composite materials are resistant to acetic acid, concentrated hydrochloric acid, sodium hydroxide, benzene, carbon tetrachloride, and n-hexane. KEY WORDS: ...
Journal of Reinforced Plastics and Composites http://jrp.sagepub.com/
Tensile, Impact, and Chemical Resistance Properties of Granite Powder-Epoxy Composites H. V. Rama Krishna, S. Padma Priya, S. K. Rai and A. Varada Rajulu Journal of Reinforced Plastics and Composites 2005 24: 451 DOI: 10.1177/0731684405043549 The online version of this article can be found at: http://jrp.sagepub.com/content/24/5/451
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Tensile, Impact, and Chemical Resistance Properties of Granite Powder–Epoxy Composites H. V. RAMA KRISHNA, S. PADMA PRIYA AND S. K. RAI* Department of Polymer Science Sir M.V.P.G Centre University of Mysore Mandya – 571 402, India A. VARADA RAJULU Department of Polymer Science & Technology Sri Krishnadevaraya University Anantapur – 515 003, India ABSTRACT: Granite powder-reinforced epoxy composites have been developed with varying granite powder content by weight percentage. The variation of tensile strength and impact strength has been studied and the tensile strength and impact strength were found to be at a maximum for the 50% granite powder-reinforced epoxy composite. The chemical resistance test indicates that the composite materials are resistant to acetic acid, concentrated hydrochloric acid, sodium hydroxide, benzene, carbon tetrachloride, and n-hexane. KEY WORDS: granite powder, epoxy resin, tensile strength, composites impact strength, chemical resistance.
INTRODUCTION ANY STUDIES ON the composites made from epoxy and renewable resources have been reported in the literature [1–4]. Varadarajulu et al. [5] reported the short bamboo fiber-reinforced plastic composites using high-performance epoxy resin Araldite LY 5052 as a matrix. Jindal [6] has reported the development of bamboo fiber, reinforced composites. Though the granite is extensively used as a valuable material for housing purposes, the studies on granite powder-reinforced composites are meager. In this work, the granite powder-reinforced epoxy composites have been developed and their tensile, impact, and chemical resistance with varying weight of granite powder have been studied.
M
*Author to whom correspondence should be addressed.
Journal of REINFORCED PLASTICS
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COMPOSITES, Vol. 24, No. 5/2005
0731-6844/05/05 0451–5 $10.00/0 DOI: 10.1177/0731684405043549 ß 2005 Sage Publications
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H.V. RAMA KRISHNA ET AL.
EXPERIMENTAL Materials The epoxy resin LY556 (M/s Hindustan Ciba-Geigy) and the hardener HY951, system was used as a matrix for composite preparation. The granite powder, was obtained from the locally available granite industries. The granite powder is washed thoroughly with water before use and dried at 100 C for 2 h, then it is used for the preparation of composites. Sample Preparation A Teflon mold of 1 sq.ft was used. The cavities for tensile and impact strength are grooved as per ASTM Standard using CNC milling machine. Then these cavities were ready for making composites. The composites with different weights of granite powder were prepared. The prepared composites were cured at room temperature. Tensile Strength Measurement Tensile tests were carried out on an Instron (4045 series) at ambient temperature. The standard dumb bell specimens are cast according to ASTM D-638. The crosshead speed was 2 mm/min and a minimum of ten specimens were tested in each case to obtain the average value. Impact Strength Measurement The impact strength of the un-notched composite specimen was determined using an Izod impact tester according to ASTM standard. Chemical Resistance For the chemical resistance test, the chemicals, glacial acetic acid, concentrated nitric acid, concentrated hydrochloric acid, aqueous sodium carbonate (20%), and aqueous sodium hydroxide(60%) were used. The organic solvents benzene, carbon tetrachloride, and n-Hexane were dried using calcium chloride before use. The pre-weighed samples of pure epoxy matrix system and the granite powder–epoxy composites were dipped in the chemicals and studied for 24 h, removed, washed thoroughly with distilled water and dried immediately by pressing with filter paper. The final weight of the samples and the percentage weight loss/gain has been determined. The measurements have been made as per ASTM D 543.87 [7] method. The chemical tests have been repeated for several samples in each case and the average value is reported. RESULTS AND DISCUSSION The Ultimate Tensile Strength and Izod Impact Strength of granite powder-reinforced epoxy composites are presented in Tables 1 and 2 respectively. The variations of tensile strength and impact strength with filler content are shown in Figures 1 and 2 respectively. It is evident that the tensile strength of the composite is increased up to 50 wt%
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Properties of Granite Powder–Epoxy Composites Table 1. Ultimate tensile strength of granite powder–epoxy composites. %Wt. Fraction of Granite Powder
Ultimate Tensile Strength in (MPa)
% Increment Over the Matrix
18.60 22.00 25.96 26.13 24.00
– 18.27 39.56 40.48 29.03
0 30 40 50 60
Table 2. Ultimate impact strength of granite powder–epoxy composites. %Wt. Fraction of Granite Powder
Ultimate Impact Strength in (J/m)
% Increment over the Matrix
30 38 42 56 52.5
– 26.66 40.00 86.60 75.33
0 30 40 50 60
Tensile strength
26
25
24
23
22
30
35
40
45
50
55
60
% Weight fraction of Granite powder Figure 1. The variation of ultimate tensile strength of the granite powder–epoxy composites with %wt fraction of the granite powder.
reinforcement of the granite powder and for 60 wt% it is decreased. Sixty weight percentage is the maximum possible filler content in the matrix system. The decrease in ultimate tensile strength may be due to improper wetting of the granite powder at a higher filler content. Similar observations have been made in the increase of the impact strength with
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H.V. RAMA KRISHNA ET AL. 58 56 54
Impact strength
52 50 48 46 44 42 40 38 36 30
35
40
45
50
55
60
% of granite powder Figure 2. The variation of ultimate impact strength of the granite powder–epoxy composites with %wt fraction of the granite powder.
Table 3. Chemical resistance of granite powder–epoxy composites for 50% reinforcement of granite powder. % Change in Weight Dipping for 24 h Chemicals
Pure Epoxy
Granite Powder–Epoxy Composites
Acetic acid Carbon tetrachloride Benzene n-Hexane Water Concentrated HNO3 Concentrated HCl NaOH 60% NaCO3 20%
þ1.75 þ0.14 þ0.21 þ0.26 þ0.62 41.48 þ0.16 þ0.70 þ0.95
þ0.52 no change þ0.01 þ0.05 þ0.19 62.5 þ1.18 þ0.10 þ0.22
the increase of the %wt fraction of granite powder up to 50% and decreased with further reinforcement. The percentage weight loss/gain of the pure matrix system and the composites for immersion in different chemicals are presented in Table 3. The negligible weight gain in the case of glacial acetic acid, carbon tetrachloride, benzene, and water indicates that composites under study are resistant to the above said chemicals. For concentrated nitric acid there is a tremendous loss in weight, nearly 62.46% of weight loss has been observed. The percentages of weight gain for concentrated hydrochloric acid, aqueous sodium hydroxide, and aqueous sodium carbonate are 1.2, 0.1, and 0.2 respectively.
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ACKNOWLEDGMENT S.K. Rai and H.V. Rama Krishna are thankful to UGC, India for the award of a major research project. REFERENCES 1. Kulkarni, A. G., Satyanarayana, K. G., Rohtagi, P. K. and Vijayan, K. (1983). Mechanical properties of Banana Fibers (musa sepientum), Journal of Material Science, 18: 2290–2296. 2. Mansur, M. A and Aziz, M. A. (1982). Study of Jute Fiber Reinforced Cement Composites, International Journal Cem. Compos. Light Weight Concrete, 4: 74–82. 3. Chand, N. and Rohatgi, P. K. (1987). Tensile and Impact Behavior of Chopped Sun-hemp–Polyester Composites, 23: 249–251. 4. Satyanarayana, K. G., Kulkarni, A. G and Vijayan, K. (1981). Fabrication and Properties of Coir based Composites, J. Sci. Ind. Res., 40: 222–226. 5. Varada Rajulu, A., Allah Baksh, S., Reddy, Rama Chandra and Narasimhachary, R. (1998). Chemical Resistance and Tensile Properties of Short Bamboo Fiber Reinforced Epoxy Composites, 17: 1507–1512. 6. Jindal, U.C. (1986). Development and Testing of Bamboo Fibers Reinforced Plastic Composites, 20: 19–29. 7. Chemical Resistance test [ASTM D 54387] for polymer composites materials (1989). Annual Book of ASTM Standards, Vol. 8, p. 128, ASTM Publishers, Philadelphia.
