Silane-Grafted Isotactic Polypropylene Used as a Coupling Agent on Glass. Consequences on The Interfacial Adhesion

Functionalized isotactic polypropylenes have been synthetized in order to be used as coupling agents on glass fibers associated with a polypropylene matrix. This new way of interface toughening requires a grafting of such polymeric chains on the glass surface and a crystallization of these grafted chains at the same time in the same crystals as the polypropylene matrix (co-crystallization). Using a Ziegler-Natta polymerization, copolymers based on propene and two different types of dienes have been prepared. Such a synthesis allows one to change the functionality and the position of double bonds used to introduce the silane functions. A Speier hydrosilylation was used for this purpose with two kinds of silanes. Silane-functionalized oligopropenes were also prepared in order to compare the effect of the position of the silane functions on the glass/polypropylene adhesion: side chain or chain end positions. The characterization of these functionalized polypropylenes is described. Their ability to be grafted on a glass surface was checked by means of wetting measurements after extractions according to the hydrophobic nature of the polypropylene and the hydrophilic character of the glass. The co-crystallization of the pure and functionalized polypropylenes was demonstrated on blends. Two silane functionalized-PP were selected to study the glass fiber/PP adhesion by means of the microdroplet test.