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International Journal of Microwave Science and Technology
Volume 2012 (2012), Article ID 152726, 8 pages
http://dx.doi.org/10.1155/2012/152726
Research Article

Fracture Toughness of Vinyl Ester Composites Reinforced with Sawdust and Postcured in Microwaves

1Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350, Australia
2Centre of Excellence in Engineered Fibre Composites, University of Southern Queensland Toowoomba, QLD 4350, Australia

Received 22 March 2012; Revised 25 May 2012; Accepted 29 May 2012

Academic Editor: Qing Quan Liang

Copyright © 2012 H. Ku et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A commercial vinyl ester resin supplied by Hetron Chemical Pty. was reinforced with varying percentages by weight of sawdust. The sawdust particles were sieved into 3 different sizes, which were <300 μm, 300–425 μm, and 425–1180 μm, respectively, with a view to increase its fracture toughness for civil and structural applications. The sawdust used varied from 0% w/t to 15% w/t in step of 5% w/t. For higher w/t% of sawdust, the mixture would be too sticky to be mixed and cast. The cast composites were cured in ambient conditions and then postcured in microwave irradiation. They were then tested for fracture toughness using short bar tests. The values of fracture toughness of the composites increased with increasing particulate size, and this is due to the size distribution of the filler. It was found that the optimum amount of sawdust (425–1180 μm) was 15% w/t, with which the increase in fracture toughness was 126% as compared to neat resin and the reduction in cost was 15%. Furthermore, the optimum amount of sawdust (300–425 μm) was also 15% w/t, with which the increase in fracture toughness was 28.3% as compared to neat resin and the reduction in cost was again 15%.