Environmental and multi reinforcing effects of micro and nano fibers on adhesion properties of slow setting epoxy adhesives

Abstract

The chopped PVA fibers and vapor grown carbon nano tube (VGCNF) were used in reinforcing a room temperature curable epoxy resin system. This epoxy based nano-composite adhesive was used to attach Sus 316 steel plates. We have prepared the samples in spring and summer to check the environmental effects on the adhesion properties. The maximum contents of PVA fiber and VGCNF were 1.39 and 0.61%, respectively. The samples have been preserved for two months at the laboratory to experience real environmental change. The mean temperature and moisture were 22°C and Relative Humidity of 52% for dry spring weather and 32°C and Relative Humidity of 85% for summer weather with monsoon. The addition of VGCNF was always helpful to increase the adhesion strength with the studied concentrations. The measured highest increase of adhesion strength was 1.84 times in the specimens with 0.61 wt% of VGCNF prepared in spring. The reinforcing effect by PVA fiber addition was dramatically changed by the concentration and seasonal environment. The maximum reinforcing effect on adhesion strength has been obtained with 0.35 wt% of PVA fiber. The increasing ratio of the strength was 3.01 times. But with the higher concentration of PVA fiber caused a very sharp decrease of adhesion strength. The combination effect of these two reinforcing materials is useful in low addition concentration, 0.35 wt%, of PVA fiber also with the low addition concentrations, 0.15 and 0.3wt%, of VGCNF.