In-situ X-ray study of the deformation mechanisms of non-woven polypropylene

Non-wovens are of emerging research and industrial importance due to the characteristic high surface area, high porosity, high damage tolerance, and low cost. However strength and toughness are difficult to design for due to the structural irregularity and multitude of deformation mechanisms. Here we investigate the mechanical properties and deformation, mechanisms of polypropylene non-wovens as a function of areal weight. Mechanical characterization showed that higher areal weight corresponds to equivalent stiffness and greater strength per weight compared to lower areal weight. Two x-ray studies were carried out with synchrotron radiation during uniaxial tensile testing: micro-computed tomography (3D microstructure) and x-ray diffraction (fiber orientation). These techniques combined to reveal that in compact non-wovens inter-fiber bonds provide strong constraints on the network structure and limit fiber rotation until the bonds fail. Conversely, in sparse non-wovens localized fibers align, plastically deform, and eventually fracture. These comprehensive combined mechanical response and microstructural data sets will serve to build microstructure-based constitutive models in future work. (C) 2016 Elsevier Ltd. All rights reserved.