Title: Summary Part Polymer Processing ONLY

Choose the correct statement.

- Thermoplastics soften above their glass transition temperature. Hence, thermoplastics can easily be shaped by a variety of processes, including extrusion, molding, and thermoforming. (correct)
- Thermoplastics soften above their melting temperature. Hence, thermoplastics can easily be shaped by a variety of processes, including extrusion, molding, and thermoforming.
- Thermoplastics are processed using liquid precursors that are cured upon chemical reactions. Hence, thermoplastics can easily be cast or molded.

- The temperature-dependend decrease in viscosity and their high strain-rate sensitivity allows extensive stretching of thermoplastics in forming operations; thus, complex and deep parts can be produced easily. (correct)
- The temperature-dependend decrease in viscosity and their high strain-rate sensitivity renders forming operations of thermoplastics difficult to control; thus, only parts of limited complexity can be produced from thermoplastics.

- Thermosetting plastics harden permanently upon curing. Curing includes the formation of covalent bonds linking the previously unlinked polymer chains upon a chemical reaction (often accelerated by heat). (correct)
- Thermosetting plastics harden permanently upon curing. Curing includes the further polymerization of polymer chains upon a chemical reaction (often accelerated by heat), increasing the molecular weight of the polymer chains.

- Cured thermosetting polymers are hard and brittle and cannot be formed, as they don't undergo a glass transition at elevated temperatures. Hence, they are generally molded or cast in their pre-cured state. (correct)
- Cured thermosetting polymers are very tough and formable. Hence they are often formed with the same processes used for thermoplastic polymers: molding and thermoforming, but also compression molding.

- Dip molding of elastomers is enabled by the vulcanizing (or crosslinking) of the polymer in a liquid-like state so that it matches the surface shape of the mold. (correct)
- Dip molding of elastomers is acheived by the drying of the polymer. The polymer filled liquid is able to coat the the surface shape of the mold while wet and hardens into the pure elastomer upon drying.

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