Abstract: A tetrafluoroethylene resin molded article obtained by fusing PTFE by heating a tetrafluoroethylene resin by heating, and then executing a gradual cooling or a cooling including a holding at a temperature equal to or higher than 313° C. and lower than 321° C. for 10 minutes or longer, and having, when heated to 365° C., then cooled to 245° C. with a rate of ?1° C./min, and then heated to 365° C. with a rate of 10° C./min, a heat of fusion which, within a range from 296 to 343° C., is equal to or larger than 32 J/g and less than 47.8 J/g, a porous article obtained by expanding the molded article, and a composite article, a filter, an impact deformation absorber and a sealing material utilizing the molded article or the porous article.

Abstract: A tetrafluoroethylene resin molded article obtained by fusing PTFE by heating a tetrafluoroethylene resin by heating, and then executing a gradual cooling or a cooling including a holding at a temperature equal to or higher than 313° C. and lower than 321° C. for 10 minutes or longer, and having, when heated to 365° C., then cooled to 245° C. with a rate of ?1° C./min, and then heated to 365° C. with a rate of 10° C./min, a heat of fusion which, within a range from 296 to 343° C., is equal to or larger than 32 J/g and less than 47.8 J/g, a porous article obtained by expanding the molded article, and a composite article, a filter, an impact deformation absorber and a sealing material utilizing the molded article or the porous article.

Abstract: Unsintered poly(tetrafluoroethylene) resin feeds are treated with ionizing radiation in an absorbed dose of no more than 1,000 Gy at room temperature in air so that only the melting temperature of the resin feeds is shifted toward the lower end without changing the quantities of heat of fusion and crystallization.

Abstract: Unsintered poly(tetrafluoroethylene) resin feeds are treated with ionizing radiation in an absorbed dose of no more than 1,000 Gy at room temperature in air so that only the melting temperature of the resin feeds is shifted toward the lower end without changing the quantities of heat of fusion and crystallization.

Abstract: Unsintered poly(tetrafluoroethylene) resin feeds are treated with ionizing radiation in an absorbed dose of no more than 1,000 Gy at room temperature in air so that only the melting temperature of the resin feeds is shifted toward the lower end without changing the quantities of heat of fusion and crystallization.

Abstract: Unsintered poly(tetrafluoroethylene) resin feeds are treated with ionizing radiation in an absorbed dose of no more than 1,000 Gy at room temperature in air so that only the melting temperature of the resin feeds is shifted toward the lower end without changing the quantities of heat of fusion and crystallization.

Abstract: Fibers as a reinforcing substrate are impregnated with the particles of polytetrafluoroethylene and pressed into a shape at the melting point of polytetrafluoroethylene. Alternatively, the reinforcing substrate sandwiched between polytetrafluoroethylene sheets is pressed into a shape at the melting point of polytetrafluoroethylene. In either case, the shaped article is then exposed to an ionizing radiation in an oxygen-free atmosphere at the melting point of polytetrafluoroethylene. The inherent characteristics of the polytetrafluoroethylene, i.e., heat resistance, chemical resistance, abrasion resistance and lubricity, are retained and yet radiation resistance and resin transparency are imparted.