Scanning Electron Microscopy Studies of Fractured Natural Rubber Surfaces

Abstract
A tensile ruptured gum specimen shows formation of crystalline regions at an angle of 45° to the flow lines, whereas a tensile ruptured filled specimen shows formation of depression. A tear fractured gum specimen shows again the formation of crystallites at an angle of 45° to the flow lines. Tear fractured filled specimens show the enhancement of crystallinity throughout the matrix, but the surface is rough. Flex fractured gum specimen show a large number of cracks on the surface while the filled vulcanizate shows formation of balls presumably due to coiling of polymer chains on the filler surface. An abraded gum surface shows dimple structure, while a filled vulcanizate indicates coarse ribbed structure. Addition of lignin, in general, reduces the crystallinity of tensile and tear fractured samples and increases the fibrosity of flex cracked and abraded samples.