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CN-121975181-A - Strain rate sensitive composite foam material and preparation method thereof

CN121975181ACN 121975181 ACN121975181 ACN 121975181ACN-121975181-A

Abstract

The invention discloses a strain rate sensitive composite foam material and a preparation method thereof, and relates to the technical field of high polymer materials, and the preparation method comprises the following steps of mixing hydroxyl-terminated polydimethylsiloxane, thermoplastic polyurethane powder, microsphere foaming agent, boric acid and derivatives thereof, and foaming at a temperature of 65-120 ℃ to obtain the strain rate sensitive composite foam material; the mass ratio of the hydroxyl-terminated polydimethylsiloxane to the thermoplastic polyurethane powder is within the range of 1 (1-10), the addition amount of the microsphere foaming agent is 0.02-15 wt% of the total mass of the foaming powder, the addition molar amount of the boric acid and the derivative thereof is 1-10 times of the addition molar amount of the hydroxyl-terminated polydimethylsiloxane, and the strain rate sensitive composite foam material prepared by the method has good size and structural stability, good strain rate effect and impact energy absorption effect and simple preparation method.

Inventors

  • XING TAO
  • CHEN JUNLIN
  • XU WENCONG
  • MA JIAJUN

Assignees

  • 中国工程物理研究院总体工程研究所

Dates

Publication Date
20260505
Application Date
20260227

Claims (10)

  1. 1. A method for preparing a strain rate sensitive composite foam material, comprising the steps of: Mixing hydroxyl-terminated polydimethylsiloxane, thermoplastic polyurethane powder, microsphere foaming agent, boric acid and derivatives thereof, and foaming at 65-120 ℃ to obtain a strain rate sensitive composite foam material; Wherein the mass ratio of the hydroxyl-terminated polydimethylsiloxane to the thermoplastic polyurethane powder is 1 (1-10), the addition amount of the microsphere foaming agent is 0.02-15 wt% of the total mass of the foaming powder, and the addition molar amount of the boric acid and the derivative thereof is 1-10 times of the addition molar amount of the hydroxyl-terminated polydimethylsiloxane.
  2. 2. The method of preparing a strain rate sensitive composite foam according to claim 1, wherein the hydroxyl terminated polydimethylsiloxane has the chemical structure: , wherein, the value range of x is 5-800.
  3. 3. The method for preparing the strain rate sensitive composite foam material according to claim 1, wherein the particle size of the thermoplastic polyurethane powder is larger than 50 meshes, and the melting point is in the range of 60-150 ℃.
  4. 4. The method for preparing a strain rate sensitive composite foam material according to claim 1, wherein the microsphere foaming agent is an organic foaming agent which can be heated to generate gas within a temperature range of 60-150 ℃.
  5. 5. The method for preparing a strain rate sensitive composite foam material according to claim 1 or 4, wherein the microsphere foaming agent is specifically a heated volume expansion microcapsule formed by wrapping low-boiling alkane with a thermoplastic polymer.
  6. 6. The method for preparing a strain rate sensitive composite foam material according to claim 1, wherein the boric acid and the derivative thereof can be any one of boric acid, diboron trioxide, trimethyl borate and triethyl borate.
  7. 7. The method of claim 1, wherein the mixing is performed by dry mixing or wet mixing with a solvent.
  8. 8. The method for preparing the strain rate sensitive composite foam material according to claim 1, wherein the preparation method specifically comprises the following steps: And (3) mixing hydroxyl-terminated polydimethylsiloxane and thermoplastic polyurethane powder uniformly, adding a microsphere foaming agent, boric acid and derivatives thereof, rapidly and uniformly mixing, transferring into a die, foaming at 65-120 ℃, and cooling to room temperature after foaming is finished to obtain the strain rate sensitive composite foam material.
  9. 9. A strain rate sensitive composite foam material prepared by the method of any one of claims 1-8.
  10. 10. A strain rate sensitive composite foam according to claim 9, wherein the strain rate sensitive composite foam density is in the range of 0.2-0.8 g/cm 3 , the strain rate sensitive composite foam having a significant strain rate effect, the change in loss factor being greater than 200% when the sweep frequency is changed by three orders of magnitude in a rheology frequency sweep.

Description

Strain rate sensitive composite foam material and preparation method thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to a strain rate sensitive composite foam material and a preparation method thereof. Background Polyborosiloxanes (PBS) are a class of polymers with significant strain rate sensitive properties. Such polymers have a lower modulus under low strain rate external forces and flow characteristics similar to viscoelastic fluids, rapidly hardening as strain rate increases, increasing modulus to near plastic. The strain rate sensitive characteristic of PBS makes it widely used in fields such as human body protection. However, due to the problem that PBS cold flows under the action of low strain rate external force (such as gravity), the preparation of strain rate sensitive foam materials by compounding PBS and various thermosetting foam materials becomes a common method for enhancing the environmental adaptability of the materials. The modulus of the polyurethane elastomer is between rubber and plastic, and the polyurethane elastomer has the characteristics of abrasion resistance, tear resistance, high elasticity, excellent shock absorption capacity and the like, and is widely applied to the national economy field. The high strength of the polyurethane elastomer makes the polyurethane material widely used as a damping and energy absorbing material. In the prior art, various methods for preparing strain rate sensitive foam materials based on polyurethane have been disclosed, for example: in the method reported by Wang et al (ACS appl. Mate. Interfaces 2016, 8, 7, 4946), strain rate sensitive foams were obtained by dipping using an open cell polyurethane foam as a starting material and a PBS liquid. The method comprises the steps of preparing PBS, dissolving the PBS, dripping, and carrying out heat drying post-treatment, wherein the preparation process is longer, and the stability of the final product is poor due to the problem of cold flow of the PBS. The preparation of strain-rate sensitive foams by in situ chemical foaming using PBS, diisocyanate and polyether polyols was reported by Kun et al (10.1088/1361-665X/ab 0be 8). In this method polyurethane is obtained by means of a chemical reaction and cells are formed from carbon dioxide generated by an isocyanate reaction, but due to the hydrolysis reaction of PBS under the action of a polyol, the strain rate effect of the strain rate foam prepared by Kun et al is likely to originate from closed cell polyurethane foam only, not from PBS, and the foam obtained therefore does not inherit the impact protection effect of PBS. Disclosure of Invention The invention aims to solve the technical problems of complex preparation process, low reliability of a preparation method and weak strain rate effect of the traditional strain rate sensitive polyurethane foam material, and provides the strain rate sensitive composite foam material and the preparation method thereof, wherein the strain rate sensitive composite foam material is prepared by adopting a one-step foaming method and taking hydroxyl-terminated polydimethylsiloxane, thermoplastic polyurethane powder, microsphere foaming agent, boric acid and derivatives thereof as raw materials, has good size and structural stability, has good strain rate effect and impact energy absorption effect when the frequency is changed by 3 orders of magnitude in a rheological frequency scanning test, and has the density of 0.2-0.8 g/cm 3. The invention is realized by the following technical scheme. The first object of the invention is to provide a method for preparing a strain rate sensitive composite foam material, comprising the following steps: Mixing hydroxyl-terminated polydimethylsiloxane, thermoplastic polyurethane powder, microsphere foaming agent, boric acid and derivatives thereof, and foaming at 65-120 ℃ to obtain a strain rate sensitive composite foam material; Wherein the mass ratio of the hydroxyl-terminated polydimethylsiloxane to the thermoplastic polyurethane powder is 1 (1-10), the addition amount of the microsphere foaming agent is 0.02-15 wt% of the total mass of the foaming powder, and the addition molar amount of the boric acid and the derivative thereof is 1-10 times of the addition molar amount of the hydroxyl-terminated polydimethylsiloxane. The invention melts thermoplastic polyurethane under the heating action, generates a matrix phase in two processes of dehydration reaction of hydroxyl-terminated polydimethylsiloxane, boric acid and derivatives thereof, and simultaneously expands the microsphere foaming agent uniformly distributed in the matrix under the heating condition to generate hollow spheres to finally obtain the composite foam material with a closed-pore structure, the composite foam material has the advantages that the hollow microspheres are compressed when being subjected to impact loading, the strain rate effect is shown in t