Studying of The Impact Strength of Rubber- Toughened Thermosets

Abstract

In this investigation, the development of composite materials was achievedin two steps. The first, by the hybridization of the resin matrix with differentelastomers to prepare binary polymer blends, these blends have been synthesizedby mixing either of (Nitrile Rubber(NBR), Styrene Butadiene Rubber(SBR) andButadiene Rubber(BR)) with the Epoxy resin(EP) and Unsaturated polyesterresin(UP). The second step is reinforcement of the polymer blends with 30% oftwo types of fibers. The first, is by using E-glass fibers alone while the second byutilizing a hybrid of E-glass fibers with Kevlar fibers (type-49). Different weightpercentages (5, 10, 15,…., 50)% of those elastomers were mixed with each of EPand UP. The optimum mixing ratios (OMR) of those blends have been selecteddepending on achieving acceptable macro miscibility, best adhesion between twophases and highest impact strength (I.S) of the resulting blends. The values of(I.S) increased gradually with increasing of rubber content until its maximumvalue (OMR), and then it goes down as the percentage of the elastomerincreases. 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 allratios; then, these blends were reinforced with single and hybrid fibers. Impacttest was carried out at different environmental conditions to have full descriptionabout the mechanical behavior of those blends and their composites under effectof the impact stress.