Abstract: A method for manufacturing molded products of thermoplastic material by injection molding or extrusion molding a material containing a thermoplastic material as a primary component and a second polymer or a blend of the thermoplastic material and second polymer as a primary component and an inorganic material. The material is molded under the following mold conditions by a general type or vent type molding machine. The material is provided with a water content of less than about 1% by weight. The wall temperatures of the molding cylinder are controlled at different locations of the molding machine. The residence time of the molding material in the cylinder is controlled in response to the cylinder temperature so that the residence time is reduced as the temperature is increased whereby the residence time of said material in the cylinder is less than about 23 minutes. The temperatures of the discharge end is maintained within the range of plus 35.degree. C. or minus 25.degree. C.

Abstract: A method for manufacturing molded products of polyethylene terephthalate by injection molding or extrusion molding a material containing polyethylene terephthalate as the principal component characterized by using virgin and/or waste polyethylene terephthalate of average molecular weight of more than 10000 to which polymer such as nylon and/or inorganic fillers can be added as required, and molding said material under the following molding conditions by a general type or vent type molding machine:(a) Control of a temperature of a cylinder of the molding machine in the range of melting temperature of resin plus/minus 35.degree. C., and(b) Control of the staying hour of resin in the cylinder to be within 15 minutes.