Polyethylene-palygorskite nanocomposite prepared via in situ coordinated polymerization

A polyethylene/palygorskite nano-composite (IPC composite) was prepared via an in-situ coordinated polymerization method, using TiCl4 supported on palygorskite fibers as catalyst and alkyl aluminum as co-catalyst. These composites were compared with those prepared by melt blending (MBC composites). It was found that in the IPC composites, nano-size fibers of palygorskite were uniformly dispersed in the polyethylene matrix. In contrast, in the MBC composites, the palygorslate was dispersed as large clusters of fibers. Regarding the mechanical properties of the IPCs, the tensile modulus increased and the elongation at break decreased with increasing fiber content, while the tensile strength passed through a maximum. The tensile strength and elongation at break were much smaller for the MBC composites. The final degree of crystallinity of the IPC composites decreased with increasing palygorskite content. Regarding the kinetics of crystallization, the ratio between the degree of crystallinity at a given time and the final one was a universal function of time. It was found that large amounts of gel were present in the IPC composites and much smaller amounts in the MBC composites.