SA型透明聚酰胺的成型加工、结构与性能

【作者】 曲良俊；

【导师】 李新法； 陈金周；

【作者基本信息】 郑州大学 ， 材料学， 2004， 硕士

【摘要】 自20世纪30年代由美国杜邦公司的W．H Carothers发明聚酰胺(尼龙，PA)以来，它由于具有机械强度高，冲击韧性好，耐热性、耐磨性和耐油性优异等特点，已广泛应用于机械、国防、化工、交通、水利等国民经济的各个领域，其生产能力和产量一直居于五大工程塑料的首位。但由于它还存在着透明性差、吸水性大、干态和低温下冲击强度低等缺陷而限制了它在某些方面的应用。为此，国内外广泛开展了聚酰胺改性方面的研究。更因为在某些对透明材料的物理机械性能要求很高的场合，一般的透明材料已经不能满足人们的要求，所以尤其是对透明聚酰胺的研究，更加引人关注。 透明聚酰胺具有优异的透明性、热稳定性、尺寸稳定性、电绝缘性和耐老化性能，强度高，无毒、无臭，成型收缩率低，线膨胀系数小，耐腐蚀，易与其它非结晶或半结晶聚酰胺形成合金等特点，可用于油箱、输油管、打火机油槽、流量计套、过滤器盖、滤杯、断路器和高压开关壳体、继电器、连接器等，特别在光学仪器、精密部件、计量仪表、食品包装和高档体育器材等方面有广泛的应用。 目前，国内对于透明聚酰胺的需求量日益增加，但是由于用于合成透明聚酰胺的带侧链基的二元胺和二元酸单体国内尚未工业化生产，所以至今没有研制成功透明聚酰胺，所需产品均要从国外进口，价格昂贵。为了满足国内对透明聚酰胺的需要，解决透明聚酰胺长期依赖进口的问题，透明聚酰胺的研究显得非常具有现实意义。 尽管许多发达国家已经掌握透明聚酰胺的合成技术，但是所用单体多限制于含有环结构或侧基的脂肪族二元胺与芳香族的二元酸，价格很高；而且有关透明聚酰胺结构性能表征以及成型加工工艺方面的研究报道很少。国内对于透明聚酰胺的研究，起步很晚，半芳香透明聚酰胺方面的研究工作至今未见报道。 郑州大学材料工程学院自1999年与平顶山华伦塑料有限公司合作，以国产廉价的直链型脂肪族二元胺和对苯二甲酸、间苯二甲酸等为单体，采用多元无规共缩聚合成工艺，制备出半芳香透明聚酰胺新材料(SA型透明聚酰胺，简称为SATPA)。SA型透明聚酞胺的成型加工、结构与性能摘要现已试生产，并应用于汽车零部件、高级打火机油槽和透明尼龙管材等方面。这种利用直链型脂肪族二元胺与混合的芳香族二元酸为单体制备的半芳香透明聚酞胺，国内外至今均未见报道。 为了确定SA型透明聚酞胺的最佳注射成型工艺条件，提高制品质量，扩大应用范围，并为其性能的进一步改善提供科学依据，我们对SA型透明聚酞胺结构、热性能、流变性能、光学性能和电性能等进行了表征，并重点研究了不同注射成型工艺条件对材料表观质量和力学性能的影响。这方面的表征和研究尚未见文献报道。通过研究，我们发现: (1)SA型透明聚酞胺是一种由直链型脂肪族二元胺与芳香族二元酸合成的主链上含有苯环的新型半芳香聚酞胺，具有非结晶结构，其透光率为90%左右，透明性优异，特性粘数〔。」为65ml/g，表面电阻率和体积电阻率分别为7.5 X 101，Q和3.0 x 1016Q·cm，具有优异的电绝缘性。 (2) SA型透明聚酞胺的维卡软化点为121℃左右，玻璃化转变温度为102℃左右，具有良好的耐热性能;其起始平衡热分解温度为427℃，热稳定性优异;热分解反应为一步反应，热分解机理初步推断为扩散控制机理。 (3) sA型透明聚酞胺的熔体流动速率为2.4留10min。sA型透明聚酞胺熔体的非牛顿指数n小于1，且n随剪切速率的增大而减小，熔体属假塑性流体。熔体表观粘度随着温度、剪切速率和剪切应力的升高而降低。并且，随着温度的升高，表观粘度对于剪切应力的敏感性减弱;随着剪切速率的增大，粘流活化能减小，表观粘度对于温度的敏感性减弱。其成型加工性能优异，适合于注射成型和挤出成型。 (4) SA型透明聚酞胺能够在较宽的成型工艺条件范围内注射成型，注射成型工艺条件直接影响着试样的表观质量与力学性能。首次研究了注射成型工艺与SA型透明聚酞胺表观质量和力学性能之间的关系，并确定了SA型透明聚酞胺的最佳注射成型工艺条件。 (5) SA型透明聚酞胺综合力学性能优良，其拉伸强度约为95MPa，断裂伸长率约为194%，弯曲强度约为78MPa，强度约为5.okj/mZ。与脂肪族聚酞胺弯曲弹性模量约为2.6GPa，悬臂梁缺口冲击PA61O、PA612等相比，%，弯曲弹性模量有明显提高，冲击强度的提高不明显;与拉伸强度提高了近50一些透明聚酞胺相比，SA型透明聚酞胺的成型加工、结构与性能摘要拉伸强度提高了30%左右，弯曲弹性模量也有所提高，但冲击强度稍低。 (6)SA型透明聚酸胺在23oC的水中浸泡24h后的吸水率为0.39%;高温调湿处理后，试样断裂伸长率和缺口冲击强度有所提高，而拉伸强度和弯曲弹性模量稍有降低;常温调湿处理后的试样，其拉伸强度、弯曲弹性模量以及缺口冲击强度都提高了，断裂伸长率稍有下降。实验结果表明，对于提高材料的力学性能，常温调湿处理比高温调湿处理的效果要好些。但从整体来看，调湿处理前后，力学性能的变化不明显，保持率较高，这一点明显优于脂肪族透明聚酞胺。更多还原

【Abstract】 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更多还原