Investigation of thermal, rheological, and physical properties of amorphous poly(ethylene terephthalate)/organoclay nanocomposite films

Thermal, rheological, and physical properties of amorphous poly(ethylene terephthalate) (PET)/organoclay nanocomposite films which were successfully prepared with melt processing method using a PET/organoclay masterbatch were studied in detail. Structural and physical properties of the films were characterized by the UV-Vis spectroscopy, XRD and SEM analysis, DSC, DMA, and rheological tests and gas permeability measurements. Cold-crystallization behavior of the samples was analyzed by the DSC and DMA methods. Aspect ratio of the organoclay layers were determined with the Nielsen and Halpin-Tsai models based on the gas permeability and DMA data, respectively. It was found that the organoclay reduced the nonisothermal cold-crystallization rate of PET chains by restricting the segmental motion of the polymer in the solid state. On the other hand, the organoclay enhanced the nonisothermal melt-crystallization of PET due to the nucleation effect. Aspect ratio (Af) of the clay layers were found to be about 20 by using the gas permeability and DMA data. Aspect ratio value was also confirmed by the analysis of SEM images of the samples. A physical model for the sample microstructure was offered that the stacks with the thickness of 20-30 nm and the lateral size of 400-600 nm, probably consisting of 5-8 layers, were uniformly dispersed in the PET structure. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013