Hergesell Adrian H, Seitzinger Claire L, Burg Justin, Baarslag Renate J, Vollmer Ina
Inorganic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
RSC Mechanochem. 2024 Dec 18;2(2):263-272. doi: 10.1039/d4mr00098f. eCollection 2025 Mar 4.
Ball-milling of addition polymers such as polyolefins, polystyrene and polyacrylates can be used for depolymerization to obtain the respective monomers. However, absolute yields are typically low, especially from polyolefins which are notoriously difficult to depolymerize. To increase the viability of ball milling as a recycling technique, the effect of milling parameters on small hydrocarbon and monomer yields has to be understood. Herein, we systematically investigate the influence of sphere material, milling frequency, plastic filling degree, and milling temperature. Heavy spheres and high milling frequencies boost hydrocarbon yields by maximizing mechanical forces and frequency of collisions. While the dose of kinetic energy is commonly used to describe mechano-chemical processes, we found that it does not capture the mechano-chemical depolymerization of polyolefins. Instead, we rationalized the results based on the Zhurkov equation, a model developed for the thermo-mechanical scission of polymers under stress. In addition, low plastic filling degrees allow for high percentage yields, but cause significant wear on the grinding tools, prohibiting sustained milling. Milling below 40 °C is beneficial for brittle chain cleavage and depolymerization. This study provides a new approach to rationalize the influence of individual milling parameters and their interplay and serves as a starting point to derive design principles for larger-scale mechano-chemical depolymerization processes.
对聚烯烃、聚苯乙烯和聚丙烯酸酯等加聚物进行球磨可用于解聚以获得相应的单体。然而，绝对产率通常较低，尤其是对于众所周知难以解聚的聚烯烃而言。为了提高球磨作为一种回收技术的可行性，必须了解研磨参数对小分子烃和单体产率的影响。在此，我们系统地研究了球体材料、研磨频率、塑料填充度和研磨温度的影响。重质球体和高研磨频率通过最大化机械力和碰撞频率提高了烃产率。虽然动能剂量通常用于描述机械化学过程，但我们发现它无法描述聚烯烃的机械化学解聚。相反，我们基于朱尔科夫方程对结果进行了合理化分析，该方程是为聚合物在应力下的热机械断裂而开发的模型。此外，低塑料填充度可实现高百分比产率，但会导致研磨工具严重磨损，从而无法持续研磨。在40°C以下进行研磨有利于脆性链断裂和解聚。本研究提供了一种新方法，可将各个研磨参数的影响及其相互作用合理化，并作为推导大规模机械化学解聚过程设计原则的起点。
