Single synthetic fibres:Nanomorphology, nanostructure and nanomechanical properties

Soft sensation of touch is often a key consumer satisfaction criterion, particularly in personal care products due to their intimate contact with delicate and sensitive anatomical parts of the body (e.g. in nappies and female sanitary pads). Synthetic fibres and fabrics, when in a raw state, often exhibit rough, tacky surfaces which can affect not only their processing (e.g. fibre breakage and production inconsistency) but also the final product properties (e.g. softness, strength and aesthetics). Fibre properties can be enhanced via various processing methods, tailoring their surface structure, nanomechanical and mechanical properties relevant for the optimal soft feel of the fabric. Since human tactile perception extends to few nanometres, it is highly relevant to probe fibre properties at nanoscale. Fatty acid amides have been widely recognised as efficient surface modifiers (i.e. slip additives). However, the structural organisation, specifically molecular orientation within the amide surface layers remains under some debate. Furthermore, slip additive transport and surface segregation has not yet been explored for anisotropic materials such as polymer fibres.The project has investigated the effects of through-air thermal bonding on bicomponent polyethylene/polyethylene terephthalate (PE/PET) fibres in the sheath/core configuration, and how slip additive (erucamide, C22H43NO) treatment of monofilament polypropylene (PP) fibres could affect the fibre surface nanostructure, nanomechanical properties and wettability. To this end, several experimental techniques have been employed, including Optical Microscopy, Atomic Force Microscopy, Scanning Electron Microscopy and contact angle (CA) measurements. Furthermore, X-ray reflectivity, AFM and CA were employed to probe the molecular orientations within erucamide film deposited on hydrophilic silica and more hydrophobic PP-coated silica as a function of the erucamide concentration. Finally, the effects of erucamide on single fibre crystal structure and mechanical properties were examined using X-ray Diffraction and a single-fibre tester