Effects of silica based fillers, surface treatment and curing method on mechanical properties of silica/unsaturated polyester composites

Abstract

This study examined the effects of silica based fillers, precipitated silica (PSi) and silica from fly ash (FASi), and a silane treatment on the mechanical and morphological properties of unsaturated polyester (UPE) resins cured by conventional thermal (CV) and microwave (MW) curing methods. The curing curves for unfilled UPE in both curing systems exhibited S-shaped character. The curing curves for PSi/UPE composites were different from those of the FASi/UPE composites due to differences in the number of hydroxyl groups on the silica surfaces. MW curing could reduce the curing time in a greater magnitude than CV curing, suggesting that microwaves are more suitable for curing polymers containing silica based fillers. The percentage conversion of silica/UPE composites increased with increasing filler content. The flexural modulus, hardness and impact strength increased with increasing filler content for both silica fillers. The presence of silica filler in the UPE resulted in a sudden decrease in flexural strength, even though the strength improved slightly with increasing silica content. The overall mechanical properties of the UPE composites were improved considerably using 3-glycidoxypropyl thimethoxysilane (KBM-403) on a silica surface.

Effect of hybrid phenolic hollow microsphere and silica-filled vinyl ester composites

“…18 Previous works had reported that the addition of inorganic fillers will normally increase the modulus of the polymer composites. 19,20 However, the results presented in Figure 10 indicates that only composites filled with silane-treated silica were found to show increasing trend in flexural modulus with the increase in filler content. The influence of surface contact between fillers and polymer matrix was reported to have minimal effect to the flexural modulus of polymer composites.…”

In situ synthesis of green bionanocomposites based on aqueous citric acid cured epoxidized soybean oil-carboxylic acid functionalized multiwalled carbon nanotubes

“…This implies that the c-MWCNTs caused an increase in the collision factor of the reactive species around the vicinity in the cross-linking system. Therefore, this resulted in an auto-acceleration reaction of the epoxidized soybean oil/citric acid/c-MWCNTs bionanocomposite system (Wang et al, 2012a,b;Sriloy et al, 2010). Moreover, the incorporation of c-MWCNTs increases the activation energy of the reactive species and thereby hastens the rate of cross-linking reaction.…”