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Experimental investigation and analysis of mechanical properties of injection
 

Experimental investigation and analysis of mechanical properties of injection

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    Experimental investigation and analysis of mechanical properties of injection Experimental investigation and analysis of mechanical properties of injection Document Transcript

    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 197 EXPERIMENTAL INVESTIGATION AND ANALYSIS OF MECHANICAL PROPERTIES OF INJECTION MOLDED JUTE AND GLASS FIBERS REINFORCED HYBRID POLYPROPYLENE COMPOSITES Ravishankar. R1 , Dr.K. Chandrashekara2 , Rudramurthy3 1 Dept. of Mechanical Engineering, Sri Jayachamarajendra College of Engg, Mysore, Karnataka State, India, Pin: 570006 2 Dept. of Mechanical Engineering, Sri Jayachamarajendra College of Engg, Mysore, Karnataka State, India, Pin: 570006 3 Dept. of Mechanical Engineering, Sri Jayachamarajendra College of Engg, Mysore, Karnataka State, India, Pin: 570006 ABSTRACT Preliminary studies were conducted on jute fiber reinforced polypropylene (PP) composites to ascertain the optimum weight percent of fiber which could give maximum values for the mechanical properties. It was found to be 40wt%. In the present investigations, effect of reinforcing glass fibers in the optimized jute fiber reinforced PP composite is studied. The properties such as tensile, flexural, impact and hardness with respect to randomly oriented jute and glass fiber variations in the pp matrix are considered. Jute and glass fibers reinforced matrix composites with different fiber contents were prepared by injection molding. Matrix content is kept as 60wt%. The variations in jute and glass fibers by weight percentage are 40:00, 35:05, 30:10, 25:15 and 20:20. It was found that tensile, flexural, impact and Shore-D hardness properties increased with increase in glass fiber content. Results and discussions are made with the help of experimental data and SEM micrographs and conclusions are presented. Key words: Jute fiber, Glass fiber, Polypropylene, Tensile, Flexural, Impact. 1. INTRODUCTION Fiber reinforced composites are in use in a variety of applications like, automotive interiors, furniture, aircraft etc. Abundant use of composites in these sectors has been facilitated by introduction of newer materials, improvement in manufacturing processes and testing methods. Fiber-reinforced materials have higher mechanical properties and their strength-to-weight ratios are INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 4, July - August (2013), pp. 197-206 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 198 superior when compared with metals and their alloys. Further, fiber reinforced plastic composite offer other advantages like non-corrosiveness, translucency, good bonding properties, and ease of repair. Natural fibers play an important role in developing high performing fully biodegradable ‘green’ composites which could solve environmental problems. Many researchers are of the opinion that, these fibers offer many attractive technological and environmental qualities when used as reinforcements in polymer composites [1-7]. Natural fibers are largely divided into two categories depending on their origin one being plant based and the other animal based. In general, plant based fibers like jute, coir, sisal, cotton etc are lignocellulose in nature composed of cellulose, hemicellulose and lignin. Animal based fibers like silk and wool are composed of proteins. Also natural fibers are low cost, abundantly available, renewable and have high specific properties. Further, they are less abrasive to machines used to fabricate them. The mechanical properties of natural fiber composites are much lower than those of the synthetic fiber composites and they are hydrophobic. Synthetic fibers have very good mechanical properties, moisture repellency, but these are difficult to recycle. To take advantage of both natural and synthetic fibers, they can be combined in the same matrix to produce hybrid composites that take full advantage of the best properties of the constituents [8-15]. With respect to the above considerations, in the present study, investigations are made to evaluate the mechanical properties of the jute and glass reinforced PP matrix hybrid composite. 2. MATERIALS AND METHODS 2.1. Materials Thermoplastic polymer PP, used as matrix material is in the form of homopolymer pellets supplied by Hindustan polymers, Bangalore, India. It has specific gravity of 0.90–0.91, melting temperatures of 165–1710 C and crystallinity of 82%. White jute fiber (Corchorus capsularis) used as reinforcing fiber was obtained from Jute Pragna Suppliers, Bangalore, India. E-Glass fibers used as reinforcing fibers was obtained from Concord Fiber Glass industries, Bangalore, India. 2.2. Fabrication of composites and test specimens Jute and glass fibers in the weight percent ratios of 40:00, 35:05, 30:10, 25:15 and 20:20, were initially mixed thoroughly with PP granules. The mixtures were passed through single screw extruder at a constant temperature of 1650 C. The extruded composites were cut into pellets using rotary cutting pellet making machine. The test specimens were prepared from the compounded pellets using injection molding machine as per ASTM standards. 2.3. Mechanical testing Tensile, Flexural, Izod impact and Hardness tests were conducted. For each test and type of composite, 4 specimens were used and the average values are presented. 2.3.1. Tensile test Tensile tests were conducted according to ASTM D 638 using a Universal Testing Machine (Make: Hounsfield, UK, Model: H 50 KM, Capacity: 50 KN, Jaw separation speed: 1 to 500 mm/min). The dimension of the dog bone shaped specimen was 175 mm x10 mm x 3.2 mm. Gauge length was 50 mm. 2.3.2. Flexural test Three-point static flexural tests were carried out according to ASTM D 790 using the same testing machine mentioned above. The dimension of the specimens used was 125 mm x12.5 mm x 3.2 mm. Span length was 100 mm.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 199 The flexural strength (1) and modulus (2) were calculated using the following equations: Flexural strength =3PL/2bd2 (1) Flexural modulus; E =L3 m/4bd3 (2) Where P is the maximum applied load, L is the length of support span, m is the slope of the tangent, b and d are the width and thickness of the specimen respectively. 2.3.3. Izod impact test Izod impact tests were conducted on un notched composite specimens according to ASTM D256, using pendulum impact tester (Range: 0 to 1.5 Joules). The dimension of the specimen was 65 mm x 12.5 mm x 3.2mm. 2.3.4. Shore-D hardness Shore-D hardness tests were conducted on specimens according to ASTM D2240 using Durometer. (Make: Techno Instrument Company, Model: SHR – Mark III, Range: 0 to 100) 2.3.5. Scanning Electron Microscopy (SEM) Interfacial bonding, dilation of matrix, fiber pulling or fracture between the fiber and PP matrix in the composites were examined and analyzed using Scanning Electron Microscope. The micrographs were taken at the magnification of 500. 3. RESULTS AND DISCUSSION 3.1. Tensile properties Variation in tensile strength with respect to addition of varying percentage by weight of glass fiber to jute-PP composite is illustrated in the Fig.1. It could be seen that, tensile strength is increasing with increase in percentage of glass fibers in the composite. Increase in tensile strength is almost linear with addition of glass fiber with increment in fiber loading in steps of 5wt% up to 20wt%. Percentage increase in strength is found to be 28.67 for glass fiber loading of 20wt%. For hybridization, addition of glass fiber with natural fiber reinforced composites, the tensile strength increased with glass fiber loading which is in accordance with the results obtained by other researchers [8, 9, 10, 11, 12, 13]. Reason is that, glass fiber adherence to the matrix is better when compared to jute fiber and the interfaces between the fiber and the matrix is more (surface area of contact). Hence, it is difficult for the prevailing forces to pull glass fibers from the matrix compared to that of jute fiber. Also the failure of the specimen is mainly due to the fracture of the glass fiber compared to jute fibers for which pull out of them is the main reason. The range of the tensile strength found in the current work is 22.18–28.54 MPa. Fig. 2 shows the variation of the tensile modulus at different glass fiber loading. Tensile modulus is increasing with increase in glass fiber loading in accordance with the results of other researchers [8, 9, 10, 11, 12, 13]. The percentage increase in modulus is found to be 9.1 for glass fiber loading up to 15wt%. From 15wt% to 20wt%, increase in modulus is 15% which is significant. This is attributed to the higher modulus of glass fiber than the jute fiber and PP matrix. Normally, the fibers in the composite restrain the deformation of the polymer matrix, reducing the tensile strain. During tensile loading, partially separated micro spaces are created, which obstruct stress propagation between the fibers and matrix. As the glass fiber loading increases, the degree of obstruction increases, which consequently increases the stiffness. Range of the tensile modulus in the current work is found to be 1482.52–1864.66 MPa.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 200 3.2. Flexural properties Flexural strength of jute fiber composites at different weight percentages of glass fiber loading in the composite are shown in Fig. 3. It increased with fiber loading. This is in accordance with the findings of other researchers [8, 9, 10, 11, 12, 13]. It is found that the flexural strength increased by 20.82% up to a glass fiber loading of 20wt%. This is due to the fact that some of the glass fibers are fractured, some are pulled out of matrix and some are still adhering to the matrix. The glass fibers in the portions of the matrix are getting aligned in the direction perpendicular to the application of the load. These observations justify the increase in load bearing capacity of the material. The range of the flexural strength obtained is 38.8–46.88 MPa. Variation in flexural modulus of jute and glass fiber hybrid composites at different glass fiber loading is shown in Fig. 4. Flexural modulus is increasing almost linearly upto 15wt% of glass fiber loading. Percentage increase is 13.32 (from 5wt% to 15wt%). Further loading of glass fiber is increasing the modulus significantly. This increase is 26%. Investigations of several other researchers have shown the same trend [8, 9, 10, 11, 12, 13]. Since glass fiber is a high modulus material compared to jute fiber and matrix, higher fiber concentration demands higher stress for the same deformation. The range of the flexural modulus obtained is 2132.64–2687.4 MPa 3.3. Impact properties Variation of Izod impact strength with jute and glass fiber composites at different glass fiber loadings are shown in Fig.5. Impact strength of the fiber reinforced composites depends on the nature of the fiber, polymer and fiber–matrix interfacial bonding. It could be seen that the impact strength is increasing with increase in percentage of glass fibers in the composite. For the synthetic fiber addition to natural fiber reinforced composites, impact strength increase with glass fiber loading [9, 11, 13]. There is increase in impact strength by 74.26% with increase in glass fiber loading up to 20%. Impact strength in fiber reinforced composites is caused by fiber fracture and fibers pull out. More energy is required to fracture the composite than it is required for fiber pull out. Since the failure of the specimen is mainly by fiber fracture and due to good interfacial adhesion between glass fiber and the matrix, strength is increasing with increase in glass fiber content. The range of the impact strength found in the current work is 4.43–7.72 KJ/m2 . 3.4. Hardness properties In the hardness test, hardness was found to increase with increase in the quantity of glass fiber content as observed from figure 6. For glass fiber addition to natural fiber reinforced composites, the hardness increased with glass fiber loading [13].This is due to decrease in flexibility and increase in stiffness of composites as glass fibers have these charecteristics. The range of the hardness found in the current work is 72–79. 3.5. SEM morphology SEM micrograph of the tensile fractured surface of 20:20wt%, jute: glass fiber composite is shown in Fig.7. It shows that failure of the specimen is mainly by glass fibers fracture, pull out of some of the same (indicated by dark holes), and jute fiber pull out. Higher tensile forces are required to fracture glass fibers and pulling them out from the matrix. Moreover, the micrographs are indicating brittle fracture of glass fibers. One must also note that, jute fibers are not fractured but they are pulled out of the matrix. Also, interfacial adhesion between glass fibers and matrix is superior when compared with that of jute and matrix. The combined effect of fracture of most of the glass fibers, pulling out of matrix of some of them and pulling of jute fibers which are embedded in the regions where, fractured and glass fibers in the matrix are predominant, call for higher magnitudes of forces to fracture the hybrid composite.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 201 SEM micrograph of cracked specimen subjected to flexural test having 20wt%:20wt%, jute: glass fiber composite is shown in fig.8. It can be clearly seen from the micrograph that, some of the jute fibers are within the matrix and some fibers are pulled out from the matrix. One must note that glass fibers and jute fibers are randomly distributed in the matrix prior to the test. It is clear from the micrograph that, both glass and jute fibers are getting axially oriented when the bending load is applied. This calls for higher magnitude of forces. Glass fibers are either pulled out or fractured. Further, the matrix having the fibers is getting dilated forming cleavages. Cleavages also offer resistance to the axial orientation of fibers. Owing to these reasons, during flexural studies, the composite material has shown increasing resistance to the prevailing loads with addition of glass fibers. SEM micrograph of specimen of 20wt:20wt%, jute: glass fiber composite fractured surface subjected to impact load is shown in fig 9. It could be seen that the failure is due to predominantly glass fibers brittle fracture and jute fiber dilation and pull out. As the percentage of glass fibers increases in the matrix, the above said reasons confirm that higher impact energy is required to fail the hybrid composite. Superior interfacial adhesion between glass fibers and matrix and disorientation of jute fibers from their original orientation are some of the reasons for the hybrid composite having higher impact strength. Fig.1 Variation of Tensile strength with Glass fiber content Fig. 2 Variation of Tensile modulus with Glass fiber content
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 202 Fig. 3 Variation of Flexural strength with Glass fiber content Fig. 4 Variation of Flexural modulus with Glass fiber content Fig. 5 Variation of Impact Strength with Glass content
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 203 Fig. 6 Variation of Hardness Value with Glass fiber content Fig.7 SEM micrograph of fractured specimen of tensile test at 20wt:20wt% Jute: glass fiber
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 204 Fig.8 SEM micrograph of cracked specimen of flexural at 20wt:20wt% Jute: glass fiber Fig.9 SEM micrograph of fractured specimen of Impact test at 20wt:20wt% Jute: glass fiber
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 205 4. CONCLUSION The mechanical properties such as tensile, flexural, Impact and hardness of the jute and glass fibers reinforced hybrid composites were studied by different weight ratios of jute and glass fibers. Tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and hardness of the composite were found to be increasing with increase in glass fiber content and the values were found to be the maximum at 20:20 percentage by weight of jute and glass. The overall increase in strength of the hybrid composite considering tensile and flexural studies is 25.31%. Percentage increase in impact strength is 63 which is very significant. Increase in hardness is 9.7%. These increases in properties of the studied material could make this applicable in components of automobiles like, dash boards, seat bases, frontal and rear bumpers, aircraft interior paneling and furniture. REFERENCES [1] Yi Zou, Helan Xu, Yiqi Yang, Lightweight Polypropylene Composites Reinforced by Long Switchgrass Stems, J Polym Environ 18, 2010, 464–473 [2] M. Zampaloni , F. Pourboghrat , S.A. Yankovich , B.N. Rodgers , J. Moore , L.T. Drzal , A.K. Mohanty , M. Misra, Kenaf natural fiber reinforced polypropylene composites: A discussion on manufacturing problems and solutions, Composites: Part A 38, 2007, 1569– 1580. [3] Han-Seung Yang , Hyun-Joong Kim , Hee-Jun Park , Bum-Jae Lee , Taek-Sung Hwang, Effect of compatibilizing agents on rice-husk flour reinforced polypropylene composites, Composite Structures 77, 2007, 45–55. [4] Krishnan Jayaraman, “Manufacturing sisal–polypropylene composites with minimum fibre degradation”, Composites Science and Technology 63, 2003, 367–374. [5] Md. Rezaur Rahman , Md. Monimul Huque , Md. Nazrul Islam , Mahbub Hasan , “Mechanical properties of polypropylene composites reinforced with chemically treated abaca”, Composites: Part A 40, 2009, 511–517. [6] Md. Mominul Haque, Md. Sakinul Islam, Md. Nazrul Islam, Preparation and characterization of polypropylene composites reinforced with chemically treated coir, J Polym Res 19:9847, 2012. [7] Md. Rezaur Rahman, Md. Monimul Huque , Md. Nazrul Islam b, Mahbub Hasan, Improvement of physico-mechanical properties of jute fiber reinforced polypropylene composites by post-treatment, Composites: Part A 39, 2008, 1739–1747. [8] A. Arbelaiz, B. Ferna´ndez, G. Cantero, R. Llano-Ponte, A. Valea, I. Mondragon, Mechanical properties of flax fibre/polypropylene composites. Influence of fibre/matrix modification and glass fibre hybridization, Composites: Part A 36, 2005, 1637–1644. [9] Sanjay K. Nayak and Smita Mohanty, Sisal Glass Fiber Reinforced PP Hybrid Composites: Effect of MAPP on the Dynamic Mechanical and Thermal Properties, Journal of reinforced plastics and composites, Vol. 29, No. 10, 2010 [10] Moe Moe Thwe, Kin Liao, Environmental effects on bamboo-glass/polypropylene hybrid composites, journal of materials science 38, 2003, 363– 376. [11] Suhara Panthapulakkal, Mohini Sain, Injection-Molded Short Hemp Fiber/Glass Fiber- Reinforced Polypropylene Hybrid Composites—Mechanical, Water Absorption and Thermal Properties, Journal of Applied Polymer Science, Vol. 103, 2007, 2432–2441. [12] Kasama Jarukumjorn , Nitinat Suppakarn, Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites, Composites: Part B 40, 2009, 623–627
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 206 [13] Kamol Dey, Nusrat Sharmin, Ruhul A. Khan, Shamsun Nahar, A.J. Parsons, C.D. Rudd, Effect of Iron Phosphate Glass onthe Physico-mechanical Properties of Jute Fabric-reinforced Polypropylene-based Composites, Journal of thermoplastic composite materials, Vol. 00— 2011 [14] G. Kalaprasad, Kuruvilla Joseph and Sabu Thomas, Influence of Short Glass Fiber Addition on the Mechanical Properties of Sisal Reinforced Low Density Polyethylene Composites, Journal of Composite Materials, 31; 509, 1997. [15] Govardhan Goud and R N Rao, “Mechanical and electrical performance of Roystonea regia/glass fiber reinforced epoxy hybrid composites, Bull. Mater. Sci., Vol. 35, No. 4, August, 2012, 595–599. [16] M.G. Rathi and Manoj D. Salunke, “Reduction of Short Shots by Optimizing Injection Molding Process Parameters”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 285 - 293, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. [17] Anurag bajpai, Sandeep Agarwal and Suruchi, “Mechanical Properties of Epoxy Resin Based Polymer Concrete”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 1, 2012, pp. 267 - 276, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. [18] Siddhant Datta, B.M.Nagabhushana and R.Harikrishna, “A New Nano-Ceria Reinforced Epoxy Polymer Composite with Improved Mechanical Properties”, International Journal of Advanced Research in Engineering & Technology (IJARET), Volume 3, Issue 2, 2012, pp. 248 - 256, ISSN Print: 0976-6480, ISSN Online: 0976-6499.