Phthalic acid-derived diluents as an effective alternative to styrene in optimization of vinyl ester resins properties

Total or partial replacement of styrene with low volatilities diluents can be considered the most effective way to reduce the environmental risks and destructive effects of styrene release on human health. In this respect, phthalic acid-derived diluents are ideal candidates to replace styrene because of their easy availability, low volatility, and inexpensive. In the present study, a reactive diluent (D-1) was synthesized from dimethyl phthalate (D-p) and hydroxyl ethyl methacrylate (HEMA) to produce a copolymer with epoxy acrylate (EA) resin. Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) confirmed the chemical structure of synthesized diluents and EA resins. Also, the viscosity, thermal stability, and mechanical properties of EA resin samples were investigated using the rheology test, thermogravimetric analysis, tensile test, and flexural test. The results showed that diluent D-1 (active diluent) is more effective than D-p (deactivated diluent) and styrene, especially in reducing the viscosity of EA resins. Overall, the great effect of diluent D-1 in improving the rheological properties (before curing) and the thermal stability and mechanical properties (after curing) of EA resins make this diluent a suitable alternative to styrene in the production of commercial EA resins. [Graphical abstract] [graphical abstract]

Automated summary

In this study, a reactive diluent (D-1) derived from phthalic acid was synthesized to replace styrene in epoxy acrylate resin. The diluent D-1 showed better performance in reducing the viscosity of the resin compared to deactivated diluent D-p and styrene. It also improved the rheological properties, thermal stability, and mechanical properties of the resin.