PARTICULARITIES CONCERNING THE MECHANICAL BEHAVIOUR IN WET ENVIRONMENT IN CASE OF A HYBRID COMPOSITE MATERIAL WITH WOOD FLOUR

Camelia CERBU
Conf.dr.eng. - Universitatea Transilvania din Brasov - Facultatea de Inginerie Mecanica
Address: B-dul Eroilor 29, 500036 Brasov, Romania
Tel. +40 268 412921 / int.171.
E-mail: cerbu@unitbv.ro

Ioan CURTU
Prof.dr.eng. - Universitatea Transilvania din Brasov - Facultatea de Inginerie Mecanica
Address: B-dul Eroilor 29, 500036 Brasov, Romania
Tel. +40 268 412921 / int.171.
E-mail: curtui@unitbv.ro

Abstract: The paper marks out the different mechanical behaviour in wet environment due to the admixture of the wood flour in case of the composite materials reinforced with glass fibres. With this purpose in view, it was tested: Composite 1 (E-glass woven fabric / oak wood flour / polyester resin Copoly 7233); Composite 2 (E-glass woven fabric / chopped E-glass fibres / polyester resin Copoly 7233); Composite 3 (chopped E-glass fibres / polyester resin HeliopoL 8431ATX). The first of all, it was periodically recorded the data concerning to the content of the absorbed water. Then, both dried specimens and the ones kept in water were subjected to the flexural tests by the method of the three points. Finally, the experimental results were comparatively analysed. It was remarked that the Young's modulus E was smaller in case of the hybrid composite material with wood flour than in case of the other two composite materials tested. It was observed a decreasing of the mechanical characteristics due to the moisture absorption in case of the composite materials that contain no wood flour. In case of the material Composite 1, the results were right unexpected because the water absorption lead to the increasing of the stiffness of the specimens. On the other hand, the flexural strength increased a little due to the water absorption. The results presented show that it may increase the flexibility of some pieces made of classical composite material of type glass fibres / polymer, by admixture of wood flour in the polymer resin used as matrix. But, it doesn't recommend their using in humid environment because the admixture of wood flour leads to the increasing of the content of absorbed moisture that acts for increasing of the rigidity.

Key words: hybrid composite, wood flour, water absorption, flexural test.

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