Properties of poly(ethylene terephthalate) containing epoxy-functionalized polyhedral oligomeric silsesquioxane

Poly(ethylene terephthalate) (PET) containing epoxy-functionalized polyhedral oligomeric silsesquloxane (POSS) was prepared by melt-mixing and in situ polymerization methods. The melt-mixed composite showed phase separation while the in situ polymerized composite did not, based on SEM characterization. During melt mixing, the reaction between the epoxy groups of POSS and hydroxyl groups of PET occurred, based on DSC results. DSC results on the in situ polymerization product showed formation of a lower-melting component compared with PET. The tensile strength and modulus of the melt-mixed composite fiber decreased compared with those properties of PET, whereas those of the in situ polymerized composite showed slightly higher values than PET despite the relatively small amounts (1-wt%) of POSS used. Dynamic mechanical analysis results showed an increase in storage modulus for the in situ polymerized composite of POSS and PET compared with PET over the temperature range of 40degreesC to 140degreesC. (C) 2004 Society of Chemical Industry.