New kinetic model for polymerization process of nylon 66 salt solution based on functional group non-isoactivity

doi:10.11949/0438-1157.20200208

Abstract

Abstract:

The polymerization process of nylon 66 salt solution is a dynamically controlled process. Based on the assumption of unequal activity of functional carboxyl and amido groups, a new nylon 66 salt solution polymerization kinetic model was established by introducing the nylon salt dehydration reaction to the acid-catalyzed third-order reaction kinetic model and fitted to obtain the corresponding key kinetic parameters. The fitted salt dehydration reaction rate constant was 8.17×10^-3 kg?mol^-1?h^-1, while the activation energy was 19859 cal?mol^-1, respectively. Compared with Mallon model, the new developed model has a better fitting effect and can accurately predict the change of the polymerization process in a wider range of temperature and water content. Simulation results showed that salt dehydration reaction has an important effect on the polymerization process and the polymerization efficiency was relatively lower with higher concentration of nylon salt, especially under low temperature and high water content. Appropriately increase the reaction temperature or reduce the initial water content can accelerate the nylon salt dehydration reaction, thereby increasing the polymerization reaction efficiency. New nylon salt polymerization kinetics modeling method is not only applicable to nylon 66, but also to nylon 1212 and other salt solution polymerization systems.

Key words: nylon 66 salt, polymerization, acid-catalyzed, reaction, kinetic modeling

摘要：

尼龙66盐溶液聚合过程属于动力学控制过程。基于官能团非等活性假设，在Mallon酸催化3阶反应动力学模型基础上，引入尼龙盐脱水反应，建立了新的尼龙66盐溶液聚合反应动力学模型，拟合得到了关键反应动力学模型参数，其中盐脱水反应速率常数为8.17×10^-3 kg?mol^-1?h^-1、活化能为19859 cal?mol^-1。与Mallon模型相比，新模型拟合效果更优，可在更宽的温度和水含量范围内准确预测聚合过程的变化。模拟仿真发现，盐脱水反应对聚合过程有重要影响，低温和高水含量下尼龙盐浓度高，聚合效率低；适当提高反应温度或降低初始水含量可以加快尼龙盐脱水反应，从而提高聚合反应效率。新的尼龙盐聚合动力学建模方法不仅适用于尼龙66，也可应用于尼龙1212等盐溶液聚合体系。

关键词: 尼龙66盐, 聚合, 酸催化, 反应, 动力学模型

CLC Number:

TQ 316.4

Ying WANG,Cheng LIN,Jing CUI,Zhenhao XI,Ling ZHAO. New kinetic model for polymerization process of nylon 66 salt solution based on functional group non-isoactivity[J]. CIESC Journal, 2020, 71(11): 5208-5215.

王颖,林程,崔晶,奚桢浩,赵玲. 基于官能团非等活性假设的尼龙66盐溶液聚合动力学模型[J]. 化工学报, 2020, 71(11): 5208-5215.

Figures/Tables 10

Fig.1 Water bridge

Fig.2 Salting-like reaction

Table 1 Parameters of new model

反应动力学模型参数	参数估计结果	Mallon等^[12]模型参数值
A/ (kg²?mol^-2)	1.50×10^-10	1.81×10^-10
?H′/ (cal?mol^-1)	-18333	-18300
?H″/(cal?mol^-1)	-233.04	404.13
?S″/(cal?mol^-1?K^-1)	10.20	12.50
k_0,s / (kg?mol^-1?h^-1)	8.17×10^-3	—
E_s,a /( cal?mol^-1)	19859	—
k_0,f /( kg²?mol^-2?h^-1)	2.01×10³	7.17×10^-3
E_a / (cal?mol^-1)	7716.65	8578
C/( cal?mol^-1)	40761.50	40716
A_e	0.06678	0.06681

Fig.3 Comparison of simulated values with experimental data of different initial water/salt molar ratios at different temperatures

Fig.4 Comparison of simulated values of two models and experimental data with the initial water/salt mole ratio of 6.23 at different temperatures

Fig.5 Comparison of simulated values of two models and experimental data at 200℃ with different initial water/salt mole ratios

Fig.6 Comparison of simulated values and experimental data under different reaction conditions

Fig.7 Changes of nylon salt and water concentration with time at different temperatures under different initial water/salt molar ratio

Table 2 Parameters of modified model

反应动力学模型参数	参数估计结果
A/ (kg²?mol^-2)	1.79×10^-10
?H′/ (cal?mol^-1)	-18263
?H″/( cal?mol^-1)	-832.07
?S″/ (cal?mol^-1?K^-1)	13.79
k_0,s /( kg?mol^-1?h^-1)	1.02 $\times$ 10^-2
E_s,a /( cal?mol^-1)	15013
k_0,f / (kg²?mol^-2?h^-1)	2.35×10³
E_a /( cal?mol^-1)	3141
C/( cal?mol^-1)	40624
A_e	0.06554

Table 2 Parameters of modified model

反应动力学模型参数	参数估计结果
A/ (kg²?mol^-2)	1.79×10^-10
?H′/ (cal?mol^-1)	-18263
?H″/( cal?mol^-1)	-832.07
?S″/ (cal?mol^-1?K^-1)	13.79
k_0,s /( kg?mol^-1?h^-1)	1.02 $\times$ 10^-2
E_s,a /( cal?mol^-1)	15013
k_0,f / (kg²?mol^-2?h^-1)	2.35×10³
E_a /( cal?mol^-1)	3141
C/( cal?mol^-1)	40624
A_e	0.06554

Fig.8 Comparison of simulated values with experimental data under different reaction conditions of new model

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