| Polyamide, generally known as nylon, is an important family of industrial materials, for its prominent properties such as relatively high strength, good toughness, good abrasion resistance and good processability. Since its synthesized by Carothers in 1934, many nylons have been developed, widely used in many fields such as machinery, chemical industry, communication, water conservancy and so on. But the drawbacks, such as low transparency, high water-absorption, relatively low impact strength at low temperature or in dry circumstance, limit its application. Therefore, modified PA are studied all over the world. Furthermore, common transparent materials could not be satisfying in some cases where outstanding physical and mechanical properties are demanded at the same time. More and more studies are developed on transparent polyamide.Transparent polyamide has attracted more and more attention in recent years, owing to their outstanding integrated properties, including good transparency, superb toughness, high thermal stability, high impact strength, good resistance to aging, good resistance to hydrolysis, low water affinity, good dimensional stability in the presence of moisture and so on. It has been widely used in the delicate optical instrument, observation mirror, gauge board, high-end athletic equipment and so on. It's reasonable to say that the research of transparent polyamide might lead to a new field of PA.On one hand, more and more transparent PA is needed in China now. On the other hand, costly transparent PA is imported because of the lack of raw materials side-chain diamines and diacids. So the study on transparent PA has actual significance.Although many developed countries have mastered the technology to prepare transparent PA , the monomers they adopted are usually side- chain diamines or diamines with circles and aromatic diacids which are exorbitant. Furthermore, characterizations on transparent PA and studies on its contour machining are little reported. In China, preparation of transparent PA is still a new subject.The new type semiaromatic transparent polyamide has been successfully developed using cheaper monomers, including linear chain aliphatic diamines, terephthalic acid, m-phthalic acid and so on,at Zhengzhou University by means of poly-copolycondensation,industrialized by Pingdingshan Plastics Co. Ltd., China , which has not been reported in the world as yet. In order to determine the optimum injection molding technological conditions, improve the quality of products, widen its applied range and perfect it, the work has developed around it, which includes structural analysis, characterizations on thermal behavior, rheological behavior, optical performance, electrical quality and so on. Especially, SATPA's injection molding technological conditions are studied and the optimum technological conditions is decided. All of the studies on SATPA show that:(l)SATPA, a new-type semiaromatic PA, are synthesized by linear chain aliphatic diamines and aromatic diacids. It has benzene ring in main chain and it is amorphous. Its intrinsic viscosity number [ ] is 65ml/g, transparency is about 90%, volume resistivity at room temperature is 3.0 X 10cm, specific surface resistivity at room temperature is 7.5 X 10, indicating it has excellent optical performance and electric insulation.(2)SATPA's Vicat softening temperature is 121 癈, T is 102C or so, indicating its' good resistance to effect of heat. The starting equilibrium heat decomposition temperature is 427C, indicating its outstanding thermostability. The heat decomposition reaction is one step reaction and the mechanism of the heat decomposition is deduced preliminary as diffusion control.(3)SATPA's melt flow rate is 2.4g/10min. The value of n (non-Newtonian index) is less than 1 for all temperatures under investigation, implying the pseudoplastic nature of SATPA in the molten state. The apparent viscosity a decreases with increasing of temperature, shear rate and shear stress. The apparent viscosity is sensitive to temperature at... |
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