Polyurethane Rubber bridging

In the synthesis above styrene reacts with butadiene to form long chains while at the same time retaining a double bond per two molecules. Subsequently sulphur is added and sulphur bridges are formed between the remaining double bonds which interconnect the chains. These bridges are represented by small dashes. SBR is for instance used in the manufacture of car tyres. Another elastomer is polyurethane rubber PUR which is used as a foam in head rests. 

Thermoplastic polyurethane elastomers are polymers that bridge the gap between rubbers and plastics. They can be used in a wide range of properties, from hard rubbers to soft engineering thermoplastics as they are elastic and melt-processable. They can be processed on extrusion as well as injection, blow and compression molding equipment. They can be vacuum-formed or solution-coated and are suited for a wide variety of fabrication methodologies. They provide a considerable number of physical property combinations high resilience, good compression set, resistance to abrasions, tears, impacts, weather, and even hydrocarbons. Such materials... 

Single part urethane is not efficient in the bonding of rubber. The addition of isocyanate improves bonding as it can act as a bridge between rubber and urethane. However, it is necessary to use polyfunctional isocyanate, as it has to react with polyurethane and rubber. 

SK Chemicals produces a thermoplastic polyurethane (TPU) [9] under the trade name Skythane . Being the bridge between rubbers and plastics, this TPU elastomer has innovative potentials for uses requiring special characteristics, such as transparency, elasticity, durability, and resistance to chemical attack, in addition to excellent physical and mechanical properties Table 14 lists grades and properties of Skythane . 

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