CHARACTERIZATION BY RAMAN MICROSPECTROMETRY OF RESIDUAL COMPRESSIVE STRESSES INDUCED BY RESIN CURING IN SINGLE FILAMENT COMPOSITE SAMPLES

The present work concerns monofilament composite samples used in the p ull-out test to quantify the effect of different fibre surface treatme nts on the adhesion of a high modulus polyethylene in a polyester resi n. Optical observations revealed local deformations induced by a compr essive stress generated in the fibre by the resin shrinkage during the curing. The sensitivity of the polyethylene Raman peak at 1130 cm(-1) to elastic strain has been used to characterize the local compression state still present in the fibre after the curing. The results show r esidual stresses varying along the fibre embedded length up to a level depending on the applied surface treatment i.e. on the degree of adhe sion between the fibre and the resin. This is consistent with the loca lization and the morphologies of shear bands observed in the samples. More the Raman microspectrometry has been used to determine the tensil e stress profile along the embedded part of the fibre when its free pa rt is stretched. Corrected of the initial compression slate this profi le represents the stress transfer effectively realized from the fibre to the resin for different adhesion conditions. Its knowledge is very useful to clarify the interlace damage and pull-out mechanisms.