Behaviour of Wood Joints Glued by One Component Polyurethane Adhesive Modified by Cotton Flakes and Basalt Fibers

Abstract

The main objective of this paper is to describe the influence of cotton flakes and basalt fibers on the resulting tensile properties of one-component polyurethane and the tensile shear strength of glued lap joints of beech wood. Fillers are an integral part of the modification of adhesives, especially because they influence rheological and mechanical properties. A one- component polyurethane adhesive for waterproof joints was used for bonding. The amount of filler was optimized by determining the tensile properties of adhesive as a material. The basalt fibers improved the tensile properties of one-component polyurethane. The average tensile strength value for basalt fibers in the amount of 5% was found to be 30% higher than for basalt fibers in the amount of 1%. The resulting properties of glued joints were determined by tensile shear strength according to standard ČSN EN 302-1. It was found that the shear strength of the bonded beech joints was higher for modified one-component polyurethane by cotton flakes than those modified by basalt fibers of 7 mm length. Significant effect was shown for cohesive failure of lap joint especially for modification by cotton flakes when the value increased by 10% to reference wood joint.