Study On The Creep Properties Of PTFE

Polyterafluoroethylene(PTFE) has many excellent properties such as outstanding resistance to attack by chemicals, superior resistance to heat ranging from the cryogenic area up to 260℃ and strong permeability resistance. PTFE is one of high-performance materials using on the aerospace materials, especially aeronautical sealing material. However its applications are hampered in many cases because of its low creep resistance and poor recovery. Little studies have been done to improve the compressive creep resistance performance of PTFE. In this paper, we devote ourselves to the research and development of compressive creep resistance performance of PTFE composites by using filling technology and obtain some achievements below.Two testing standards of the compressive creep resistance performance for PTFE composites developed in this study includes compression and resilience test which qualitatively judges the compressive creep resistance performance of composites to the existing international standards quickly, and long-time compressive creep test which many parameters of creep.The selection of sintering technology in its molding process and its influence on the properties of PTFE products were discussed. An excellent sintering process was determined for the suitable PTFE molding process.The BaSO₄/PTFE filling composites were prepared. The influences of contents of BaSO₄ on the mechanical properties and the compression and resilience properties of the untreated PTFE composites and the PTFE composites by heat-temperature treatment and the PTFE composites by heat-temperature oriented treatment were systematically investigated. Microstructures of pure PTFE and the untreated PTFE composites surface were studied by SEM and TEM. The crystallization and melting behavior of the untreated PTFE composites was studied by DSC. The results showed that the mechanical properties of pure PTFE products and the untreated PTFE composites whether untreated or treated by heat temperature showed the same results basically, while the PTFE composites by heat-temperature oriented treatment showed more higher tensile strength and more lower elongation at break. The compression and resilience properties of the untreated PTFE composites got an advantage over which of the heat-temperature oriented treatment PTFE composites. The untreated PTFE with 20%～30% contents of BaSO₄ with the excellent creep resistance properties can be as the sealing material.