Q1: Thermoplastics are never moulded using

ANS:D - compression moulding

Thermoplastics are molded using all of the methods mentioned except compression molding. Here's an explanation of each molding method:

1. Injection Molding: This process involves injecting molten thermoplastic material into a mold cavity at high pressure. Once the material cools and solidifies, the mold opens, and the finished part is ejected. Injection molding is one of the most common and versatile methods for producing plastic parts with complex shapes and tight tolerances.
2. Blow Molding: Blow molding is used to create hollow plastic parts, such as bottles and containers. In this process, a tube of molten thermoplastic material, called a parison, is extruded and placed in a mold cavity. Compressed air is then blown into the parison, causing it to expand and take the shape of the mold. Once cooled, the mold opens, and the finished part is removed.
3. Extrusion: Extrusion is a continuous process used to create plastic profiles, pipes, tubes, and sheets. In extrusion, thermoplastic material is melted and forced through a die to produce a continuous shape with a constant cross-section. The extruded material is then cooled and cut to the desired length.
4. Compression Molding: While compression molding is commonly used for thermosetting plastics, such as fiberglass and phenolic resins, it is not typically used for thermoplastics. In compression molding, powdered or pelletized plastic material is placed in a heated mold cavity, and pressure is applied to compress the material into the desired shape. The mold is then cooled, and the finished part is removed.