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Effect of Laccol-modified Epoxy (Epolac) on Toughness of Epoxy Resins
N. H. Tran, V. D. Tran and H. T. Dang
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ABSTRACT
In this study, a series of Laccol-modified epoxy (Epolac) was directly dispersed in the epoxy resin and then the modified matrices were cured with cyanethyldiethylenetriamine  as a curing agent. Tension and critical stress intensity factor (KIC) measurements were performed in order to observe the effect of Laccol modification on the fracture properties of resin. Results showed an optimum concentration of Laccol (15 wt%) into epoxy matrix, which offered maximum toughening. Fractured surfaces of the specimens have been critically studied through scanning electron microscopic (SEM) analysis to gain insight into phase morphology. SEM photographs showed that phase separation did not occur in these cases because Laccol participated in epoxy polymer networks. Results obtained from dynamic mechanical thermal analysis showed that the glass transition temperatures of the epoxy resin matrix were slightly reduced on the addition of Laccol. The overall results  showed that it was possible to obtain excellent impact strength and good mechanical properties with the use of Laccol as a toughness agent for the epoxy resins.

Key words: Epoxy resin; Laccol-modified epoxy; fracture toughness; mechanical properties; Dynamic Mechanical Thermal Analysis

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