Properties and Aggregate Structure of Unsaturated Polyester/Phenolic Resin Blends

In this study, unsaturated polyester resin (UP) is blended with resole type phenolic resin, co-crosslinking process performed and the resin blends show miscibility and interpenetration network (IPN) structure. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are employed to examine the aggregate structure of crosslinked network of the UP/phenolic resin blend. Tensile fractured sections of the resin blends are observed using scanning electronic microscopy (SEM) to shed light on their miscibility. Tensile and flexural tests were also conducted to examine the mechanical properties of the UP/phenolic resin blends. The results show that UP20/Ph80 and UP40/Ph60 resin blends have well-formed Interpenetrating Network (IPN) structures while phase separation is observed for UP60/Ph40 resin blend. Finally, thermal cure of UP80/Ph20 resin blend is incomplete, thus showing immiscibility. The mechanical properties of all resin blends at different mixing proportions deviate from a linear relationship and show a concave curve, indicating the non-additive effect of blending.