Chain disentanglement in POSS/UHMWPE composites prepared via in-situ polymerization

Polyhedral oligomeric silsesquioxanes (POSS) /ultrahigh molecular weight polyethylene (UHMWPE) composites were produced by in-situ polymerization. POSS was supposed to intercalate the entangled chains of UHMWPE and induce chain disentanglement. The entanglement degree of POSS/UHMWPE composites was measured qualitatively and quantitatively by a rotary rheometer and a dynamic mechanical analysis (DMA). The reduced melt viscosity and the increased Me (the molecular weight between entanglements) revealed that the addition of POSS can induce the disentanglement of UHMWPE and the optimal content is 1.89 wt‰. The nucleating effect and plasticizing effect of POSS were observed in the increased crystallization temperature and reduced glass transition temperature (Tg), respectively. The annealing study of POSS/UHMWPE composites was carried out by a Flash DSC and POSS was found to lower the melting activation energy of UHMWPE. The results revealed that in-situ polymerization can induce homogeneous dispersion of POSS to interpenetrate the molecular network, dramatically diluting the entanglement.