Synthesis And Application Of Polyhedral Oligomeric Silsesquioxand

Polyhedral oligomeric silsesquioxane (POSS), was regarded as theunique nano-hybrid compound now. It's general formula was (RSiO3/2)n,where n was an odd number (n≧4) and R=H, organyl, halogen, etc. Thestructure of POSS included inorganic nuclear as SiO2 and organic lateralgroups and it could be synthesized from organic silicane or modified SiO2. In this thesis, six kinds of (RSiO3/2)8 were synthesized by thehydrolytic polycondensation of trifunctional monomers RSiOX3, in whichR was methyl, phenyl, nitrophenyl, isobutyl, vinyl and hydrogen, and X isCl or oxethyl, respectively. The other two kinds of POSS,((CH3)4N)8Si8O20and ((CH3)3OSiO3/2)8, were synthesized from tetraethyl silicate. Thestructures of products were confirmed by solid NMR, liquid NMR, FT-IR,GPC and XRD. Four kinds of polypropylene(PP)/POSS composites were prepared by - III -北京化工大学硕士学位论文twin screw extruder. These four composites were iso-polypropylene/octa(methyl) silsesquioxane (iPP/OMS), iso-polypropylene/octa (isobuthyl)silsesquioxane (iPP/OIBS), co-polypropylene/octa (methyl) silsesquioxane(cPP/OMS) and co-polypropylene/octa (isobuthyl) silsesquioxane(cPP/OIBS), respectively. The crystallization, thermal resistant andmechanical characters of the composites was tested. The results indicatedthat both OIBS and OMS were dispersing in the matrix in nano scale.Compared with raw materials, the brittleness of all composites wasimproved, and the crystal granularity was more uniform. In addition, thethermal resistant of cPP/OMS had remarkable increasing and the impactstrength of cPP/OIBS also was improved. With the introduction of OIBSthe nucleation of iPP was improved, which was confirmed by thecrystallization kinetics parameters calculated by modifiedAvrami-Jeziorny's method.