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The Role of Nanoclay and the Effect of Morphological Changes on 

the Heat Deflection Temperature of Poly(e-Caprolactone)

Introduction -- Poly(e-Caprolactone) (PCL) is currently being much investigated in medical applications and biodegradable packaging. Despite their hydrolytic and enzymatic degradability, potential applications similar to conventional thermoplastics such as polyethylene and polystyrene are hindered mainly because of their low heat Deflection Temperature (HDT), as low as room temperature. Introduction of nanoclays to the PCL body matrix results in the increase of stiffness of the polymer, however, several recent studies concerning such PCL composites disclosed that the HDT was not increased. This was partially attributed to the lack of intercalation and exfoliation in PCL nanoclay composite. The objective of the proposed research is to study the role of nanoclay and the effect of morphological changes on the HDT of PCL. Pioneering work on nanoclay systems at Toyota's Research Center in Japan showed that a hybrid nylon nanocomposite has a HDT as high as 164 C that is 100 C higher than that of pure nylon 6. On the other hand, morphology was shown long time ago that it has very significant effects on HDT of various semi-crystalline polymers, such as polypropylene, poly(ethylene terephthalate) (PET) and ploly(butylene terephthalate) (PBT). For example, an increase of crystallinity from 30% or below to 35-40% due to a heat-setting process resulted in an increase of the heat distortion temperature from 80 C or below to 95 C for blow-molded PET bottles.