This work aims at modelling and characterizing the kinetics of biodegradation of acrylic acid-grafted polypropylene. Different films of acrylic acid-grafted polypropylene were prepared. These films were degraded aerobically during thermophilic phase of composting process for measurement of carbon dioxide evolution as per ASTM D 5338. The experimental data were analyzed using an eight-parameter Komilis model containing a flat lag phase. The model formulations involved hydrolysis of primary solid carbon and its subsequent mineralization. The first step was rate controlling and it included hydrolysis of primary slowly, moderately, and readily hydrolyzable carbon fractions in parallel. The model parameters were evaluated by means of nonlinear regression technique. The model parameters, undegraded/hydrolyzable/mineralizable carbon evolutions and morphology revealed two typical kinetic regimes. The first five films exhibited slow degradation in the first regime involving slowly and moderately hydrolyzable carbons. They exhibited low degradability value in the range of 1.5–3.7% in 45 days. Their degradability decreased with an increase in the slowly hydrolyzable carbon refractory in nature. The remaining three films exhibited the second regime involving the moderately and readily hydrolyzable carbons. These showed relatively high degradability in the range of 4.7–5.6% in 45 days. The magnitudes of their moderately hydrolyzable carbon fractions were substantially higher than those of the first regime. All the eight films showed the absence of growth phase because of their small initial readily hydrolyzable carbon fractions. The study shows progressive enhancement in the biodegradation of effectively non-biodegradable polypropylene with an increase in degree of acrylic acid grafting. The methods presented here can be used for the design and control of other similar systems.

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堆肥高温阶段丙烯酸接枝聚丙烯的生物降解动力学模型

这项工作旨在建模和表征丙烯酸接枝聚丙烯的生物降解动力学。制备丙烯酸接枝聚丙烯的不同膜。根据ASTM D 5338，在堆肥过程的嗜热阶段将这些膜进行有氧降解，以测量二氧化碳的排放。使用包含平坦滞后阶段的八参数Komilis模型分析实验数据。模型公式涉及初级固体碳的水解及其随后的矿化。第一步是速率控制，它包括缓慢，中度和易于水解的碳级分平行并行水解。通过非线性回归技术评估模型参数。模型参数 未降解/可水解/可矿化的碳的演化和形态揭示了两种典型的动力学机制。在涉及缓慢和适度可水解碳的第一种方案中，前五个膜表现出缓慢降解。他们在45天内表现出较低的可降解性值，范围在1.5–3.7％之间。它们的可降解性随着自然界中缓慢水解的碳质耐火材料的增加而降低。其余三张膜表现出第二种状态，涉及中等和易水解的碳。这些在45天内显示出较高的可降解性，范围为4.7-5.6％。它们的适度可水解碳馏分的量级明显高于第一方案的量级。所有八张膜都显示出没有生长期，因为它们的初始易水解碳含量很小。研究表明，随着丙烯酸接枝度的增加，有效不可生物降解聚丙烯的生物降解作用逐步增强。此处介绍的方法可用于其他类似系统的设计和控制。