| Autor: |
Fuentes, C. A., Federico, C., Mertz, G., Cosas, J., Van Hoof, S., Ramharter, K., Van Vuure, A. W. |
| Zdroj: |
Abstracts of the Fiber Society Symposium; Spring2022, p56-56, 1p |
| Abstrakt: |
With the increasing demand for natural fibre reinforced composites, a lot of effort is put in improving their mechanical properties. The weakest part of these composites is often the fibre-matrix interface. This weakness is usually attributed to a bad compatibility between the typically hydrophilic reinforcing fibre and in particular hydrophobic thermoplastic matrices, and to the anisotropic nature of natural fibres, and particularly bamboo in this study, that provokes a great reduction of their transversal and shear mechanical properties. To achieve a composite with good mechanical properties, a strong fibre-matrix adhesion must be obtained by interfacial interactions, including mechanical interlocking, chemical bonding and physical adhesion. Even though the chemistry of the surface of the fibre displays a favourable interaction with a given matrix, apparently low transversal mechanical properties fail to transfer stress at the interface. This may be related to the limited mechanical properties of lignin which is predominant at the surface of technical bamboo fibres. Here we describe a novel surface treatment based on the degradation of the lignin layer that is naturally present on the bamboo fibre (guadua angustifolia) surface by UV-A radiation (315nm≤ λ ≤ 400nm). This specific wavelength range maximizes lignin degradation. After the treatment, the lignin layer is then easily removed, leading to an increment of the stress transfer capability at the fibre-matrix interphase assessed by single fibre pull out tests. Bamboo fibres were exposed to ultraviolet light (UV) radiation to degrade and remove the lignin layer on the surface of the fibre, in order to improve the interfacial bonding strength between fibres and polyvinylidene fluoride (PVDF). Before and after surface treatment, the chemical groups on the fibre surface was analysed trough x-ray photoelectron spectroscopy (XPS), as well as their wetting behaviour. XPS analysis showed a clear reduction of lignin content, and cellulose exposure at the fibre surface. Atomic Force Microscopy (AFM) and microtomography analysis, showed also the reduction of lignin after the treatment. The wetting analysis shows the same trend with contact angles of water on bamboo fibres moving from 65° to 48° before and after the treatment respectively. The mechanical strength of the interface was assessed by single fibre pull-out tests, showing an interfacial shear strength value increment of ~ 40% with respect to untreated fibres. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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