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首页> 外文期刊>Journal of Applied Polymer Science >Crystallization behavior of poly(N-methyldodecano-12-lactam). III. Kinetics of isothermal crystallization
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Crystallization behavior of poly(N-methyldodecano-12-lactam). III. Kinetics of isothermal crystallization

机译：聚（N-甲基十二烷-12-内酰胺）的结晶行为。三，等温结晶动力学

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摘要

Differential scanning calorimetry, combined with Avrami theory, was used to investigate the kinetics of three steps of the complex crystallization process of poly(N-methyldodecano-12-lactam) (MPA): (1) primary melt crystallization at respective crystallization temperature (T,), (2) additional crystallization at 30degreesC, and (3) recrystallization at 54degreesC. Kinetics of the three steps was discussed with respect to T, The Avrami exponent n of primary melt crystallization decreased between 2.5 and 1.9 in the range of T, values of -10 to 20degreesC, which suggests heterogeneous nucleation, followed by two-dimensional growth, with a larger involvement of homogeneous thermal nucleation at greater super-coolings. The crystallization rate constant k decreased with increasing T, The value of n = 1.5 for additional crystallization implies a two-dimensional diffusion-controlled crystal growth with a suppressed nucleation phase. For T-c values ranging from -10 to 0degreesC and 0 to 20degreesC, k showed weak and quite strong decreasing dependencies on T-c, respectively. The recrystallization mechanism involved partial melting of primary crystallites and two-dimensional rearrangement of chains into a more perfect structure. The rate of this process was almost independent of T-c. The values of activation energies were derived for the three steps of MPA crystallization using the Arrhenius equation. (C) 2004 Wiley Periodicals, Inc.
机译：差示扫描量热法结合Avrami理论，研究了聚（N-甲基十二烷-12-内酰胺）（MPA）复杂结晶过程的三个步骤的动力学：（1）在各自的结晶温度（T ，），（2）在30°C进行额外结晶，以及（3）在54°C进行重结晶。讨论了关于T的三个步骤的动力学，在T范围-10至20°C范围内，一次熔体结晶的Avrami指数n在2.5至1.9之间降低，这表明异相成核，然后二维生长在较高的过冷度下，均相热核化的参与更大。结晶速率常数k随着T的增加而降低。n= 1.5表示进一步结晶，这表明二维扩散控制的晶体生长且成核相受到抑制。对于-10至0摄氏度和0至20摄氏度的T-c值，k分别显示出对T-c的弱依赖性和相当强的降低依赖性。重结晶机制涉及初级微晶的部分熔融和链的二维重排成更完美的结构。此过程的速度几乎与T-c无关。使用Arrhenius方程得出MPA结晶三个步骤的活化能值。 （C）2004年Wiley Periodicals，Inc.

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