CONTRIBITION OF MICRO-SILICA AND NANO-MONTMORILLONITE REINFORCEMENTS ON THE MECHANICAL PROPERTIES OF UV-CURABLE THERMOSET RESIN

Abstract

UV-curable thermoset resins had been utilized in organic coating industry because of their benefits over conventional adhesives like fast curing, less energy consumption and equipment. In this article, the effects of micro and nano-scaled reinforcements on the mechanical properties of a UV-curable thermoset resin were investigated. The reinforcements are chosen to be nano-scaled Montmorillonite (MMT) and micro-scaled Silica (SiO2). The reason for this choice is that the aforementioned particles are non-toxic, low-cost and in the case of MMT; abundant in nature. According to our knowledge, there is no study on the synergistic effects of those two additives in thermoset resins. 
 The instrumented microindentation test results reveal that maximum improvement on hardness (288%) was achieved by single addition of MMT thanks to the well-distributed silicate layers. Conversely, SiO2 addition diminished both strength (-51%) and modulus (-68%) drastically which is attributed to the possible poor dispersion and weak surface attraction. On the other hand, when those additives were utilized together, the property improvements namely; hardness and modulus are observed to be in between of single addition of either additive. It is suggested that SiO2 contribution does not disturb intercalated/exfoliated-MMT structure and similarly by simultaneous MMT reinforcement, quality of SiO2 dispersion is not affected. It is concluded that one benefit of these SiO2-MMT combinations over single MMT reinforcement could be related to plasticity since they result in less plasticity reduction of -22%-27% compared to MMT (-43%) with the further benefit of higher hardness improvement (+66%) than bare SiO2 addition (-51%).