Denim Fabric Reinforced Unsaturated Polyester Composite

Chua, Lee Hong (2022) Denim Fabric Reinforced Unsaturated Polyester Composite. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The use of waste resources to create new raw materials for manufacturing industries to replace exhaustible resources is a topic of concern in current times. Since denim is a type of fabric that is hard-wearing and high-density, denim fabric was expected to have positive synergy effect on properties of the reinforced composite. Furthermore, unsaturated polyester was employed as the matrix in the composite fabrication due to its high dimensionally stability upon hardened. The goals of this project were to produce denim fabric reinforced unsaturated polyester composite using three types of composite fabrication method, namely hand lay-up, compression moulding and resin vacuum infusion method, and to evaluate the effect of the fabrication methods on the mechanical properties including tensile, flexural and impact properties, morphological study and water absorption properties of the produced composite. The average unsaturated polyester-to-composite weight ratio in hand lay-up technique was found to be the highest which is 70.63%, followed by 55% in resin vacuum infusion technique, and the least was 51.62% in compression moulding. Unsaturated polyester weight ratios in the composite samples were found to be corresponded to most of the mechanical properties such as tensile strength, impact strength and flexural modulus. It was found that the higher the unsaturated polyester weight ratio, the lower the mentioned mechanical strength. Nonetheless, the mechanical results have shown that the overall mechanical properties of denim fabric reinforced unsaturated polyester composite were generally improved, as compared to those of neat unsaturated polyester. In terms of tensile properties, compression moulding obtained the composites with maximum tensile strength and elastic modulus, whereas resin vacuum infusion achieved the highest in elongation at break. Compression moulding composites also achieved the best in impact strength, flexural strength and flexural modulus. On the other hand, resin vacuum infusion obtained the composites with the highest average percentage in water absorption test. Through SEM micrograph observation, the best composite structure was observed in compression moulding composites where denim fibers were well-embedded in the matrix. The observation has confirmed that compression moulding method provide composite with better interfacial adhesion between fiber-matrix interface and thus superior mechanical properties among the three fabrication techniques. The SEM observation further corroborated the statement that the higher the unsaturated polyester weight ratio, the more flaws in the fiber-matrix interface, such as voids, debonding, and fiber pull-out, resulting in inferior mechanical properties, particularly for composite strength. As a result, the hand lay-up composites were found to have the lowest values in majority of mechanical properties, mainly due to their high unsaturated polyester weight ratio. Nonetheless, because there were fewer denim layers in the hand lay-up composite to absorb water molecules, they performed better in terms of water absorption properties by absorbing the least amount of water.