Turmeric FRP composites: experimental determination of flexural and impact properties.

Srinivasababu, N. ; Rao, K. Murali Mohan ; Kumar, J. Suresh 等

Introduction

Utilization of naturally available, eco friendly materials have special attraction in their applications. In that concern natural fiber reinforced composites plays a vital role with respect to environment by possessing a property of biodegradability and structural applications by giving high strength and stiffness with light weight.

Flexural strength of the ABS / GF composites first increases linearly with increasing fiber content followed by a slight decrease. There is a sharp decrease in impact energy with the addition of GFs or GBs [1]. Jute reinforced polyester composites shown a flexural strength of 92.5 MPa, flexural modulus of 5.1 GPa and impact strength of 29 KJ/[m.sup.2] [2]. A relatively high flexural performance of ACSF composite compared to ATSF and UTSF composites [3]. Flexural strength of alkali treated (4 h) jute vinyl ester composites at 35% volume jute fiber is 238.9 MPa and flexural modulus of 12.85 GPa for alkali treated (2 h) jute vinyl ester composites at 30% volume of jute.Alkali treated jute fiber (treated for 6 h) at 35 vol% given impact strength of 23.05 KJ/[m.sup.2] [4]. The SAN matrix composites with cellulose and PMMA g-cellulose reinforcements show a linear increment of their relative modulus with increasing fiber content. The relative flexural strength of the PMMA-matrix composites reinforced with cellulose and PBA-g-cellulose/PMMA-grafted cellulose. The impact strength of composites with the PBA-g-cellulose or the cellulose fibers showed an increment of 57 and 15%, respectively, with respect to the impact strength of matrix. For banana fiber composites and glass fiber composites the impact strength increases with increasing volume fraction [5]. Flexural strength of banana/PF composites having fiber length of 30 mm and 40 mm is 50 MPa [6]. DMRT indicated significant differences between all three groups at the 95% confidence limit, the hybrid composite had a flexural modulus that was precisely the average of the other two composites [7]. Flexural strength and modulus of Flax/MA + peroxide (30 wt %) composites is 76 MPa and 5495 MPa respectively [8]. Flexural strength and modulus of the matrix and composites with 40 wt % of H. Populifolia reinforced in an epoxy/poly carbonate (10%) blend matrix with WCA are 215.73 MPa and 74.33 GPa respectively [9]. Impact strength values for composites PC1-PC4 showed that the presence of ssisal fibers improved this property [10]. It is seen that flexural stress increases linearly with strain followed by non linear portion. It is due to increase in ductility nature by the addition of fibers [11].

India is the world's largest producer, consumer and exporter of turmeric. The annual production is about 635,950 t from an area of 175,190 ha (2002 to 2003). In the last 30 years, the area, production and productivity of turmeric exhibited increasing trend and the production has moved up at an annual growth rate of 7.6% and area at 2.8%. Ancient Indians had given many names for turmeric, each one denoting a particular quality as listed below [12].

Ranjani: denotes that which gives color

Mangal Parda: bringing luck

Krimighni: Killing worms, antimicrobial Mahaghni: Indicates antidiabetic properties.

Along with the turmeric gargantuan amount of solid waste is also generated i.e. turmeric plant stems. Utilization of such a waste material in composites is obviously a significant subject.

In the present research two turmeric fiber varieties namely tekurpeta turmeric, cuddapha turmeric are considered for the preparation of composites. The below table gives clear indication of various abbreviations used in the research.

Abbreviation used in the                  Expansion name
    present research

         TP, TS                   Turmeric petiole, Turmeric stem
          TP-5                 Turmeric Petiole 5 mm width specimens
          TS-5                  Turmeric Stem 5 mm width specimens
          TP-10               Turmeric Petiole 10 mm width specimens
          TS-10                 Turmeric Stem 10 mm width specimens
         TP-12.7             Turmeric Petiole 12.7 mm width specimens
         TS-12.7               Turmeric Stem 12.7 mm width specimens

Experimental

Fiber

Turmeric Tekurpera, Cuddapha stems are placed between two rubber sheets and are rolled manually with a pressure of 0.014 MPa until the stems were split. Then turmeric petiole (TP) and turmeric stem (TS) fiber is separated from turmeric stems. Fiber is heated in a NSW-143 Oven Universal (Super deluxe model), supplied by Narang Scientific Works Private Limited, New Delhi, India; for 1 h at 70[degrees] for removing moisture in the fiber.

Matrix

Ecmalon 4413 general purpose unsaturated polyester resin of medium reactivity is used in the present investigation. The properties of the liquid resin are tested in accordance with IS 6746-1994. and the values can vary within tolerances mentioned therein Table 1.

The resin contains a volatile monomer with a flash point at 32[degrees]C and is of moderate fire hazard.

Chemical Treatment (CT)

Turmeric Tekurpeta and Cuddapha stems are chemically treated with NaOH, KMN[O.sub.4], and [H.sub.2]S[O.sub.4] at different concentration of solution by varying treatment time. The concentration of solution, chemical used for treatment and treatment time is summarized in the following Table 2. NaOH, KMN[O.sub.4] were kindly supplied by Merck Specialties Private Limited, Shiv Sagar Estate 'A', Mumbai-400 018, India.

Preparation of composites and testing

Hand lay-up technique is used for the preparation of all the composites considered in the resent research. Flexural testing samples were prepared according to ASTM D 790 - [07.sup.[member of]]1] [13]. Charpy impact test samples were prepared according to ASTM D 6110-08 by varying the sample width from 5mm to 12.7 mm to analyze the effect of specimen width on impact resistance [14].

Flexural tests were conducted using PC 2000 Electronic Tensometer, supplied by Kudale Instruments Private Limited, Pune, India.

To avoid the problems of uneven notch on Charpy impact testing specimen and to provide uniform notch for all specimens Motorized notch cutter is used. After the notch impact tests were conducted using Computerized Izod / Charpy Impact tester, supplied by International Equipments, Mumbai, India.

Results and Discussion

Initially flexural testing samples were prepared without chemical treatment. The problems encountered are as follows. In general during flexural testing lower surface/layers of the specimen is subjected to tension and upper layers subjected to compression there by the specimen fail in the outermost fiber/layer only due to bending. Actually due to non sticking nature of turmeric fiber with the matrix there is weak bonding between fiber and matrix and the composite is failing haphazardly and fiber is not taking any load.

Turmeric Tekurpeta CT-5 Flexural strength is 1.362 times, 1.526 times and flexural modulus 4.335 times, 3.936 times higher than rice straw polyester composites [15] and Arecanut FRP composites respectively [16]. The above said flexural strength and modulus are obtained for Turmeric Tekurpeta CT-5 with volume fraction 0.49% and 12.5% less than the volume fractions of rice straw and arecanut fiber.

Turmeric cuddapha CT-10 showed a flexural strength 0.31 MPa lower than CT-8, but this value achieved at 9.91% less volume fraction than CT-8. So increase in chemical treatment time causes the modification of raw turmeric fiber there by relative improvement in strength.

Flexural strength and modulus of all turmeric FRP composites considered in the present research are increased with increase in percentage volume fraction of fiber except Turmeric Tekurpeta CT-5, which shown decrese in flexural strength and modulus at a volume fraction of 25.7% Figure 1 and 2. Decrease in stiffness is due to decrease in strength and the decrease in strength is due to non-uniform distribution and bonding of matrix with fiber at the highest volume fraction.

Flexural strength and modulus of turmeric fiber reinforced polyester composites are normalized with density to get specific flexural strength (MPa/[Kgm.sup.-3]) and specific flexural modulus (MPa/[Kgm.sup.-3]) Figure 3 and 4.

[FIGURE 1 OMITTED]

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It is clearly evident from Figure 3 and Figure 4 [7] WF, KF, PP-KF-WF composites flexural strength and modulus are much less than the strength of Turemeric Tekurpeta CT-5 FRP composites.

Turmeric Petiole (TP), Turmeric Stem (TS) of Tekurpeta turmeric and Cuddapha turmeric FRP composites irrespective of their width of the specimen the Impact resistance increases with increase in volume fraction of fiber Figure 5 & 6. TP shown more impact resistance than TS because petiole is stronger than stem.

TP-5 FRP composites shown more impact resistance than TP-10, TS-5, TS-10, TS-12.7 FRP composites. Because testing specimens of thin width (5 mm width) during sudden load tries to lift from the position due to moment there by giving disingenuous data.

There is a clear increase in impact resistance for turmeric FRP composites with increase in specimen width from 10 mm to 12.7 mm. So 10 mm width impact testing specimen is necessary to examine the impact resistance. In order to know the impact resistance at high volume fraction 12.7 mm width specimen is preferable.

[FIGURE 5 OMITTED]

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Turmeric CT-5-10 & 12.7 showed decrease in impact resistance due to loss of strengthened cellulose due to chemical treatment.

Figure 7 shows the impact resistance of turmeric FRP composites at highest percentage volume fraction of turmeric fiber. Out of all the specimens tested turmeric petiole tekurpeta having specimen width 12.7 mm showed an impact resistance of 243.08 higher than turmeric stem tekurpeta 12.7 mm width, 10 mm wdth, turmeric petiole tekurpeta 10 mm width specimens and is lower than TP-5 and TS-5 specimens. The increase in impact resistance for 5 mm width sample is due to momentum causing along the longitudinal axis of the specimen there by it is lifting and turning which is visually observed during impact test. Where as 10 mm and 12.7 mm width specimens behaved normally. With increase in volume fraction of fiber impact resistance is increased. But to know the maximum impact resistance it is necessary to prepare 12.7 mm width specimens which will accommodate more fiber than 10 mm width specimens. Because according to ASTM there is a provision to use width of specimen from 3 mm to 12.7mm [14].

The densities of flexural and impact testing specimens is shown in Figure 8 & 9. Turmeric Cuddapha CT-10 FRP composites shown lowest density and relatively good flexural strength. Turmeric petiole 12.7 shown lowest density with good impact resistance.

Figure 10 a shows hinge for 12.7 mm width turmeric impact testing sample with hinge break denoted by a letter H. According to ASTM. Hinge break can be defined as an incomplete break, such that one part of the specimen cannot support itself above the horizontal when the other part is held vertically (less than 90[degrees] included angle). Figure 10 b and c shows 10 mm and 5 mm width specimens broken completely i.e. complete break denoted by a letter C. In all the cases the fiber is pulled out from the sample due to lack of good interface between turmeric fiber and matrix.

Figure 11 d shows the flexural testing sample broken in bending. Figure 11 e shows the closed view of sample at breaking face. There is a good interface between the fiber and matrix after chemical treatment. Without chemical treatment the flexural testing sample is invalid for testing. The outermost fiber layer in a composite must be failed initially due to bending, but lack of bonding unable the specimen to fail according to rule. This necessitates the chemical treatment of turmeric fiber specifically in bending.

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Conclusions

Turmeric fiber reinforced polyester composites flexural strength and modulus improved through chemical treatment. Chemical treatment is essential for flexural testing. But using the chemically treated fiber in sudden loadings caused decrease in resistance evident from Charpy impact test. Preferable width of specimens for impact testing is 10 mm and to evaluate the impact resistance at high volume fractions 12.7 mm width of specimen is necessary.

References

[1] Ulku Yilmazer, 1992, "Tensile, Flexural and impact properties of a thermoplastic matrix reinforced by glass fiber and glass bead hybrids", Composites Science and Technology, 44, pp.119-125.

[2] Munikenche Gowda T, Naidu A C B, Rajput Chhaya, 1999, "Some mechanical properties of untreated jute fabric-reinforced polyester composites", Composites Part A: applied science and manufacturing, 30, pp. 277-284

[3] Min Zhi Rong, Ming Qiu Zhang, Yuan Liu, Gui cheng yang, han Min Zeng, 2001, "The effect of fiber treatment on the mechanical properties of unidirectional sisal-reinforced epoxy composites", Composites Science and Technology, 61, pp. 1437-1447.

[4] D. Ray, B.K. Sarkar, A.K. Rana, N.R. Bose, 2001, "The mechanical properties of vinyl ester resinmatrix composites reinforced with alkali treated jute fibers", Composites Part A: applied science and manufacturing, 32, pp. 119-127.

[5] Ray D., Sarkar B.K., Rana A.K., Bose N.R, 2001, "The mechanical properties of vinyl ester resin matrix composites reinforced with alkali-treated jute fibers", Composites Part A: applied science and manufacturing, 32, pp. 119-127.

[6] Seena Joseph, Sreekala M.S., Oommen Z., Koshy P., Sabu Thomas, 2002, "A comparasion of the mechanical properties of phenol formaldehyde composites reinforced with banana fibers and glass fibers", Composites Science and Technology, 62, pp. 1857-1868.

[7] Mehdi Tajvidi, 2005, "Static and Dynamic Mechanical Properties of a Kenaf fiber-wood flour/polypropylene Hybrid composite", Journal of Applied Polymer Science, 98, pp. 665-672.

[8] Arbelaiz A, Fernandez B, Cantero G, Llano-Ponte R, Valea A, Mondragon I, 2005 "Mechanical properties of flax fiber/poly propylene composites. Influence of fiber/matrix modification and glass fiber hybridization", Composites Part A: applied science and manufacturing, 36, pp. 1637-1644.

[9] Guduri B.R., Rajulu A.V., Luyt A.S., 2006, "Effect of Alkali treatment on the Flexural Properties of Hildegardia Fabric Composites", Journal of Applied Polymer Science. 102, pp. 1297-1302.

[10] Francieli B. Oliveira, Christian Gardrat, Christine Enjalbal, Elisabete frollini, Alain castellan, "Phenol-Furfural Resins to elaborate composites reinforced with sisal fibers-molecular analysis of resin and properties of composites" Journal of Applied Polymer Science, 109, pp. 2291-2203.

[11] Sreekumar P A, Pradesh Albert, Unnikrishnan G, Kuruvilla Joseph, Sabu Thomas, 2008, "Mechanical and water sorption studies of ecofriendly banana fiber reinforced polyester composites fabricated by RTM", Journal of Applied polymer science, 109, pp. 1547-1555.

[12] P.N. Ravindran, K. Nirmal babu, K. Sivaraman, "Turmeric, The genus Curcuma", pp 1-2, CRC Press, New York, 2007.

[13] ASTM D 790-[07.sup.[member of]1] Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.

[14] ASTM D 6110-08: Standard Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics

[15] Ratna Prasad A V, Murali Mohan Rao K, Anil Kumar M, 2006, "Flexural properties of rice straw reinforced polyester composites", Indian journal of fibre and textile research. 31, pp. 335-338.

[16] Ratna Prasad A V, Murali Mohan Rao K, Mohan Rao K, Gupta A V S S K S, 2006, "Effect of fibre loading on mechanical properties of arecanut fibre reinforced polyester composites", National Journal of Technology. 2, pp. 56-62.

N. Srinivasababu (1) *, K. Murali Mohan Rao (2) and J. Suresh Kumar (3)

(1) * Corresponding author: N. Srinivasababu, E-mail: [email protected] Assistant professor, Department of Mechanical Engineering, PVP Siddhartha Institute of Technology, Vijayawada, India.

(2) Dr. K.Murali Mohan Rao, Principal, Sri Viveka Institute of Technology, Madalavarigudem, India

(3) Dr. J.Suresh Kumar, Associate Professor, Mechanical Engineering Department, JNT University, Hyderabad, India

Table 1: Properties of Matrix Ecmalon 4413.

Appearance                                 Clear
                                      500 (Brookfield
Viscosity @ 25[degrees]C                 viscometer

Specific gravity (25/25[degrees]C)          1.13
Acid value (mgKOH/g)                        25
Volatiles @ 150[degrees]C (%)               35
Gel time @ 25[degrees]C (minutes)           20

Table 2: Chemical Treatment time, concentration of Turmeric Tekurpeta,
Cuddapha stems

                  Treatment     Concentration of        Chemical
Treatment name    time          solution in molar (M)   name

Turmeric          10 h 45 min   0.375                   NaOH
Tekurpeta CT-5    20 min        0.05062                 KMN[O.sub.4]
                                0.003752                [H.sub.2]
                                                        S[O.sub.4]
Turmeric
Tekurpeta CT-6    10 h 10 min   0.111                   NaOH
Turmeric
Cuddapha CT-8     13 h          0.25                    NaOH
Turmeric
Cuddapha CT-9     9 h 5 min     0.06325                 NaOH
CT-10             87 h 55 min   0.25                    NaOH