Methods of making self-reinforced composition of amorphous thermoplastics

A method for making a self-reinforced composite of an amorphous thermoplastic material comprising the steps of melt-extruding and simultaneously drawing and cooling an amorphous thermoplastic material consisting essentially of poly(methylmethacrylate) to produce fibers with longitudinally-oriented molecular chains in which each fiber has a diameter within the range of about 5 to about 500 .mu.m and a heat relaxation ratio no less than about 3 to 1 in length;

• arranging said fibers to form an aggregation of fibers in which adjacent fibers are in contact with each other;
• and thereafter heating said aggregation of fibers to a temperature above the glass transition temperature of said material and below its degradation temperature, and applying pressure thereto, to soften and fuse together the outer surfaces of said fibers while maintaining at least some of the longitudinal orientation of the molecules of said material within said fibers.

A method for making a self-reinforced composite of an amorphous thermoplastic material comprising the steps of melt-extruding and simultaneously drawing and cooling an amorphous thermoplastic material consisting essentially of polycarbonate to produce fibers with longitudinally-oriented molecular chains in which each fiber has a diameter within the range of about 5 to about 500 .mu.m and a heat relaxation ratio no less than about 3 to 1 in length;

• arranging said fibers to form an aggregation of fibers in which adjacent fibers are in contact with each other;
• and thereafter heating said aggregation of fibers to a temperature above the glass transition temperature of said material and below its degradation temperature, and applying pressure thereto, to soften and fuse together the outer surfaces of said fibers while maintaining at least some of the longitudinal orientation of the molecules of said material within said fibers.

A method for making a self-reinforced composite of an amorphous thermoplastic material comprising the steps of melt-extruding and simultaneously drawing and cooling an amorphous thermoplastic material consisting essentially of polysulfone to produce fibers with longitudinally-oriented molecular chains in which each fiber has a diameter within the range of about 5 to about 500 .mu.m and a heat relaxation ratio no less than about 3 to 1 in length;

• arranging said fibers to form an aggregation of fibers in which adjacent fibers are in contact with each other;
• and thereafter heating said aggregation of fibers to a temperature above the glass transition temperature of said material and below its degradation temperature, and applying pressure thereto, to soften and fuse together the outer surfaces of said fibers while maintaining at least some of the longitudinal orientation of the molecules of said material within said fibers.