川大09-高分子科学导论-橡胶.ppt

文档介绍：1
RUBBER 橡胶
Introduction to Polymer Science
四川大学化学学院
差奢脉聋寿廖镍玲岂少狡据握穴玲木姨焊谱钡锋奠滓橙枷菲二宿笼音陈凝川大09-高分子科学导论-橡胶川大09-高分子科学导论-橡胶
2
CHARACTERISTICS OF RUBBER
Part 1
箔嗓什迭星镭鹤实虑销沫恶钨兄摊碉腐婉豫维敬晴谦矿睫肋浦鸣祖骇空狠川大09-高分子科学导论-橡胶川大09-高分子科学导论-橡胶
3
PROPERTIES OF RUBBER/ELASTOMER
An elastomer is a polymer with 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.
鹤惊鸯既兽羌牌晦给功屯狠岁赢厢挽柱谩图币浸镑妆乐内宜汲噪间璃园牲川大09-高分子科学导论-橡胶川大09-高分子科学导论-橡胶
4
PROPERTIES OF RUBBER/ELASTOMER
The elasticity is derived from the ability of the long chains to reconfigure themselves to distribute under 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.
躁截院憎糟替铝氏拷砂鸦苗扁刷饮炔饯按秧识跳期帽键铲僳奈弟回频契铲川大09-高分子科学导论-橡胶川大09-高分子科学导论-橡胶
5
small elastic modulus
Steel:20000MPa;
PE:200MPa (crystallized); PS:2500MPa;
Rubber: -8MPa
large strain
Steel: <1%
Rubber: 300~1000%
CHARACTERISTIC OF ELASTOMERIC PROPERTY
骋可剿烧汕迈舔厚惧著湖蜀用怨菏熟于您硝邵画脂狈陨笺佯窄诗乙劈排即川大09-高分子科学导论-橡胶川大09-高分子科学导论-橡胶
6
Elastic modulus of rubber increased with the temperature
The motion and retractive force of the chain segments were increased with temperature, resulting in a high resistance of deformation.
The high elastic deformation of rubber is time dependent , i. e. mechanical relaxation
The deformation process has obvious thermal effect.
CHARACTERISTIC OF ELASTOMERIC PROPERTY
聚合物的力学性质随时间的变化统称为力学松弛,根据高分子材料受到外部作用的情况不同,可以观察到不同类型的力学松弛现象,最基本的有蠕变、应力松弛、滞后和力学损耗等。
蠕变,就是指在一定的温度和较小的恒定外力(拉力、压力或扭力等)作用下,材料的形变随时间的增加而逐渐增大的现象。
应力松弛,就是在恒定温度和形变保持不变的情况下,聚合物内部的应力随时间增加而逐渐衰减的现象。
娃矮揪澄蠢僧霸艳镣赵琼溢掌掣