Effect of blend composition on physicochemical properties of natural rubber/linear low density polyethylene blend

Abstract

Blending of polymers can create new materials with a broad spectrum of physicochemical properties and therefore can be used for a wide range of applications. The aim of this study was to investigate the effect of blend composition on physicochemical properties of blends, prepared from natural rubber (NR) and linear low density polyethylene (LLDPE). In this study, a series of blends was formulated varying NR to LLDPE weight ratio, from 100:0 to 20:80, at intervals of 10 w/w% of each. The blends were prepared with and without diallyl malateas as the compatibilizing agent. The blends were prepared using a Brabender Plasticorder by melt mixing at a temperature of 160 ˚C, and at a rotor speed of 60 rpm. Dicumyl peroxide was used as the vulcanizing agent, and vulcanizates were prepared using a hydraulic press operated at a temperature of 150 ˚C.  The morphology of the blends was studied by means of a reflected light microscope. Swelling properties of the blends were studied by equilibrium swelling method for 7 days at room temperature using toluene and xylene as solvents. Physical and chemical properties were determined according to ASTM standards. Tear strength and modulus at 300% elongation of NR/LLDPE blends at every composition were greater than those of NR containing compound prepared without LLDPE. When tensile properties of the blends are concerned, they decreased with increase in LLDPE loading. However, the blends with LLDPE loading from 10 w/w% up to 40 w/w% showed higher tensile properties than those of NR compound. Hardness of the blends increased with increase in LLDPE loading. The reactive blends prepared with the compatibilizer showed improved physical properties compared to simple blends, prepared without the compatibilizer. Solvent resistance increased with increase in LLDPE loading, and further, the resistance was greater for the compatibilized blends at each composition. The lowest solvent resistance showed with NR. The microscopic image of a simple NR/LLDPE blend, at a specific blend composition, illustrated relatively large agglomerants of LLDPE phase and void at the interface. Reactive NR/LLDPE blend at the same composition illustrated small LLDPE agglomerants uniformly distributed with NR phase. Blends with different properties required for different applications could be obtained by varying the blend composition. The enhanced properties of the reactive blends prepared with diallyl malateas suggest its activity as a good compatibilizer for NR/LLDPE blends.