Interfacial Adhesion Improvement by Polypropylene Polymerization onto Glass Fibers

MARIANA ETCHEVERRY; MARÍA LUJÁN FERREIRA; NUMA CAPIATI; ANDREA PEGORETTI; SILVIA BARBOSA

Río de Janeiro

Congreso; Fourth International Conference on Science and Technology of Composite Materials, COMAT 2007; 2007

Glass Fibers reinforced polypropylene is a very attractive material for general purpose pieces due to the good processability, good price and chemical resistance. However, for extend its application to high performance composites; the final mechanical properties should be increased. The key to reach this improvement is to obtain an increment in the adhesion between fibers and matrix. It is well known that polypropylene has no chemical functionality which bond effectively with glass fibers surfaces and glass fibers have low chemical functionality. This problem is overcome for many years by using silane sizing, which can chemically modify the fiber surface and promotes chemical coupling from fiber and matrix. This kind of solutions increases the adhesion but not enough to achieve high performance composites. In this work, a new approach to increase polypropylene-fiber adhesion based on propylene polymerization onto fibers is proposed. In this sense, chemical anchoring of the matrix on glass fibers was performed by direct metallocenic propylene polymerization. The experimental route involves an initial contact with methilaluminoxane (MAO) and hidroxy-a -olefin to generate the anchorage points on fiber surface following of propylene polymerization catalyzed by EtInd2ZrCl2 (metallocene)/MAO. Then, the "polypropylene" chains grow from glass fibers. This reaction was studied for different hidroxy-a -olefin concentrations. The effectiveness of the copolymerization reaction was characterized by Scanning Electron Microscopy (SEM) with X-ray Disperse Energy Microanalysis on line (SEM/EDX). The adhesion measurements were performed by single-fiber fragmentation test.