Use of lignin as a compatibiliser in hemp/epoxy composites

• Published in: Composites science and technology 2011-11, Vol.71 (16), p.1804-1810
• Main Authors: Wood, Benjamin M., Coles, Stuart R., Maggs, Steven, Meredith, James, Kirwan, Kerry
• Format: Article
• Language: English
• Subjects: A: Polymer-matrix composites (PMCs); Applied sciences; B: Fibre/matrix bond; B: Impact behaviour; Composites; D: Scanning electron microscopy (SEM); E: Resin transfer moulding (RTM); Exact sciences and technology; Forms of application and semi-finished materials; Hemp; Infusion; Mechanical properties; Modulus of elasticity; Polymer industry, paints, wood; Polymer matrix composites; Polymers; Resins; Technology of polymers
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2011.06.005

► Lignin was used as a compatibiliser in hemp-epoxy composite samples ► Impact strength of samples are increased as amount of lignin is increased ► Tensile and flexural strength of samples show optimal amount of lignin is required ► Addition of lignin gives improved structural properties of composites This study was designed to ascertain if the addition of lignin to hemp-epoxy composites was beneficial to their mechanical properties. Composites were made using a VARTM method with a two-part epoxy resin and a non-woven hemp fibre mat. Lignin was added to the resin before infusion at concentrations varying between 0 and 10% w/w. Samples were then tested according to the relevant ISO standards. There was an increase in impact properties of the fabricated composites with the energy absorbed by the composite containing 5% w/w lignin being 145% higher than the composite with no lignin added. Both flexural and tensile modulus showed an increase when lignin was added up to 2.5% w/w, although there was a drop in both when the lignin was increased to 5% w/w, attributed to poor mixing and infusion due to the increased viscosity of the resin. In all cases, the addition of lignin increased the structural properties of the composites to some degree when compared with composites with no additional lignin.