Study On The Crystallization Behavior And Properties Of Nano-siO₂/Uhmwpe Composite

In recent years,the modifications of UHMWPE have received increasingresearch interests.In this study,nanosilica was used as filler to improve the heatresistance and mechanical property of UHMWPE.Then the heating treatmentand organosiloxane-induced cross-linking was also adopted.In the paper,the effect of nanosilica on the molecular structure andcrystallization behavior of UHMWPE was studied in order to determine themodification mechanism.Then heating treatment and organosiloxane-inducedcross-linking was used to treat the nanosilica/UHMWPE composite.The results show that the addation of nanosilica can enhance the chainentanglement,increased the degree of crystallization and crystallization rate.Inthe composite the SiO₂acts as a physical cross-link point and a nucleatingagent.At5wt%nanosilica,the properties of composite reaches theirmaximum.The vicat softening point of composite raise from85℃to103℃,the tensile strength raise from29.8MPa to35MPa. Heating treatment lead to the movement of chain segment andrecrystallization.The processing residual and crystal defects can be minimized.The chain entanglement and the degree of crystallization increased afterheating treatment.The heat resistance and mechanical property ofnano-SiO₂/UHMWPE composite were further improved.Organosiloxane was used to cross-link the nano-SiO₂/UHMWPEcomposite. Organosiloxane also can improve the the interface compatibilitybetween nanosilica and UHMWPE.The heat resistance and mechanicalproperty of composite improved due to the increasing of chain entanglementand the degree of crystallization.At about0.7phr organsiloxane,the vicatsoftening point of nano-SiO₂/UHMWPE composite reaches101℃,the tensilestrength reaches38.2MPa.