Interfacial phenomena, adhesion and macroscopic properties in polymer composites

The microfragmentation or the single-fiber composite method for the evaluat ion of,fiber-matrix adhesion in polymer composites is presented emphasizing advantages and drawbacks. The improvements of the methods introduced in re cent years (laser Raman spectroscopy, optical examination of interfacial re gion, estimation of the stress state at the interface, consideration of vis coelastic properties of the matrix) to obtain more detailed information on the interface failure mechanisms are described. A modified method with a co axial geometry, which extends the applicability of the test to brittle matr ices, is shown. A number of experimental results obtained both with thermop lastic and thermoset matrices containing carbon and glass fibers is reporte d. Chemical modifications of carbon fiber surfaces were carried out, which effectively changed the adhesion to the high-performance bismaleimide matri x. In particular, the treatment with ammonia is shown to be promising for i mprovement of adhesion in graphite/bismaleimide composites.