, 1-6%wt / wt, 1-5%wt / wt, 1-4%wt / wt, 1-3%wt / wt, 1 - A concentration of 2% wt / wt, 4-9% wt / wt, 4-7% wt / wt, 4-5% wt / wt, 5-9% wt / wt or 7-9% wt / wt is present. In certain embodiments, the nucleating agent may be present in the PLA / biomass composite at a concentration of about 4% wt / wt, about 5% wt / wt, about 7% wt / wt, or about 9% wt / wt.

[0106] Also provided herein is a method for preparing the PLA / biomass composite material described herein, the method comprising: melt blending PLA, a biomass material, a compatibilizer, a crosslinking agent, a chain extender, an antioxidant, and a nucleating agent; optionally granulating, and optionally drying, thereby forming a PLA / biomass composite material.

[0107] PLA, biomass material, compatibilizer, crosslinking agent, chain extender, antioxidant and nucleating agent can be melt blended using any conventional method. In certain embodiments, melt blending can be carried out in a machine such as a single screw, twin screw or multi-screw extruder, Buss kneader, Eirich mixer, Henschel, Helicones, Ross mixer, Banbury, roll kneader, molding machine (e.g., injection molding machine, vacuum forming machine, blow molding machine, etc.) or a combination comprising two or more of the foregoing machines.

[0108] In certain embodiments, melt blending is achieved on a mixer or single / twin screw extruder operating in an appropriate processing temperature range, depending on the different melting temperatures (e.g., 150-250° C.) of PLA and other major components used to modify PLA. The melt blending duration may be 60 seconds to 600 seconds. The selection of appropriate melt blending conditions is well within the skill of those of ordinary skill in the art.

[0109] After melt blending, the resulting PLA / biomass composite material can be optionally granulated. Then, the granular PLA / biomass composite material thus obtained can be directly injection molded to be reshaped into a product with a desired shape and size. In addition to injection molding, other molding methods (such as profile extrusion, blow molding, blown film, film casting, spinning and coating antimicrobial polymer composite materials on plastic substrates) can also be used to be reshaped into products. PLA / biomass composite materials can be molded into shapes such as pellets, but they can also be made into semi-finished products or products.

[0110] In certain embodiments, the method further comprises contacting PLA with a compound of Formula V or VI, or a pharmaceutically acceptable salt thereof:

[0111]

[0112] Where: R 5 is independently in each occurrence hydrogen or a moiety of formula IV:

[0113]

[0114] The condition is at least 3 R 5 is a moiety of formula IV, thereby forming a compatibilizer, wherein the compatibilizer is a self-synthesized network branched compatibilizing particle represented by chemical structure I or II:

[0115]

[0116] or a pharmaceutically acceptable salt thereof, wherein R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV:

[0117]

[0118] Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

[0119] Compounds of formula V or formula VI are readily prepared by reacting hexahydroxycyclohexane or hexahydroxyphenol with epichlorohydrin in the presence of a base, such as Hünig base (N,N-diisopropylethylamine), ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine (DMEA), pyridine, pyrazine, trimethylamine (TMA), triethylamine (TEA), morpholine, N-methylmorpholine, piperidine, piperazine, pyrrolidine, 1,4-diazabicyclo[2.2.2]octane (DABCO), imidazole, N-methylmorpholine, NaOH, CsOH, LiOH, NaOH, KOH, Na2CO3, K2CO3, Cs2CO3, LiOtBu, NaOtBu, KOtBu, and the like.

[0120] Example 1

[0121] The bio-based material wood was crushed to a small size of 80-200 mesh. The bio-based material powder was dried at 100-130°C for 3 hours. Polylactic acid (PLA) (average molecular weight 85000 amu) was dried at 60-90°C for 3 hours. 30.0% polylactic acid (PLA), 49.5% wood powder, 12.0% polybutylene adipate terephthalate grafted maleic anhydride (PBAT-g-MAH) (average molecular weight 120000 amu), 0.7% epoxidized soybean oil (ESO), 0.3% neopentyl glycol diglycidyl ether (NGDE), 1.0% tannic acid (TA), 0.2% ADR4368C (average molecular weight 6800 amu), 0.8% ADR4300 (average molecular weight 5500 amu), 0.5% tri-(2,4-di-tert-butylphenyl)-phosphite (Anti-168), 1.0% organic montmorillonite (OM), 2.0% TMC300 and 2.0% calcium carbonate (CC) were added into a mixer and mixed at room temperature for 2 minutes. The above mixture is put into a twin-screw extruder, and the extrusion conditions are: 180℃, main screw speed is 50rpm, and feed screw speed is 8rpm. After melting, extrusion and granulation, the product can obtain plastic pellets. Dry the pellets at 80℃ for 3 hours. The pellets can be made into different commercial products by injection method. Conditions: 180℃, 50BAR. The injected product should be annealed at 90℃ for 3 minutes to obtain a final product with high crystallinity and high heat resistance.

[0122] Example 2

[0123] The bio-based material bamboo was crushed to a small size of 80-200 mesh. The bio-based material powder was dried at 100-130°C for 3 hours. PLA (average molecular weight 150000 amu) was dried at 60-90°C for 3 hours. 45.0% PLA, 37.3% bamboo powder, 10.0% polylactic acid grafted maleic anhydride (PLA-g-MAH) (average molecular weight 100000amu), 0.4% polyethylene glycol diglycidyl ether (DGDE), 0.3% 1,4-butanediol diglycidyl ether (BDE), 1.0% gallic acid (GA), 0.4% ADR4300 (average molecular weight 5500amu), 0.6% ADR4468 (average molecular weight 7250amu), 1.0% Anti-1010, 2.0% OM, 1.0% TMC300 and 1.0% CC were added to a mixer and mixed at room temperature for 2 minutes. The above mixture was placed in a twin-screw extruder under the extrusion conditions of 190°C, a main screw speed of 70rpm, and a feed screw speed of 7rpm. After melting, extrusion and granulation, the product can obtain plastic pellets. Dry the pellets at 80℃ for 3 hours. The pellets can be made into different commercial products by injection method. Conditions: 190℃, 45BAR. The injected product should be annealed at 90℃ for 3 minutes to obtain the final product with high crystallinity and high heat resistance.

[0124] Example 3

[0125] The bio-based material corncob is crushed to a small size of 80-200 mesh. The bio-based material powder is dried at 100-130°C for 3 hours. PLA (average molecular weight 250000amu) is dried at 60-90°C for 3 hours. 60.0% PLA, 21.6% corncob powder, 5.0% PLA-g-MAH, 5.0% PBAT-g-MAH (average molecular weight 200000amu), 0.9% ESO, 0.1% DE, 0.8% DB, 0.3% ADR4368C (average molecular weight 6800amu), 0.3% ADR4468 (average molecular weight 7250amu), 0.4% Anti-168, 0.6% Anti-1010, 1.0% OM, 1.0% TMC300 and 3.0% CC are added to a mixer and mixed at room temperature for 2 minutes. The above mixture is put into a twin-screw extruder, and the extrusion conditions are: 200℃, main screw speed is 80rpm, and feed screw speed is 6rpm. After melting, extrusion and granulation, the product can obtain plastic pellets. Dry the pellets at 80℃ for 3 hours. The pellets can be made into different commercial products by injection method. Conditions: 200℃, 40BAR. The injected product should be annealed at 90℃ for 3 minutes to obtain a final product with high crystallinity and high heat resistance.

[0126] Example 4

[0127] The bio-based material wood is crushed to a small size of 80-200 mesh. The bio-based material powder is dried at 100-130°C for 3 hours. PLA (average molecular weight 400000amu) is dried at 60-90°C for 3 hours. 40.0% PLA, 40.8% wood powder, 7.0% PBAT-g-MAH (average molecular weight 300000amu), 0.2% NGDE, 0.4% DGDE, 0.1% BDE, 0.5% pyrogallol, 1.0% ADR4368C (average molecular weight 6800amu), 0.2% Anti-168, 0.8% Anti-1010, 1.0% OM, 3.0% TMC300 and 5% CC are added to a mixer and mixed at room temperature for 2 minutes. The above mixture is put into a twin-screw extruder, and the extrusion conditions are: 180°C, the main screw speed is 75rpm, and the feed screw speed is 7rpm. After melting, extrusion and granulation, the product can obtain plastic pellets. Dry the pellets at 90°C for 3 hours. The pellets can be made into different commercial products by injection method. Conditions: 180°C, 50BAR. The injected product should be annealed at 90°C for 3 minutes to obtain a final product with high crystallinity and high heat resistance.

[0128] Example 5

[0129] The network branched compatibilizer uses 1 mol of hexahydroxycyclohexane as a starting material and reacts with 7.2 mol of epichlorohydrin under alkaline conditions (12 mol of triethylamine in acetone, 70°C, 3.5 hours). In a twin-screw extruder, a certain proportion of the network branched compatibilizer and PLA (1 / 3 molar ratio) are melted and extruded (180-200°C, 50rpm), and the epoxy groups on the compatibilizer react with the terminal hydroxyl groups of PLA to prepare network branched compatible pellets.

[0130] The bio-based material bamboo was crushed to a small size of 80-200 mesh. The bio-based material powder was dried at 100-130°C for 3 hours. PLA was dried at 60-90°C for 3 hours. 50.0% PLA, 32.0% bamboo powder, 8.0% self-synthesized network branched compatible granules, 0.2% TA, 0.5% GA, 0.1% DB, 0.5% pyrogallol, 0.3% ADR4368C, 0.3% ADR4300, 0.4% ADR4468, 0.3% Anti-168, 0.4% Anti-1010, 3.0% OM, 1.0% TMC300 and 3.0% CC were added to a mixer and mixed at room temperature for 2 minutes. The above mixture was placed in a twin-screw extruder, and the extrusion conditions were: 180°C, the main screw speed was 75rpm, and the feed screw speed was 7rpm. After melting, extrusion and granulation, the product can obtain plastic pellets. Dry the pellets at 90°C for 3 hours. The pellets can be made into different commercial products by injection method. Conditions: 180°C, 50BAR. The injected product should be annealed at 90°C for 3 minutes to obtain a final product with high crystallinity and high heat resistance.

[0131] Table 1

[0132] Example Tensile strength(MPa) Bending strength(MPa) Heat resistance temperature(℃) Example 1 33.8 52.3 80 Example 2 47.5 70.8 86 Example 3 53.0 81.5 88 Example 4 42.6 64.2 83 Example 5 61.4 95.0 95

Claims

1. A polylactic acid (PLA) / biomass composite material, comprising: polylactic acid (PLA), biomass material, compatibilizer, crosslinking agent, chain extender, antioxidant and nucleating agent, wherein the PLA, biomass material, compatibilizer, crosslinking agent, chain extender, antioxidant and nucleating agent are present in the concentration of 30-60% wt / wt, 20-70% wt / wt, 5-20% wt / wt, 0.1-3% wt / wt, 0.1-2% wt / wt, 0.1-1% wt / wt and 1-10% wt / wt in the PLA / biomass composite material, respectively.

2. The PLA / biomass composite material according to claim 1, wherein the biomass material is selected from the group consisting of wood, bamboo, corn cob and combinations thereof.

3. The PLA / biomass composite material according to claim 1, wherein the compatibilizer is selected from polylactic acid grafted maleic anhydride (PLA-g-MAH); polybutylene adipate terephthalate grafted maleic anhydride (PBAT-g-MAH); a self-synthesized network branched compatible granular material represented by chemical structure I or II: or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV: Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

4. The PLA / biomass composite material according to claim 1, wherein the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol and combinations thereof.

5. The PLA / biomass composite material according to claim 1, wherein the chain extender is selected from the group consisting of the following substances and combinations thereof: Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is an alkyl group, and m, n and p are each independently 1-20.

6. The PLA / biomass composite material according to claim 1, wherein the antioxidant is selected from the group consisting of the following substances and combinations thereof:

7. The PLA / biomass composite material according to claim 1, wherein the nucleating agent is selected from the group consisting of diphenyl dihydrazide sebacate, montmorillonite, calcium carbonate and combinations thereof.

8. The PLA / biomass composite material according to claim 3, wherein the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol and combinations thereof; the chain extender is selected from the group consisting of the following substances and combinations thereof: Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20; The antioxidant is selected from the group consisting of the following substances and combinations thereof: as well as The nucleating agent is selected from the group consisting of diphenyl dihydrazide sebacate, montmorillonite, calcium carbonate and combinations thereof.

9. The PLA / biomass composite material according to claim 8, wherein the PLA, the biomass material, the compatibilizer, the cross-linking agent, the chain extender, the antioxidant and the nucleating agent are present in the PLA / biomass composite material at concentrations of 30-60% wt / wt, 21.6-49.5% wt / wt, 8-12% wt / wt, 1.2-2% wt / wt, 0.6-1% wt / wt, 0.5-1% wt / wt and 4-9% wt / wt, respectively.

10. The PLA / biomass composite material according to claim 1, wherein the compatibilizer is a self-synthesized network branched compatible granular material represented by chemical structure I or II: or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV: Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV; The cross-linking agent includes tannic acid, gallic acid, 3,4-dihydroxybenzaldehyde and pyrogallol; The chain extender comprises: Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20; The antioxidants include: as well as The nucleating agents include sebacate diphenyl dihydrazide, montmorillonite and calcium carbonate.

11. The PLA / biomass composite material according to claim 10, wherein the PLA, the biomass material, the compatibilizer, the cross-linking agent, the chain extender, the antioxidant and the nucleating agent are present in the PLA / biomass composite material at a concentration of about 50% wt / wt, about 32% wt / wt, about 8% wt / wt, about 1.3% wt / wt, about 1% wt / wt, about 0.7% wt / wt and about 7% wt / wt, respectively.

12. A method for preparing the PLA / biomass composite material according to claim 1, the method comprising: PLA, biomass material, compatibilizer, crosslinker, chain extender, antioxidant and nucleating agent are melt blended; optionally pelletized, and optionally dried to form the PLA / biomass composite material.

13. The method of claim 12, wherein the biomass material is selected from the group consisting of wood, bamboo, corn cobs, and combinations thereof.

14. The method according to claim 12, wherein the compatibilizer is selected from polylactic acid grafted maleic anhydride (PLA-g-MAH); polybutylene adipate terephthalate grafted maleic anhydride (PBAT-g-MAH); a self-synthesized network branched compatible granular material represented by chemical structure I or II: or a pharmaceutically acceptable salt thereof; and combinations thereof, wherein: R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV: Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

15. The method of claim 12, wherein the cross-linking agent is selected from the group consisting of epoxidized soybean oil (ESO), neopentyl glycol diglycidyl ether (NGDE), polyethylene glycol diglycidyl ether (DGDE), 1,4-butanediol diglycidyl ether (BDE), diglycidyl ether (DE), tannic acid (TA), gallic acid (GA), 3,4-dihydroxybenzaldehyde (DB), pyrogallol, and combinations thereof.

16. The method according to claim 12, wherein the chain extender is selected from the group consisting of the following substances and combinations thereof: Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is an alkyl group, and m, n and p are each independently 1-20.

17. The method according to claim 12, further comprising: Contacting PLA with a compound of Formula V or VI, or a pharmaceutically acceptable salt thereof: Where: R 5 is independently in each occurrence hydrogen or a moiety of formula IV: The condition is at least 3 R 5 is a moiety of formula IV, thereby forming the compatibilizer, wherein the compatibilizer is a self-synthesized network branched compatible particle represented by chemical structure I or II: or a pharmaceutically acceptable salt thereof, wherein R 4 is independently in each case hydrogen, a moiety of formula III or a moiety of formula IV: Where q is an integer from 650 to 6500, provided that at least one R 4 is a moiety of formula III, and at least two R 4 is a moiety of formula IV.

18. The method of claim 17, wherein the method comprises melt blending PLA and the compound of formula V or VI to form the self-synthesized network branched compatible pellets; and melt blending the self-synthesized network branched compatible pellets with PLA, biomass material, crosslinking agent, antioxidant and nucleating agent, optionally pelletizing, and optionally drying to form the PLA / biomass composite material.

19. The method according to claim 18, wherein: The PLA and the compound of formula V or VI are melt-extruded at 160-190° C. to form the network branched compatible pellets; and the network branched compatible pellets, PLA, biomass material, antioxidant and nucleating agent are melt-extruded at 190-220° C.; optionally pelletized, and optionally dried to form the PLA / biomass composite material.

20. The method according to claim 17, wherein the cross-linking agent comprises tannic acid, gallic acid, 3,4-dihydroxybenzaldehyde and pyrogallol; and the chain extender comprises Where R 1 and R 2 are each independently H, CH3 or alkyl; R 3 is alkyl, and m, n and p are each independently 1-20; The antioxidants include: as well as The nucleating agents include sebacate diphenyl dihydrazide, montmorillonite and calcium carbonate.

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