Preparation And Properties Of PTFE Nanocomposite Microporous Foaming Materials

In this paper,polytetrafluoroethylene(PTFE)was used as the modified filler to prepare its reinforced composite and its microporous foaming materials through melt processing.Polymer microporous foaming material has the characteristics of light weight,good insulation,heat insulation,sound insulation,etc.,but the polymer's low melt strength often limits its foaming performance.Modification by filler is one of the effective methods at present.PTFE has good dispersibility and thermal stability,especially in the process of in-situ fiber,greatly improving the polymer matrix viscoelastic properties.Therefore,this paper focuses on the PTFE reinforced polymer and its foaming properties for experimental research,the main contents are as follows:Firstly,PTFE-reinforced crystalline biodegradable polymer polybutylene succinate(PBS)and its foaming properties at different scales(FA-500,L-5,JH-220)were studied in this paper.Three kinds of PBS/PTFE composites were prepared by refining.The results show that the three kinds of PTFE can improve the crystallization property,viscoelastic property,mechanical property and foaming property of PBS matrix in different degrees.Among them,PTFE FA-500 formed a large number of nanofibers in situ,which had the most obvious strengthening effect on the polymer matrix.The cellular diameter of PTFE FA-500 foaming material was 5.46 ?m,and the cellular density was 1.86 × 109cells/cm3,which was much higher than that of pure PBS foaming material(32.49 ?m,1.95 × 107cells/cm3).The tensile strength increased from 23.6MPa of pure PBS to 31.1MPa,and the elongation at break increased from 10.4%to 13.7%.Based on the above conclusions,the enhancement effect of in-situ fibrinable PTFE FA-500 on amorphous polymer polystyrene(PS)was further studied in this paper.PS/PTFE nanocomposites with different mass fractions of PTFE FA-500 were prepared by dense refining.The results show that PTFE FA-500 with different contents has in-situ fibrinization,and the toughness,energy storage modulus and complex viscosity of PS/PTFE composite are all improved.When the content of PTFE was 3wt.%,the elongation at break was the highest,which was 3 times that of pure PS and the tensile strength of the foaming material increased from 35.4MPa to 39.6MPa.In addition,the addition of PTFE significantly improved the pore morphology of PS/PTFE composite foaming material.At different foaming temperatures,the foam morphology of PS/PTFE(5wt.%)composite foam at 110? is the best,the diameter of the bubble is 3.27?m,the density of the bubble is 1.11 × 1010cells/cm3.Finally,the 3wt.%in-situ fibrinated PTFE FA-50 was used as the research object and modified by polydopamine(PDA),and the enhancement effect of PDA-coated modified PTFE on thermoplastic polyurethane elastomer(TPU)was studied.Pure TPU,TPU/PTFE(3wt.%)and TPU/PDA@PTFE(3wt.%)nanocomposites were prepared by twin-screw extruding.The results show that the binding force between PTFE and TPU matrix is increased obviously,the diameter of in-situ nanofibers is reduced,and the viscoelastic properties and foaming properties of TPU matrix are improved to a greater extent after PTFE coated with PDA.The cellular diameter of TPU/PDA@PTFE composite decreased from 17.4 ?m of pure TPU to 7.68 ?m,and the cellular density increased from 7.55 × 106cells/cm3 to 1.59 × 108cells/cm3.