高分子物理(北京化工大学)6-2.pptVIP

第十七讲 橡胶弹性的统计理论和唯象理论 重点及要求： 6.3 Statistical Theories of Rubber Elasticity 橡胶弹性的统计理论 交联点由四个有效链组成 高斯链 Gaussian chain 构象数 ? 仿射形变 Affine deformation 主伸长比率 ?1 ?2 ?3 构象熵的变化 Isotropic network 各向同性 The change of free energy ?F Uniaxial elongation 单轴拉伸 拉伸力 f force-elongation ratio relation 力-伸长比关系 应力 Stress ? 橡胶状态方程 2 一般固体物质符合虎克定律 橡胶形变时体积不变，泊松比?为0.5 橡胶状态方程总结 Comparison of theoretical curve and experimental results 6.4 橡胶状态方程的一般修正 (2) 自由末端修正 修正后的单位体积内的有效网链数N’ (3) Mooney-Rivlin Equation Empirical law (4) 幻象网络 Phantom network （5）S.F Edwards approach (1976) Different relationships between modulus and elongation ratio 6.5 Swelling effect 溶涨效应 交联橡胶的溶涨包括两部分： 化学位达平衡 If the volume fraction of polymer ?2 is very small 弹性自由能 求偏导 Application 6.6 Thermoplastic elastomer - TPE Definition in English 热固性塑料 Thermoset MOLDED TPE POLYMER W/PVC STITCHED HOCKEY BOOT FOAM-PADDED, SOFT TRICOT LINING Thermoplastic elastomer (TPE) films that are permeable to water vapor, or breathable, are finding increasing use in the medical industry hard-segment resins 聚氨酯弹性体 SBS Styrene-Butadiene-Styrene 共混型 Question: With one kind of polymer? 本讲和本章小结 即溶涨体内部溶剂的化学位和溶涨体外部的化学位相等 According to Flory-Huggins Theory 溶涨平衡时 If the number of segments x becomes very large ?=?1=?2=?3 理想交联网等温等压拉伸过程中内能不变，体积不变 代入到平衡条件中 网链的平均分子量 聚合物的密度 溶剂的摩尔体积 Hunggins parameter 溶涨前后体积比 To obtain the Hunggins parameters To obtain the average molecular weight between cross-linked points Mc 交联度低时Mc大，Q大即溶涨后体积增加多 交联为弹性体（橡胶）具有高弹性的条件之一，如果交联点为物理交联，则形成热塑弹性体。 兼有橡胶和塑料两者的特性，在常温下显示高弹，高温下又能塑化成型。 生产方法 聚合方法，得嵌段共聚物， TPE 机械共混法，得共混物， Ethylene propylene rubber/PP Elastomer - rubber. Hot shot scientists say a rubber or elastomer is any material that can be stretched many times its original length without breaking, and will snap back to its original size when it is released. Thermoplastic - a material that can be molded and shaped when its heated. Thermoset - a hard and stiff crosslinked material. Thermosets are different from thermoplastics, which become mo