INVESTIGATION OF MECHANICAL PROPERTIES OF POLYESTER FIBER, ACRYLIC FIBER AND POLYAMIDE FIBER REINFORCED COMPOSITES

Abstract Composite materials are materials obtained by combining materials with two or more different properties that are used by people for thousands of years to solve problems without being aware of them. Polymer based composite materials have recently been developed to improve the properties of these materials, as they have many superior properties as well as insufficient strength. Depending on technological developments, different types of composites have been produced using different types of matrix and reinforcement. The purpose  of this study, a new composite material using by polyester fibers, acrylic fibers and polyamide fibers  combining with araldite resin is  produced  and  examined its  mechanical properties. The new  composites were produced by the method of  hand lay-up . The mechanical properties such as tensile strength, impact strength, flexural strength and interlaminar shear strength (ILSS) were performed. Based on the applications of the mechanical tests of the composite samples, increasing of the fiber type and rate were seen an increase or decrease in mechanical properties. Keywords: Polyester Fiber, Acrylic Fiber, Polyamide Fiber, Araldite Resin, Composite Materials PACS: 72.80.Tm 1. INTRODUCTION The polymers play very important role in our daily life. They can be combined with different materials to achieve special properties according to end use applications. Polymer based composites are being used more and more intensively in space, aviation, medicine, automotive, textile, construction, building and other developing technologies. Reinforcing fibers, which are generally used in polymer composites, provide strength and other desirable properties to the composite material [1,2]. In parallel with these developments, working on fibers with better mechanical properties and higher heat-resistant, non-cracking, high impact strength and hard polymer matrices continue in the world [3-7]. Today, most of the synthetic polymer fibers in use span applications such as clothing, carpets, ropes and reinforcement materials. Some of these fibers include polyamides such as nylon, polyesters (as PET, PBT), PP, PE, vinyl polymers (as PVA, PVC), PU and acrylic fibers (e.g. PAN), [8,9]. Polyamide refers to family of polymers called linear polyamides made from petroleum. The generic name polyamide fibre has the same meaning as nylon fibre, but nylon fibre is used principally in countries [10]. Polyamides generally are tough, strong, durable fibers useful in a wide range of textile applications. The distinguishing characteristics are high elasticity, tear and abrasion free, low humidity absorption capability, fast drying, no loss of solidity in a wet condition, crease free, and rot and seawater proof. Application areas range from underwear to outdoor sports clothing [11], from automotive to aerospace [12]. PET is the world's most widely used fiber in a variety of forms. PET is widely used in both fiber and filament forms as a strong, dimensionally stable fiber. Large quantities of PET fibers are also used for both woven and nonwoven fabrics used for industrial and technical applications. Polyester fibers have many excellent properties such as high strength, good stretchability, durability and easy care characteristics [13]. Acrylic fiber is named as acrylonitrile containing at least 85% of its chemical structure according to ISO (International Standards Organization) definition. Since acrylonitrile, which is predominantly homopolymerized with 100% acrylonitrile polymerization, is hard, brittle and difficult to paint, it has been converted into copolymers by the addition of a second monomer and is particularly suitably used in textiles. Acrylic fibers have a wide range of uses such as knitting, hand knitting, carpet, blankets, velvet, socks [14]. Also acrylic fibre has been extensively used in a number of industrial applications for example as a cursor for carbon fiber, as substitute for asbestos in-fibre reinforced cement, and in hot gas and wet filtration [15].   2. EXPERIMENTAL PROCEDURE 2.1. Experimental Preparation and Mechanical Analysis RENLAM LY113 araldite resin (Huntsman) as the resin, Ren HY97 (Huntsman) as reaction initiator and Benzyldimethylamine (BDMA-Eastman) as accelerator were used in the composite matrix formulation. Acrylic fiber (Acrylic Tow, Type Extra / Gloss Dtex 2,2 - Lotno / Apre E-4316 / RA-01 Ktex 97) supplied from Aksa Acrylic Industry Company and polyester fiber and aramid fiber supplied from private sector were used as reinforcing materials. Composite materials using by polyester fibers, acrylic fibers and polyamide fibers combining with araldite resin is produced and examined its mechanical properties. Composite materials were produced by the method of hand lay-up. The mechanical properties such as tensile strength, impact strength, 3-point bending strength and interlaminar shear strength (ILSS) were investigated. In this study, two-piece semi-open mold made of stainless steel was produced to prepare standard tensile and impact samples (Figure 1). Surfaces of the mold that are in contact with the composite are grind to prevent adhesion.   Figure 1 . Mold in which composite samples are produced.   2.1.1. Tensile analysis The tensile tests of composite specimens were subjected to uniaxial tension with a constant tensile speed of 5 mm/min and corresponding stress-strain values were recorded for maximum tensile strength determination with respect to fiber orientation. Tensile analysis was applied on a Zwick Z010 universal tensile device.   2.1.2. Flexural analysis Flexural strength of the composite laminates were determined via 3-point bending tests done according to ASTM D790-02 standart. Flexural analysis was applied with test speed of 5 mm/min on a Zwick Z010 universal tensile device. Span to depth ratio was hold as 16:1.   2.1.3. Interlaminar shear strength (ILSS) analysis The interlaminar shear strength test samples (ILSS) according to ASTM D2344 standard was prepared and all of the tests made on a Zwick Z010 universal tensile device and applied with a test speed of 5 mm/min.   2.1.4. Impact analysis The impact strength of the unnotched specimens was tested using a 5.4 J izod impact hammer on the Zwick B5113.30 Izod Impact Device according to the ASTM D 256 standard.   2.2. Calculation of mold volume and resin formulation Volume of the mold: V