Crystallization kinetics of poly (butylene terephthalate) (non-talc-PBT) and its 0.1 wt % talc composites (talc-PBT) was determined for a wide range of cooling rates and isothermal temperatures. The critical cooling rate to suppress crystallization is 2000 K s 21 for non-talc-PBT and 7000 K s 21 for talc-PBT. The cooling rate dependence of the total enthalpy change and heating rate dependence of enthalpy of cold crystallization are quantitatively discussed on the basis of the Ozawa's method. For isothermal crystallization, the annealing-temperature (T iso ) dependence of crystallization half-time (t 1/2 ) shows a bimodal curve with two minima. Talc shortens the t 1/2 at T iso above 340 K and acts as a heterogeneous nucleation agent. Tammann's approach revealed that the t 1/2 is shortened by pre-nucleation for non-talc-PBT but not for talc-PBT.
Polylactic acid (PLA) is a plant-based plastic, which is derived from annually renewable resources such as corn, thus it is an environmentally friendly material. However, the thermal resistance of pure PLA is insufficient for optical disc use. To improve the thermal resistance we developed a newly polymer alloy that consists of a PLA as a main component, and fabricated a DVD-ROM whose substrate is made of the new polymer alloy. This disc showed excellent static optical property, and satisfied with the fundamental specifications of physical and signal characteristics. The results of high temperature and humidity tests reveals that the PLApolymer alloy DVD-ROM with an 8cm diameter has the durability on room use and distribution from a factory to consumers.
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