2026-03-05 バッファロー大学（UB）
New studies suggest the energy efficient and eco-friendly approach could help reuse millions of tons of plastics
＜関連情報＞
- https://www.buffalo.edu/news/releases/2026/03/university-at-buffalo-solvent-based-recycling-flexible-plastics.html
- https://www.sciencedirect.com/science/article/abs/pii/S0017931026001547
- https://www.mdpi.com/2073-4360/17/23/3213
- https://onlinelibrary.wiley.com/doi/10.1002/pol.20250207
半結晶性ポリエチレンの溶解：統合実験とモデリングにより明らかにされた脱結晶化と解離の速度論への寄与 Dissolution of semicrystalline polyethylene: Contributions of decrystallization and disentanglement to kinetics revealed by integrated experiments and modelling
Ali Ghasemi, Nicholas Stavinski, Christian M. Ferger, Luke Baylon, Luis Velarde, Paschalis Alexandridis, Marina Tsianou
International Journal of Heat and Mass Transfer Available online: 12 February 2026
DOI:https://doi.org/10.1016/j.ijheatmasstransfer.2026.128478
Highlights
- First integrated experimental+modeling framework to address polyethylene dissolution kinetics.
- Real-time crystallinity and mass loss measurements and semicrystalline polymer dissolution model.
- Time for complete dissolution increases linearly with film thickness.
- Initial degree of crystallinity affects primarily the early stages of polyethylene dissolution.
Abstract
Increased use of plastics and corresponding generation of plastic waste leads to growing pressure for recycling technologies that are both economically viable and environmentally sound. For plastic films, widely used in packaging and comprising mostly polyolefins, mechanical recycling is not practical, hence the interest in chemical recycling. Dissolution/precipitation recycling can recover polyolefins for re-use, with energy needs and emissions much lower than pyrolysis. The dissolution of polyolefins is key to this recycling process, however, the underlying phenomena which govern the dissolution of semicrystalline polymers are little studied. To address this gap in knowledge, the swelling and dissolution kinetics of high-density polyethylene (HDPE) films are investigated here. Experiments are designed to obtain the time evolution of HDPE dissolved mass and degree of crystallinity. A mathematical model is developed to describe the swelling and dissolution of semicrystalline HDPE based on the transport phenomena and thermodynamics governing the process. Experimental data are used to validate the model and to obtain values for the two key fitted parameters, decrystallization constant and disentanglement rate. The detailed information provided by the model, spatial and temporal composition and solvent diffusion, reveals the molecular mechanism of HDPE dissolution. A parametric analysis is performed using the validated model to simulate dissolution phenomena at varying conditions, including initial degree of crystallinity and film thickness. These insights on polyethylene dissolution facilitate the design of more energy efficient and environment-friendly dissolution-precipitation recycling processes. The model can be extended to probe the dissolution of other semicrystalline polymers.
ポリプロピレンの溶解速度論：溶媒、温度、粒子サイズの影響 Polypropylene Dissolution Kinetics: Effects of Solvent, Temperature, and Particle Size
Paschalis Alexandridis,Ali Ghasemi and Marina Tsianou
Polymers Published:2 December 2025
DOI:https://doi.org/10.3390/polym17233213
Abstract
Polypropylene (PP) is widely used and currently very little recycled. A promising method for recycling the PP present in plastic waste involves its selective dissolution and subsequent separation from undissolved compounds. We address here the fundamentals of PP dissolution. Specifically, we present a model that describes the different phenomena involved in the dissolution of semicrystalline PP and validate the model with the experimental results on the decrystallization and dissolution kinetics of PP pellets. The model provides detailed time-resolved and position-resolved information on composition (i.e., crystalline PP, amorphous PP, and solvent) and solvent diffusivity (which depends on composition) across the dissolving polymer particle, in different solvents and temperatures. Such information is unavailable experimentally or difficult to obtain. The key fitted parameters that capture decrystallization and polymer chain disentanglement decrease with increasing temperature following an Arrhenius relationship, with activation energies higher than that for crystallization and comparable to that for melt viscosity. Both decrystallization and dissolution times increase with particle size. For smaller particles, decrystallization and dissolution occur nearly simultaneously, while for larger particles, their interior remains solvent-poor and crystalline for longer times. This work offers insights into the interplay of decrystallization and polymer chain disentanglement during the time-course of PP dissolution. Further, this work facilitates the design and optimization of a dissolution–precipitation recycling process that can unlock value from the million tons of PP annually that is currently being landfilled or incinerated following its use.
中赤外・近赤外相関分光法によるポリエチレン結晶度のリアルタイム定量：融解と溶解 Real-Time Quantification of Polyethylene Crystallinity via In Situ Mid- and Near-Infrared Correlation Spectroscopy: Melting and Dissolution
Nicholas Stavinski, Ali Ghasemi, Luis J. Bruno, Carmen L. Sánchez Delgado, Marina Tsianou, Paschalis Alexandridis, Luis Velarde
Journal of Polymer Science Published: 07 April 2025
DOI:https://doi.org/10.1002/pol.20250207
ABSTRACT
Elucidating the crystalline-amorphous interface during decrystallization processes in semi-crystalline polyethylene (PE) is crucial for the advancement of polymer theory and plastic-to-plastic recycling technologies. In this study, we carried out an in-depth investigation of PE thin films undergoing melting or dissolution using a temperature-controlled liquid flow-cell experimental setup which provided in situ mid-infrared (MIR, 4000–700 cm−1) and near-infrared (NIR, 6000–4000 cm−1) spectra in real time. The spectroscopic results yielded molecular-level information regarding PE decrystallization and chain disentanglement via fundamental vibrations, combination bands, and overtones which were correlated using hetero-spectral two-dimensional correlation spectroscopy (2D-COS). A quantitative procedure for the calculation of PE degree of crystallinity was developed to track transformations of crystalline domains during melting and dissolution. This semi-empirical model achieved a strong linear correlation of at least +0.93 in four spectral regions: 750–700 cm−1, 1500–1400 cm−1, 3000–2800 cm−1, and 4400–4200 cm−1. This analysis revealed important spectral trends about the interfacial solvation environment during these processes. Lastly, the time evolution of the unraveling, terminal methyl (CH3) groups of PE cilia was examined in relation to the decrystallization mechanism of PE. The insights obtained from this study advance the fundamental understanding necessary for developing new depolymerization and dissolution-precipitation recycling strategies.
