DIELECTRIC-RELAXATION BEHAVIOR OF POLYETHYLENE GRAFTED WITH ACRYLIC-ACID, 2-HYDROXYETHYLMETHACRYLATE AND THEIR BINARY-MIXTURES

Dielectric investigation of low density polyethylene grafted with acrylic acid (AA) and 2-hydroxyethylmethacrylate (HEMA) and their mixtures was carried out. The dielectric properties of different samples with different graft contents lower than 30% wt. were measured in the frequency range of 10(-2) - 10(6) Hz and the temperature range of 50-degrees - 175-degrees-C. Only one relaxation process is observed in the case of polyethylene grafted with acrylic acid (PE-PAA). The observed process is attributed to the cooperative reorientation of the poly-acrylic acid chains modified by their connections to the polyethylene. The melting of the polyethylene crystalline phase does not influence the relaxation behavior of the polyacrylic acid phase. On the other hand, two relaxation processes are observed in the samples of polyethylene grafted with HEMA, (PE-PHEMA). The high frequency process is identified to be a local relaxation process (beta-relaxation), while the low frequency one is attributed to the glass process of the poly(HEMA) phase. The copolymerization grafting of AA and HEMA on polyethylene samples, PE-P(AA-HEMA), showed that the grafted chains are a random copolymer enriched with HEMA so that it behaves very similar to PE-PHEMA.