Effect of Stretching on Properties of Polytetrafluoroethylene

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 reaches46. 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.