ABSTRACT
Thermoforming is often used to convert plastic sheet into parts, and, if under a vacuum, the process is known as vacuum-forming. Acrylics are usually sold as cast sheeting, and polystyrene is often available as expandable molding for foamed products. Foamed polystyrene sheet extrusion is another commercially important product. Many thermosetting polymers are processed by compression molding which is the oldest plastic processing technique. A compressed “cake” of the granular resin is placed in a mold, at which time, the resin melts and the pressure forces the molten material to fill the mold cavity. The automotive industry’s emphasis on higher productivity and lower-volume market niches has spurred interest in these methods of relatively low-cost production of fully consolidated composite parts. Mechanical tests include, tensile strength, impact-strength, elongation, tear strength, abrasion resistance, etc. Most tests are generally grouped into four categories: general, mechanical, thermal and electrical.
