Fast curing versus conventional resins – degradation due to hygrothermal and UV exposure

Abstract

In the current paper, three resin systems are investigated, the first is a high temperature fast curing system, the second is a high-temperature system that requires several hours to cure and the third is a slow room temperature curing system. All systems are exposed to hygrothermal and combined moisture/temperature/UV protocols, and their durability is assessed using Fourier transform infrared (FTIR) spectroscopy, mechanical and thermomechanical characterization. The conventional slow curing system presents a wide distribution of polymer chains that leads in excess free volume/increased susceptibility to water. The medium curing system is more homogenous and shows lower absorption profiles. The fast curing system shows two network domains, one that is more crosslinked and contributes towards higher free volume/water absorption and the other that is partially cured and supports chain scission/leaching processes during exposure. Continuation of crosslinking prevails in conventional resins upon hygrothermal and combined UV exposure. At the same time antagonistic effects (i.e. continuation of the crosslinking process versus plasticization, chain scission, and leaching) are observed in medium curing and fast curing systems upon exposure.

Keywords

• thermosetting resins
• fast curing
• environmental exposure
• mean molecular weight between crosslinks
• tg