论文标题:Kevlar纤维表面阴离子接枝尼龙6及其对复合材料结构性能的影响
Anionic Grafting of Nylon 6 onto Kevlar Fiber and Its Effect on the Structure and Capability of Composites
论文作者 傅明连
论文导师 郑玉婴,论文学位 硕士,论文专业 化学工程
论文单位 福州大学,点击次数 2,论文页数 78页File Size1962k
2005-06-01论文免费下载 http://paper.dic123.com/lunwen_90059942/ Kevlar 纤维;尼龙6;复合材料;阴离子接枝
Kevlar fiber; Nylon 6; Composites; Anionic grafting
复合材料是由两种或两种以上性质不同而互补的材料组成的结构材料。它具有比组成材料更优越的综合性能。但在一些高科技领域,特别是航空航天领域,单一复合材料已不能满足其对高性能的要求。芳纶纤维增强复合材料因具有高强度、高模量等特征,已得到广泛应用,尤其在航空航天等结构材料领域中越来越显示出重要作用。纤维/基体树脂的界面结合一直是纤维增强树脂基复合材料的薄弱环节,因此如何通过对纤维表面的改性来提高其界面结合一直是复合材料研究的热点,具有重要的意义。针对上述问题,本文主要进行了以下几方面的工作: 一、在文献调研的基础上,综述了目前国内外复合材料的应用与发展概况,了解有机高性能芳纶纤维的结构、性能、应用与发展,介绍了芳纶纤维几种主要的改性方法,阐述研究芳纶纤维增强复合材料结构性能的意义。二、采用化学接枝方法对Kevlar 纤维(KF)表面进行改性,通过水解在KF 表面引入活性基团,然后对其进行酰氯化改性,并用己内酰胺封端稳定化后,作为己内酰胺阴离子聚合的助催化剂,引发己内酰胺阴离子聚合,并考察反应温度和反应时间对接枝率的影响。采用FT-IR、XPS 及ESEM 等实验手段分析接枝前后KF的表面形貌和化学组成,分析结果表明在KF 表面实现了阴离子接枝PA6。三、利用改性前后的KF 作为增强纤维制备尼龙6/Kevlar 纤维(PA6/KF)复合材料,进一步探讨KF 表面阴离子接枝PA6 对PA6/KF 复合材料结晶和熔融行为的影响。DSC 分析表明PA6 的等温结晶过程主要为成核作用控制,KF 的加入对基体PA6 起到了异相成核作用,提高了结晶速率;非等温结晶过程中,KF 的加入提高了基体结晶的起始温度Tconset,减小其总结晶时间ttotal;KF 的加入同时使PA6 的熔融行为发生显著变化。四、采用PLM 对PA6/KF 复合材料的界面结晶情况加以观察,发现PA6 与许多结晶性聚合物一样,在不受阻碍,没有外力的作用下能形成完整的球晶,KF 可以诱发横晶的生长,其诱发横晶的能力随着结晶温度Tc 的升高而增强,在相同条件下改性KF 所诱发横晶的密度及完整程度明显高于未改性的KF。五、通过测试PA6/KF 复合材料的拉伸、弯曲和冲击性能,并采用SEM 对其破坏断口加以分析,探讨了KF 表面阴离子接枝PA6 对其复合材料力学性能与破坏形态的影响。
Composites are constitued of various components which have different properties. It’s synthesize function is more superior than the component.But in some high technology fields,especial in aerospace industry,Kevlar fiber(KF) is widely applied for its high strength and modulus,and special shows important function in aerospace and other construction material fields. However,the interface between fiber and matrix is the weak area in composites which are reinforced by fiber,therefore the improvement of interfacial adhesion,the hotspot in composites research,is of great significance.To deal with the aforementioned problems,the research plans of this thesis are as follows: 1.On the basis of the literature review,the general situation of composites at home and abroad,the structure 、function 、application and development of KF were summarized.At the same time a review was made systematically in the methods of KF surfacial modification,and the meaning of research the structure and capability of composites strengthened by KF was expatiated. 2.Chemical disposal was used to treat the surface of KF,and activity groups were induced onto the surface of KF by hydrolyzation;after that KF was treated by adipyl choloride and stabilized by carprolactam;Finally,the anionic grafting of nylon 6 onto the the surface of KF was proceeded,and the effect of react temperature and time were also discussed.FT-IR、XPS and ESEM were used to study the appearance and chemical components of the KF which was grafted and ungrafted by nylon 6.The results showed that the grafted polymer on the surface of KF is greatly similar to matrix,and the anionic grafting of nylon 6 onto KF surface could be available. 3.The KF which treated and untreated were used to make reinforcing nylon6/Kevlar fiber (PA6/KF) composites.Particular attention was paid to the effect of surface treatment on the crystalline and melting behaviour of PA6/KF composites.The analysis of DSC showed that the isothermal crystallization of PA6 was dominated by nucleation while the KF played a role of heterogeneous nucleation agent in the process of crystallization of PA6 and increased its crystalline rate;KF has improved the initial crystalline temperature (Tconset) of PA6 while reduced its total crystalline time (ttotal) during the nonisothermal crystalline process;the induction of KF also could influence the melting behavior of PA6. 4.PLM was carried out to observe the interfacial crystalline effect of PA6/KF composites.The results showed that the ungrafted KF and grafted KF can both induce transcrystallization in PA6/KF composites in the range of the beginning crystallization temperature and approaching melting temperature.The transcrystallization was more fine and perfect at higher crystallization temperature than at lower crystallization temperature,so was the ability of inducing transcrystallization.The grafted KF enhanced the growth ability of transcrystallization and promoted PA6 to form more fine and perfect transcrystallization than the ungrafted KF atrelative lower crystallization temperature. 5.The effect on mechanical properties and fracture morphologies of PA6/KF composites by anionic grafting nylon 6 onto KF was studied.It showed that the composites which were reinforced by untreated KF would destroy from the interface, while the composites which were reinforced by treated KF would destroy from other place partly, which contributed to improving the tensile strength, flexural strength and flexural modulus,however,the impact strength declined.
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