Chapter4Rubber(Elastomers)4.1An introduction4.2 The structure and properties4.3Naturalrubber4.4 General-purpose rubbers4.5Specialityrubbers4.6Thermoplastic elastomers(TPR)
Chapter 4 Rubber( Elastomers) 4.1 An introduction 4.2 The structure and properties 4.3 Natural rubber 4.4 General-purpose rubbers 4.5 Speciality rubbers 4.6 Thermoplastic elastomers(TPR)
4.4 General-purpose rubbers4.4.1Styrene-butadienerubbers(SBR)Introduction75% of the world's rubber marketsnaturalrubberSBR
75% of the world's rubber markets natural rubber SBR 4.4.1 Styrene-butadiene rubbers (SBR) Introduction 4.4 General-purpose rubbers
4.4.1.1IntroductionStyrene-butadienerubbers:firstpreparedin Germanyin 1929Buna S:in Germany(beforeWorldWarⅡ)GR-S:in America (afterWorld War
▪Styrene-butadiene rubbers : first prepared in Germany in 1929 ▪Buna S : in Germany (before World WarⅡ ) ▪GR-S: in America (after World WarⅡ ) 4.4.1.1 Introduction
4.4.1.1Introduction-Bythe 1960s the material hadcaptured a large part of the motortyremarketDuring 1960sSBRbecamethemost important rubber
▪By the 1960s the material had captured a large part of the motor tyre market ▪ During 1960s SBR became the most important rubber 4.4.1.1 Introduction
4.4.1.2PreparationThefirst generation:Before1950peroxide50oC72%Conversion'hot rubbers': very limited use today
4.4.1.2 Preparation ▪The first generation :Before 1950 peroxide 50oC 72% Conversion ▪'hot rubbers' : very limited use today
4.4.1.2PreparationThesecond generation:about1950about 5oC,a redox initiating system'cold rubbers':mostimportant
▪The second generation :about 1950 about 5oC , a redox initiating system ▪'cold rubbers' :most important 4.4.1.2 Preparation
4.4.1.3Generalproperties1.Properties:similar to natural rubber2.properties:different from natural rubber
4.4.1.3 General properties 1.Properties : similar to natural rubber 2. properties : different from natural rubber
4.4.1.3GeneralpropertiesAmajordifferencenaturalrubber:breakdown onmasticationSBR:does not breakdown on mastication
A major difference ▪natural rubber: break down on mastication ▪ SBR : does not break down on mastication. 4.4.1.3 General properties
4.4.1.3General propertiesOtherdifferencesslower Vulcanization-the lack of crystallinityLower tensile strengthgood abrasion resistance
Other differences ▪slower Vulcanization ▪the lack of crystallinity ▪Lower tensile strength ▪good abrasion resistance 4.4.1.3 General properties
4.4.1.3GeneralpropertiesOnageing■SBR:tends to cross-link on oxidation-NR:exhibit chain scission on oxidation
On ageing ▪ SBR : tends to cross-link on oxidation ▪NR : exhibit chain scission on oxidation 4.4.1.3 General properties