Plastic deformation in polypropylene/(ethylene-propylene) copolymer blend during paint debonding

Polypropylene (PP) and polypropylene/(ethylene-propylene) copolymer (EP) bl end (PP/EP) injection-moulded plates were painted with a chlorinated polypr opylene (CPO) based adhesion promoter. Three-point bending and crosscut adh esion tests performed on these plates show that adherence is better on PP/E P than on PP. X-ray photoelectron spectroscopy (XPS) and force modulation m icroscopy (FMM) analyses were performed on the failure surface obtained aft er the three-point bending test. XPS shows that the Cl atomic fraction is l ess than 0.5% on the polymer side and close to 4% on the paint side indicat ing that the fracture is located at the CPO-polymer interface. The analysis of the PPEP surface by FMM reveals that paint debonding occurs with plasti c deformations located into the EP elastomer phase. The magnitude of the pl astic deformation is dependent on the depth location of the nodules. The ad herence improvement induced by the presence of EP nodules can thus be expla ined by energy dissipation occurring during EP deformation. (C) 2000 Elsevi er Science Ltd. All rights reserved.