Scanning Electron Microscopy Examination of the Fracture Surface of NR/SBR and NR/BR Blends

Blending of two or more rubbers is carried out for three main reasons,1 (1) improvement in technical properties (2) better processing (3) lower compound cost. Many products in the rubber industry are based on blends in all or part of their construction. Tyres are typical examples of products in large-scale volume production. Natural rubber (NR)/styrene-butadiene rubber (SBR) and natural rubber/polybutadiene rubber (BR) blends are extensively used in the manufacture of tyres.2 Scanning electron microscopy (SEM) is now widely employed to observe the microstructure of fracture surfaces and hence to study the fracture mechanism3-5. Fracture may be caused due to faults in the material or operating conditions. The fracture surfaces of polymeric materials show many characteristic features which enable the destructive influence to be recognized. Since the mechanical behaviour of blended rubbers is very sensitive to the filler distribution and level,6-8 curing aspects,9-11 compatibility of the rubber12-14 etc. an attempt has been made to observe the microstructure of the fracture surface of test samples in tension and abrasion of NRlSBR and NRlBR blends to correlate it with the strength and type of failure of these materials.