Abstract-Natural fibers have gained attention in composite making since it is sustainable, renewable and environmental friendly. However, there are some drawbacks such as low tensile strength, modulus and flexural strength compared to industrial synthetic fibers. Various techniques have been used to increase the mechanical properties of the reinforced material in order to compete with synthetic fibers. This study is to produce reinforced fabric made from kenaf fibers woven into four different weave patterns. The reason for the use of different weave patterns is to reduce the crimp percentage as it may increase the tensile strength of the fabric. The weave patterns are Twill 4/4, Satin 8/3 and Basket 4/4, while Plain 1/1 is used as a benchmark for its tensile strength. The dry fabrics structure with different weave pattern was optimized using a simulation of WiseTex software. The dry fabrics were infused with unsaturated polyester to produce composite panel using vacuum infusion process. The dry fabric and the composites were tested on tensile strength and compared with the Plain 1/1 weave pattern. The result shows the breaking strength of dry fabric increased when different weave pattern with low crimp percentage were used compared with Plain 1/1. Yet, in composite form there is reduction in tensile strength for Basket 4/4 due to changes in the fabric structure making some parts of the composite became weaker. The other weave patterns still retain the trend of increment in tensile strength compared with Plain 1/1 weave.

To produce a good quality of dry fabric for reinforced material in a natural-based polymer composite, yarn linear density should be in consideration. A woven kenaf dry fabric with three different linear densities of 276tex, 413.4tex and 759tex were produced. The fabrics with different linear densities were been optimize with the assistance of WiseTex software. The optimized dry fabrics were infused with unsaturated polyester to produce composite panel using vacuum infusion process. The composites properties were tested on the tensile strength, flexural strength and the impact strength. The result shows that the mechanical properties of the composite increased when the yarn linear densities increased.

Abstract:Woven composite based on natural fiber increasingly used for many applications in industries because of their advantages such as good relative mechanical properties and renewable resources, but there are some issues as cost and protracted development period to perform reliability evaluation by experimental with real scale. Predictive modeling technique is use to minimize the need for physical testing, shorten design timescales and provide optimized designs. Mechanical properties of woven fabrics for technical textile depend on a) type of raw materials b) type and count of warp and weft yarns c) yarn density and d) the type of weave structure. The effect of fabric architecture to the mechanical properties is investigated. Woven kenaf composite is modeled using the modeling software to get the properties of the model. Further, the model is analyzed using finite element analysis to predict the mechanical properties of the woven kenaf composite. In addition, the effect of the combination of yarn size and weave pattern to the woven kenaf composite is stated base on the mechanical properties to predict the optimum structure of woven kenaf composite.

Currently, there is a growing interest of using woven material in composite production for many applications such as structural applications, non-structural applications, household utilities, parts for automobile, aerospace components, flooring and ballistic laminate composites. The structure and properties of the woven fabric is very important as it dictate the woven composite properties. The properties of yarn like linear density, twist factor and strength can influence most of the woven fabric properties. Strength of woven fabric is one of the most important properties which make it superior in final composite applications. In this study, the effects of linear density i.e. 500, 1000, 1500 and 2000 tex on physical and mechanical properties of kenaf yarn were evaluated. The assessment on twist type, twist angle, yarn diameter, yarn structure, fibre density, moisture content, water absorption and mechanical properties were carried out on kenaf yarns. The yarn mechanical properties were tested on the tensile strength, Young's Modulus and elongation. It was found that, different linear density of yarn exhibited different behavior of yarn properties. Higher linear density yarn produced wider yarn diameter compared to lower linear density yarn, resulting to higher fibre and moisture content yarn. Yarn tensile strength has increased by 46% when linear density was changed from 500 to 2000 tex due to higher amount of individual fibres. However, for Young's Modulus, the values reduced as the yarn linear density increased due to several factors including number of fibres and moisture content of yarn.