INVESTIGADORES
BARBOSA silvia Elena
capítulos de libros
Título:
Adhesion Improvement in Thermoplastic Composites Polypropylene-Glass by Grafting
Autor/es:
ETCHEVERRY, MARIANA; FERREIRA, MARÍA LUJÁN; BARBOSA, SILVIA ELENA; CAPIATI, NUMA JOSÉ
Libro:
Polymer Composites: Properties, Performance, and Applications
Editorial:
Nova Science Publishers
Referencias:
Lugar: Nueva York; Año: 2010; p. 933 - 952
Resumen:
A new approach to increase PP-GF adhesion, based on propylene polymerization directly onto the fibers surface, is explored in the present work. The chemical anchoring of the matrix polymer on glass fibers was improved by direct metallocenic copolymerization of propylene onto the fibers. The experimental route involves an initial contact with methylaluminoxane and a hydroxy-a-olefin to generate anchorage points on the fiber surface, followed by a propylene polymerization catalyzed by EtInd2ZrCl2 (metallocene)/methylaluminoxane. As a result of this reaction, PP chains grow by copolymerization of propylene with the olefin anchored to the GF surface. The reaction occurrence was verified by scanning electron microscopy (SEM) with X-ray disperse energy microanalysis (EDX). Part of the tested samples was subjected to solvent extraction to eliminate the PP physically adhered and then compared to non-extracted samples to determine if PP is chemically bonded to glass. Different morphologies of grafted PP, cluster or layer type, result as the hydroxy-a-olefin concentration increases. In order to characterize the PP-GF adhesion, the interfacial shear strength (ISS) was determined by single-fiber fragmentation tests on model composites for different hydroxy-a-olefin concentrations. The surface treatment induced increases of ISS ranging from 1.7 to 2.1 times as compared to the untreated fibers. The improved interfacial adhesion level was confirmed by SEM observation of the morphology at the fiber-matrix region of cryogenic-fractured samples. This route for polymer grafting onto a glass surface can be suitable for technological applications to improve the fiber-matrix adhesion in glass fiber thermoplastic composites.