Abstract:
Maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) was used to toughen the calcium sulfate whiskers (CaSO
4W)/nylon6 (PA6) composites. The CaSO
4W/PA6 and CaSO
4W-(EVA-g-MAH)/PA6 composites were prepared using by a twin screw extruder, and analyzed by means of SEM, DSC, XRD and mechanical testing. The results indicate that addition of small amounts of CaSO
4W can increase the rate of crystallization, however, higher CaSO
4W contents lead to a decreased rate of crystalization and promotion of forming γ-crystals of PA6. Adding 10% (mass fraction) CaSO
4W increases both the stiffness and toughness of PA6. Adding 30% CaSO
4W can further improve the stiffness but significantly decreases the fracture toughness of PA6. With 2.5% and 5% mass fraction of EVA-g-MAH, the impact strength of 30%CaSO
4W-(EVA-g-MAH)/PA6 increases by 25.0% and 76.7%, respectively, thus imparting the higher toughness to the 30%CaSO
4W/PA6. The improvement of impact strength of the composites mainly results from energy-absorption process, effective stress transfering, the increasing in interfacial adhesion between CaSO
4W and PA6 in the presence of EVA-g-MAH as well as good miscibility of EVA-g-MAH/PA6 blend system.