Chapter 2 (Plastic process) Flashcards
What makes plastics versatile for a wide range of applications?
Plastics are lightweight, corrosion-resistant, easy to process, can be molded into complex shapes, low electrical and thermal conductivity, good noise reduction
Explain the role of polymer processing in plastics manufacturing.
Mixing: Addition of additives to alter physical, mechanical or aesthetic properties of finished product.
Melting: Liquefy polymer and destroy memory of chain configurations.
Melt flow: Flow and shaping of the liquid by mechanical process.
Cross-linking: Formation of chemical cross-links to induce dimensional stability
Cooling and solidification: Transfer heat away from polymer. Important for thermoplastic.
What is the purpose of adding reinforcing or non reinforcing fillers in the mixing stage? Provide examples.
Reinforcing fillers: Enhance mechanical strength eg. silica
Non: To ease process and lower the cost eg. Carbonate
Adding plasticizers in mixing process function as?
Lower the Tg.
Increase flexibility.
How does viscosity affect mixing in plastics processing?
High viscosity allows for simultaneous distribution and dispersion, necessary for blending additives in rubber or highly viscous liquids.
Heat transfer issues in melting process?
Beware of degradation temperature of polymer.
What is compounding, and what types of machinery are used for it?
Compounding involves blending basic plastics with plasticizers, fillers, and additives. Machinery includes Banbury mixers and single/twin-screw compounders.
