FRACTURE OF BINARY BLENDS OF LINEAR AND BRANCHED POLYETHYLENE

The fracture behaviour of binary mixtures of low molar mass linear pol yethylene (L2.5: <(M)over bar (w)>, = 2500 g mol(-1), <(M)over bar (w) >/M(n) = 1.15) and higher molar mass linear and branched polyethylenes has been studied. The average tie-chain concentration of the differen t samples has been indirectly estimated. It was found that the true st ress at fracture, fracture strain and fracture energy increased with t he calculated average tie-chain concentration for all the binary blend s. For the binary mixtures of L2.5 and the higher molar mass linear po lyethylenes, there is no unique relationship between true stress at fr acture and calculated average tie-chain concentration, suggesting that segregation of L2.5 is an important factor determining the strength o f these samples. The fact that the L2.5/branched polyethylene blends w ith intimately mixed constituents exhibited a higher strength than the L2.5/linear polyethylene mixtures, with a distinct segregation of L2. 5, could be explained as being due to the higher average tie-chain con centration in the former blends. Copyright (C) 1996 Elsevier Science L td.