Reactive Processing of Polyethylene with Azidotriazine: From Modified Thermoplastics to Injection Moldable Covalent Adaptable Networks

ACS Applied Polymer Materials, Journal Year: 2025, Volume and Issue: 7(3), P. 2123 - 2133

Published: Jan. 31, 2025

The increasing consumption of polyethylene (PE) is an important concern for society because the rate PE recycling remains low compared to scale production. There thus great interest in strategies revalorizing waste. In this context, our group recently reported approach transforming into nanostructured covalent adaptable networks (CANs) with azidotriazine grafting agents using reactive extrusion. These CANs feature polyazane cross-links that undergo thermomechanically activated exchange reactions, permitting material flow when subjected high temperature and strain. Herein, we exploited chemistry develop modified materials intriguing thermomechanical properties exceptional processability. A family compositions was prepared by reactively extruding varying amounts agent, resulting were studied a combination electron microscopy, small-angle X-ray scattering, calorimetry, rheometry, mechanical testing. As loading agent increased from 0.05 1.0 mol %, transitioned being thermoplastic-like thermoset-like, revealing balance properties, melt strength, high-temperature creep resistance. Surprisingly, all samples─even loadings azidotriazine─could be easily shaped injection molding. We believe promising, industrially relevant way enhance polyolefins.

Language: Английский

Circular Cross-Linked Polyethylene Enabled by In-Chain Ketones

ACS Macro Letters, Journal Year: 2024, Volume and Issue: unknown, P. 1655 - 1661

Published: Nov. 15, 2024

Cross-linked polyethylenes (PEs) are widely employed, but the permanent links between chains impede recycling. We show that via imine formation with diamines keto-functionalized from both free-radical (keto-low-density PE, keto-LDPE) and catalytic (keto-high-density keto-HDPE) nonalternating ethylene-CO copolymerization can be cross-linked efficiently in melt, resulting gel fractions of formed PEs up to 85% improved tensile properties. The imine-based cross-links material hydrolyzed at 140 °C recycle 97% initial thermoplastic keto-polyethylene. Low keto contents ≤1.5 mol % found ideal retain PE-like thermal properties, achieve sufficient cross-link density, maintain circular recyclability.

Language: Английский