一种聚乳酸基的聚酯酰胺的制备及结晶性能研究

发布时间：2019-01-17 10:27

【摘要】：聚乳酸(PLA)是一种源自可再生资源的生物降解材料,因具有良好的生物相容性和优异的综合性能被广泛的关注,但其存在热稳定性差、结晶困难等缺陷,而共聚改性的方式能够有效的改善PLA的结晶性能和热稳定性,故本文利用聚己内酰胺和PLA共聚制备一种聚酯酰胺,通过在PLA链段中引入热稳定性较好且含有氢键作用的聚己内酰胺链段,在聚乳酸结晶时充分利用氢键作用对PLA分子链的重排的影响来改善PLA的结晶性能,对于开发PLA在包装等领域的应用有很大的潜在意义。本文采用不同的聚合体系制备聚酯酰胺,探讨了催化剂的用量、聚合时间和聚合温度等因素对聚酯酰胺粘均分子量的影响,通过红外图谱和核磁图谱对合成的聚酯酰胺的结构进行了表征,采用差示扫描量热仪(DSC)、热失重分析仪(TG)、偏光显微镜(POM)、X射线衍射仪(XRD)和旋转流变仪等研究了聚酯酰胺的热性能、结晶性能和流变性能。结果表明,选用PLA预聚物和聚己内酰胺预聚物共聚体系更容易制备出聚酯酰胺,聚己内酰胺链段的引入改善了PLA的热稳定性,加快了PLA的结晶,储能模量降低,而损耗模量增加。同时,为了进一步研究聚己内酰胺链段的引入对PLA结晶性能的影响,本文采用DSC测试了聚酯酰胺的不同温度下的等温结晶过程和不同降温速率下的非等温结晶过程,并采用不同的理论和方法分析了该体系的等温和非等温结晶动力学的过程。分析结果表明,Avrami方程可以较好地分析聚酯酰胺的等温结晶动力学过程,莫志深法和Jeziorny法分析该体系的非等温结晶过程较理想,而Oz awa法并不理想,等温结晶的动力学参数n值处于2.5到3.4之间,较好的验证了聚酯酰胺的三维球晶形貌,结晶的活化能的大小反映出高温有利于该物质的等温结晶过程,PA6组分含量的增加,有利于聚酯酰胺的结晶,提高降温速率有利于提高其结晶速率。
[Abstract]:Polylactic acid (PLA) is a kind of biodegradable material derived from renewable resources. It has been widely concerned because of its good biocompatibility and excellent comprehensive properties, but it has some defects such as poor thermal stability and difficult crystallization. The method of copolymerization modification can effectively improve the crystallization and thermal stability of PLA. Therefore, a kind of polyester amide was prepared by copolymerization of poly (caprolactam) and PLA. By introducing poly (caprolactam) segments with good thermal stability and hydrogen bonding into the PLA segment, the crystallization properties of PLA were improved by making full use of the effect of hydrogen bonding on the rearrangement of PLA chains during the crystallization of poly (lactic acid). For the development of PLA in packaging and other areas of application has a great potential significance. In this paper, polyester amides were prepared with different polymerization systems. The effects of the amount of catalyst, polymerization time and polymerization temperature on the viscosity average molecular weight of polyester amides were discussed. The structure of the synthesized polyester amide was characterized by IR and NMR spectra. The differential scanning calorimeter (DSC),) thermogravimetric analyzer (TG),) polarizing microscope (POM),) was used. The thermal, crystallization and rheological properties of polyester amide were studied by X-ray diffractometer (XRD) and rotary rheometer. The results show that it is easier to prepare polyester amide by using PLA prepolymer and polycaprolactam prepolymer copolymerization system. The introduction of polycaprolactam chain improves the thermal stability of PLA, accelerates the crystallization of PLA, and decreases the storage modulus. The loss modulus increases. At the same time, in order to further study the effect of the introduction of polycaprolactam on the crystallization properties of PLA, the isothermal crystallization process of polyester amide at different temperatures and the non-isothermal crystallization process at different cooling rates were measured by DSC. Different theories and methods were used to analyze the isothermal and non isothermal crystallization kinetics of the system. The results show that the isothermal crystallization kinetics of polyester amide can be well analyzed by Avrami equation, the non-isothermal crystallization process of the system by Mozhi-depth method and Jeziorny method is ideal, but the Oz awa method is not ideal. The kinetic parameter n of isothermal crystallization is between 2.5 and 3.4, which verifies the three-dimensional spherulite morphology of polyester amide, and the activation energy of crystallization reflects that high temperature is favorable to the isothermal crystallization process. The increase of PA6 content is beneficial to the crystallization of polyester amide and the increase of cooling rate.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O633

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