Studies On Modification Of Polyolefins With Red Mud

Red mud (RM) as a growing pollution problem, its comprehensive utilization has recently attracted wide attention. In this paper, the surfaces of RM were modified by coupling agent, then it was used to modify polypropylene (PP), linear low density polyethylene (LLDPE) and polyvinyl chloride (PVC) . The main research results are as follows:(1) RM was treated by coupling agent, such as stearic acid (SA), aluminate coupling agent (AAE) and titanate coupling agent (TAE), and then used to fill with polypropylene (PP). The effects of surface treatment agent type and RM filling amount on the mechanical properties, fracture surface morphology, crystallization behavior, melting behavior and thermal stability of PP/RM composites were investigated. The results show that the comprehensive performance of PP/RM composites is the best when the amount of RM treated by titanate coupling agent is 20Phr, and the tensile strength and notched impact strength are improved by 11.1%and 42.1%, respectively. RM has heterogeneous nucleation effect, which improves the crystallization temperature, melting temperature and crystallinity of PP, and promotes the formation of ? crystal. Moreover, the addition of RM also improves the thermal stability of PP. The results also show that there is synergistic toughening effect between RM and EPDM, and the comprehensive performance of PP/EPDM/RM ternary system is best.(2) The effects of coupling agent type and RM filling amount on the mechanical properties, fracture surface morphology, crystallization behavior, melting behavior and thermal stability of LLDPE were studied. The results show that the modified RM can improve the comprehensive performance of LLDPE obviously, and the mechanical properties of the composites filled with 20Phr TAE-RM reach the maximum. RM also has heterogeneous nucleation effect, leading to the decrease of microcrystalline size and semi-crystallization time of LLDPE. Moreover, the addition of RM can also improve the thermal stability of LLDPE.(3) The effects of coupling agent type and RM filling amount on the mechanical properties, fracture surface morphology, temperature of glass transition, melting behavior and thermal stability of PVC were studied. The results show that the modified RM can improve the comprehensive properties of PVC, and the mechanical properties of the composites filled with 30Phr AAE-RM are best. The addition of RM can enhance the glass transition temperature of PVC, and absorb hydrogen chloride which makes the thermal decomposition temperature of PVC improve obviously.