Optimization of epoxy resins for chemical anchor adhesives and molding compounds

This study has focused on the influence of the chemical structure of the epoxies, epoxy diluents, and curing agents on the glass transition temperature (Tg) and mechanical properties of the cured epoxy network. It was concluded that the epoxy network formed by ingredients containing aromatic or ring structures resulted in higher Tg and better mechanical properties than compositions containing only aliphatics.; The results from above were used to study the relationship of Tg to the elevated temperature pullout strength of epoxy formulations used in the chemical anchor adhesives applications. The relationship of Tg to the thermal resistance for molding compounds was also studied. The study concluded that Tg has an influence on the 80°C pullout strength for chemical anchor adhesives but the formulation with the higher Tg did not always show higher 80°C pullout strengths. The concrete strength also plays a critical role. High value at 80°C can be achieved by a formulation that gives cohesive failures after the 80°C heat cycle. In the case of molding compounds, a similar conclusion was drawn for the relationship with Tg. It was concluded that the thermal conductivity of the cured epoxy also plays an important role for better hot crucible resistance. Finite Element Analysis (FEA) confirmed the results. The study showed that higher thermal conductivity could be achieved by high loading of fillers such as silica and incorporating filler with high thermal conductivity such as graphite.