Introduction to Polymer Science RUBBER 橡胶
RUBBER 橡胶 Introduction to Polymer Science
Part 1 CHARACTERISTICS OF THE RUBBER
CHARACTERISTICS OF THE RUBBER Part 1
PROPERTIES OF RUBBER/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. o 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
PROPERTIES OF RUBBER/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
CHARACTERISTIC OF ELASTOMERIC PROPERTY o small elastic modulus ·Steel:20000MPa; PE:200MPa(crystallized);PS:2500MPa; 。Rubber:0.2-8MPa o large strain 。Steel:<1% ·Rubber:300~1000% o 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. o The high elastic deformation of the rubber is time dependent,i.e. mechanical relaxation o The deformation process have obvious thermal effect
small elastic modulus Steel：20000MPa； PE：200MPa (crystallized)； PS：2500MPa； Rubber: 0.2-8MPa 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 effect. CHARACTERISTIC OF ELASTOMERIC PROPERTY
RUBBER ELASTICITY 。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。 glass glass high elastic viscous state transation state state II viscoelastic III transition Tg T Temperature (C) 。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
RUBBER 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。 deformation Temperature (oC) I glass state high elastic state viscous state II III Tg Tf glass transation viscoelastic transition