Study of the influence of thermal history on the load transfer efficiency and fibre failure in carbon/polypropylene microcomposites using Raman spectroscopy

The influence of thermal history on the interfacial load transfer efficienc y and fibre failure in carbon/polypropylene microcomposites has been studie d using Micro Raman spectroscopy. Microcomposites were manufactured by cool ing from the melt at different constant cooling rates or isothermally cryst allized. Thermal residual strains were measured during and after manufactur e of the microcomposites. The residual strains resulted in compressive fibr e failure. Based on the experimental data, interfacial load transfer effici ency was determined quantitatively for the different cooling procedures. Re sults indicate that thermal history has a Very large influence on the inter facial load transfer efficiency of the microcomposites. This was shown to b e due to the influence of thermal history on transcrystallinity and interfa cial residual stresses. A transcrystalline interphase provides a more effec tive load transfer compared to the non-transcrystalline interphase. Further more, decreasing cooling rates leads to an increase in load transfer effici ency due to increased transcrystallinity and higher crystallization tempera ture resulting in higher interfacial stresses.