络合改性PA6复合体系的结晶性能与流变性能研究

发布时间：2018-04-13 08:16

本文选题：尼龙6 + 氯化钙　；参考：《贵州大学》2015年硕士论文

【摘要】：课题组在前期工作中,采用DSC和XRD等表征手段对络合剂(CaCl_2和LiCl)改性PA6的结晶行为进行了研究,但对CaCl_2和LiCl使PA6结晶受限的机理知之甚少。并且当PA6结晶受限严重时,结晶热流较小,导致DSC测试误差较大。所以本文采用流变学方法研究了不同络合剂(CaCl_2和LiCl)改性PA6的结晶行为和结晶受限的机理。并且进一步研究了尼龙6/弹性体/氯化钙复合材料和尼龙6/环氧树脂/氯化钙复合材料的结晶性能与流变性能。具体的研究内容如下:首先研究了不同含量下CaCl_2和LiCl对PA6的结晶性能与流变性能的影响,并利用红外、DSC、XRD和流变学等表征方法对其结晶行为及受限机理进行了研究,结果表明:随着CaCl_2和LiCl含量的增加,PA6的成核及增长温度均向低温方向移动,成核密度和成核速率也逐渐减小。复合材料的总结晶度显著下降,γ型结晶度逐渐减低,α型结晶度呈先增加后减低的趋势,γ晶与α晶发生转变,PA6结晶受限。这主要因为一方面CaCl_2和LiCl与PA6中的羰基上的氧原子发生了络合反应,破坏了使PA6易结晶的氢键。另一方面是因为CaCl_2和LiCl与PA6络合后形成的缠结度更高更稳定络合物,导致链段运动的流动阻力增大,松弛困难,在PA6结晶时排入晶格困难,结晶受到限制。比较不同络合剂(CaCl_2和LiCl)改性PA6后复合材料的力学性能发现,LiCl比CaCl_2使PA6结晶受限更严重,力学性能提高更显著。其次,本文利用POE-g-MAH作为增韧剂来改性低熔点PA6,研究发现:POE-g-MAH的加入对PA6结晶熔融行为影响较小,当j(POE-g-MAH)=10~15phr时,可得到冲击强度较好,而拉伸强度下降较少的PA6/CaCl_2/POE-g-MAH复合材料。另外,本文固定了增韧剂POE-g-MAH含量,研究了CaCl_2含量对PA6/POE-g-MAH/CaCl_2复合材料结晶性能与流变性能的影响。研究表明:CaCl_2与PA6的络合反应破坏了PA6中的极性酰胺基团,释放出游离的N-H,从而使得络合后的PA6极性降低,与POE-g-MAH界面张力减弱,复合体系的相容性变好,CaCl_2在体系中起到了增容剂的效果。在研究CaCl_2对PA6/POE-g-MAH和PA6/POE体系增容效果时发现,当CaCl_2含量较高时,增容效果显著,在一定程度上,可以利用POE代替POE-g-MAH作为增韧剂来改性低熔点尼龙。最后,本文利用环氧树脂(E51)改性低熔点PA6后发现,E51与PA6分子间的氨基、羧基和酰胺基的扩链反应会限制PA6的结晶,使得复合材料的熔点降低,结晶不完善程度增大,而当PA6结晶受限严重时,DSC已不能表征PA6/CaCl_2/E51复合材料的结晶熔融行为。在线性粘弹区,复合材料损耗模量(G’’)呈先增大后减小的趋势,当j(E51)=3 phr时达到极值。另外,本文研究了当j(E51)=3 phr时,Ca Cl_2含量对PA6/E51/CaCl_2复合材料流变性能的影响,研究发现:CaCl_2的加入会限制E51和PA6的扩链反应,从而导致储能模量(G’)和G’’呈下降趋势,然而随着CaCl_2含量的增加,CaCl_2与PA6的络合反应程度增大,缠结程度增大,链段运动的流动阻力增加,随之G’和G’’增大。综合得知,利用适量的E51和CaCl_2对PA6进行改性,可以有效的降低PA6的熔点,并提高复合材料的力学性能与流变性能,当E51含量为3 phr,CaCl_2含量为6 phr时可以制备熔点较低、力学性能和流变性能较好的复合材料。综合得知,流变学方法可以较好的反映PA6在结晶受限时的结晶行为,它比DSC更准确和敏感。另外,在研究多相体系微观结构的演化和PA6结晶受限机理时,它不失为一个较有效的方法。
[Abstract]:In previous research work, using DSC and XRD techniques of complexing agents (CaCl_2 and LiCl) crystallization behavior of modified PA6 were studied on CaCl_2 and LiCl, but the mechanism of crystallization of PA6 limited poorlyunderstood. And when the crystallization of PA6 is restricted seriously, resulting in DSC crystallization heat flux is small, the big test error the rheological research. So this article uses different complexing agent methods (CaCl_2 and LiCl) mechanism of crystallization behavior and limited modification of PA6. And further study of nylon 6/ elastomer / calcium chloride composite and nylon 6/ / epoxy resin composite calcium chloride crystallization properties and rheological properties. The specific contents are as follows first: To study the effect of different content of CaCl_2 and LiCl on PA6 crystallization properties and rheological properties, and the use of DSC, infrared, XRD and rheological characterization methods were studied on the crystallization behavior and restriction mechanism, results Show that with the increase of CaCl_2 and LiCl content, nuclear and growth temperature shifts to lower temperature PA6, nucleation density and nucleation rate also decreased. The composite total crystallinity decreased significantly, gamma crystallinity decreased and the crystallinity is alpha trend reduced after the first increase, gamma the crystal and alpha crystal change, PA6. This is mainly because the confined crystallization occurred in the complexation reaction of carbonyl oxygen atoms on the one hand CaCl_2 and LiCl and PA6 in the destruction of the PA6 crystallization of the hydrogen bond. On the other hand because of the formation of CaCl_2 and LiCl and PA6 complex after the entanglement degree higher and more stable complexes, resulting in the flow resistance of segmental motion increases, relaxation is difficult, difficult into the lattice in PA6 crystallization, crystallization is limited. Comparison of complexing agents (CaCl_2 and LiCl) found that the mechanical properties of the composite modified PA6, LiCl than CaCl_2 to the crystallization of PA6 is restricted more serious, mechanical properties Can be improved more significantly. Secondly, this paper uses POE-g-MAH as toughening agent modified low melting point PA6, results show that the addition of POE-g-MAH PA6 on the crystallization and melting behavior has little effect, when J (POE-g-MAH) =10~15phr, can obtain better impact strength, and the tensile strength decreased PA6/CaCl_2/POE-g-MAH composite less. In addition, this paper fixed the toughening agent POE-g-MAH content, the effects of CaCl_2 content on the crystallization properties of PA6/POE-g-MAH/CaCl_2 composites and rheological properties. Research shows that the complexation of CaCl_2 and PA6 destroyed the polar amide group PA6, free N-H, so that the complexation of PA6 polarity decreased, and POE-g-MAH decreased the interfacial tension of composites good compatibility, CaCl_2 plays a compatibilizer effect in the system. In the PA6/POE-g-MAH PA6/POE system and compatibilization effect on CaCl_2, when the CaCl_2 content is high When the compatibilization effect, to a certain extent, can use POE instead of POE-g-MAH as toughening agent of modified low melting nylon. Finally, using epoxy resin (E51) modified low melting point PA6 and found that E51 and PA6 molecules of amino, crystalline chain extension reaction of carboxyl and amide groups will limit PA6 the composite material, low melting point, crystallization degree increases, and when the crystallization of PA6 is restricted seriously, crystallization and melting behavior of DSC has not been able to characterization of PA6/CaCl_2/E51 composite materials. In the linear viscoelastic region, loss modulus of composites (G ') was first increased and then decreased, reached the maximum when J (E51) =3 phr. In addition, this paper studied when J (E51) =3 phr, Ca Cl_2 study found that the effect of content on rheological properties of PA6/E51/CaCl_2 composites: the chain extension reaction by the addition of CaCl_2 E51 and PA6, which leads to the storage modulus (G') and 'G' decreased The trend, however, with the increase of CaCl_2 content, CaCl_2 and PA6 complexation reaction degree increases, increasing the degree of entanglement, increase the flow resistance of segmental motion, then G 'and G' 'comprehensive increases. That of PA6 was modified by the amount of E51 and CaCl_2, can effectively reduce the melting point of PA6, and improve the mechanical properties and rheological properties of the composites, when the content of E51 is 3 phr, the content of CaCl_2 6 phr can be prepared with low melting point, the mechanical properties of the composites and good rheology. The comprehensive rheological method that can reflect the PA6 crystallization behavior in the limit of crystallization, it is more accurate than DSC and sensitive. In addition, in the study of evolution and crystallization mechanism of multiphase PA6 restricted the microscopic structure of the system, it is a more effective method.

【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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