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CN-121991471-A - Low-density biodegradable composite material based on interface pore effect and preparation method thereof

CN121991471ACN 121991471 ACN121991471 ACN 121991471ACN-121991471-A

Abstract

The invention relates to the technical field of high polymer materials, and discloses a low-density biodegradable composite material based on an interface pore effect and a preparation method thereof, the composite material is prepared from a resin matrix composed of poly (adipic acid)/poly (butylene terephthalate) and poly (propylene carbonate), modified activated plant fibers with surfaces grafted with nano rigid particles and passivated by polyethyleneimine, a high-melting heterogeneous crystallization nucleating agent and a matrix reinforcing chain extender. The preparation method comprises the steps of grafting the nano particles on the surface of the fiber through a silane coupling agent, passivating, and performing reactive extrusion through a double-screw extruder with the length-diameter ratio of more than or equal to 52:1 under the high vacuum condition. The invention utilizes the interface micropore nucleation principle, reduces the material density on the premise of not adding a chemical foaming agent, solves the problem of matrix degradation caused by plant fibers, and obtains the composite material with light weight, high strength and full biodegradation characteristics.

Inventors

  • ZHU FU
  • ZHANG CHENGHONG
  • ZHANG CHANGPING

Assignees

  • 四川晟鸿科技发展有限公司

Dates

Publication Date
20260508
Application Date
20260211

Claims (10)

  1. 1. The low-density biodegradable composite material based on the interfacial pore effect is characterized in that the density of the composite material is 0.55-0.65g/cm 3 , and the composite material is prepared from the following raw materials in parts by weight: 50.0-80.0 parts of degradable resin matrix; 15.0-35.0 parts of modified activated plant fiber; 0.1-1.0 parts of high-melting heterogeneous crystallization nucleating agent; 0.5-1.5 parts of matrix reinforcing chain extender; the degradable resin matrix consists of poly (adipic acid)/poly (butylene terephthalate) and poly (propylene carbonate); the modified activated plant fiber is plant fiber with nano rigid particles grafted on the surface and subjected to polyethyleneimine passivation treatment, and in the preparation raw material of the modified activated plant fiber, the dosage of the silane coupling agent is 2.0% -4.0%, the dosage of the nano rigid particles is 2.0% -5.0% and the dosage of the polyethyleneimine is 0.2% -0.5% relative to the mass of the plant fiber.
  2. 2. The low-density biodegradable composite material based on interfacial pore effect according to claim 1, wherein the degradable resin matrix has a weight part of poly (adipic acid)/poly (butylene terephthalate) of 35.0-60.0 parts and a weight part of poly (propylene carbonate) of 15.0-30.0 parts; the polybutylene adipate/terephthalate contains a branched structure or also contains 0.2 to 0.5 parts of a peroxide initiator in the feedstock to form the branched structure in situ.
  3. 3. The low-density biodegradable composite material based on interfacial pore effect according to claim 1, characterized in that said nano-rigid particles are hydrophilic nano-silica or nano-calcium carbonate; the silane coupling agent is gamma-aminopropyl triethoxysilane.
  4. 4. The low-density biodegradable composite material based on interfacial pore effect according to claim 1, wherein the high-melting heterogeneous crystallization nucleating agent is ultrafine talcum powder or zinc phenylphosphonate, and the crystallization peak temperature of the high-melting heterogeneous crystallization nucleating agent induced by the poly (butylene adipate)/terephthalate) is not less than 85 ℃; the matrix reinforcing chain extender is a styrene-acrylic ester-glycidyl methacrylate copolymer.
  5. 5. A method for preparing a low-density biodegradable composite material based on an interfacial pore effect, characterized in that the preparation of the low-density biodegradable composite material based on an interfacial pore effect according to any one of claims 1 to 4 comprises the following steps: Dispersing the nano rigid particles in absolute ethanol solution containing a silane coupling agent, and forming suspension by ultrasonic dispersion; Placing the dried plant fiber in a high-speed mixer, spraying the suspension at 75-85 ℃ and mixing for reaction, then adding polyethyleneimine for continuous mixing for surface passivation, drying and curing to obtain the modified activated plant fiber; Mixing the modified activated plant fiber, the degradable resin matrix, the high-melting-point heterogeneous crystallization nucleating agent and the matrix reinforcing chain extender, and then sending the mixture into a double-screw extruder for reaction extrusion; The length-diameter ratio of the double-screw extruder is more than or equal to 52:1, two-stage vacuum devolatilization is arranged in the extrusion process, and the absolute pressure of a second-stage vacuum devolatilization section is less than or equal to 100Pa.
  6. 6. The method for preparing a low-density biodegradable composite material based on interfacial pore effect according to claim 5, wherein the mass fraction of the silane coupling agent in the suspension is 20wt% -30wt%, and the mass ratio of the nano-rigid particles to the silane coupling agent is 1:1 to 1.25:1; The ultrasonic dispersion is carried out for 20-30 minutes under the cooling of ice water bath.
  7. 7. The method for preparing the low-density biodegradable composite material based on the interfacial pore effect according to claim 5, wherein the spraying process is performed at a rotation speed of 1200-1500rpm, and the spraying time is 5-10 minutes; the temperature and the rotating speed are kept after the spraying to continue the mixing reaction for 10 to 15 minutes; After the addition of the polyethylenimine, mixing was continued for 3-7 minutes at 500-800 rpm.
  8. 8. The method for preparing a low-density biodegradable composite material based on interfacial pore effect according to claim 5, wherein the screw combination of the twin-screw extruder comprises at least three sets of engagement blocks, and the metering section adopts a large-lead deep groove element; the melt pressure of the machine head is controlled to be in the range of 3.0-6.0MPa by adjusting the screen changer and the granulating process.
  9. 9. The method for preparing a low-density biodegradable composite material based on interfacial pore effect according to claim 5, wherein the temperature of said twin-screw extruder is set as follows: the temperature of the feeding area is 130-140 ℃, the temperature of the melting and dispersing area is 150-165 ℃, the temperature of the reaction enhancing area is 165-175 ℃, the temperature of the vacuum devolatilization area is 160-170 ℃, and the temperature of the machine head is 155-165 ℃.
  10. 10. The method of preparing a low density biodegradable composite material based on interfacial pore effect according to claim 5, wherein said extruding further comprises: The extruded material strip is conveyed by air cooling through an air cooling conveying belt, the distance of the air cooling conveying is more than or equal to 5 meters, then the extruded material strip enters a granulator for granulating, and the granulated particles are dried for 2-4 hours at 60-70 ℃.

Description

Low-density biodegradable composite material based on interface pore effect and preparation method thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to a low-density biodegradable composite material based on an interface pore effect and a preparation method thereof. Background The fully biodegradable polyester such as poly (butylene adipate/terephthalate) (PBAT) and poly (propylene carbonate) (PPC) has wide application prospect in the fields of packaging films, agricultural mulching films and the like due to the excellent biodegradability and processability. However, such biodegradable polyesters generally have higher density and raw material costs than conventional polyethylene and other general-purpose plastics, limiting their market competitiveness in large-scale commercial applications. Therefore, the realization of the light weight of the material to reduce the cost on the premise of ensuring the mechanical property and the full biodegradation characteristic of the material is a key technical problem to be solved in the current biodegradation material modification field. In order to achieve cost reduction and synergy, the prior art usually adopts the steps of adding biomass fillers such as plant fibers and the like or performing foaming treatment. However, the direct introduction of plant fibers which are not specially treated often faces serious interfacial compatibility problems, and the active hydroxyl groups and adsorbed water which are rich on the surface of the plant fibers are very easy to induce ester bonds of a polyester matrix to generate hydrolytic fracture in the high-temperature processing process, so that the molecular weight of the matrix is greatly reduced, the melt strength is insufficient, and the tensile strength and tear resistance of the composite material are greatly weakened. Although the traditional chemical foaming technology can effectively reduce the density, the process depends on the thermal decomposition of a chemical foaming agent, the foaming behavior is difficult to accurately control, coarse cells with uneven size and broken cell walls are easily formed in a film product, the mechanical structural integrity of the material is seriously damaged, and the residual components of the chemical foaming agent can generate potential toxicity to the composting environment and do not meet the high environmental protection standard of the full-biodegradable material. Physical foaming techniques, while free of residual problems, generally require expensive high pressure gas injection equipment and complex process control, and are difficult to popularize on conventional extrusion lines. In addition, the base materials such as PBAT (Poly-p-phenylene diamine) have the common problems of low crystallization rate and low crystallization temperature, so that in the cooling and shaping stage after extrusion, the melt is in a softened state for a long time, the pore structure inside cannot be locked in time, the collapse or retraction of cells is easy to occur, and meanwhile, the processing defects such as unstable film bubble, easy adhesion and the like in the film blowing process are also caused. Therefore, the biodegradable composite material which can overcome the matrix degradation problem caused by plant fibers without adding a chemical foaming agent and realize the balance between low density and high performance by regulating and controlling the microstructure is developed, and has important application value. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a low-density biodegradable composite material based on an interface pore effect and a preparation method thereof, and solves the problems that the existing biodegradable material has high use cost caused by high density, and the density is difficult to be reduced by adopting conventional chemical foaming or plant fiber filling modification, and meanwhile, the excellent mechanical property and processing stability are difficult to maintain. In order to achieve the above purpose, the invention is realized by the following technical scheme: The first aspect of the invention provides a low-density biodegradable composite material based on interfacial pore effect The density of the composite material is controlled to be 0.55-0.65g/cm 3, and the composite material is prepared from the following raw materials, by weight, 50.0-80.0 parts of a degradable resin matrix, 15.0-35.0 parts of modified activated plant fibers, 0.1-1.0 parts of a high-melting heterogeneous crystallization nucleating agent and 0.5-1.5 parts of a matrix reinforcing chain extender. Wherein the degradable resin matrix is composed of poly (adipic acid)/butylene terephthalate (PBAT) and poly (propylene carbonate) (PPC). The modified activated plant fiber is plant fiber with nano rigid particles grafted on the surface and subjected to polyethyleneimine passivation treatme