The Influence Of Nylon-46 On The Crystallization Behavior Of Nylon-66 And Polycarbonate

Nyln-46, an engineering plastic, has better strength and toughness, a higher melting point and better size stability. Most of the excellent mechanical properties are due to its high crystallinity, crystal structure and high crystallization speed. Until now, only a few studies have been reported on this polymer, mainly on its chemical synthesis, thermal behavior and lamellar structure. The important aspect of crystallization process is its kinetics, both from the fundamental view of polymer physics and for the modeling and control of polymer processing operations. As the high melting point, nylon-46 is an ideal nucleating agent, especially for nylons. It is naturally compatible with nylons of lower melting points. In this paper, we chose nylon-46 as a nucleating agent, and studied on the influence of the crystallization behavior of nylon-66 and polycarbonate on the isothermal and nonisothermal crystallization process.1 Study on isothermal crystallization process, nonisothermal crystallization and crystallization morphology of nylon-46The study of isothermal crystallization process showed that crystallization speed decrease as the increase of crystallization temperature; Avrami equation was applied to describe the process of isothermal crystallization. It shows that the way of crystal growth fixes the Avrami manner at the early stage of crystallization, but it cannot apply to the latter stage of isothermal crystallization; Hoffman-Weeks equation was applied to calculate the equilibrium melting temperature, and a value of 303.9℃was obtained; Arrhenius equation was applied to calculate the isothermal crystallization activation energy, and a value of 557.5kJ/mol was obtained.The study of nonisothermal crystallization process showed that the peak of crystallization moved to low temperature as the increase of the cooling speed, and the shape of crystallization peak became flat and wide; the approach of Eopxobuckuu was applied to nonisothermal crystallization kinetics. It shows that secondary crystallization was abvious during the nonisothermal crystallization process, and crystallization mechanisms are completely different; Ozawa equation and Jeziorny approach were also applied to the nonisothermal crystallization kinetics of nylon-46. We compared with three approaches, it showed that Eopxobuckuu was better.The morphology of nylon-46 melted at 298-320℃for 3～60min was studied. It shows that the size of sperulite increased by the melting temperature, and the size of sample melted 310℃was the biggest, which was about 40μm. As the melting temperature increasing, the size of samples stopped at 20μm. Samples melted for less than 30min could have homogenous sperulite, and sample melted for 10min had the largest sperulite size, which is about 40μm. The morphology of samples quenched with cryohydric water was more regular.2 The influence of nylon-46 on isothermal crystallization process, nonisothemal crystallization and crystallization morphology of nylon-66Avrami equation was applied to describe the isothermal crystallization process of nylon-66 and samples modified by nylon-46. It showed that the crystallization speed was increased with the content of nylon-46, and the sample which had a content of 3% had the largest speed; the approach of Eopxobckuu was applied to describe the kinetics of nonisothermal crystallization process. It showed that nylon-46 had an obvious influence on the kinetics of nonisothermal crystallization process; Samples modified with nylon-46 had more homogeneous morphology, and the size of nylon-66 decreased at first, and then increased as the increase of content of nylon-46. The sample which had a content of 0.5% had the smallest size.3 The influence of nylon-46 on crystallization morphology of polycarbonate The study on crystallization morphology showed that the diameter of sperulite linear increased with crystallization time; The annealing process had an important influence on the morphology of polycarbonate. Samples annealed for more than 30min had more excellent sperulite, and annealing time less than 30min had little influence on the size of sperulites; the comparation of polycarbonate and samples modified with nylon-46 showed that nylon-46 was not an effective nucleating agent, and samples modified by nylon-46 had little sperulites. It revealed that nylon-46 had an effect of prevent the crystallization process of polycarbonate. As the substitute of glasses, it maybe useful for carbonate to reduce its crystallinity.