LDPE PP BLENDS MODIFIED BY PEROXIDE AND RADIATION-INDUCED REACTIONS/

LDPE/PP polyblends, modified through either peroxide initiated reactio ns or irradiation, were characterized in terms of rheological and mech anical properties and microstructure. In the presence of peroxide, or through irradiation LDPE crosslinks, PP degrades. Data were obtained a t two peroxide concentration levels (0.1 and 1% by weight) and two rad iation doses (30 and 100 kGy). The results show that in peroxide modif ication, the degradation of PP prevails over the crosslinking of LDPE. However, the effect of irradiation on LDPE (crosslinking) is predomin ant over that of PP (degradation). The irradiation process tends to yi eld improved mechanical properties vs. peroxide modification for the P P-rich blends. In addition, the melt viscosity and elasticity of the i rradiated PP-rich blends are higher than those of the peroxide-reacted blends at a given level of PP content and frequencies between 10 and 100 rad/s. Attempts were made to relate the shape of the rheological c urves and the mechanical properties of the blends to the observed chan ges in their microstructure. (C) 1994 John Wiley & Sons, Inc.