Creep of carbon polypropylene model composites - a Raman spectroscopic investigation

The paper considers the load-transfer mechanisms in carbon-fibre/polypropyl ene matrix model composites subjected to creep loading and subsequent recov ery. The fibre strains are measured in situ by micro Raman spectroscopy. Th e coefficient of friction is calculated on the basis of the measured initia l residual strains and the initial interfacial pressure on the fibre obtain ed from the Lame solution. A theoretical approach is utilised to describe t he creep strain in the matrix material. The analysis shows that the load tr ansfer between the fibre and the matrix is of a mechanical nature governed by the radial pressure on the fibre and the coefficient of friction. The ca lculations indicate that this load transfer mechanism will-for longer loadi ng times-cause the composite to behave as a pure matrix with holes. (C) 199 9 Elsevier Science Ltd. All rights reserved.