Abstract: The usage of Composite materials in industries is a growing trend due to material properties such as good strength, very low thermal expansion, and high strength-to-weight ratio. Among the many classifications of composite materials, natural fibre composites are generally preferred because they are reused and naturally degradable in environment. These fiber are selected on the basis of availability, extraction cost, processing difficulties and so on. In this study, based on the above selection criteria, From Borassus Tree, Palmyra palm fiber and tamarind powder is selected. This plant comes under the stalk category and seed comes under weed category, so it is abundant in nature and doesn’t require any controlled environment conditions to grow and the extracted fibers is done by dry retting process and mechanical property testing is done. Based on the results from tensile, impact, water resistance and flexural testing, the Palmyra fiber which is without tamarind seed is better than with seed. Dynamic components of wind mill blade is manufactured with the help of the fibers.
Keywords:
Introduction
The temperature of earth has accruing and the emergent alertness on go green activities has started the research activities towards degradable products. The rules and regulation of various countries and the consumer responsiveness on eco-friendly products also accentuate the necessity of producing recyclable and bio-degradable composite materials.
Fibers are available in particle and long constant length filaments or discrete extended pieces. Fibers are classified as two major categories; they are Nature fibers and synthetic or artificial fibers. Natural fibers own the advantage of eco-friendliness, poor in density, great specific strength, biodegradability and cost efficiency.
Wambua et al [1] have reported that the research on natural fiber composites has been in concentrated for recent years, due to their renewability,recyclability and high mechanical properties. Gassan and Bledzki [2] has used the coupling methods to expand the properties of composites. Composites have absorbed extreme level of moisture, poor wettability, and inadequate bond between unprocessed fibers and the polymer matrix leads to debonding with agent. To enhance the properties of the composites, the natural reinforcing fibers can be altered coupling methods. The coupling agents have chemical sets of groups which can react with fiber or polymer and thus enhance the interfacial adhesion.Thakur et al [3] have reported that natural fibers in polymer matrix composites has been din creasing for developing low-cost, eco-friendly products for the need of poor density and great specific properties of these natural fibers. Li et al [4] have studied the plant fiber for its micro level, mechanical properties and the results shown that these fibers have a graded cell structure that consisted of a crucial wall, a secondary wall, a fiber lumen and middle lamellae.
Bhoopathi et al [5] has carried out a research to study the mechanical characteristics, especially the interface between the magnified area of the composites based upon the natural fibers due to the inappropriate interface between the natural fibers and the polymer matrices. Liva et al [6] have fabricated that the three wood fiber composites with PLA matrix and artificial cellulosic (Tencel) fiber/PLA composites with four fiber formations have been manufactured using dynamic sheet former and explored using SEM, CT and tensile testing.The influence of the fiber/matrix volume ratio content variation on mechanical behavior (elastic modulus and strength) of composites has been examined. Hassan et al [7] have transformed the bagasse into a thermo formable material through esterification of the fiber matrix. The dimensional permanence and mechanical characteristics of the composites prepared from the esterified fibers were described in this work. Joshi et al. [8] have investigated the durability analysis of eco-friendly efficiency of natural fiber composites with glass fiber reinforced composites and found that natural fiber composites are environmentally better in the specific requirements studied. Singha and Thakur [9] has reported that mechanical strength and wear resistance of the urea–formaldehyde resin increases to considerable extent when reinforced with the fiber. Thermal (TGA/DTA/DTG) and morphological studies (SEM) of the resin and bio composites have also been made. Palanikumar et al [10] have conducted mechanical experiment as per the ASTM guidelines and probed the strength properties such as flexural, tensile, and impact strength.
Materials
The fiber must be selected based on its availability, extraction cost, processing difficulties, to foresee the demand based on its production and so on. Based on the above conditions, palmyra palm fiber from borassus is selected and as shown in the Fig.1.
Borassus
It is a large shrub growing to 3m (98ft) tall. It has clusters of waxy flowers that are either white or lavender in color. Lengthy and healthy trunks with separate leaf scars in some class the trunk develops a different just below the crown, through for unknown reasons. The leaves are fan shaped 2m-3m long with spines along the petiole margins. The young seedling extends downwards into the soil and only a few leaves are visible above the ground this provides some protections against frequent fire in its savanna habitat after in determined number of years, the seedling form a stem and quickly grow above the savanna vegetation
Tamarind Seed
Tamarind seed it has a property of stiffness and it is used as a shock proof resistance which is much needed for an automobile components. In this process the tamarind seed is grinded with the cover so that the property can be sustained. It is directly mixed with epoxy resin in a certain ratio and coated with palmyra palm fiber.
Palmyra palm fiber
The fibers were processed from the leaf stalk of the Palmyra palm tree. The thorns on the sides of the leaf stalk and the skin of the leaf stalk were removed manually and the leaf stalks were retted in water for 6 number of days followed by gently hammering and separating the fibers manually from the stalk. The removed fibers are then cleaned, washed, and dried to remove the moisture and other impurities sticking to the fibers. Then it is extracted from the stalk and used for various applications. Dimensional characteristics of the extracted palm fiber are analyzed and the length is of 30 – 35 cm. These fibers are long, with a thin wall relative to their diameter and are therefore lightweight.
Borassus Tree
Tamarind Seed
Palmyra palm fiber
Fig.1 Typical Natural Fibres
Fiber Extraction and Fabrication Techniques
A process called Retting is employed to extract fiber from plants. This process involves the action of bacteria and moisture on plants to dissolve and rot away cellular tissues and gummy substances that surrounds the fiber bundles in the plant. Once the surrounding tissue and other substances are dissolved, they fall away and the fiber is then easily separated from the stem. Retting process is done either with the help of water or with the help of dew. Various techniques used in retting process. The recommended of retting is water retting, as it gives good strength fiber. In this method, packs of plant stalks are submerged in water. The time duration for the plants to remain submerged in water is carefully monitored. If submerging time allowed is not enough, the separation process becomes difficult and so the yield is affected. On the other hand, if submerging time allowed is too much, fiber quality is affected and hence, the fiber is weak.
Process of fiber preparation shown in the Fig.2.
Fig.2 Water retting process
A electrically heated hot press compression molding technique used to fabricate the composite instead of using hand layup method as it takes a lot time to cure. Polymer matrix like Epoxy of grade LY556 is mixed with a proper hardener of grade HY906 at the proportion of 10:1. Compressive force is applied to distribute the resin throughout the fiber surface and to ensure even distribution, the plate is allowed to cure for 30 minutes by maintaining a curing temperature of 100oC.
Mechanical Testing
Once the composite plate fabrication is done, the plate is subjected to various mechanical property testing to determine its ability to replace the existing part for the suitable application.
Tensile Test
The well known purpose of the tensile testing is to measure the ultimate tensile strength and modulus of the composite. The standard specimen used for tensile testing of continuous fiber composites is a flat, straight-sided coupon. A flat coupons in ASTM standard. Specimen of 250x25x3 mm dimension that is cut for tensile testing according to the ASTM-D3039 standard and Tensile Test Specimenis given below.
(a)Tensile test specimen without tamarind seed
(b) Tensile test specimen with tamarind seed
Fig. 3 Tensile Test Specimen
Flexural Test
Flexural strength is defined as a materials ability to resist deformation under applied load. It is a 3-point bend test, which generally promotes failure by inter-laminar shear. This test is conductedas per ASTM standard using UTM. The loading arrangement is shown in Fig.4 . The dimension of the specimen is 127x25x5 mm.
Fig.4 Flexural test setup
Impact Test
The impact test specimens are prepared as per the ASTM standard and the specimen is placed in the testing machine and it allows the pendulum, until it breaks (the pendulum is allowed to strike to fracture it). The Izod impact strength is carried out on composites laminates according with ASTM standard[11] using impact testing machine. The dimensions of the GFRTP specimens 66 x 13 x 4 mm are prepared without V-notch.
Water Resistance Test
Fig.5 water absorption
The effect of water absorption on glass fibers reinforced hybrid composites were investigated in accordance with BS EN ISO 62: 1999. The specimens were dried in an oven at 500°C and then they were allowed to cool till they have reached the room temperature. The specimens were weighed to an accuracy of 0.1mg. Water absorption tests were conducted by immersing the composite specimens in distilled water in plastic tub at room temperature for different time durations. Once in 24 hours, the specimens were taken out from the water and all surface water was removed with a clean dry cloth and the specimens were reweighed to the nearest 0.1 mg. The specimens were weighed regularly from 24hours to 672 hours exposure, at an interval of 24 hours. The moisture absorption was calculated by the weight difference. The percentage weight gain of the samples was measured at different time intervals. Similarly, the specimens were immersed in water at 100°C to determine water absorption at a higher temperature.For this test, the specimens were placed in a container of boiling water. After 30 min of immersion, the specimens were removed from the boiling water, cooled in water for 15 min at room temperature then removed and weighed to the nearest 0.1 mg. The weight of the samples was measured at different time intervals up to 40 h of exposure until the water content reached saturation. The moisture absorption was calculated by the weight difference.
Result and Discussion
Six specimens both with and without tamarind seed plates are cut and are subjected to mechanical property testing such as tensile test, three point bending also called flexural test and izod impact test.
Tensile Test
The effect of treated and untreated Palm payrama content on the tensile strength of the composite is shown in Table 1. It is observed that the tensile strength varies from
. The tensile strength increases with the increase in treated and untreated it decreases. The increase in tensile strength with the increase in treated can be attributed to the good interfacial bonding between the treated and the matrix.
Table 1: Tensile properties of with and without tamarind seed
Sample No.
Cross sectional area (mm2)
Peak load (N)
% elongation
Ultimate tensile strength (N/mm2)
1
75
2849.324
9.253
37.994
2
75
2176.015
2.000
29.018
3
75
2978.453
6.000
39.711
4
75
1741.295
1.847
23.220
5
75
1766.752
4.200
23.554
6
75
1603.189
2.600
21.379
Flexural Test
Same as of tensile test, three specimens each from treated and untreated composite plate are taken and are subjected to flexural testing to determine the flexural strength and flexural modulus of the specimens
Table 2. Flexural properties of with and without tamarind seed
Sample No.
Cross sectional area (mm2)
Peak
load (N)
Flexural strength (MPa)
Flexural modulus (GPa)
1
39
76.665
61.922
3237.254
2
39
75.880
61.288
3390.773
3
39
83.797
67.682
3293.888
4
39
70.710
57.112
3528.441
5
39
78.146
63.118
3763.172
6
39
67.051
54.157
3388.636
Impact Test
The capability of impact of the specimens is carried out in izod impact machine and the energy loss of the above specimens is found out through the reading taken from the impact testing machine. The response of impact leads to the formation and development of crack along with resin and fiber breakage. Izod impact value of all the above mentioned specimens is given below.
Table 3 Izod impact values of with and without tamarind seed
S.No
Izod Impact value (J)
1
2.50
2
1.95
3
2.50
4
1.75
5
2.25
6
1.85
Fabrication Model
Palmyra palm fiber plant is new to the composite materials field and also it has many applications due to its properties. In automobile field, inner panels parts can be manufactured using this fiber which includes mudguard, gear cover, car panels, bike dome and wind blades so on.Using this fiber, a wind blades are prepared by using die and fabrication of the component is done using molding technique. The component is then dried in sunlight for two days and the component is removed from the mold. Plamyra palm fiber can use for various application other than automobile parts. The advantages of above composite is high strength weight ratio, corrosion resistant, transparent, design flexibility and low weight.
The wind blade material required higher materials strength, stiffness, fatigue strength and lower density. The wind blade should resist the extreme and time varying loads and higher stiffness. The wind blade is required very low density due to gravity force and to minimize the cost of power. Fig.6 shows the various load and load direction acting on the wind blade. Wind turbine blades are complex structures whose design involves the two basic aspects of selection of the aerodynamic shape, structural configuration and materials selection. Modern blades consist of different kinds of materials (typically composite materials in monolithic or sandwich configuration), use various connections solutions between different substructures include many materials or geometric transitions.
Fig.6 wind blade load factor
From these results it is clear that Palmyra palm reinforcement is more effective and long fiber reinforcements. This may be due to larger surface area and more fiber/matrix interaction in case of particle reinforced composites.
(a)
(b)
Fig.7 (a) CAD Model and (b) wind mill blade in Palmyra palm fiber
Conclusion
Three specimens each with and without tamarind seed fiber composite plate is taken and are subjected to mechanical property testing like tensile, flexural and impact tests. Based on the results the following conclusions are drawn:
- Fiber is randomly oriented while fabricating the plate due to its length and hence, voids are created while fabricating the plate.
- which are drawn from tensile test yields that, the without tamarind seed fiber have better ultimate tensile strength of value, 39.711 N/mm2 than the with tamarind one of value, 23.554 N/mm2.
- Palmyra palm fiber results in increased fiber stiffness, thereby resulting in less elongation percentage of 1.847 and maximum elongation percentage 9.253.
- Palmyra palm fiber composite specimen is capable of having a maximum flexural strength of 67.682 MPa at a peak load of 83.797 N.
- Izod impact strength is for Palmyra palm fiber value is 2.50 J and tamarind seed added value is 2.25 J.