A study of transcrystalline polypropylene/single-aramid-fibre pull-out behaviour using Raman spectroscopy

The pull-out behaviour of isotactic polypropylene/Twaron D1056 single-fibre composites was investigated. Three matrix morphology types, two transcrystalline [fast-cooled (FCTC) and slow-crystallized (SCTC)] and one spherulitic [slow-crystallized (SCS)], were compared. The detailed point-to-point stress distributions along the embedded fibres were measured during pull-out using Raman spectroscopy. These stress distributions were modelled using a partial debonding theory, and it was found that the debond shear stress (tau(max)) was of the order of 10 MPa for the three morphologies. Analysis of the pull-out data revealed that the mean interfacial frictional shear stress (tau(i)) of the FCTC and SCTC samples is similar at similar to 2.2 MPa, higher than that of the SCS samples (similar to 1.5 MPa).