A Study On Preparation Of PET/nano-SiO₂ Composite And Its Structure And Properties

A PET/nano-SiO2 composite used for fiber spinning was prepared by adding certain amount of nano-SiOa to take part of the reaction of synthesis of PET. The dispersivity of nano-SiO2 was studied. The effects of the dispersion time, methods, the kinds of dispersants and the concentration of dispersant were studied in case ethyl eneglycol was used as dispersion medium. The dispersion of run SiO2 in EG and PET was observed by TEM . The result shows that the dispersivity of nano-SiO2 is different with dispersion time, methods, kinds of dispersion agent and its concentrations. The best dispersivity of nano-SiO2 is obtained by ball milling with dispersion agent amino-silane, and more than 80% of SiO2 in nanometer size is in the composite.The effects of the nano-SiO2 on the reaction velocity of ester-exchange and polycondensation was also studied, the results show that the ester-exchange reaction rate is decreased with mano-SiO2 and dispersion agent, while the polycondensation reaction rate is increased with addtion of nano-SiO2. The structure of the composite was studied through IR and XSP , the results show that Si atom in SiO2 coordinates with the oxygen atom in the carbonyl group , the -CONH- group is produced by reaction of amino group in dispersion agent with the PET, as a result, the nano-SiO2 is well-distributed in the composite. The crystalline property of the composite was studied by JJY, DSC and X-ray. The results show that the rate of crystallization of the composite is higher thanthat of PET.TG results indicate that in presence of nano-SiOathe thermal decomposition rateof the composite is decreased . The dispersion agent has a little effect on its heatstability, but the Td is decreased by adding PEG for composite.The rheological analysis shows that the Theological behavior of the composite isalso a shear-thinning fluid, the thickening effect of nano-SiOi decreases with theincreasing of the shearing rate, the melt viscosity is decreased with the rise intemperature and PEG added.The spinnability of the composite was studied. The result shows that it has a goodspinnability in case the amount of nano-SiOi added is less 2% and can be spuninto lower tenacity pill-resistance fiber.