采用高分子钠盐类离聚物AClyn作为成核剂对均苯四甲酸二酐(PMDA)扩链增黏的聚对苯二甲酸乙二醇酯(PET)进行改性；研究了AClyn对PET/PMDA扩链体系熔体的黏弹性、分子链支化程度及结晶行为的影响；采用偏光显微镜(POM)观察改性PET的晶体形态，并采用X射线衍射仪(XRD)分析了改性PET的晶体构型，计算出各典型晶面的晶粒尺寸。结果表明：与未添加AClyn的PET/PMDA体系相比，添加0.2%~1.0%(质量分数)AClyn可以加快PET/PMDA体系的扩链反应速率，增大PET熔体的黏弹性，提高PET的分子链支化程度；AClyn对PET具有一定的降黏增塑作用，并且AClyn含量越高，增塑作用越大；AClyn添加量从0增大到1.0%时，改性PET的结晶温度和结晶度在总体上呈现出先减小后增大的变化趋势；AClyn作为异相成核剂可以促进PET结晶，加快结晶速率；相较于未添加AClyn的PET/PMDA体系，添加0.5%AClyn可以显著细化PET晶粒，减小晶粒尺寸。
Abstract
Polyethylene terephthalate (PET) with chain extension and viscosity enhancement by pyromellitic dianhydride (PMDA) was modified using the polymer sodium salt ionomer AClyn as a nucleating agent. The effects of AClyn on the viscoelasticity, molecular chain branching degree and the crystallization behavior of the PET/PMDA chain extension system were studied. The crystal morphology of modified PET was observed by polarizing microscopy (POM). The crystal structure of the modified PET was analyzed by X-ray diffraction (XRD), and the grain size on each typical crystal plane was calculated. The results showed that compared with the PET/PMDA system without AClyn, the addition of 0.2%-1.0% AClyn accelerated the chain extension reaction rate of the PET/PMDA system, increased the viscoelasticity of the PET melt and improved the molecular chain branching degree of PET. AClyn has a certain viscosity-reducing and plasticizing effect on PET, and the higher the content of AClyn, the greater the plasticizing effect. When the AClyn content was increased from 0 to 1.0%, the crystallization temperature and crystallinity of the modified PET initially decreased and then increased. The use of AClyn as a heterogeneous nucleating agent promotes PET crystallization and accelerates the crystallization rate. Compared with the PET/PMDA system without AClyn, adding 0.5% AClyn significantly alters the PET grains and reduces the grain size.
关键词
离聚物AClyn /
PET/PMDA扩链体系 /
流变性能 /
结晶行为
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Key words
ionomer AClyn /
PET/PMDA chain extension system /
rheological property /
crystallization behavior
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参考文献
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