Influence of yarn structure and coating on the mechanical performance of continuous viscose fiber/epoxy composites

• Published in: Polymer composites Vol. 43; no. 2; pp. 1012 - 1021
• Main Authors: Ungerer, Bernhard, Müller, Ulrich, Pramreiter, Maximilian, Herrero Acero, Enrique, Veigel, Stefan
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.02.2022; Blackwell Publishing Ltd
• Subjects: Acrylic resins; biofibers; composites; Continuous fiber composites; Design optimization; Ductile fracture; Epoxy resins; Filaments; Folding; Mechanical properties; Prestressing; Rayon; Stiffness; structure–property relations; Tensile tests; Warp; Weft; Yarn; Yarns
• ISSN: 0272-8397; 1548-0569
• DOI: 10.1002/pc.26430

The present study investigated the effect of selected structural parameters on the mechanical performance of regenerated cellulose composites. The experimental setup comprised continuous viscose (rayon) yarns embedded in a matrix of epoxy resin. Mechanical and microscopic characterizations involved comparing the following: yarns consisting of untwisted filaments and twisted warp and weft yarns taken from a plain weave fabric, yarns with and without avivage (fiber finish), as well as yarns with and without an acrylic coating. During the epoxy treatment, samples were either prestressed or laid horizontally to preserve the original yarn structure. Tensile tests revealed that yarn crimp had a significant impact on the strength properties of composite specimens, a higher crimp ratio leading to a decrease in performance. Applying prestress to crimped yarns has proven to be an effective way to enable straight alignment in the loading direction, which is essential for the design of stiffness‐ and strength‐optimized yarn composites. Unlike an avivage, which did not markedly affect the mechanical properties of composite yarns, the application of an acrylic coating prior to resin impregnation was found to provide significantly increased extensibility and more ductile fracture behavior.