拉伸处理对聚四氟乙烯性能的影响

Effect of Stretching on Properties of Polytetrafluoroethylene

针对聚四氟乙烯(PTFE)回弹性差的问题,应用室温单轴拉伸的方法,在相同的拉伸速率下PTFE将试样拉伸至不同长度,以研究拉伸处理对PTFE性能的影响。采用扫描电镜(SEM)观察材料微观形貌,结果表明拉伸处理后PTFE内部出现大量的孔隙与微纤。由于空隙的产生,其密度随着拉伸长度的增加而下降。当拉伸长度为59%时,拉伸强度由未拉伸时的27.34MPa提高至46.90MPa,同时断后伸长率由310%增至410%,邵氏硬度降低。对不同拉伸倍率PTFE的压缩回复性测试可知,随着拉伸长度的增加,PTFE的压缩率由6.74%增加至14.29%,弹性回复率由4.17%增加到6.07%。拉伸处理的PTFE更加适合高性能密封材料。

Based on the poor resiliency of polytetrafluoroethylene（PTFE）,PTFE was stretched at room temperature uniaxially.Samples were stretched to different lengths at the same tensile speed,and the effect of stretching on properties was investigated.Microstructures show that lots of fibrils and cavities form in PTFE.Density decreases with the increase of tensile length due to the formation of cavities.Tensile strength of the non-drawn one is 27.34MPa,and when the tensile length is 59％,tension strength reaches 46.90MPa.Elongation at break increases from 310％ to 410％ during the same process.Hardness is reduced because of the formation of cavities.The results of the test of compressibility and recovery indicate that with the increasing of tensile ratios,compressibility enhances from 6.74％ to 14.29％,while resiliency improves from 4.17％ to 6.07％.The stretched PTFE is more suitable to be used as high performance sealing material.