Processability and miscibility of linear low-density polyethylene/ poly(vinyl alcohol) blends: In situ compatibilization with maleic acid

Blends of linear low-density polyethylene (LLDPE)/poly(vinyl alcohol) (PVA) were prepared by conventional thermoplastic processing technique. The blends were mixed using a Haake rheometer at 150°C and 50 rpm for 10 min. The LLDPE and PVA were blended to give the following blend ratios (php): 90/10, 80/20, 60/40, 50/50 and 40/60. The effect of maleic acid via in situ cross-linking on processability, component interaction, miscibility, thermal stability, tensile properties, and morphology of LLDPE/PVA blends was investigated in this research. The results indicated that the presence of maleic acid increases the equilibrium torque of LLDPE/PVA blends. This observation may be due to better compatibility and cross-linking between LLDPE and PVA. The formation of cross-linking was confirmed by Fourier transform infrared analysis and depression of melting points of PVA and LLDPE in the blends. The thermal stability and mechanical properties such as tensile strength, elongation-atbreak, and Young's modulus of the LLDPE/PVA blends also improved in the presence of maleic acid. Evidence for greater compatibility between LLDPE and PVA was confirmed by emergence of elongated fibrils extending over the surface of the PVA dispersed phases in the LLDPE matrix as revealed by scanning electron microscopy micrographs.