Thermal degradation of vegetable-tanned leather fiber (VLF) was investigated by thermogravimetric analysis aiming to know the exact kinetics and degradation mechanism. The thermogravimetric (TG) and differential thermogravimetric (DTG) curves showed that decomposition of the VLF occurs mainly in the range of 150–600 °C, and the latter exhibits asymmetrical peak with a pronounced shoulder. The decomposition process was first analyzed by deconvolution of the experimental DTG curves, followed by reconstruction of the weight loss profiles of two individual processes. Several common isoconversional approaches were applied to calculate the activation energy over a wide range of conversion for the sample, including modified Kissinger-Akahira-Sunose (MKAS), Friedman, and Flynn-Wall-Ozawa. The average activation energy of vegetable-tanned leather fiber was found to be 241.9 kJ mol− 1 by MKAS method. The activation energy values obtained for the pseudocomponents representing highly-crosslinked and low-crosslinked collagen in VLF were given as 190.6 and 124.8 kJ mol− 1, respectively. Generalized master plots results suggested that the reaction mechanism for highly-crosslinked collagen follows the random nucleation and growth process at conversion values lower than 0.5. When the conversion is higher than 0.5, the mechanism tends to random scission model. For low-crosslinked collagen, the degradation is mainly governed by random nucleation and nuclei growth. The gaseous products of VLF thermal degradation were analyzed with an online-coupled TG-Fourier transform infrared spectroscopy system.

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植鞣革纤维热降解的动力学及机理

为了了解确切的动力学和降解机理，通过热重分析法研究了植鞣革纤维的热降解。热重（TG）和微分热重（DTG）曲线表明，VLF的分解主要发生在150–600°C的范围内，后者表现出不对称峰并带有明显的肩峰。首先通过对实验DTG曲线进行去卷积分析分解过程，然后重建两个独立过程的失重曲线。应用了几种常见的等转换方法来计算样品在广泛转换范围内的活化能，包括改良的Kissinger-Akahira-Sunose（MKAS），Friedman和Flynn-Wall-Ozawa。通过MKAS方法发现，植鞣皮革纤维的平均活化能为241.9 kJ mol-1。为代表VLF中高交联和低交联胶原蛋白的假组分获得的活化能值分别为190.6和124.8 kJ mol-1。通用主图结果表明，高度交联的胶原蛋白的反应机理遵循随机成核和生长过程，转化率低于0.5。当转化率高于0.5时，该机理趋向于随机断裂模型。对于低交联的胶原蛋白，降解主要由无规成核和成核生长决定。用在线耦合TG-傅里叶变换红外光谱系统分析了VLF热降解的气态产物。