文档介绍：RUBBERRUBBER橡胶橡胶Introduction to Polymer ScienceIntroduction to Polymer Science四川大学化学学院四川大学化学学院CHARACTERISTICS CHARACTERISTICS OF THE RUBBEROF THE RUBBERPart 1Part 1Part 1PROPERTIES OF PROPERTIES OF RUBBER/ELASTOMERRUBBER/ELASTOMER?An elastomer is a polymer with the property of elasticity. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, although the latter is preferred when referring to vulcanisates. ?Elastomers are amorphous polymers existing above their glass transition temperature, so that considerable segmental motion is possible. At ambient temperatures rubbers are thus relatively soft and deformable. ?The elasticity is derived from the ability of the long chains to reconfigure themselves to distribute an applied stress. The covalent cross-linkages ensure that the elastomer will return to its original configuration when the stress is removed.?Their primary uses are for seals, adhesives and molded flexible parts.?small elastic modulus?Steel:20000MPa;?PE:200MPa (crystallized);PS:2500MPa;?Rubber: -8MPa?large strain?Steel: <1%?Rubber: 300~1000%?elastic modulus of the rubber increased with the temperature?The motion and retractive force of the chain segments increased with the temperature, resulted in a high resistance of deformation.?The high elastic deformation of the rubber is time dependent , i. e. mechanical relaxation?The deformation process have obvious thermal OF ELASTOMERIC PROPERTYCHARACTERISTIC OF ELASTOMERIC PROPERTYRUBBER ELASTICITYRUBBER ELASTICITY?高弹态是聚合物特有的力学状态。在Tg以上的非晶态聚合物处于高弹态,典型的代表是各种橡胶,因为其Tg≈-60 ~-20)℃,所以在一般使用温度下均呈高弹态。?高弹态(high elastic state)是高分子运动的特点之一;大部分高分子在Tg~ Tf间都可表现出一定的高弹性。deformationTemperature (oC)IIglass glass statestatehigh elastic high elastic statestateviscous viscous statestateIIIIIIIIIITTggTTffglass transationglass glass transationtransationviscoelastic transition viscoelastic viscoelastic transition transition RUBBER ELASTICITYRUBBER ELASTICITY?橡胶带在绝热的情况下拉