Adhesion Between Natural Fibers and Thermosets
Ilomäki, Kirsti Maria
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The aim of my Master Thesis was developing a reliable adhesion testing method for natural fiber reinforced composites. Flax fiber, synthetic viscose fiber, two different thermoset matrix and chemical surface treatment were used in this investigation. Bio-based Epobiox and basic epoxy, Envirez G8600 INF-60, were used as thermoset matrix. Chemical surface treatment increased the adhesion between the natural fiber and ther-moset resin. This Master Thesis was divided in theoretical part and experimental part. The purpose of the theoretical part was determining the factors affecting on the adhe-sion in natural fiber composites and how to improve the adhesion and how the adhesion can be tested. The aim of the experimental part is to obtain adhesion testing results, which were able to compare with each other. Micro-bond test was used as an adhesion testing method in which small amount of thermoset resin was cured on the fiber surface. The droplet was pulled out of the fiber surface by micrometer, which was connected to the tensile testing machine. Low cross head speed and 1-5N load cell were used so that the fibers did not break during the test. The microbond test was difficult, because single fiber broke easily during the test. Only a few samples per each fiber-matrix combination were successful, where the interfacial shear strength, IFSS, can be calculated. A single fiber tensile test was done for alkali and silane treated flax fiber, non-treated flax fiber, viscose fiber and glass fiber. The test results show that fiber strength was improved with chemical surface treatment.