Phase structure and viscoelastic properties of compatibilized blends of PET and HDPE recyclates

Immiscible blends of recycled polyethylene terephthalate) (R-PET), containi ng some amount of polymeric impurities, and high-density polyethylene (R-PE ), containing admixture of other polyolefins, in weight compositions of 75 : 25 and 25 : 75 were compatibilized with selected compatibilizers: maleate d styrene- ethylene/butylene-styrene block copolymer (SEBS-g-MA) and ethyle ne-glycidyl methacrylate copolymer (EGMA). The efficiency of compatibilizat ion was investigated as a function of the compatibilizer content. The rheol ogical properties, phase structure, thermal, and viscoelastic behavior for compatibilized and binary blends were studied. The results are discussed in terms of phase morphology and interfacial adhesion among components. It wa s shown that the addition of the compatibilizer to R-PET-rich blends and R- PE-rich blends increases the melt viscosity of these systems above the leve l characteristic for the respective binary blends. The dispersion of the mi nor phase improved with increasing compatibilizer content, and the largest effects were observed for blends compatibilized with EGMA. Calorimetric stu dies indicated that the presence of a compatibilizer had a slight affect on the crystallization behavior of the blends. The dynamic mechanical analysi s provided evidence that the occurrence of interactions of the compatibiliz er with blend components occurs through temperature shift and intensity cha nge of a P-relaxation process of the PET component. An analysis of the loss spectra behavior suggests that the optimal concentration of the compatibil izers in the considered blends is close to 5 wt %. (C) 2001 John Wiley & So ns Inc.