Abstract:
Thermal curing is usually used for epoxy composites manufacturing. The thermal degradation occurs when the exothermic reaction produces sufficient heat. As a result, this study investigated the pre-curing process by adding the photo-initiator into epoxy composites and using ultraviolet rays to accelerate the reaction and reducing the curing time.
The solution of a photo-initiator Bisacyl Phosphine Oxide (BaPO) and a hardener Cyclohexylamide were added at the rate of 0.0, 3.0 and 5.0 per percent in proportion to resin (phr) mixed with epoxy resin and then activated by ultraviolet-A (UV-A) for 0.0, 2.0, and 4.0 minutes, at the isothermal curing of 80, 100, and 120 °C, respectively. Differential scanning calorimetry was used to analyze the curing behavior in terms of the proportion and reaction.
The study found that irradiated epoxy composites activated by UV-A for 2 minutes at the curing temperature 100 °C obtained the proper viscosity and the highest reaction rate. Additionally, the most suitable curing time was 40 minutes. The results showed that the higher content of photo-initiator solution resulted in a higher rate of reaction and a number of crosslinks in every curing condition. However, mechanical characterization with 3.0 phr of photo-initiator solution and at the curing temperature 100 °C for 40 minutes showed the optimal tensile and impact strength. As a consequence, this research concludes that the application of photo-initiators accelerated by ultraviolet rays helps reduce the time and energy in the curing process of epoxy composite manufacturing.