Composite Materials Journal of Thermoplastic

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Thermo-mechanical, Degradation, and Interfacial Properties of Jute Fiber-reinforced PET-based Composite Tanzina Huq, Avik Khan, Tahmina Akter, Nazia Noor, Kamol Dey, Bapi Sarker, M. Saha and Ruhul A. Khan Journal of Thermoplastic Composite Materials published online 9 May 2011 DOI: 10.1177/0892705711401846 The online version of this article can be found at: http://jtc.sagepub.com/content/early/2011/04/05/0892705711401846

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Thermo-mechanical, Degradation, and Interfacial Properties of Jute Fiber-reinforced PET-based Composite Tanzina Huq,* Avik Khan, Tahmina Akter, Nazia Noor, Kamol Dey, Bapi Sarker and M. Saha Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka 1000, Bangladesh Ruhul A. Khan Nuclear and Radiation Chemistry Division, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh ABSTRACT: Jute fiber-reinforced polyethylene terephthalate (PET) matrix composite was prepared by compression molding. Tensile strength (TS), tensile modulus (TM), elongation at break (Eb%), bending strength (BS), bending modulus (BM), impact strength (IS), and hardness of the composites (50% fiber by weight) were found to be 56 MPa, 1950 MPa, 5%, 73 MPa, 3620 MPa, 24 kJ/m2, and 97 Shore-A, respectively. After 6 weeks of soil degradation, composites lost 28.5% and 24.6% of their original TS and BS, respectively. Interfacial characterization was performed by scanning electron microscope. KEY WORDS: jute, natural fiber, composite, PET, mechanical properties.

INTRODUCTION

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using natural raw materials has contributed to an increase in the interest on the development and use

RESERVING THE ENVIRONMENT

*Author to whom correspondence should be addressed. E-mail: [email protected] Figure 1–4 appears in color online http://jtc.sagepub.com

Journal of THERMOPLASTIC COMPOSITE MATERIALS, Vol. 00—2011 0892-7057/11/00 1–10 $10.00/0 DOI: 10.1177/0892705711401846 ß The Author(s), 2011. Reprints and permissions: sagepub.co.uk/journalsPermissions.nav


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of biomaterials. Polymer composites derived from biomaterials have been studied since the middle of the past century. The automotive industry pioneers the development of biocomposites, also known as ‘green composites.’ Natural fiber composites are used in various applications, in components subjected from light to moderate loadings, in many cases substituting polymers or fiberglass composites. Typical applications include civil construction, furniture, packing, and mainly the automotive industry. Doors and lateral parts of vehicles have already been produced using natural fibers in association with phenol, polyester, or polypropylene (PP). Due to their large availability and low cost, jute, sisal, flax, coconut, and ramie are the most used reinforcing fibers. Basically, the fiber properties depend on the vegetal variety, crop conditions, and processing techniques. Jute fibers are quite promising for the development of composites due to their superior mechanical properties and availability [1–6]. Fiber-based composite materials have some advantages such as high stiffness, ease of installation, good processability, relatively good resistance to environmental agents, fatigue, etc. A good number of matrices and fibers with a wide range of properties are being used in processing composites. Natural fibers have low abrasion multi-functionality, low density, low cost, availability, high toughness, acceptable specific strength properties, good thermal properties, enhanced energy recovery, and biodegradability. Therefore, natural fibers have gained much interest among technologists and scientists for applications in civil, military, industrial, space craft, and biomedical sectors. Among all the natural fibers, jute appears to be the most useful, inexpensive, and commercially available fiber. Jute fiber contains 82–85% of holocellulose of which 58–63% is a-cellulose. In addition, it contains minor constituents such as fats and waxes, inorganic and nitrogenous matters, and traces of pigments like b-carotene and Xanthophylls. The main component of jute fiber is a hydrophilic gluten polymer consisting of a linear chain of 1,4-b-D-hydro glucose units. Jute fibers present some disadvantages such as high moisture sorption, poor dimensional stability, intrinsic polarity, low thermal resistance, anisotropic fiber resistance, and variability. A number of papers have been published on jute fibers where jute was used as a reinforcing agent in thermoplastics like polyethylene (PE) and PP [7–14]. In this investigation, polyethylene terephthalate (PET) is used as matrix material. PET is a low-cost and high-performance thermoplastic. It is widely used in packaging materials, fibers, and sheet due to good rigidity, hardness, abrasion resistance, solvent resistance, and electric insulation properties. PET is famous in the area of synthetic fibers and bottle production. PET has some drawbacks such as notch sensitivity, brittleness, and comparatively high melting points than that of PP or polyethylene [15–17]. This investigation involves measurment of the


Jute Fiber-reinforced PET-based Composite

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mechanical, degradation, and interfacial properties of jute fiber-reinforced PET matrix composites. EXPERIMENTAL Materials Hessian cloth (bleached commercial grade, Tossa Jute) was collected from Bangladesh Jute Research Institute (BJRI), Dhaka, Bangladesh. PET was purchased from Mitsuipet Company, Thailand. Composite Preparation Granules of PET were heat pressed and made into thin sheets (0.25– 0.30 mm thickness) individually using Carver Laboratory (Carver, INC, USA Model 3856) press at 2808C. The PET sheet was cut into small pieces (15 12 cm2) and kept in the desiccators until composite fabrication. Jute fabrics were dried in an oven at 1058C to remove moisture and then cut into small pieces of dimensions 15 12 cm2. Composites were prepared by sandwiching four layers of jute fabrics (50% fiber by weight) between five layers of pre-weighted PET sheets and pressed at 2808C for 5 min between two steel plates under a pressure of 5 tons. Then, the composite containing steel mold was cooled to room temperature using another press (Carver, USA) and then cut to the desired size. Mechanical Properties of the Composites Tensile and bending properties of the composites were evaluated using the Hounsfield series S testing machine (UK) with a crosshead speed of 1 mm/s. The dimension of the test specimen was (ISO 14125): 60 15 2 mm3. Composite samples were cut to the required dimension using a band saw. Impact strength (IS) of the composites was measured using Impact tester (MT-3016, Pendulum type, Germany). Hardness was determined by HPE Shore-A Hardness Tester (model 60578, Germany). Scanning Electron Microscopic Analysis The fracture surface of the composites (after bending test) was studied using a JEOL 6400 SEM at an accelerating voltage of 10 keV. Scanning electron microscopic (SEM) specimens were sputter-coated with gold.


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Soil Degradation Tests of the Composites Composite samples were buried in soil (having at least 25% moisture) for different periods of time. After a certain period, samples were withdrawn carefully, washed with distilled water, dried at 1058C for 6 h, and kept at room temperature for 24 h; then, the mechanical properties were measured. RESULTS AND DISCUSSION Mechanical Properties of the Composite (Jute Fiber/PET) Jute fabric-reinforced PET matrix composite was prepared by compression molding and the mechanical properties were evaluated. The jute content in the composites was maintained at about 50% by weight. The mechanical properties such as tensile, bending, impact, and hardness of the PET sheet and the composites (PET/jute fiber) were evaluated. The results are given in Tables 1–2. It was found that tensile strength (TS), tensile modulus (TM), elongation at break (%), bending strength (BS), bending modulus (BM), IS, and hardness of the PP sheet were found to be 42 MPa, 1260 MPa, Table 1. Tensile and bending properties of PET and composite (50 wt% fiber). Tensile and bending properties Tensile properties Materials PET sheet Composite (50% fiber) (PET/jute fiber)

Bending properties

Strength (MPa)

Modulus (MPa)

Elongation at break (%)

Strength (MPa)

Modulus (MPa)

42 6 56 8

1260 200 1950 300

85 15 52

56 4 73 5

2140 230 3620 250

Table 2. Impact strength and hardness of PET and composite (50 wt% fiber). Impact strength and hardness Materials PET Composite (50% fiber) (PET/jute fiber)

Impact strength (kJ/m2)

Hardness (Shore-A)

4.6 2 24 4

96 0.5 97 1


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85%, 56 MPa, 2140 MPa, 4.6 kJ/m2, and 96 Shore-A, respectively. But jute fiber-reinforced PET based composites made of 50% fiber significantly gained mechanical properties. The composites gained 25% TS and 35% TM over that of the matrix PET. Similarly BS, BM, and IS improved significantly than that of the PET. On the other hand, percentage elongation at break (Eb%) was reduced because of low Eb% of the fibers compared to PET. Shore hardness of the composites indicated that due to incorporation of jute fibers inside PET, the hardness of the composite slightly improved. From this investigation, this is clear that jute fiber-reinforced PET matrix composites gained higher mechanical properties over the matrix PET, thus indicating good fiber–matrix adhesion.

Degradation Test of the Composite (Jute Fiber/PET) in Soil Medium Degradation tests of the composites (50% fiber by weight) were performed in soil at ambient condition for up to 6 months. The results are depicted in Figures 1–3. Both TS and BS values decreased in a similar manner and the results are plotted against degradation time (Figure 1).

80 TS

BS

Strength (MPa)

70

60

50

40

30 0

2

4 Duration (week)

6

8

Figure 1. Degradation of tensile and BS of the composites (jute fiber/PET) during soil degradation tests.


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It was found that after 6 months of soil degradation, composites lost 28.5% and 24.6% of their TS and BS, respectively. For example, the original TS and BS of the composites were 56 and 73 MPa, but after 6 months of degradation, TS and BS reached 40 and 55 MPa. Similarly, TM, BM, and IS decreased with time in a manner similar to TS and BS; the results are shown in Figures 2 and 3. TM, BM, and IS of composites were found to be 1950 MPa, 3620 MPa, and 24 kJ/m2, but after 6 months of degradation, the values reached 1120 MPa, 2450 MPa, and 11 kJ/m2, respectively. Initially, the loss of mechanical properties was higher, which then reached a plateau. It is clear that all the mechanical properties (TS, TM, BS, BM, and IS) of the composites slowly decreased over time, thus indicating its degradable nature. Jute is a degradable fiber which is mainly responsible for the loss of the mechanical properties [2]. After 6 months of degradation in soil, composites lost a minor fraction of the mass and the results are presented in Figure 4. It was found that the composites lost 3.6% of their mass in 6 months, which supports the partial loss of the mechanical properties of the composites as described. Jute is a natural biodegradable fiber of vegetable origin and this fiber is cellulose based which absorbs water within a couple of minutes, indicating its strong hydrophilic character. Cellulose has

4000 TM

3500

BM

Modulus (MPa)

3000 2500 2000 1500 1000 500 0

2

4

6

8

Duration (week) Figure 2. Degradation of tensile and bending moduli of the composites (jute fiber/PET) during soil degradation tests.


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Jute Fiber-reinforced PET-based Composite 30

Impact Strength (kJ/m2)

25

20

15

10

5

0 0

2

4

6

8

Duration (week) Figure 3. Degradation of IS of the composites (jute fiber/PET) during soil degradation tests.

4

Mass Loss (%)

3

2

1

0 0

2

4 Duration (week)

6

8

Figure 4. Weight loss of the composites (jute fiber/PET) for soil degradation tests of the composite samples.


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a strong tendency to degrade when buried in soil [14]. During soil degradation tests, moisture penetrates from the cutting edges of the composites to jute. Degradation of cellulose occurred in jute and as a result, the fiber–matrix adhesion became poor which attributed to the loss of the mechanical properties of the composites.

Scanning Electron Microscopic Analysis of the Composites SEM studies were carried out to find out the fiber–matrix adhesion inside the composites. SEM images of the fracture sides of the jute fiber/PET composites (a) and 6 months degraded (b) in soil medium are presented in Figure 5. From Figure 5(a), it is clearly indicated that the jute fiber pull-out is quite higher but the bonding between jute and PET is quite promising though few gaps are evident in the composites. On the other hand, soildegraded specimens (Figure 5(b)) showed that jute fibers became degraded and some gaps are clearly found. So, from this investigation, it is clear that the PET/jute fiber is a partially degradable composite but has good mechanical properties. CONCLUSION Jute fiber-reinforced PET matrix composite was prepared by using four layers of jute and five layers of PET sheets at 2808C and 5 ton pressure by compression molding. Mechanical properties of the matrix PET and the composites (PET/jute) were evaluated and it was found that the jute fiberreinforced PET attributed significantly higher mechanical properties. Degradation tests of the composites were performed in soil medium. After 6 months of soil degradation, composites lost about one-fourth of their (a)

(b)

Figure 5. Fracture surface (a) of the PET/jute fiber composite and (b) after 6 weeks of degradation of the composite in soil medium.



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original strength. Composites lost their mass slowly in soil medium, thus indicating their semi-degradable characters attributed from jute. Fiber– matrix adhesion was found quite promising and proved by SEM. REFERENCES 1. Silva, R.V., Spinelli, D., Bose Filho, W.W., Claro Neto, S., Chierice, G.O. and Tarpani, J.R. (2006). Fracture Toughness of Natural Fibers/Castor Oil Polyurethane Composites, Compos. Sci. Technol., 66: 1328–1335. 2. Zaman, H.U., Khan, A.H., Hossain, M.A., Khan, M.A. and Khan, R.A. (2009). Mechanical and Electrical Properties of Jute Fabrics Reinforced Polyethylene/ Polypropylene Composites: Role of Gamma Radiation, Polym. Plast. Technol. Eng., 48: 760–766. 3. Barkoula, N.M., Garkhail, S.K. and Peijs, T. (2010). Effect of Compounding and Injection Molding on the Mechanical Properties of Flax Fiber Polypropylene Composites, J. Reinforc. Plast. Compos., 29: 1366–1385. 4. Khan, A.R., Haque, E.M., Huq, T., Khan, A.M., Zaman, U.H., Fatema, J.K., Al-Mamun, M., Khan, A. and Ahmad, A.M. (2010). Studies on the Relative Degradation and Interfacial Properties Between Jute/Polypropylene and Jute/Natural Rubber Composites. J. Thermoplast. Compos. Mater., 23(5): 665–681. 5. Mishra, S., Mohanty, A.K., Drzal, L.T., Misra, M., Parija, S., Nayak, S.K. and Tripathy, S.S. (2003). Studies on Mechanical Performance of Biofibre/Glass Reinforced Polyester Hybrid Composites, Compos. Sci. Technol., 63: 1377–1385. 6. Bullions, T.A., Gillespie, R.A., Price-O’Brien, J. and Loos, A.C. (2004). The Effect of Maleic Anhydride Modified Polypropylene on the Mechanical Properties of Feather Fiber, Kraft Pulp, Polypropylene Composites, J. Appl. Polym. Sci., 92: 3771–3783. 7. Joseph, P.V., Joseph, K. and Thomas, S. (2002). Short Sisal Fiber Reinforced Polypropylene Composites: The Role of Interface Modification on Ultimate Properties, Compos. Interface, 9(2): 171–205. 8. Rahman, R., Hasan, M., Huque, M. and Islam, N. (2009). Phisico-mechanical Properties of Maleic Acid Post Treated Jute Fiber Reinforced Polypropylene Composites, J. Thermoplast. Compos. Mater., 22(4): 365–381. 9. Mukhopadhay, S. and Fangueiro, R. (2009). Physical Modification of Natural Fiber and Thermoplastic Films for Composites – A Review. J. Thermoplast. Compos. Mater., 22(2): 135–162. 10. Cantero, G., Arbelaiz, A., Llano-Ponte, R. and Mondragon, I. (2003). Effects of Fiber Treatment on Wettability and Mechanical Behavior of Flax/Polypropylene Composites, Compos. Sci. Technol., 63: 1247–1254. 11. Saheb, D.N. and Jog, J.P. (1999). Natural Fiber Polymer Composites: A Review. Adv. Polym. Technol., 18(4): 351–363. 12. Cantero, G., Arbelaiz, A., Llano-Ponte, R. and Mondragon, I. (2003). Effects of Fiber Treatment on Wettability and Mechanical Behavior of Flax/Polypropylene Composites, Compos. Sci. Technol., 9(63): 1247–1258. 13. Mohanti, A.K. and Mirsa, M. (1995). Studies on Jute Composites: A Literature Review, Polym. Plast. Technol. Eng., 35(5): 729–738. 14. Zhang, H., Zhang, Y., Guo, W. and Wu, C. (2008). Thermal Properties and Morphology of Recycled Poly(ethylene terephthalate)/Maleic Andydride Grafted linear Low-Density Polyethylene Blends, J. Appl. Polym. Sci., 109: 3546–3553. 15. Kagan, V.A., Palley, I. and Jia, N. (2004). Plastics Part Design: Low Cycle Fatigue Strength of Glass-fiber-reinforced Polyethylene Terephthalate (PET), J. Reinforc. Plast. Compos., 23(15): 1607–1614.


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