Study On Surface Modified Nano-SiO₂/PVC Hybrid Materials Synthesized By In-situ Polymerization

In this thesis,the surface modified nanosilica/PVC hybrid materials were synthesized by in-situ polymerization with no more change of the traditional PVC production equipments and production technologies.The mechanical properties and thermo stabilities of the nanosilica/PVC hybrid materials were evaluated,and the effects of the nanosilica on the properties of the hybrid materials were analyzed.1.Preparation of the nanosilica/PVC hybrid materialsThe effects of the preparation technologies of the nanosilica/PVC hybrid materials on the properties of the hybrid materials,on the polymerization system and on the polyreaction were explored,and the optimal preparation technology was obtained.The nanosilica/PVC hybrid materials with excellent properties were synthesized with no damage for the polymerization system and the polyreaction,and with no more change of the traditional PVC production equipments and production technologies.2.The combines between the nanosilica and PVC resinsThe nanosilica and PVC molecule had been well combined in the in-situ polymerization process illustrated by FTIR absorption spectra of nanosilica/PVC resins. The FTIR absorption spectra of the nanosilica extracted from the hybrid resins proved that the RNS-D could chemical bond with the PVC base because of the double bond wafted on its surface.But the DNS-2 and DNS-4 could not achieve the chemical bonds with PVC bace because the functional groups grafted on its surface were inert.3.The mechanical properties of the nanosilica/PVC hybrid materialsThe toughness of the nanosilica/PVC materials were improved obviously compared with pure PVC.The notched izod impact strength of the DNS-2/PVC and DNS-4/PVC increased remarkably with no more changes of the tensile strength of the nanosilica/PVC materials. The toughness and strength of the RNS-D/PVC were increased at the same time with the increase of RNS-D contents because the chemical bond formed between the nanosilica and PVC base.Compared with the nanosilica/PVC composites synthesized by melt-lbend method, the nanosilica could remain its net shape structure in the hybrids materials synthesized by in-situ polymerization,and the hybrid materials could achieve excellent properties with very low nanosilica contents.4.Thermo stabilities of the nanosilica/PVC hybrid materialsThe thermo stability of the nanosilica/PVC resins increased obviously with the increase of the nanosilica contents.The temperatures at the onset thermo degradation improved about 10℃with 1 wt%nanosilica content and the degradation giblets increased with the contents of nanosilica.The present nanosilica could absorb the HCl released in the PVC thermo degradation to prevent the catalysis of the HCl on the thermo degradation of PVC molecules.It was valuable to lower the hardness of the processing of PVC and to reduce the degradations of the hybrid materials in the machine shaping process.