Toughening of ground rubber tire filled thermoplastic compounds using different compatibilizer systems

The impact properties of the thermoplastic composites containing ground rubber tires (GRT) have been investigated. Linear low density polyethylene (LLDPE) was used as the thermoplastic polymer matrix. Ground rubber tire crumb of average mesh sizes 40 (GRT40) and 80 (GRT80) were used. To improve the impact strength different compatibilizers were added to the above systems or the GRT was modified by different pretreatments. The use of two-component compatibilizers like epoxydized natural rubber (ENR) and ethylene-co-acrylic acid copolymer (EAA) improves the impact property depending upon the composition of the composites. The impact energies or ductilities of some composites are found to increase with the increase in the ENR content. A combination of the maleic anhydride (MA) and dicumyl peroxide (DCP) shows a significant increase in impact strength along with an increase in the melt viscosity of the composites. However, composites obtained from monomer pretreated GRT revealed a moderate increase in the impact strength. The improvement in impact properties is believed to occur as a result of several competing mechanisms. In some cases, it is due to interaction of a compatibilizer at the plastic/rubber interface through the improved surface activity of GRT particles. In other cases, matrix crosslinking appears dominant.