Effect of long-term thermo-oxidative aging on weight and fracture toughness of polycyanate neat resin

Abstract

This study focuses on the effect of long-term thermo-oxidative aging on weight and fracture toughness (KIC) of polycyanate ester (PCy) neat resin (FSD-M-08178). Thermo-oxidative aging was conducted at 180 °C up to 8000 h under atmospheric pressure in order to investigate susceptibility to thermo-oxidative environment in the PCy. Weight and KIC changes were investigated with chemical structure changes due to thermo-oxidative degradation. The chemical structure changes were analyzed by means of Fourier transformed infrared spectroscopy with attenuated total reflection system. To investigate degree of degradation, carbonyl index (CI) was analyzed with triazine ring peak which is characteristic peak of the cured polycyanate resin. Single-edge-notch bending test was conducted for each aged (non-aged, 100, 197, 500, 1000, 2000, 4000, and 8000 h) condition to investigate KIC change and evaluated with CI. The result indicated that the weight increased first 500 h. Then, the weight decreased. The result also indicated that the KIC sharply dropped first 100 h. After 100 h, the KIC was almost same up to 8000 h. The result suggested the KIC depend on the CI which was chemical structure changes of the specimen surface due to thermo-oxidation degradation.