【作者】 郜娅；

【导师】 朱诚身； 何素芹；

【作者基本信息】 郑州大学 ， 材料学， 2007， 硕士

【摘要】 尼龙46作为一种工程塑料，具有强韧性、耐热性好、高温尺寸稳定性等优异性能，而这些优异的性能大多与其高结晶度、完善的球晶结构和快的结晶速度有关。国内外的研究多集中在其化学合成、热行为与晶体结构上，而对尼龙46熔融结晶过程的研究只有少数报道。对尼龙46熔融结晶过程的研究不仅是高聚物基础研究的补充，也可为尼龙46的成型加工过程提供一些理论指导。由于尼龙46有很高的熔点，是一种理想的高分子成核剂，尤其是作为尼龙类的成核剂，具有良好的相容性。本工作以尼龙46为尼龙66和聚碳酸酯的成核剂，考察了尼龙46的加入对尼龙66和聚碳酸酯等温结晶过程、非等温结晶过程和结晶形态的影响。1．尼龙46的等温结晶、非等温结晶过程与结晶形态的研究通过尼龙46在不同结晶温度下等温结晶过程的考察，发现随着结晶温度的提高，结晶吸热峰峰形变宽，结晶速度下降；用Avrami方程描述了尼龙46的等温结晶动力学，发现尼龙46等温结晶初期的生长方式符合Avrami模型，Avrami指数n=3～4，这可能是初期成核作用的时间依赖性、均相成核和异相成核同时存在，但随着结晶时间的延长，结晶生长方式不再符合Avrami模型；由Hoffman-Weeks公式求得尼龙46的平衡熔点为303.9℃；由Arrhenius公式求得尼龙46的等温结晶活化能为557.5kJ/mol；由Lauritzen-Hoffman方程求得尼龙46的端表面自由能为135.3erg/cm~2。通过尼龙46在不同冷却速率下非等温结晶过程的考察，发现尼龙46的结晶峰随着冷却速率的增加，向低温移动，峰形也由尖锐变得宽平；用Eopxobckuü法对尼龙46的非等温结晶动力学进行描述，结果表明尼龙46的非等温结晶过程中存在明显的二次结晶现象，且结晶初期与后期的成核机理有明显的差异；用Ozawa方程描述了尼龙46的非等温结晶动力学，结果表明其Avrami指数随着结晶温度的升高而增大，这与尼龙46复杂的结晶成核机理有关；用Jeziorny法处理了尼龙46的非等温结晶动力学，并与Avrami方程处理尼龙46非等温结晶动力学过程进行了比较。通过对尼龙46在298℃～320℃下熔融3min～60min结晶形态的研究，发现随着熔融温度的升高，球晶尺寸先增大后减小，最后趋于稳定，约为20μm，其中在310℃熔融的样品球晶尺寸最大，约为40μm；熔融时间在30min以下均可生成排列紧密、尺寸均匀的球晶，且随着熔融时间的延长，球晶尺寸先增大后减小其中熔融10min的样品球晶尺寸最大，约为40gm；冷却方式对尼龙46的结晶形态影响较大，其中冰盐水淬火有利于生成结晶紧密，球晶尺寸均匀的样品。2．尼龙46对尼龙66等温结晶、非等温结晶过程及结晶形态的影响用Avrami方程对尼龙66及添加不同含量尼龙46的样品的等温结晶动力学进行了描述，得到一系列等温结晶动力学参数，随着尼龙46含量的增加，其结晶速率先增大后减小，其中含量为3％的样品结晶速率最大；随着尼龙46含量的增加，尼龙66的熔融峰先向高温移动后向低温移动，用Eopxobckuü法对其进行非等温结晶动力学的处理，尼龙46的加入对其非等温结晶动力学的影响显著；尼龙46的加入都可减小尼龙66的球晶尺寸，细化球晶，增加结晶程度，且随着含量增加，球晶尺寸有先减小后增大，最后趋于稳定的趋势。3．尼龙46对聚碳酸酯结晶形态的影响研究了结晶时间对聚碳酸酯结晶形态的影响，发现球晶直径随结晶时间的延长，呈现出线性增长的趋势，并求得其关系式；考察了退火过程对聚碳酸酯结晶形态的影响，发现退火过程可大大增加聚碳酸酯的球晶尺寸，并且经过退火过程的样品生成的球晶也较完善；考察了退火温度对聚碳酸酯结晶形态的影响，发现较低的退火温度有利于形成较大、排列较疏散的球晶，较高的退火温度有利于形成尺寸均匀、排列较紧密的球晶。考察了退火时间对聚碳酸酯结晶形态的影响，结果表明，只有退火时间在30min以上才对结晶形态有明显的影响，且随着退火时间的延长，球晶尺寸变化不大，稳定在30μm；考察了尼龙46对聚碳酸酯结晶形态的影响，结果表明尼龙46的加入没有起到预期成核剂的作用，而在一定程度上抑止了聚碳酸酯的结晶，这对于作为光学替代品的聚碳酸酯来说应该是有利的。更多还原

【Abstract】 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.更多还原