(161h) Synthesis, Processing, Characterisation and Degradation of Polymers: The State of the Art

Polymers hold advantages in recompence because they are used in massive and increasing quantities and replacing more traditional materials such as metals, wood, ceramics, etc. Volume consumption of plastics has surpassed than that of steel. Polymeric materials, both plastics and rubber, are readily moldable, which allows easy production of complex shapes with a minimum of fabrication and finishing. They have low densities, a property which leads to low weight products. They are resistant to corrosion and to chemical attack and are usually electrical and thermal insulators.

Although the absolute strength and modulus values of polymers are low, often have temperature limitations in service and mechanical tests, e.g. creeping behavior. The specific values per unit weight or volume are usually favorable. For this, specialty polymers find diversified applications.

Most polymers have been synthesized under the motivation of requirements for new and improved properties. Composites are being increasingly used in sophisticated ways to obtain special properties. Great improvement in physical properties in stereoregular polymers is observed due to ordered molecular arrangement that allows the formation of crystalline regions in polymer morphology. Stereoregular Polypropylene (PP) is available as a hard plastic due to its ordered regions and sufficiently regular chemical structure of molecule. Polyethylene terephthalate (PET), is widely used as a high strength textile fibre (e.g., Terylene, Trevira), it is the material for high- quality transparent films (e.g., Melinex). For years it has been used as the polymer for bottles for carbonated drinks and it is now an important material for injection molded electrical goods because of its outstanding dielectric properties.

The mixing process also provide an opportunity to alter the physical form of the polymer at the final conversion stage of its processing. The additives are sometimes needed to alter the properties of the material, e.g., by making it harder or more flexible or cheaper; the second is that it is often important to prevent degradation of the polymer in service or during processing or both by means of appropriate additives. Reinforcing fillers are used to toughen polymers e.g., carbon black- the main effect is a marked improvement in abrasion resistance. Non- reinforcing fillers, or extenders such as calcium carbonate and china clay, are added to cheapen the mix. Plasticizers are used in cases where it is desired to increase flexibility.

Present work reviews the present state of the art of commodity, engineering and specialty polymeric materials. This work comprehensively portrays the synthesis, processing, characterization and degradation of traditional (synthetic & Natural) as well as nontraditional (nanocomposites etc.) polymers.