Processability and Miscibility of Linear Low-densityPolyethylene/Poly(vinyl alcohol) Blends: In SituCompatibilization with Maleic Acid

Blends of linear low-density polyethylene (LLDPE)/poly(vinyl alcohol) (PVA) wereprepared by conventional thermoplastic processing technique. The blends weremixed using a Haake rheometer at 150°C and 50 rpm for 10 min. The LLDPEand 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 morphologyof LLDPE/PVA blends was investigated in this research. The results indicated that thepresence of maleic acid increases the equilibrium torque of LLDPE/PVA blends. Thisobservation may be due to better compatibility and cross-linking between LLDPE andPVA. The formation of cross-linking was confirmed by Fourier transform infraredanalysis and depression of melting points of PVA and LLDPE in the blends. Thethermal stability and mechanical properties such as tensile strength, elongation-atbreak,and Young s modulus of the LLDPE/PVA blends also improved in the presenceof maleic acid. Evidence for greater compatibility between LLDPE and PVA wasconfirmed by emergence of elongated fibrils extending over the surface of the PVAdispersed phases in the LLDPE matrix as revealed by scanning electron microscopymicrographs.