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  • 1. International Journal of Advanced JOURNAL OF ADVANCED RESEARCH ISSN 0976 – INTERNATIONAL Research in Engineering and Technology (IJARET), IN 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME ENGINEERING AND TECHNOLOGY (IJARET) ISSN 0976 - 6480 (Print) ISSN 0976 - 6499 (Online) Volume 4, Issue 7, November-December 2013, pp. 60-70 © IAEME: www.iaeme.com/ijaret.asp Journal Impact Factor (2013): 5.8376 (Calculated by GISI) www.jifactor.com IJARET ©IAEME EFFECT OF UREA AND THIOUREA ON PHYSICO-CHEMICAL AND THERMAL CHARACTERISTICS OF POLYURETHANE FILAMENT B. H. Patel1, S. B. Chaudhari2, A. A. Mandot2 1 Department of Textile Chemistry, Faculty of Technology & Engineering, The M. S. University of Baroda, Vadodara, India 2 Department of Textile Engineering, Faculty of Technology & Engineering, The M. S. University of Baroda, Vadodara, India ABSTRACT This article reports modification of polyurethane filament by urea and thiourea. Change in physical and chemical properties of treated filament were evaluated and compared with the untreated filament which indicate that the nitrogen content was increased with minor loss in physical properties of the filament. The treated polyurethane dyed with reactive dyes show improvement in percentage exhaustion with improved fastness properties. Structural transformation in polyurethane filament was further confirmed by using IR spectroscopy and Differential Scanning Colorimeter (DSC) analysis. Keywords: Dyeing, Physical property, Polyurethane filament, Reactive dye, Thermal property, Urea. 1. INTRODUCTION The urethane polymer forming system has received intensive attention especially in plastics, rubber, surface coating, adhesive and fibre due to its unique structural property [1-4]. Chemical structure of polyurethane filament contains soft section (polyether or polyester) and hard section (polyurethane) which tie the chains together and the resulting polymer is called segmented polyurethane. Such fibres are generally called spandex fibres, which are defined as manufactured fibres in which the fibre forming substance is a long chain synthetic polymer comprised of at least 85% of segmented polyurethane [4, 5]. The unique structure of polyurethane, in contrast to any other polymeric fiber possesses different chemical composition of amorphous and crystalline regions. Polar groups, which could preferentially take part in secondary non-ionic bonding, are the ether groups in polyether urethanes and the ester groups in polyester urethanes. The urethane and urea groups are found only in the 60
  • 2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME crystalline, interfaced segments, which do not participate in the bonding dyestuffs [5-7]. The dyestuff is adhered only on the surface of the crystalline regions. It is plain enough that polyurethane filament can be dyed with various classes of dyestuff, still the dyestuff uptake is limited and the fastness properties are often unsatisfactory [7, 8]. Polyurethane filament has been in practical use for decades now, and so one would think that there should no longer be any problems and that even theoretically everything should be perfectly clear. Nevertheless new insights can always being attained. In this paper an attempt has been made to study the effect of urea and thiourea: typical chemicals used for dyeing and finishing of fabric containing polyurethane. Their effects on physical, chemical and thermal characteristics as well as on the dyeing performances along with fastness properties of polyurethane filaments have been studied. 2. MATERIAL & METHODS 2.1 Material 2.1.1 Fiber: Single filament polyurethane fiber (40s Denier; 70 µ Diameter) was used for the study. The fiber was supplied by Bharat Vijay Mills, Ahmedabad, Gujarat. 2.1.2 Chemicals: Urea and thiourea used for the study were of analytical grade and were purchased from Suvidhanath Chemicals. All others chemicals and auxiliaries used in this work were of LR grade. 2.1.3 Dyestuffs: Three commercial reactive dyes namely RDI- Corazole yellow 7GL, RDIICoractive yellow H4G, RDIII- Procion yellow HE4R were used without any further purification. 2.2 Experimental Methods 2.2.1 Pretreatment with urea and thiourea: The polyurethane filament (1 gm filament in hank form) samples were treated at 10, 20 and 30 gpl concentration of urea and thiourea at room temperature (40 ±1 °C) for 15 min. The samples were dried in an oven at 80o C, cured in the curing chamber at 115o C for 3 min. without tension. Finally, the samples were washed thoroughly and air-dried. 2.2.2 Dyeing polyurethane fibers with reactive dyes: Purified polyurethane fiber was dyed with commercial reactive dyes on a laboratory constant temperature water bath (Model: Paramount Instrument Pvt. Ltd.), using 1, 3, and 5% (owf) concentrations of the dye. A required quantity of dyestuff solution was taken in dyebath and 30 gpl Glauber’s salt was added to dyebath at room temperature using liquor ratio 50:1 and 3 % shade (owf). Material was then entered in dyebath and worked for 5 minutes. A further addition of 30 gpl glauber’s salt was made in two lots in interval of 10 minutes. Temperature was gradually raised upto required level depending on reactive dye. After 30 minutes alkali was added to the bath and temperature was maintained for another 15 min. Then, material was taken out, washed with water and soaped with a good non-ionic detergent (Lissapol N) at room temperature for 10 min, then washed and air-dried. 2.3 Testing and Analysis 2.3.1 Measurement of physical properties 2.3.1.1 Tensile properties: The treated as well as untreated samples were tested for breaking load and elongation at break on Instron 1121 Tensile Tester (UK) using 200 mm/min extension rate and 500 mm gauze length. An average of 10 readings was taken. 61
  • 3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME 2.3.1.2 Shrinkage behavior: The shrinkage due to the pretreatment was determined by measuring the length before and after the pretreatment. Consequently, the percentage shrinkage was calculated using the following equation (1); ܲ݁‫ ݁݃ܽ݇݊݅ݎ݄ݏ ݐ݊݁ܿݎ‬ൌ ଡ଼ିଢ଼ ଡ଼ ൈ 100 …….Equation (1) Where; x and y are the initial and final lengths of the samples before and after the pretreatment 2.3.1.3 Weight analysis: The change in weight due to the pretreatment was also measured in the same manner as shrinkage by taking weights of the samples before and after the pretreatment. The percentage change in weight was calculated as follow (2): ܲ݁‫ ݁݃ܽ݇݊݅ݎ݄ݏ ݐ݊݁ܿݎ‬ൌ ୵ଵି୵ଶ ୵ଵ ൈ 100 …….Equation (2) Where; w1 and w2 are the initial and final weights of the samples before and after the pretreatment. 2.3.1.4 Determination of percentage exhaustion: The optical density of initial dyebath and the final left-over liquor was measured spectrophotometrically using UV-vis Spectrophotometer 117 (Systronic Pvt. Ltd.) at λmax of a particular dye. The percent exhaustion of the dye on the fiber was calculated using following equation (3). ܲ݁‫ ݁݃ܽ݇݊݅ݎ݄ݏ ݐ݊݁ܿݎ‬ൌ ୍୬୧୲୧ୟ୪ ୓.ୈ.ି୊୧୬ୟ୪ ୓.ୈ. ୍୬୧୲୧ୟ୪ ୓.ୈ. ൈ 100 …….Equation (3) Where, Initial O.D. = Optical density of dye liquor before dyeing. Final O.D. = Optical density of dye liquor after dyeing. 2.3.2 Analysis of chemical composition 2.3.2.1 IR Analysis: The chemical analysis of the fiber, before and after the treatment, was recorded on Shimadzu FTIR Spectrometer 8300 using KBr Palatte technique. 2.3.3 Determination of nitrogen content Nitrogen content of the treated and untreated samples was determined on C, H, N Analyzer (Coleman Elemental Analyzer). 2.3.4 Evaluation of thermal properties The thermal analysis of the treated and untreated samples was performed on Differential Scanning Colorimeter (METTLER (Λexo) by METTLER TOLEDO STARe system). The analysis was performed on the system at a heating rate of 10oC/min under nitrogen atmosphere. 2.3.5 Evaluation of dyed samples 2.3.5.1 Colour measurement: Dyeing performance of various dyed samples was assessed by measuring the relative colour strength (K/S value) spectrophotometrically. These values are computer (on Spectra Scan 5100 (RT) spectrophotometer; Premium Colourscan Instruments, India) calculated from reflectance data according to Kubelka - Munk equation. 62
  • 4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME 2.3.5.2 Assessment of fastness properties: All the dyed samples were evaluated for fastness to various agencies like washing, light and rubbing using standard methods. Fastness to washing: Wash fastness of different dyed samples was assessed on Launder-ometer using ISO standard Test No. 3. The change in shade was visualized using grey scale and graded from 1 to 5, where 1 indicates poor and 5 excellent fastness to washing. Fastness to light: Colour fastness to light was evaluated by exposing the dyed samples to sunlight according to AATCC test method 16B-1977. They were graded from 1 to 8; where 1 indicates poor and 8 excellent fastness to light. 3 RESULT & DISCUSSION 3.1 Effect of treatment on physical properties of polyurethane filament Polyurethane single filament was pretreated with urea and thiourea at various concentration levels. The changes in various physic-mechanical characteristics due to the pretreatment have been analyzed. The tensile strength (dry) and elongation at break of untreated as well as pretreated polyurethane single filament are mentioned in Table 1. ' Table 1 Change in physical properties of polyurethane due to urea and thiourea Sample Concentration Breaking Shrinkage Weight Breaking (gpl) strength (%) reduction elongation (%) (gmf) (%) Untreated -- 47.00 412.42 -- -- 10 45.00 (-4.25) 463.23 (+12.32) 1.14 2.18 20 40.20 (-14.89) 501.12 (+21.51) 2.82 2.13 30 35.40 (-25.68) 545.66 (+32.31) 4.07 1.60 10 38.00 (-19.14) 479.8 (+16.33) 3.08 3.60 20 38.40 (-18.29) 522.6 (+26.72) 4.63 3.44 30 36.25 (-22.87) 566.2 (+37.29) 6.11 3.34 Treated with urea Treated with thiourea Note: Data in the parenthesis indicates percent loss or gain in respective property 63
  • 5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME From the table 1, it can be visualized that the treatment with urea and thiourea reduces the tensile strength of the fiber. The tensile strength of the untreated fiber was 47.00 gmf, while that of samples treated with 10 gpl urea and 10 gpl thiourea were 45.00 and 38.00 gmf respectively. The reduction in the tensile strength may be due to the structural transformation of polyurethane filament. The loss in strength was further enhanced with increase in the concentration of the treating chemicals. The elongation at break for untreated was 412.12 %. On treatment with 10 g/l urea and thiourea, the respective values of elongation at break were 463.23% and 479.80%, which was comparatively higher than the parent sample. The increased in the values of elongation at break also becomes more prominent with the increase in the concentration of urea and thiourea. The probable reason for the change in the tensile properties of the polyurethane fiber due to the pretreatment largely depends on the chain length of the macromolecule and also on the intermolecular hydrogen bonding in the soft segments. The hydrogen bond (a non-covalent, weak bond) plays a major role in bolstering the strength of the polyurethane fiber. Thus, the decline in the tensile strength of the filament may be attributed to the breaking of weak hydrogen bonds formed in between the soft segments of the polyurethane macromolecule. The changes in the length of the filament due to pretreatment were also indicated in Table 1. The shrinkage incurred due to the treatment was quite negligible, which indicates that the treatment with urea and thiourea chemicals was not sufficient enough to cause significant swelling of the fiber. However, the concentration of treating chemical influences the shrinkage behavior; as the concentration of urea or thiourea was increased in the treating liquor, the percent shrinkage also increased to a small extent. The results mentioned in the Table 1 clearly indicated the extent of weight loss due to variation in the concentration of both urea and thiourea chemicals. 3.2 Effect of treatment on chemical composition of polyurethane filament 3.2.1 Infrared spectral analysis The polyurethane filament pretreated with urea and thiourea was analyzed by IR spectroscopy. The IR spectrum of pure polyurethane filament and filament treated with urea are illustrated in fig. 1 and 2 respectively. Figure 1 IR Characterisation absorption peaks of (a) untreated polyurethane filament 64
  • 6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Figure 2 IR Characterisation absorption peaks of (b) polyurethane filament treated with urea The characteristic absorption peak of 3325 cm-1 demonstrates the -NH stretching vibration, and the -CH2- was observed at 2839 cm-1, The characteristic absorption of C=O was observed at 1705 cm-1; the aromatic -NH at 1600 cm-1 ; C-O at 1257 cm-1. Moreover, the peak for polyurethane treated with urea appears at 1512.1 cm-1. These confirm the presence of C=O and NH2 groups on the polymer structure. The probable reaction between the fibre and urea can be anticipated in fig. 3. Figure 3 Modified structure of polyurethane filament with urea The infrared spectrum of polyurethane treated with thiourea is shown in fig. 4. It can be clearly seen that all the characteristic groups present in the untreated fibre; similar trend is also observed in the infrared spectrum of polyurethane pretreated with thiourea. One additional characteristic absorption peak was observed at 1068.5 cm-1 represent C=S stretching vibration indicates modification of polyurethane by the treatment with thiourea. In case of fibre treated with thiourea, the probable reaction is shown in fig. 5. 65
  • 7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Figure 4 IR Characterisation absorption peaks of (c) polyurethane filament treated with thiourea Figure 5 Modified structure of polyurethane filament with thiourea 3.2.2 Nitrogen content analysis The results given in Table 2 show that, as the nominal concentration of urea in the treatment bath increases, there is minor increase in nitrogen content. Similar trend is observed in case of samples treated with thiourea. Table 2 Nitrogen content in untreated and treated polyurethane filament Sample Concentration (gpl) Nitrogen content (%) Control 12.12 Treated with Urea 10 13.86 (+14.35) 20 17.15 (+41.50) 30 19.28 (+58.91) Treated Thiourea 10 12.63 (+4.21) 20 12.90 (+6.44) 30 13.06 (+7.75) NOTE: Data in the parenthesis indicate percentage gain in nitrogen content compared to (Control) untreated sample. 66
  • 8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME 3.3 Effect of treatment on thermal property of polyurethane filament The thermal properties of untreated as well as pretreated polyurethane fibre, which were measured by differential scanning colourimetry (DSC) are listed in Table 3 and shown in fig. 6, 7 and 8. Table 3 Thermal analysis of untreated and treated polyurethane filament Sample On set temperature T peak ∆H° (Enthalpy) ° (mj) range ( °C) (°C) ° Untreated (a) 204.41 - 254.12 220.35 437.53 Treated with 30 gpl Urea (b) 201.39 - 244.63 215.19 630.22 Treated with 30 gpl Thiourea (c) 204.19 - 253.66 223.11 292.83 Note- 3U : Treated with 30 gpl urea, 3T : Treated with 30 gpl thiourea Figure 6 Thermal analysis curve of (a) untreated polyurethane filament Figure 7 Thermal analysis curve of polyurethane filament treated with urea 67
  • 9. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Figure 8 Thermal analysis curve of polyurethane filament treated with thiourea From the table 3 and fig. 6, 7, 8; it has been found that the melting point as well as the decomposition temperature of polyurethane was highly affected by the treatment. The melting point of untreated fibre was found to be 220°C, but when the substrate was treated with urea (30 gpl), the melting point was decreased to 215°C. On the other hand, treatment with thiourea increased the melting point to 223°C. The thermal decomposition of the untreated sample occurred at about 258°C, but treatment with urea as well as thiourea slightly lowered down the thermal degradation temperature. The treatment probably increases the length of chain in soft segment and the larger soft segment domain leads to a lower decomposition temperature. It has been also seen from Table 3, that the melting temperature of polyurethane fibre treated with urea was decreased and the filament treated with thiourea was increased by 2-3°C temperature. This may be attributed due to the fact that the polyurethane consisted of copolymer with the hard and the soft segment. The melting temperature of copolymer decreases with the increase of hard segment content. Besides, it was not clearly seen in the DSC fig. 6, 7, 8 for the melting temperature of the hard and soft segment. 3.4 Dyeing behavior of pretreated polyurethane The exhaustion percentage of untreated and treated polyurethane filament dyed with reactive dyes is shown in Table 4. The untreated polyurethane filament hank dyed with RDI, RDII and RDIII dyes exhibits 11.70, 10.95, and 32.31% exhaustion percentage respectively. On the other hand, when the samples pretreated with urea or thiourea subsequently dyed with reactive dyes at 3% shade (owf). The exhaustion percentage vary widely with the pretreatment chemical and its concentration used for pretreatment. As visualised from Table 4, with thiourea the increase in exhaustion percentage was considerably lower than that of urea, still it was higher than the sample dyed without pretreatment. The maximum increase in the exhaustion percentage was observed with the urea pretreatment. The probable reason for the increase in exhaustion may be due to the increase in -NH2 groups on the fibre. This was further confirmed by quantitative nitrogen analysis of pretreated polyurethane filament. Table 4 also represents the washing, light and perspiration fastness (acidic and alkaline) grades of polyurethane dyed with and without pretreatment by reactive dyes. These grades were compared with those of control samples dyed without pretreatment with all three dyes used for the study. The wash fastness grading were in the range of 2 to 3 indicating that washing fastness ranges 68
  • 10. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME from poor to satisfactory. A washing fastness grade of 3/4 is particularly observed for pretreated samples. The light fastness grades are in the range of 3 to 4 for untreated fibre. The pretreated fibre having light fastness grades of 3/4 to 4 from the results, it is clear that due to the pretreatment the light fastness was improved by one or two points. Table 4 Effect of pre-treatment on the dying performance of polyurethane filament with reactive dye Pre-treatment Concentration Dye (3%, Exhaustion Fastness ratings Chemical of treatment owf) (%) WF FL PF chemical (gpl) APF BPF Untreated RD I 11.70 2/3 3 2/3 3 RD II 10.95 3 3/4 2/3 3 RD III 32.31 3 4 3 ¾ Urea 10 RD I 12.52 (+7.0) 2/3 3/4 2/3 3 20 14.5 (+20.0) 3 3/4 3/4 2/3 30 15.23 (+30.1) 3 4 3/4 3 10 RD II 11.63 (+6.2) 2/3 3/4 3 2/3 20 12.26 (+11.9) 3/4 3/4 3 3 30 12.97 (+18.4) 3/4 3/4 3/4 3 10 RD III 33.02 (+2.2) 3 3/4 3 3 20 34.50 (+6.7) 3 4 3/4 3 30 36.54 (+13.1) 3 4 3/4 3 Thiourea 10 20 30 10 20 30 10 20 30 RD I 11.99 (+2.4) 12.78 (+9.2) 13.61 (+16.3) 11.32 (+3.4) 11.63 (+6.2) 12.35 (+12.8) 32.38 (+0.2) 32.68 (+1.15) 33.02 (+2.2) RD II RD III 2/3 2/3 3 2/3 2/3 2/3 2/3 3 3 3/4 3/4 3/4 3 3/4 3/4 3/4 3/4 4 3 3 3/4 3 3 3/4 3 3/4 3/4 2/3 2/3 3 2/3 2/3 3 2./3 2/.3 3 Note: Data in the parenthesis indicate percentage increase in exhaustion compared to untreated dyed samples. RD I - Corazole Yellow 7GL, RD IICoractive Yellow H4G, RD III- Procion yellow HE4R, WF - Wash fastness, LF- Light fastness, PF- Perspiration fastness, APF- Acidic Perspiration fastness, BPF- Alkaline perspiration fastness. The perspiration fastness (acidic and alkaline) grades were in the range 2/3 to 3 and 3 to 3/4 for untreated sample. The treatment in some cases lowered the perspiration fastness grade by one point. The perspiration fastness ranges from good to very good in both the cases i.e. acidic and alkaline perspiration fastness property. 4 CONCLUSIONS Pretreatment with urea and thiourea can be used to modify the physico-chemical properties. Due to the pretreatment the tensile strength was reduced to 4-28.72%, depending upon the pretreatment chemical and its concentration. The melting point of polyurethane was increased in case of thiourea, i.e. 222.43 °C. But in case of urea it was decreased to 215.19°C. The nitrogen is also increased by the pretreatment, which can influence the exhaustion of the dye. 69
  • 11. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME The polyurethane filament can be dyed uniformly with reactive dyes. The pretreatment with urea and thiourea not only improves the exhaustion of reactive dye (30% at 3% shade) but also improves washing, light and perspiration (both alkaline as well as acidic) fastness properties by 1-2 points. Now-a-days the polyurethane fibre and its blends are gaining importance in the global market, so, to produce higher quality goods it can be dyed with reactive dyes. Reactive dye can be successfully applied on pretreated polyurethane with improved exhaustion so, the pretreatment with urea and thiourea can be adopted to economise the dyeing process. REFERENCES 1. Woods G., The ICI polyurethanes, John Wiley Publications, Chichester, 1990. 2. Hepbunn C., Polyurethane elastomers, Elsevier Publishers, N.Y.1992. 3. Bhattacharya S. D. & Patel B. H., Processing of polyurethane fibre and its blends Man-made Textiles in India, 46(7), 2003, 248-254. 4. Saunders, K.J., and Frisch. K.C., Polyurethanes: Chemistry and Technology, Vol. I and II, Interscience, N.Y., 1962. 5. Patel B. H. and Chattopadhyay D. P., Kinetics and thermodynamics of dyeing elastane/spandex fiber with direct dyes, Melliand International, 17(1), 2011, 41-44. 6. Patel B. H. and Patel P. B., Dyeing of polyurethane fibre with Ocimum sanctum, Indian Journal of Fibre & Textile Research, 31(3), 2006, 474-476. 7. Patel B. H. and Bhattacharya S. D., Dyeing of polyurethane fiber with acid dyes The Indian Textile Journal, 119(12), 2009, 16-23. 8. Nunn.D.M., The Dyeing of Synthetic polymer and Acetate fibre, Dyers company Publications Trust, 1979. 9. H.C.Chittappa, “Energy Absorption Behaviour of Semi-Rigid Polyurethane Foam Under Low Velocity Impact”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 3, 2013, pp. 118 - 124, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 10. Suruchi and Ramvinode, “Investigation of Thermoelectret State Polyurethane-Cds Nanocomposite”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 1, 2012, pp. 258 - 266, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 11. R. Anbazhagan and Dr.G.P. Rajamani, “Review on Polyurethane-Matrix Nano Composites, Processing, Manufacturing and Application”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012, pp. 722 - 729, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 12. Piyush Chandra Verma and Ajay Gupta, “Study of Electrochemical Oxidation Behaviour of High Build Epoxy, Cold Applied Poly Defined Tape and Polyurethane Coating System in Saline Environment”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012, pp. 73 - 84, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 13. B. J. Agarwal, “Eco-Friendly Dyeing of Viscose Fabric with Reactive Dyes”, International Journal of Advanced Research in Engineering & Technology (IJARET), Volume 1, Issue 1, 2010, pp. 25 - 37, ISSN Print: 0976-6480, ISSN Online: 0976-6499. 70