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

Dielectric investigation of low density polyethylene grafted with acry lic 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 frequ ency range of 10(-2) - 10(6) Hz and the temperature range of 50-degree s - 175-degrees-C. Only one relaxation process is observed in the case of polyethylene grafted with acrylic acid (PE-PAA). The observed proc ess is attributed to the cooperative reorientation of the poly-acrylic acid chains modified by their connections to the polyethylene. The me lting of the polyethylene crystalline phase does not influence the rel axation behavior of the polyacrylic acid phase. On the other hand, two relaxation processes are observed in the samples of polyethylene graf ted with HEMA, (PE-PHEMA). The high frequency process is identified to be a local relaxation process (beta-relaxation), while the low freque ncy one is attributed to the glass process of the poly(HEMA) phase. Th e copolymerization grafting of AA and HEMA on polyethylene samples, PE -P(AA-HEMA), showed that the grafted chains are a random copolymer enr iched with HEMA so that it behaves very similar to PE-PHEMA.