Hilgers, Hans-Willi
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Hilgers, Hans-Willi
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Hilgers, Hans-Willi
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Item-typ:Veröffentlichung, Hemp From disordered lines for new staple fibre yarns and high-performance composite applications(Frontiers Media, 2022-01-28); ; ; ; The use of natural fibre-reinforced plastics for higher-stressed applications is currently often limited by the high price of high-quality semi-finished products. Therefore, the present study deals with developing yarns from cost-effective hemp from a disordered separation process (total fibre line) for composite reinforcements. Composites were fabricated using a miniature pultrusion process with thermosetting matrices from the yarns. The results show that around 90% of the flexural strength and flexural modulus of identically produced flax composites could be achieved with maximum values of 282 MPa for the flexural strength and 23.4 GPa for the flexural modulus. The yarns were additionally used to manufacture quasi-unidirectional fabrics to produce composite laminates using different manufacturing processes. The highest values were obtained for a laminate with 39 vol% fibre content, produced with a resin injection process in an autoclave, achieving a tensile strength of 155 MPa, Young's modulus of 19.4 GPa, a flexural strength of 174 MPa and bending modulus of 12.4 GPa. The characteristic values are sufficient to use the materials in applications with higher mechanical requirements.Wissenschaftlicher ArtikelBand:8141 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Novel Low-Twist Bast Fibre Yarns from Flax Tow for High-Performance Composite Applications(MDPI, 2020-12-29); ; ; ; The use of natural fibres for components subjected to higher mechanical requirements tends to be limited by the high price of high-quality semi-finished products. Therefore, the present study deals with the development of more cost-effective staple fibre yarns made from flax tow. In the subsequent processing stage, the yarns were processed into quasi-unidirectional (UD) fabrics. The results of the fibre characterisation along the process chain have shown that no significant mechanical fibre damage occurs after slivers' production. Fibres prepared from yarns and fabrics show comparable characteristics. The yarns were processed to composites by pultrusion to verify the reinforcement effect. The mechanical properties were comparable to those of composites made from a high-quality UD flax roving. The fabrics were industrially processed into composite laminates using a vacuum infusion and an autoclave injection process (vacuum injection method in an autoclave). While impact strength compared to a reference laminate based on the UD flax roving was achieved, tensile and flexural properties were not reached. An analysis showed that the staple fibre yarns in the fabric show an undulation, leading to a reorientation of the fibres and lower characteristic values, which show 86-92% of the laminate made from the flax roving. Hybrid laminates with outer glass and inner flax layers were manufactured for the intended development of a leaf spring for the bogie of a narrow-gauge railroad as a demonstrator. The hybrid composites display excellent mechanical properties and showed clear advantages over a pure glass fibre-reinforced composite in lightweight construction potential, particularly flexural stiffness.Wissenschaftlicher ArtikelBand:14Heft:187