Thermal Aging and Degradation of Polyvinyl Chloride Polymers

Polyvinyl chloride (PVC) polymers are widely employed across electrical insulation, construction membranes, packaging and heritage collections. Thermal ageing of PVC involves progressive chemical and physical transformations when exposed to elevated temperatures over extended periods. The primary degradation mechanism is dehydrochlorination, through which hydrogen chloride is eliminated from the polymer backbone, yielding conjugated polyene sequences that manifest as visible yellowing and embrittlement. Concurrent plasticiser migration further modifies mechanical performance, as low-molecular-weight additives diffuse to the surface, leading to increased stiffness and surface tackiness. Secondary processes such as cross-linking and chain scission alter molecular weight distributions, influencing tensile properties, dielectric response and thermal stability. The kinetics of these transformations are governed by activation energies that vary with polymer formulation, plasticiser content and environmental factors such as humidity and light exposure. Analytical approaches—ranging from spectroscopic techniques (FTIR, UV-Vis) to chromatographic methods (GC-MS, SEC-MALS) and thermal analysis (TGA, DSC)—permit quantification of chemical changes and prediction of service lifetimes. Recent advances have also introduced electrical and dielectric measurements as non-destructive probes of ageing in cable insulation. Understanding these interlinked processes is vital to optimising PVC formulations, extending material longevity, guiding heritage conservation strategies and mitigating environmental impacts associated with hydrogen chloride emissions and microplastics release.

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Thermal Aging and Degradation of Polyvinyl Chloride Polymers publication trend

The graph below shows the total number of articles in thermal aging and degradation of polyvinyl chloride polymers across all publications each year (not limited to Nature Index journals).

Technical terms

Thermal ageing: Progressive chemical and physical alterations in a polymer matrix resulting from prolonged exposure to elevated temperatures.

Dehydrochlorination: The elimination of hydrogen chloride from the PVC backbone, leading to unsaturated polyene sequences and material discolouration.

Plasticiser migration: The diffusion and evaporation of low-molecular-weight additives from within the polymer to its surface, affecting mechanical and thermal properties.

Activation energy: The minimum energy barrier required to initiate a chemical degradation process, often determined from temperature-dependent kinetics.

References

1. Damage function for poly(vinyl chloride) in heritage collections. Polymer Degradation and Stability (2023).
2. Investigation of the Structural Dependence of the Cyclical Thermal Aging of Low-Voltage PVC-Insulated Cables. Symmetry (2023).
3. A Method for Assessing the Degradation of PVC-Insulated Low-Voltage Distribution Cables Exposed to Short-Term Cyclic Aging. Electronics (2024).