thickness swelling behaviour of hybrid natural fiber ...

Journal of Purity, Utility Reaction and Environment Vol.1 No.10, December 2012, 517-524

THICKNESS SWELLING BEHAVIOUR OF HYBRID NATURAL FIBER REINFORCED UF COMPOSITES

Article Info Received: 25th November 2012 Accepted: 31th November 2012 Published online: 1st December 2012

K. N. Bharath1, a, R. P. Swamy2, G. C. Mohankumar3 1

Dept. of Mechanical Engineering, G.M. Institute of Technology, Davangere, Karnataka, India

2

Dept. of Mechanical Engineering, Uni. BDT College of Engg., Davangere, Karnataka, India 3

Dept. of Mechanical Engineering, National Institute of Technology, Suratkal, Karnataka, India

a

ISSN: 2232-1179

[email protected]

© 2012 Design for Scientific Renaissance All rights reserved

ABSTRACT The swelling behavior was investigated for different weight fractions of randomly distributed areca fiber and maize powder reinforced urea formaldehyde composites and also for various volume fractions of the matrix. Areca fibers were chemically treated, and composites plates were prepared by using a hydraulic hot press. The tests were conducted according to ASTM standards. The thickness swelling test was conducted to investigate the water absorption of the composite. The moisture content in the composite was measured by the gain of the material in regular intervals. Hence, the swelling property improved at a particular composition of areca fibers and maize powder composite. Areca fiber composites exhibit maximum water absorption when the composite is immersed in water. Due to hybridization, i.e. water reduction was reduced significantly in the case of areca fiber with maize powder. It was concluded that the studied composites are promising alternatives and substitute material for conventional wood-based plywood or particle board. Keywords: Natural fibers, Swelling behaviour, Urea formaldehyde resin, hybrid composites.


1. Introduction The need for materials that are non-toxic and have appropriate characteristics for specific purposes is very increasing due to the lack of resources and increasing levels of environmental pollution. Thus, research is proceeding to develop composites using various recycled wastes, especially in developing composites using environmental friendly agro-wastes (yang et al. 2004) such as rice husk, areca fibers, or bamboo, etc. Structural beams or panels are successfully being manufactured out of natural fiber composites (Dweib et al. 2004). An advantage can be taken in the present study, by converting some agriculture byproducts to usable composites. Though extensive work is being carried out for the preparation and properties of green composites, work on the properties and other applications of natural fibers is scanty (Mohanty et al. 2002). Though considerable work on the properties of the natural fibers is going on in India, it is still insufficient. Natural fibers such as sisal, jute, hemp, cotton, and bamboo exhibit many advantageous properties as reinforcement in polymer matrix composites. There has been a growing interest in recent years in utilizing natural fibers as reinforcement in polymer composites for making low-cost construction or packing materials, automotive body parts. Also, biofibers from agricultural byproducts have become widely used for industrial applications (Reddy and Yang 2005). The mechanical properties of the fibers extracted from areca have been determined and compared with the other known natural fibers. Mechanical properties using adhesion tensile test, static bending strength, and swelling of areca composite plates have been reported (Swamy et al. 2004). The structural characteristics and mechanical strength of polymer matrix composites incorporated with coconut fruit fibers (also known as coir fibers) wastes was evaluated. It was found that, in principal, coir fiber reinforced polyester composites could, technically, replace wooden boards or gypsum panels, depending on the amount of incorporated fibers. The global demand for wood as a building material is steadily growing, while the availability of this natural resource is diminishing. The present papers surveys the research work published in the field of sisal fiber reinforced polymer composites with special reference to the structure and properties of sisal fiber, processing techniques, and the physical and mechanical properties of the composites. The effect of stacking sequence on tensile, flexural and interlaminar shear properties of untreated woven jute and glass fabric reinforced polyester hybrid composites has been investigated experimentally (Sabeel et al. 2007). A comparative study was made between the moisture absorption behaviors of sisal and jute fiber composites in an epoxy matrix under immersion conditions (Giridhar et al. 1986). Sisal fibers, in spite of possessing more compact structure than jute fibres, exhibited higher moisture absorption levels in their composite form, contrary to expectations. 2. Experimental 2.1 Materials Areca fibers extracted from areca husk and maize powder from maize stem were used as reinforcing materials. Urea formaldehyde was used as the matrix material and ammonium chloride as hardener. Areca husk was soaked in water for about 2 days. Areca fibers and maize 518


powder were extracted with a pulversizer through a machining process. Maize powder was taken to the blower which separates the fine maize powder from the unwanted dust particles. 2.2 Chemical Treatment Untreated short fibers were immersed in 5% aqueous NaOH for 3 to 4 h, then washed with water and dried in an air oven at 70°C for 3 hours. 2.3 Specimen Preparation A hot hydraulic press was used to prepare the boards. The mould was placed in a hydraulic press, which was maintained at 140°C, and then a pressure of 1 Mpa was applied. The set-up was maintained undisturbed for about an hour. After an hour, the mould was taken out and allowed to cool for half an hour, and the composite board from the mould is then removed. Figure 1 show the composite plate prepared. Specimens were prepared, and tests were conducted as per ASTM D 570 standards.

Fig.1. Composite plate

2.4 Different Types of Composite Plates For preparation of 100A composite plate, 900 g of areca fiber and 100 g of maize powder along with 100 ml of urea formaldehyde resin were uniformly mixed and used for preparation of boards. For preparation of 100B composite plate, 800 g of areca fiber and 200 g of maize powder along with 100 ml of urea formaldehyde resin were uniformly mixed and used for preparation of boards. Similarly for the 100C, 100D, 100E, and 100F samples, composite plates were prepared as per their proportions as shown in the Table 1. Preparation procedures were carried out similarly for 200 ml, 300 ml, and 400 ml as shown in Tables 2, 3, and 4, respectively. 519


Table 1. 100 ml UF Composite

Table 2. 200 ml UF Composite

Plate Name

Areca fiber in g

Maize powder in g

Plate Name

Areca fiber in g

Maize powder in g

100A 100B 100C 100D 100E 100F

900 800 700 600 500 400

100 200 300 400 500 600

200A 200B 200C 200D 200E 200F

900 800 700 600 500 400

100 200 300 400 500 600

Table 3. 300ml UF Composite

Plate Name

Areca fiber in g

300A 300B 300C 300D 300E 300F

900 800 700 600 500 400

Maize powder in g 100 200 300 400 500 600

Table 4. 400ml UF Composite

Plate Name

Areca fiber in g

400A 400B 400C 400D 400E 400F

900 800 700 600 500 400

Maize powder in g 100 200 300 400 500 600

2.5 Thickness Swelling Test Most natural fibers absorb more water compared to synthetic fibers. Water is predominantly absorbed at the fiber interface and matrix. The effect of this absorbed water is to degrade the properties such as tensile strength. The specimens were prepared from a 12 mm thickness plate with size 50 mm wide and 75 mm long. The following formula was used for calculation: % of increased thickness = Final thickness – Initial thickness × 100 Initial thickness

520


3. Results And Discussion Figure 2 shows the thickness vs. the square root of time curves for areca fiber and maize powder reinforced UF composite plates. The thickness increased with decrease in areca fiber and increase in maize powder from 900 gms of Areca and 100 gms of maize powder. The maximum thickness was 94 mm for 100A composite plate compared to remaining composite plates and remains stable. 3.1 Thickness vs. Square Root of Time Curves for Various Composite Plates Figure 3 shows the thickness vs. square root of time curves for areca fiber and maize powder reinforced UF composite plates. The thickness increased with decrease in areca fiber and increase in maize powder from 900 gms of areca and 100 gms of maize powder. Maximum thickness was 57 mm for 200A composite plate compared to remaining composite plates and remains stable.

Fig. 2. Swelling test results for 100 mL UF composites

521


Fig. 3. Swelling test results for 200 ml UF composites Figure 4 shows the thickness vs. square root of time curves for areca fiber and maize powder reinforced UF composite plates. The thickness increased with decrease in areca fiber and increase in maize powder up to 600 g of areca and 400 g of maize powder. Maximum thickness was 42 mm for 300D composite plate compared to remaining composite plates and remains stable.

Fig. 4. Swelling test results for 300 ml UF composites

522


Fig. 5. Swelling Test Result for 400ml UF Composites Figure 5 shows the thickness vs. square root of time curves for areca fiber and maize powder reinforced UF composite plates. The thickness increases with decrease in areca fiber and increase in maize powder from 900 g of areca and 100 gms of maize powder. Maximum thickness was 23 mm for 400A composite plate compared to remaining composite plates and remained stable. The specifications were immersed in water for a period of 30 days. The moisture content in the composite was measured by the gain of the material in regular intervals. Figure 2, 3, 4 and 5 shows that the amount in the composite increased with time and later it became constant. It absorbed about 30 to 40% of its thickness. Compared to conventional wood-based particle board it is very small, given that water absorption for wood-based particleboard is more than 40%. Therefore, this experiment shows that the composite made of areca fibers and maize powder was able to achieve significantly less water absorption. 4. Conclusions   





The areca fiber/maize powder and UF composite exhibited excellent resistance to moisture up to 40% when compared to wood-based particleboard. Results revealed that application of the areca fibers increased in the water absorption significantly in the hybrid composites due to formed micro-gaps in interfaces. Composites containing alkali-treated fiber absorbed less solvent, indicating that alkali treatment improves the adhesion between fiber and matrix. At higher fiber loadings swelling predominantly takes place in the thickness direction. Areca fiber composites exhibited maximum water absorption when the composite was immersed in water. Due to hybridization i.e., areca fiber with maize powder, there was significantly less water absorption. Finally, it is concluded that the composite plate with areca fiber and maize powder reinforced with UF resin are very promising alternate and substitute materials for the conventional wood-based plywood or particle board. 523


References Bharath. K.N., Swamy. R. P., Mohankumar. G. C. (2010). “Experimental studies on biodegradable and swelling characteristics of natural fibers composites”, International Journal of Agriculture Sciences. 2, 01-04. Giridhar, J., Kishore and Rao, R. M. V. G. K. (1986). “Moisture absorption characteristics of natural fibre composites,” Journal of Reinforced Plastics and Composites. 5, 141-150. Han-Seung yang, Hyun-Joong Kim, Jungil Son, Hee-Jun Park, Bum-Jae Lee, Taek-Sung Hwang (2004). “Rice Husk flour filled polypropylene composites; mechanical and morphological study,” Composite Structures. 63, 305-312. Dweib, M. A., and Hu, B. (2004). “All natural composite sandwich beams for structural applications,” Composite Structures 63, 147-157. Mohanty, A. K., and Misra, M. (2002). “Sustainable bio-composites from renewable resources: Opportunities and challenges in green materials world,” Journal of Polymers and the Environment. 10, 19-26. Reddy, Narendra and Yiqi Yang. (2005). “Biofibers from agricultural by products for industrial applications,” Trends in Biotechnology. 23, 22-27. Swamy, R. P. (2004). “Study of Areca reinforced phenol formaldehyde composites,” Journal of Reinforced Plastics and Composites. 23, 1373-1382. Sabeel, A. K. (2007). “Elastic properties, notched strength and fracture criterion in untreated woven Jute-glass fabric reinforced polyester hybrid composites,” Materials & Design. 28, 2287-2294.

524