Editing Rheology (section)

==== Polymers ====

Examples may be given to illustrate the potential applications of these principles to practical problems in the processing<ref>{{cite book |last1=Shenoy |first1=Aroon V. |last2=Saini |first2=D. R. |title=Thermoplastic melt rheology and processing |date=1996 |publisher=Marcel Dekker Inc. |location=New York |isbn=9780824797232}}</ref> and use of [[rubber]]s, [[plastics]], and [[fiber]]s. [[Polymers]] constitute the basic materials of the rubber and plastic industries and are of vital importance to the textile, [[petroleum industry|petroleum]], [[automobile industry|automobile]], [[paper industry|paper]], and [[pharmaceutical industries]]. Their viscoelastic properties determine the mechanical performance of the final products of these industries, and also the success of processing methods at intermediate stages of production.

In [[Viscoelasticity|viscoelastic]] materials, such as most polymers and plastics, the presence of liquid-like behaviour depends on the properties of  and so varies with rate of applied load, i.e., how quickly a force is applied. The [[silicone]] toy '[[Silly Putty]]' behaves quite differently depending on the time rate of applying a force. Pull on it slowly and it exhibits continuous flow, similar to that evidenced in a highly viscous liquid. Alternatively, when hit hard and directly, it shatters like a [[silicate glass]].

In addition, conventional rubber undergoes a [[glass transition]] (often called a ''rubber-glass transition''). E.g. The [[Space Shuttle Challenger|Space Shuttle ''Challenger'']] disaster was caused by rubber O-rings that were being used well below their glass transition temperature on an unusually cold Florida morning, and thus could not flex adequately to form proper seals between sections of the two [[Space Shuttle Solid Rocket Booster|solid-fuel rocket boosters]].