Impact fracture morphology of nylon 6 toughened with a maleated polyethylene-octene elastomer

This study aimed at using scanning electron microscopy to study the Izod im pact fracture surface morphology of super-tough nylon 6 blends prepared by blending nylon 6 with a maleic anhydride-grafted polyethylene-octene elasto mer (POE) in the presence of a multifunctional epoxy resin (CE-96) as compa tibilizer. The fracture surface morphology and the impact strength of the n ylon 6 blends were well correlated. The fracture surface morphology could b e divided into a slow-crack-growth region and a fast-crack-growth region. U nder low magnification, the fractured surface morphologies of the low-impac t-strength nylon 6 blends appeared to be featureless. The area of the slow- crack-growth region was small. There were numerous featherlike geometric fi gures in the fast crack growth region. The fractured surface morphologies o f the high-impact-strength nylon 6 blends exhibited a much larger area in t he slow-crack-growth region and parabola markings in the fast-growth region . Under high magnification, some rubber particles of the low-impact-strengt h nylon 6 blends showed limited cavitation in the slow-crack-growth region and featherlike markings in the fast-crack-growth region. Rubber particles of high-impact-strength nylon 6 blends experienced intensive cavitation in the slow-crack-growth region and both cavitation and matrix shear yielding in the fast-crack-growth region, allowing the blends to dissipate a signifi cant amount of impact energy. A nylon 6 blend containing 30 wt % POEgMA exh ibited shear yielding and a great amount of plastic flow of the matrix thro ughout the entire slow-crack-growth region, thus showing the highest impact strength. (C) 2000 John Wiley & Sons, Inc.