General Characteristics of Semi-Crystalline Engineering Plastics General purpose structural parts Moderate strength Moderate temperature Good dimensional stability Good izod impact Easily fabricated Semi-crystalline engineering plastics can be considered for applications with an approximate maximum temperature of 250°F. Selecting a plastic material for use in a high temperature environment requires careful review of material properties data. View our interactive Thermoplastics Triangle to compare materials. Explore Semi-Crystalline Engineering Plastics Acetal High strength, stiff, low friction engineering plastic with good wear properties. Nylon Strong, stiff engineering plastic often used to replace metal bearings and bushings. PBT Strong, stiff plastic, good machining characteristics, bearing and wear, and chemical resistance. PET A strong, dimensionally stable plastic with outstanding chemical resistance and wear properties.