Chapter 06 橡胶弹性 Rubber Elasticity

Polymer Physics)高分子物理 房事工黄大学 Guangdong University of Technology 6 Rubber Elasticity 橡脸弹性

6 Rubber Elasticity 橡胶弹性 Polymer Physics高分子物理

产事2黄大学 Gunpdong University af Technolopy 6.I Rubber and Rubber Elasticity

6.1 Rubber and RubberElasticity Chapter 6

房束2堂大学 10 Guangdong University of Technology 9 8 7 6 5 4 3 Temperature

109876543 III I II IV log G, Pa Temperature

廣事2孝大学 十CH2C=CHCH, Guangdong University of Technolopy natural rubber CH3 Types of rubbe polybutadiene synthetic rubber Polyisobutene (Breathable) Neoprene rubber(oil resistant) Hevea Brasiliensis橡胶树 Goodyear Tire

Types of rubbe CH2 C CH CH3 n CH3 natural rubber synthetic rubber Goodyear Tire Hevea Brasiliensis 橡胶树 polybutadiene Polyisobutene (Breathable) Neoprene rubber (oil resistant)

房幸2黄大学 Guangdong University of Technolopy COLUMBUS哥伦布 (1451-1506) 海地的印地安人土著人用 一种类似牛奶的白色乳液 放在木制的模子中，用烟 熏的方法，蒸发掉水份来 固化制成球做游戏

CHRISTOPHER COLUMBUS 哥伦布 (1451-1506) 海地的印地安人土著人用 一种类似牛奶的白色乳液 放在木制的模子中，用烟 熏的方法，蒸发掉水份来 固化制成球做游戏

GOODY在ART1RE Hancock Tire 廣事工黄大学 Guangdong University af Technolopy Dunlop Tire Michelin Tire

Dunlop Tire Michelin Tire GOODYEAR TIRE Hancock Tire

房事2黄大学 THE DEFINITION OF RUBBER uangdong University of Technology 施加外力时发生大的形变、外力除去后可以恢复的弹性材料称为橡胶：美 中文定义 国材料协会标准(ASTM-AMERICAN SOCIETY FOR TESTING AND MATERIALS) 规定：20-70摄氏度下，1min可拉伸2倍的试样，当外力除去后1min内至少回 缩到原长的1.5倍以下或者在使用条件下，具有106107Pa的杨氏模量者称 为橡胶。 Rubber is a polymer which exhibits rubber elastic 英文定义 properties,i.e.a material which can be stretched to several times its original length without breaking and which,on release of the stress,immediately returns to its original length

THE DEFINITION OF RUBBER 施加外力时发生大的形变、外力除去后可以恢复的弹性材料称为橡胶;美 国材料协会标准(ASTM-AMERICAN SOCIETY FOR TESTING AND MATERIALS) 规定:20-70摄氏度下,1min可拉伸2倍的试样,当外力除去后1min内至少回 缩到原长的1.5倍以下或者在使用条件下,具有106 ~107 Pa的杨氏模量者称 为橡胶。 中 文 定 义 Rubber is a polymer which exhibits rubber elastic properties, i.e. a material which can be stretched to several times its original length without breaking and which, on release of the stress, immediately returns to its original length. 英 文 定 义

房事2黄大学 Guangdong University of Technolopy THE NATURE OF HIGH ELASTICITY High elasticity is caused by entropy change.Under the action of external force, the rubber molecular chain changes from curled state to stretched state,and the entropy decreases.When the external force is removed,the molecular chain spontaneously tends to the state of increased entropy due to thermal motion, and the molecular chain returns to curled state from stretched state,so the deformation is reversible

THE NATURE OF HIGH ELASTICITY High elasticity is caused by entropy change. Under the action of external force, the rubber molecular chain changes from curled state to stretched state, and the entropy decreases. When the external force is removed, the molecular chain spontaneously tends to the state of increased entropy due to thermal motion, and the molecular chain returns to curled state from stretched state, so the deformation is reversible

Rubber(Elastomers)and Rubber Elasticity 房束2黄大学 Guangdong University of Technology >General properties of elastomers > The individual polymer chains of elastomers are held together by weak intermolecular bonding forces,which allow rapid chain slippage when a moderate pulling force is employed. Cross-links,which are introduced during yulcanization(a疏化)，permit rapid elongation of the principal sections,to a point where the chains Typical applied-force- are stretched to their elastic limit.Any additional elongation behavior of rubber elongation causes primary bond breakage.The cross-links,which are the boundaries for the principal sections,permitthe rubber to "remember"its originalshape,that is, the original orientation ofthe Sulphur bridges ee linking cis-1,4- Structure of thermo- particular chains. polyisoprene plastic elastomers 6

Rubber (Elastomers) and Rubber Elasticity ➢ General properties of elastomers ➢ The individual polymer chains of elastomers are held together by weak intermolecular bonding forces,which allow rapid chain slippage when a moderate pulling force is employed. ➢ Cross-links, which are introduced during vulcanization ( 硫 化 ), permit rapid elongation of the principal sections, to a point where the chains are stretched to their elastic limit. Any additional elongation causes primary bondbreakage. The cross-links, which are the boundaries for the principal sections, permitthe rubber to “remember” its originalshape, that is, the original orientation ofthe particularchains. Typical applied-force￾elongation behavior of rubber Sulphur bridges linking cis-1,4- polyisoprene Structure of thermo￾plastic elastomers 6

房事2黄大学 Guanpdong University of Technolopy 12 8 Vulcanized rubber Unvulcanized rubber 200 400 600 Elongation

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