A degradation mechanism is the sequence of chemical steps by which a polymer loses its useful properties under a given environment. Hydrolytic degradation proceeds by the attack of water on a hydrolysable bond, and the rate depends on the accessibility of that bond rather than on its intrinsic reactivity [1]. Oxidative degradation starts with a radical, and the propagation step consumes oxygen while the termination step crosslinks or scissions the chain [2]. Thermal degradation at low temperature is usually oxidative, while pyrolysis above the ceiling temperature proceeds by unzipping to the monomer [3]. Because several routes can act at the same time, distinguishing them requires the kinetics to be measured at more than one condition [4]. The mechanism determines whether the product is a harmless fragment or a persistent microplastic, and that distinction governs the end-of-life assessment [5].
- hydrolytic scission
- oxidative degradation
- radical propagation
- pyrolysis
- chain unzipping
- kinetics
- microplastic
References
- Li, R.; Hu, X.; Study on discoloration mechanism of polyamide 6 during thermo-oxidative degradation. Polymer Degradation and Stability 1998, 62, 523-528, 10.1016/s0141-3910(98)00037-8.
- Polyák, P.; Szemerszki, D.; Vörös, G.; Pukánszky, B.; Mechanism and kinetics of the hydrolytic degradation of amorphous poly(3-hydroxybutyrate). Polymer Degradation and Stability 2017, 140, 1-8, 10.1016/j.polymdegradstab.2017.03.021.
- Huang, K.; Ma, B.; Dai, J.; Sha, J.; Mechanical Properties and Degradation Mechanism of SiC Fibers Exposed to Oxidative Environment up to 1600 °C. Applied Sciences 2025, 16, 64, 10.3390/app16010064.
- Zaikov, G.; Livshits, V.; The mechanism of chemical degradation of polymers: Part I—Quantitative prediction of hydrolytic stability of polyesters. Polymer Degradation and Stability 1984, 9, 41-50, 10.1016/0141-3910(84)90083-1.
- Morgan, R.J.; Butler, N.L.; Hydrolytic degradation mechanism of Kevlar 49 fibers when dissolved in sulfuric acid. Polymer Bulletin 1992, 27, 689-696, 10.1007/bf00297440.