Studying of the impact strength of rubber-toughened thermosets

Abstract EN

Abstract In this investigation, the development of composite materials was achieved in two steps.

The first, by the hybridization of the resin matrix with different elastomers to prepare binary polymer blends, these blends have been synthesized by mixing either of (Nitrile Rubber(NBR), Styrene Butadiene Rubber(SBR) and Butadiene Rubber(BR)) with the Epoxy resin(EP) and Unsaturated polyester resin(UP).

The second step is reinforcement of the polymer blends with 30% of two types of fibers.

The first, is by using E-glass fibers alone while the second by utilizing a hybrid of E-glass fibers with Kevlar fibers (type-49).

Different weight percentages (5, 10, 15,…., 50)% of those elastomers were mixed with each of EP and UP.

The optimum mixing ratios (OMR) of those blends have been selected depending on achieving acceptable macro miscibility, best adhesion between two phases and highest impact strength (I.S) of the resulting blends.

The values of (I.S) increased gradually with increasing of rubber content until its maximum value (OMR), and then it goes down as the percentage of the elastomer increases.

Five blends with (OMR) were prepared : EP/NBR(80/20)% , EP/BR(70/30)% , UP/NBR (90/10)%, UP/SBR (90/10)% , UP/BR (90/10)%, while a phase separation of SBR rubber from EP resin has taken place at all ratios; then, these blends were reinforced with single and hybrid fibers.

Impact test was carried out at different environmental conditions to have full description about the mechanical behavior of those blends and their composites under effect of the impact stress.