Journal of Applied Science and Engineering, Vol. 18, No. 3, pp. 289-294 (2015)
DOI: 10.6180/jase.2015.18.3.09
Effect of Fiber Orientation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composites Kumaresan. M1*, Sathish. S2 and Karthi. N3 1
Kalaignarkarunanidhi Institute of Technology, Coimbatore-641402, Indian KPR Institute of Engineering and Technology, Coimbatore-641407, Indian 3 Sri Krishna College of Technology, Coimbatore-641042, Indian
2
Abstract This present work evaluated the effect of fiber orientation on mechanical properties of sisal fiber reinforced epoxy composites. In this work sisal fiber is used as reinforcement which treated with NaOH solution for enhancing the bonding strength between fiber and resin by removing moisture contents. Samples of different orientations of sisal fiber reinforced composites were fabricated by compression molding and investigated their mechanical properties like tensile strength and flexural strength. The work of this experimental study has been carried out to determine the mechanical properties due to the effect of sisal fiber orientations such as 0°/90°, 90°and ±45° orientation. The results of this study indicate the orientation 90° shows the better mechanical properties compare than 0°/90° and ±45°. Key Words: Sisal Fiber, Epoxy Resin, Compression Molding, Fiber Orientation
1. Introduction Fiber reinforced polymer composites are being used in almost every type of applications in our daily life and its usage continues to grow at an impressive rate. The manufacture, use and removal of traditional composite structures usually made of synthetic fibers are considered critically because of the growing environmental pollution. It creates interest in the use of biofibers as reinforcing components for thermoplastics and thermo sets. Sisal fiber (SF), a member of the Agavaceae family is a biodegradable and environmental friendly plant. Sisal fiber is a strong, durable, stable and versatile material and it has been recognized as an important source of fiber for composites. It is generally accepted that the mechanical properties of fiber reinforced polymer composites are controlled by factors such as nature of matrix, fiber-matrix interface, fiber volume or weight fraction, fiber aspect ratio, fiber orientation etc [1]. The combination results in superior properties not exhibited by the indi*Corresponding author. E-mail:
[email protected]
vidual materials. Many composite materials are composed of just two phases one is termed as matrix phase, which is continuous and surrounds the other phase often called the dispersed phase [2-5]. Composites reinforced with natural fibers received increasing interest from industries in a wide field of application such as automobile, construction, aerospace and packing (Ku H et al. 2011; Pickering KL et al. 2007). The main drawback of using natural fiber is their high level of moisture absorption, insufficient adhesion between untreated fibers and the polymer matrix which can lead to deboning with age (Gassan J 2002). Many of the plant fibers such as coir, sisal, jute, banana, palmyra, pineapple, talipot, hemp, etc. find applications as a resource for industrial materials (Satyanarayana et al., 1990b; Thomas & Udo, 1997; Rowell et al., 1997) Proper design of a composite system subjected to high loading rates can be accomplished only if the strain rate sensitivity of the material has been measured and the modes of failure and energy absorption are well characterized [6]. For instance, sisal is a hard leaf fiber but jute and hemp are both bast fibres and are generally referred to as ‘soft’ fibers to distinguish them from
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the hard leaf fibers. Both leaf and bast fibres are multicellular with very small individual cells bonded together (Preston, 1963; Hearle, 1963 and Hegbom, 1990). Composites filled with micro particles in epoxy system gained significant importance in the development of thermosetting composites. Epoxy resins the most important matrix polymer preferred when it comes to high performance. Its combination with glass fibers gives an advanced composite with properties like low weight, good mechanical and tribological properties [7-16]. The study deals with the effects of natural fibers on some mechanical properties of the Epoxy composite. Jayamol George [17] made experimental studies on Short Pineapple-Leaf-Fiber-Reinforced Low-Density Polyethylene Composites. The influence of fiber length, fiber loading, and orientation on the mechanical properties has also been evaluated. Measurement of fiber length is often performed on photographs of short fibers obtained from burning off or dissolving the matrix. Correction of the measurement of fiber length was carried out and the real value of mean fiber length and the real fiber length distribution were obtained [18].
2. Materials and Methods 2.1 Sisal Fiber Sisal is a natural fiber (Scientific name is Agave sisalana) of Agavaceae (Agave) family yields a stiff fiber traditionally used in making twine and rope. Sisal is fully biodegradable and highly renewable resource of energy. Sisal fiber is exceptionally durable and a low maintenance with minimal wear and tear strength. Sisal fiber is produced by the way known as decortications, where leaves are compressed by a rotating wheel set with blunt knives, so that only fibers will remain. 2.2 Physical Property Sisal Fiber Density (g/cm3) upto1.5 Specific modulus (Gpa) 6-15 Cellulose content (%) 67-78 Young’s modulus (Gpa) 9-22 Diameter of ultimates (mm) 18.3-23.7 2.3 Matrix and Hardener Epoxy is a thermosetting polymer that cures when
mixed with a hardener. Epoxy resin of the grade LY556 was used in this study. The hardener of the grade HY951. The reinforced matrix material was prepared with a mixture of epoxy and hardener at a ratio of 10:1.
2.4 Chemical Treatment Alkali treatment or mercerization using sodium hydroxide (NaOH) is the most commonly used treatment for bleaching and cleaning the surface of natural fibers to produce high-quality fibers. 5% NaOH solution was prepared using sodium hydroxide pellets and distilled water. When the percentage of NaOH is increased it affect the fibers properties by reduce the bonding capacity during preparation of composites. Sisal fibers were then dipped in the solution for 2 hour separately. Then it is washed with running water. It was then kept in hot air oven for 3 hours at 80 °C. 2.5 Composite Preparation Mold is used for preparing the specimen which is made up of EN90 steel and having dimensions of 250 ´ 250 ´ 5 mm. First, the mould is polished and then a mould releasing agent is applied on the surface used to facilitate easy removal of the composite from the mold. The epoxy resin LY556 and hardener (HY951) is mixed in a ratio of 10:1 by weight as used. The weight percentage of fiber used is 250 grams. The sisal fiber are placed over the mold at required orientation manually and then required amount of epoxy resin was poured over it. The process is continued until the required thickness and weight percentage of fiber was obtained. For each time a roller was used to roll over the fiber in order to remove the air bubbles from it. It can pressed in a hydraulic press at the temperature of 120 °C for 30 minutes and a pressure of 35 kg/cm2 for 45 minutes is applied before it is removed from the mould. After this sample is post cured at atmosphere for three hours of time according to the manufacturer’s guidance. Figure 1 shows the compression molding machine with specimen.
3. Experimental Tests 3.1 Tensile Test The tensile test specimen is prepared according to the ASTM D3039 standard and the machine specifica-
Effect of Fiber Orientation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composites
tions are also chosen according to the ASTM D3039. According to the ASTM D3039 standard the dimensions of specimen used are 250 ´ 25 mm. This test involves placing the specimen in a machine and subjecting it to the tension according to specific load until it fractures. Figure 2 shows the tensile testing machine with specimen.
3.2 Flexural Test Flexural test is also known as bending test and consists in applying a point load at the centre of composite material specimen. The flexural tests were done on the universal testing machine according to ASTMD790 with the crosshead speed of 10 mm/min. According to the ASTMD790 standard the dimensions of specimen used are 125 ´ 12.7 mm. Figure 3 shows the flexural testing
machine with specimen.
3.3 Impact Test Impact test were carried out using charpy impact test machine with specimen is shown in Figure 4 with standard of ASTM A370. Generally sisal fibers possess good impact absorbing properties. The fracture values were calculated by dividing the energy by cross sectional area of the specimen.
4. Results and Discussion The test results are shown and discussed in this sec-
Figure 3. Flexural testing machines. Figure 1. Compression molding.
Figure 2. Tensile testing machine.
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Figure 4. Impact testing machine.
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tion. Table 1 shows the tensile test results for different orientations of treated sisal fiber reinforced composites are listed and compare them. In this we take 3 trials of specimens for testing tensile strength. Among these the orientation 90° (uni directional) shows maximum strength. Figure 5 shows the tensile strength of treated sisal fiber reinforced composites on their different orientation. Among these the orientation 90° orientation (uni directional) shows maximum tensile strength. Table 2 shows the flexural test results for different orientations of treated sisal fiber reinforced composites. In this we take 3 trials of specimens for testing tensile strength. Among these the 90° orientation (uni directional) shows maximum flexural strength. Figure 6 shows the flexural strength of treated sisal fiber reinforced composites on their different orientation. Among these the 90° orientation (uni directional) shows
maximum flexural strength. Table 3 shows the impact test results for different orientations of treated sisal fiber reinforced composites. The 90° orientation (uni directional) shows the maximum impact strength of 7.30 joules obtained. Figure 7 shows the impact strength of treated sisal Table 2. Flexural test results Specimen orientation
No. of trials
0°/90°
T1 T2 T3 Avg
282.16 282.75 284.52 283.12
88.56 94.50 91.28 91.44
90°
T1 T2 T3 Avg
467.19 470.26 467.21 468.22
175.36 187.52 97.77 151.12
±45°
T1 T2 T3 Avg
199.21 202.54 202.26 201.34
68.36 76.12 50.59 65.02
Table 1. Tensile testing result Ultimate tensile load (N)
Tensile strength (MPa)
Elongation at break (%)
0°/90°
T1 T2 T3 Avg
2048.22 2123.43 2110.16 2093.93
16.28 16.87 17.07 16.74
2.36 2.43 2.11 2.30
90°
T1 T2 T3 Avg
4820.27 4894.44 4854.46 4856.39
38.22 37.91 40.36 38.83
4.12 4.44 4.24 4.26
±45°
T1 T2 T3 Avg
2496.68 2464.32 2493.52 2484.82
19.76 19.21 20.64 19.87
2.81 2.88 2.50 2.73
Specimen No. of orientation trials
Flexural load Flexural strength (N) (MPa)
Figure 6. Flexural strength results.
Table 3. Impact test results Orientations Impact strength (joules)
Figure 5. Tensile strength results.
0°/90°
90°
±45°
3.65
7.30
5.75
Figure 7. Impact strength results.
Effect of Fiber Orientation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composites
fiber reinforced composites on their different orientation. Among these the 90° orientation (uni directional) shows maximum impact strength.
5. Conclusions In the present work three types of orientations were achieved as per ASTM standards were used for testing. The part might require 0° to react to axial loads, ±45° to react to shear loads, and 90° to react to side loads. The experimental investigation on the effect of fiber orientation on the treated sisal fiber reinforced epoxy composites leads to following conclusion. The mechanical properties such as tensile strength and flexural strength shows the maximum value of 38.84 Mpa and 151.22 Mpa in the 90° orientation (uni directional) compared to others. Generally sisal fibers possess good impact absorbing properties. The charpy impact strength of treated sisal fiber reinforced composites show the orientation 90° (uni directional) yielded the maximum impact strength of 3.53 J.
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Manuscript Received: Apr. 10, 2015 Accepted: Aug. 23, 2015
