Toughened adhesives automotive applications

In recent years, the range of adhesive materials used in automotive manufacture has expanded to include polyurethanes, plastisols, phenolics, hot melts, anaerobics, cyanoacrylates, toughened acrylics and epoxies (see Structural and Hot melt adhesives). Selection criteria are based principally upon the nature of the adherends, the mechanical properties required under service conditions and application and curing characteristics. 

The surface content and the distribution of (ethylene-propylene) copolymer (EP) in toughened polypropylene (PP) resins (PP/EP) have important impact on a lot of properties such as gloss, paint adhesion, hardness,. .. These surface properties are more and more important in the multiple applications of these resins, for instance for paint adhesion in the automotive industry. It has already been shown that the introduction of EP in PP provides better paint adhesion but its role remains speculative (1-4), A major drawback to the understanding of the EP influence on PP/EP surface properties is the lack of knowledge concerning the blends surface morphology (EP content, EP lateral distribution,. ..). This is essentially due to the similar chemical composition of both polymers that prevents surface analysis by classical chemical surface spectroscopies. 

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