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Progress in Organic Coatings 64 (2009) 27–32

Contents lists available at ScienceDirect

Progress in Organic Coatings

journa l homepage: www.e lsev ier .com/ locate /porgcoat

oly (urethane fatty amide) resin from linseed oil—A renewable resource

uman Yadav, Fahmina Zafar, Abul Hasnat, Sharif Ahmad ∗

aterials Research Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, India

r t i c l e i n f o

rticle history:eceived 24 July 2007eceived in revised form 26 February 2008ccepted 10 July 2008

eywords:oly (urethane fatty amide)inseed oilnticorrosiveoating

a b s t r a c t

Poly (urethane fatty amide) [PULFA] resin was synthesized by using a one-shot technique at room tem-perature from diol linseed fatty amide [DLFA; a monomer obtained from the aminolysis of renewableresource, such as linseed oil with diethanolamine and sodium methoxide used as a catalyst], 1.0 moles,and varying ratio of toluylene-2,4(6)-diisocyanate [TDI, 0.08–1.5 moles] in minimum amount of xylenewithout any chain extender and catalyst. In this process phthalic acid/anhydride which is normally usedin the synthesis of polyesteramide was completely replaced by TDI as in case of uralkyd. The reactionmechanism of the same has been discussed here. The mode of reaction and structure of the resin wasconfirmed by physico-chemical tests and spectral analysis. The performance of the coatings on mild steelstrips was tested by physico-mechanical and chemical/corrosion resistance tests. Thermo gravimetricanalysis [TGA] and differential scanning calorimetry [DSC] techniques were used to investigate the ther-mal stability and curing behavior of the resin. The aforementioned properties of newly synthesized resinwere compared with those of reported linseed oil-based polyesteramide urethane [Ur-LPEA, synthesized

by partial replacement of phthalic anhydride by TDI] and uralkyd. The newly synthesized resin has shownimproved physico-mechanical and corrosion resistance performance to Ur-LPEA and alkyd, whereas tothose of uralkyd has comparable results. The PULFA resin exhibits not only superior properties to some ofthe reported resins, but also helps in the conservation of energy by being synthesized at room temperatureas compared to other similar reported systems which were synthesized at reasonably high temperatures.The present study reveals that the PULFA resin can be used as a substitute to Ur-LPEA, alkyd and uralkyd

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. Introduction

Oils and fats of vegetable origin constitute the greatest propor-ion of the current consumption of renewable raw materials in thehemical industry, since they can offer versatile applications in theeld of polymers and coatings. Over the past few decades oils haveerved as a viable alternative of petroleum resources [1]. The uti-ization of seed oil in the manufacture of useful polymer-based endroducts solves not only the problem of waste disposal, but also itan help in bringing down the cost of production. Owing to theiron-toxicity, biodegradability as well as eco-friendly nature theyre consumed in abundance all over the world [1–4].

Oil—a triglyceride of different saturated and unsaturated fatty

cids has been widely used in inks, diluents, plasticizers, lubricants,grochemicals, food industry, composite materials, paints and coat-ngs [5–8]. Oils alone do not show good properties and therefore,or value addition they are modified according to their use [4].

∗ Corresponding author. Tel.: +91 112 6981717 3268; fax: +91 112 684 0229.E-mail address: sharifahmad jmi@yahoo.co.in (S. Ahmad).

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300-9440/$ – see front matter © 2008 Elsevier B.V. All rights reserved.oi:10.1016/j.porgcoat.2008.07.006

ive paints and coatings.© 2008 Elsevier B.V. All rights reserved.

heir modification includes boiled oil [7], vinylation [9], metathe-is [9], acrylation [8,10], maleinization [11–12], epoxidation [8,13],ydroxylation [8,13], urethanation [8,13], hydroformylation [14],alogenation [15], hydromethylation [16], haloacrylation [17–18],ydrolysis [19] and aminolysis [20]. Latter modification results

n the formation of N,N′-bis(2-hydroxyethyl) fatty amide. Thisonomer plays a vital role in the synthesis of organic polymers

nd also finds application as a polymer cross-linker [21]. It issed as starting material for the development of polyetheramides22], polyesteramides [23–24], polyesteramide urethanes [25] andolyamide urethanes [26]. These polymers have until now foundpplication as corrosion protective materials [22–26].

Polyurethane is defined as a polymer, which contains urethaneroups (–NH–COO–) in the main polymeric chain, and may alsoontain other functional groups, such as ester, ether, urea and amide27]. The polymeric chains consist of alternating short sequencef soft (flexible) polyol and hard (rigid) isocyanate segments.

he physical, mechanical and adhesive properties of polyurethaneepend strongly on the composition and chemical structure ofard and soft segments [28–29]. It possesses excellent abrasionesistance, low temperature flexibility, high strength, aging andhemical resistance [22,26–27,30]. It has diverse applications and

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an be tailored as adhesives [31], foams [32], plastics [14,33], elas-omers [34] and coating materials [8,13,22,25,35–37]. Several seedil-based polyols have been synthesized and can expect to replacehe petroleum-based polyols [38].

In the present work, we have made an attempt to develop lin-eed oil-based poly (urethane fatty amide) [PULFA], which wasynthesized by the reaction of diol linseed fatty amide [DLFA] witholuylene-2,4(6)-diisocyanate [TDI]. Its physico-chemical, spectral,hysico-mechanical and anticorrosive properties were investigatednd compared with those of alkyd [39], uralkyd [19] and Ur-LPEA25].

. Experimental

.1. Materials

Linseed (obtained from local market) was air-dried, groundedo a powdered form, subjected to oil extraction in petroleum ethera solvent, bp 60–80 ◦C) through Soxhlet apparatus. The oil was

cnrad

Scheme 1. (a) Synthesis of DLFA, (b) synthesis of PULFA and (c) prob

Coatings 64 (2009) 27–32

ewaxed and stored in a sealed clean glass bottle for experimen-al use. The fatty acid composition of oil was determined by gasiquid chromatography (GLC; 111/8 s. s. column, FID detector) [41].odium methoxide, xylene, diethanolamine and phthalic anhydrideSD Fine Chemicals, India), TDI (Merck, India) were of analyticalrade. DLFA [40] and linseed oil-based alkyd [LOA] [39] were syn-hesized as per reported methods.

.2. Synthesis

PULFA was prepared by using a one-shot technique (single stagerocess). DLFA (1.0 moles) and TDI (0.8–1.5 moles, solution in min-

mum possible xylene solvent) were taken in four necked flatottom flask fitted with the dropping funnel, thermometer and

ondenser. The reaction mixture was continuously stirred underitrogen environment at room temperature. The progress of theeaction was monitored by thin layer chromatography [TLC] andlso by determining the hydroxyl value at regular interval. Atesired hydroxyl value the reaction was stopped and xylene was

able reaction mechanism involved in the synthesis of PULFA.

rganic Coatings 64 (2009) 27–32 29

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Table 1FTIR spectral assignment of DLFA and PULFA

Functional group IR (cm−1)

DLFA PULFA

–OH 3415 3375>C O (amide) 1635 1620C–N str. (amide) 1464 1450CH2sym 2855.6 2855.8CH2asym 2916.8 2926.4C C–H str. 3007 3007ArC C–H out of plane bending – 795.2ArC C–H str. – 3077ArC C– – 1600, 1540.18>–NC

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emoved through rotary vacuum evaporator to obtain the pureULFA resin.

.3. Test methods

FTIR, 1H NMR, and 13C NMR characterized the chemical struc-ure of PULFA. FTIR spectra of the resin was taken over the Perkinlmer 1750 FTIR Spectrophotometer (Perkin Elmer Cetus, Instru-ent, Norwalk, CT, USA) using a NaCl cell. 1H NMR and 13C NMR

pectra were recorded on JEOL GSX 300 MHZ FX-1000 Spectrome-er using deuterated chloroform as a solvent, and tetramethylsilanes an internal standard. The thermo gravimetric analysis [TGA] waserformed with the help of Thermo Gravimetric Analyzer, TA-51T.A. Instruments, USA) at 20 ◦C/min in nitrogen atmosphere. Iodinealue, hydroxyl value, saponification value, inherent viscosity, spe-ific gravity and refractive index of the same were determined bytandard laboratory methods (Table 2).

.4. Preparation of coatings

The mild steel strips were polished on various grade of siliconarbide papers, then washed with water and degreased with alco-ol and carbon tetrachloride. They were dried under vacuum foreveral hours. The coatings were prepared by brush technique usingolution containing 60 wt% of resin in xylene applied on mild steeltrips. PULFA coatings were obtained at room temperature (Table 3).he standard sizes of strips of 30 mm × 10 mm × 1 mm size wereaken for chemical resistance test in water, acid (5 wt% HCl), alkali5 wt%), xylene solvent by placing them in 3 in. diameter porcelainishes. The salt spray test (ASTM B177-94), in 3.5 wt% NaCl solu-ion was also carried out in a salt mist chamber. The coated panelsere dipped in aforementioned media, and periodic examinationas conducted until coatings showed visual evidence of softening,eterioration in gloss, discoloration or weight loss (Table 3). Thetrips of 70 mm × 25 mm × 1 mm size were taken to evaluate theirhysico-mechanical properties, such as scratch hardness (BS 3900),ending (ASTM D 3281–84), impact resistance (IS: 101 part 5/Sec., 1988), and specular gloss at 45◦ by gloss meter (Model RSPT 20;igital Instrument, Santa Barbara, CA). The thickness of the coat-

ngs was found to be in between 75 and 100 �m as measured bylcometer (Model 345; Elcometer Instrument, Manchester, UK).

. Results and discussions

The synthesis and reaction mechanism of PULFA resin from lin-eed oil is given in Scheme 1a and b. It reveals that for one-packageoating material of PULFA resin was prepared by aminolysis of lin-eed oil with diethanolamine in the presence of sodium methoxides catalyst, followed by the reaction of resulting DLFA with dif-erent amount of TDI (0.8–1.5 moles). DLFA was used not only as

monomer, but also acts as a catalyst in this addition reaction40]. The reaction consists of very efficient intermixing of DLFA andDI in one step and also in a short time (one-shot technique). Theynthesis temperature of PULFA was much lower than the overallynthesis temperature of Ur-LPEA, alkyd and uralkyd [19,25,39]. Inther words, lesser energy is required for the synthesis of PULFAesin as compared to the synthesis of Ur-LPEA, alkyd and uralkyd.his can be correlated to the much higher reactivity of hydroxylroups of DLFA that facilitate the reaction at room temperature.he structure of PULFA was confirmed by physico-chemical and

pectral analysis.

It is observed during the synthesis of PULFA resin that above theolar ratio 1.5:1.0 of TDI and DLFA results in the formation of lumpy

ggregate, which makes it unbrushable. This may be due to theormation of highly viscous and cross-linked network of the resin. It

3

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C O (urethane) – 1716.11NH (urethane) – 3336–3333–H deformation – 1540–N str. (urethane) – 1227.56

an be further explained by the reaction of isocyanate groups of TDIith active hydrogen of hydroxyl groups to form urethane linearly

primary reaction) leads to increase in molar mass and viscosity.he urethane hydrogen, which formed in primary reaction, reactsith the isocyanate group of TDI (beyond 1.5 moles loading) to form

llophanate (secondary reaction). This could be responsible for theigher cross-link network leading to formation of lumpy aggregate25,40].

.1. Spectral analysis

The IR spectral studies, Table 1, reveal bands at 3375 cm−1 (broadand, –OH primary alcohol) and 1070 cm−1 (C–O primary alco-ol) as well as additional bands, which are characteristic signalsf urethane bands. These bands are correlated to the formationf polyurethane through –OH groups of DLFA and –NCO groupsf TDI. Close examination of DLFA and PULFA spectra reveals thehifting of bands in lower frequency region especially in regionsf >C O (amide carbonyl, 15 cm−1) and C–N str. (amide, 14 cm−1).ands at 1716.11 cm−1 and 1227.56 cm−1 are attributed to free >C Ond C–N of urethane groups, respectively. This observation cane correlated to the formation of hydrogen bond in PULFA. Sincehe band of >C O str. of TDI is observed at 1735 cm−1. 1H NMRFig. 1) and 13C NMR (Fig. 2) spectra show the characteristic sig-als of urethane groups in addition to characteristic signals of DLFA41] confirmed the structure of PULFA. Additional signals are asollows: ı (ppm), 7.99–7.82 (hydrogen bonded –HNCOO–), 7.1–6.9non-hydrogen bonded –HNCOO–), 7.5–7.22 (ring protons of TDI),.1–3.9 (–HNCOOCH2–), 2.25 (CH3 of TDI), 17 (CH3 of TDI), 143.97–NH–(C O)–O–} and 137.46, 136.2, 134.4, 125.94, 125.4, 116.0ring carbon of TDI). These spectral studies support the formation ofULFA through the reaction of free –OH groups of DLFA with –NCOroups of TDI.

.2. Physico-chemical characterizations

It is observed from Table 2 that the hydroxyl value and iodinealue of PULFA is lower while specific gravity and refractive indexf the same is higher in comparison to LOA. It is also observed thatn increasing the content of TDI in DLFA the hydroxyl value andodine value progressively decreases while specific gravity, inherentiscosity and refractive index increase. These can be correlated tohe increase in molar mass through urethane linkages.

.3. Curing of PULFA film

It is observed that curing of PULFA film involves three stagess in case of uralkyd [19]. First and second stage obtained within

30 S. Yadav et al. / Progress in Organic Coatings 64 (2009) 27–32

Fig. 1. 1H NMR spectra of PULFA.

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0–60 min that is dry to touch time and dry to touch-hard timebtained firstly by the evaporation of solvent (physical process)eading to chain entanglement, and secondarily by the reaction ofree isocyanate groups with unreacted hydroxyl and atmospheric

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able 2hysico-chemical characterizations

esin codea Linseed oil DLFA P

ydroxyl value (%) 0.3 9.4odine value (gI2/100 g) 181 86 1pecific gravity (g/ml) 0.896 0.926nherent viscosity (dl/dg) – –efractive index 1.478 1.497

a Ambient cured.

ctra of PULFA.

oisture (chemical process, primary reaction) to form urethanend amine. The latter is further reacted with isocyanate groups ofnother chain to form urea. Urethane and urea further react withnreacted isocyanate group of another chain to form allophanate

ULFA-0.8 PULFA-1.0 PULFA-1.5 LOA

5.98 4.42 1.5 137 12 10 45.50.98 0.985 0.995 0.9430.730 0.738 0.890 –1.549 1.580 1.590 1.478

rganic Coatings 64 (2009) 27–32 31

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nd biuret (secondary reaction) leading to formation of cross-linkedtructure. The first and second stage process is very rapid event room temperature [13,27,40]. While the third stage, the dry toard, is obtained within a week’s time. This process is very slownd occurs through autoxidation of residual unsaturation of linseedatty acid chains of the resin [19,40]. The latter have diallylic groups,CH CH–CH2–CH CH–, which are responsible sites for additionalross-linking. Hydrogen on methylene group (�-methylene groups)hich flank with two double bonds initially loses the hydrogen

tom and yields a resonance stabilized free-radical. That radicals capable to react with atmospheric oxygen leading to peroxideadical. The peroxide radical leads to the abstraction of hydrogenrom another �-methylene group to form hydroperoxide and itenerates free-radicals. Thus a chain reaction is initiated, result-ng in autoxidation. At least, part of the cross-linking occurs byadical–radical combination reaction forming C–C, ether and per-xide bonds. These reactions result in termination by combinationeaction in free-radical chain growth polymerization, which is anal-gous to the addition step in chain growth polymerization thatould also form cross-linked structure [19,40].

.4. Coatings properties

The studies reveals that free –OH groups, –NCO groups, linseedatty acid chain, amide and urethane linkages make a PULFA sys-em. In addition to these groups, the hydrogen bonding betweenULFA chains is also involved in this system. These are collectivelyesponsible for curing of film as mentioned in the earlier sec-ion. Performance of the coatings, such as scratch hardness, impactesistance (toughness), bending ability (flexibility) and chemicalesistance of the film mainly depends on these reactive polar func-ional groups and hydrogen bonding (between PULFA chains asell as between PULFA films and the substrate) that form infusible

hermoset and well adhered coatings. The coating performance ofULFA is given in Table 3. It shows that curing time of PULFA coat-ngs (3 h to 20 min) is much lower in comparison to the curingime of LOA coating (10 days). The curing time of PULFA coat-ngs decreases with the increase in loading of TDI up to a certainimit. Then it becomes constant (drying time order: PULFA-0.8≫ULFA-1.0 = PULFA-1.5). The drying time for PULFA-0.8 system isuite large compare to the other compositions of PULFA systemhich are more or less equal. This can be correlated to the optimum

ross-linking required to have the fast curing of coating materials,hich was achieved in case of PULFA-1.0 system. The curing of the

oating occurs in a three stage process as mentioned earlier, i.e.,hysical process – involves evaporation of solvent, chemical pro-ess – through the –NCO of PULFA with moisture and other side

able 3oatings properties

esin PULFA-0.8 PULFA-1.0 PULFA-1.5 LOA

rying timea(min) 3 h 20 20 10 daysloss at 45◦ 63 73 73 40

hysico-mechanical propertiescratch hardness (kg) 1.8 2.5 2.0 1.0mpact resistance (lb/in.) 200 200 150 150ending (1/8 in.) Passes Passes Failed Passes

hemical/corrosion resistanceoisture (10 days) A A A AaOH (2%) 3 h C A C DCl (3%) 10 days A A A BaCl (3.5%) 10 days C B C D

he coating passes adhesion test with no visible damage. A, unaffected; B, slightlyoss in gloss; C, film cracked and removed; D, film completely removed.

a Ambient cured.

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Fig. 3. TGA thermogram of PULFA-1.0.

eactions, and autoxidation – via residual unsaturation of PULFA.cratch hardness of PULFA is higher, whereas impact resistance andending tests are same in comparison to LOA that can be correlatedo the urethane formation which leads to the optimum cross-linkedtructure. Scratch hardness, impact resistance and bending abilityests on PULFA coatings follow a same trend that is they increaseith the increase in loading of TDI upto a certain limit beyond which

hey decreases. It can be correlated to the optimum cross-linked,niform and well-adhered structure of the coating. The requiredoughness and flexibility of the coatings are achieved by the com-osition, PULFA-1.0, beyond which an excessive cross-linking andtiffness occurs within the film that produces an internal strainn the system that leads to the deterioration of aforementionedlm properties [25]. Gloss of PULFA coatings is high in compar-

son to LOA. Gloss of PULFA further increases with the increasen loading of TDI. It can be due to the urethane groups, long fattycid chains and denseness of the structure [13]. In chemical resis-ance tests of PULFA-1.0 system shows excellent performance inomparison to PULFA-1.0 and PULFA-1.5, show far better resultsn comparison to LOA [39], and comparable result to Ur-LPEA [19]nd uralkyd [19]. Such excellent performance can be correlatedo the urethane linkages optimum cross-linked structure and welldherent coating that prevents corrosive ions to penetrate into theoating.

.5. Thermal analysis

Thermograms of PULFA show three degradations. Initially 5% ofeight losses at 230 ◦C correspond to entrapped moisture and sol-

ent. The derivative of TGA curves of the PULFA reveals actuallyhree or four degradation processes (Fig. 3). The first step associ-ted with 27.73% of weight loss at 260 ◦C, the second with 21.11% ofeight loss at 360 ◦C, the third with 40.62% of weight loss at 505 ◦C

nd the last with 9.22% of weight loss at 640 ◦C. The first step cor-esponds to the degradation of the urethane bonds. It is reportedhat the decomposition of urethane bond starts between 150 and00 ◦C depending on the type of substituents on the isocyanate andolyol side [42]. The decomposition of urethane bonds takes placehrough dissociation to isocyanate and alcohol, the formation of pri-

ary amines and olefins and the formation of secondary amines.econd, third and last decomposition steps correspond to decom-osition of ester, amide and hydrocarbon chains, respectively42]. Thermal stability of PULFA system is higher in compari-

◦ ◦

on to alkyd (10 wt% at 95.4 C, 20 wt% at 147.6 C and 50 wt% at67.12 ◦C) and uralkyd. This can be due to the entanglement ofore thermal resistant amide bonded polymeric chains (known

or higher thermal stability) and to hydrogen bonding within thesehains.

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. Conclusion

PULFA was successfully developed in different loadings of TDIhrough one-shot technique at ambient temperature. It was syn-hesized at much lower temperature (lower energy consumption)n comparison to those of polyesteramide urethane, alkyd andralkyd. PULFA-1.0 system shows excellent result and exhibitsuperior performance to alkyd while having comparable perfor-ance to uralkyd. TGA studies suggest that coating PULFA-1.0

ystem can safely be used upto 230 ◦C as a corrosion-protectiveco-friendly coating material.

cknowledgements

Dr. Fahmina Zafar is thankful to CSIR (New Delhi), India for RAgainst Grant No. 9/466 (0092) 2K7-EMR-I.

eferences

[1] F.E. Okieimen, C. Pavithran, I.O. Bakare, Eur. J. Lipid Sci. Technol. 107 (2005) 330.[2] L. Yu, K. Dean, L. Li, Prog. Polym. Sci. 31 (2006) 576.[3] C.D. Lorenz, M.J. Stevens, R.P. Wool, J. Appl. Polym. Sci. Part B: Polym. Phys. 42

(2004) 3333.[4] H.P. Bhunia, A. Basak, T.K. Chaki, G.B. Nando, Eur. Polym. J. 36 (2000) 1157.[5] S.N. Khot, J.J. Lascala, E. Can, S.S. Morye, G.I. Williams, G.R. Palmese, S.H. Kuse-

foglu, R.P. Wool, J. Appl. Polym. Sci. 82 (2001) 703.[6] H. Pelletier, A. Gandini, Eur. J. Lipid Sci. 108 (2006) 411.[7] J.T.P. Derksen, F.P. Cuperus, P. Kolster, Prog. Org. Coat. 27 (1996) 45.

[8] E. Sharmin, S.M. Ashraf, S. Ahmad, Eur. J. Lipid Sci. Technol. 109 (2007) 134.[9] F.S. Guner, Y. Yagci, A.T. Erciyes, Prog. Polym. Sci. 31 (2006) 633.10] B. Cakmakli, B. Hazer, I.O. Tekin, S. Kizgut, M. Koksal, Y. Menceloglu, Macromol.

Biosci. 4 (2004) 649.11] E. Can, S. Kusefoglu, R.P. Wool, J. Appl. Polym. Sci. 81 (2001) 69.12] J. Lu, S. Khot, R.P. Wool, Polymer 46 (2005) 71.

[

[[

Coatings 64 (2009) 27–32

13] E. Sharmin, S.M. Ashraf, S. Ahmad, Int. J. Biol. Macromol. 40 (2007) 407.14] A. Guo, D. Demydov, W. Zhang, Z.S. Petrovic, J. Polym. Environ. 10 (2002) 49.15] A. Guo, Y. Cho, Z.S. Petrovic, J. Polym. Sci. Part A: Polym Chem. 39 (2000) 3900.16] T. Eren, S.H. Kusefoglu, J. Appl. Polym. Sci. 91 (2004) 4037.17] T. Eren, S.H. Kusefoglu, J. Appl. Polym. Sci. 91 (2004) 2700.18] T. Eren, S.H. Kusefoglu, J. Appl. Polym. Sci. 91 (2004) 2475.19] D.A. Wicks, Z.W. Wicks Jr., Prog. Org. Coat. 54 (2005) 141.20] F. Zafar, S.M. Ashraf, S. Ahmad, J. Appl. Polym. Sci. 104 (2007) 51.21] D.A. Raval, V.M. Patel, Paintindia LV 3 (2005) 51.22] M. Alam, E. Sharmin, S.M. Ashraf, S. Ahmad, Prog. Org. Coat. 50 (2004) 224.23] F. Zafar, S.M. Ashraf, S. Ahmad, Prog. Org. Coat. 51 (2004) 250.24] F. Zafar, E. Sharmin, S.M. Ashraf, S. Ahmad, J. Appl. Polym. Sci. 92 (2004) 2538.25] S. Ahmad, S.M. Ashraf, A. Hasnat, S. Yadav, A. Jamal, J. Appl. Polym. Sci. 82 (2001)

1855.26] S. Dutta, N. Karak, Prog. Org. Coat. 53 (2005) 147.27] S. Poul, Surface Coatings: Science and Technology, second ed., Wiley, West

Sussex, England, 1996, p. 284.28] L. Valette, C.P. Hsu, Polymer 40 (1999) 2059.29] M. Begum, Siddaramaiah, J. Mater. Sci. 39 (2004) 4615.30] R. Jayakumar, S. Radhakrishnan, S. Nanjundan, React. Funct. Polym. 57 (2003)

23.31] G. Malucelli, A. Priola, F. Ferrero, A. Quaglia, M. Frigione, C. Carfagna, Int. J.

Adhesive Adhesive 25 (2005) 87.32] K.H. Badri, Z. Othman, S.H. Ahmad, J. Mater. Sci. 39 (2004) 5541.33] G. Lligadas, J.C. Ronda, M. Galia, U. Beirnann, J.O. Metger, J. Polym. Sci. Part A:

Polym. Chem. 44 (2005) 634.34] H. Yeganesh, H.R. Mehdizadeb, Eur. Polym. J. 40 (2004) 1233.35] S. Ahmad, S.M. Ashraf, U. Riaz, Polym. Adv. Technol. 16 (2005) 1.36] A.M. Motawie, E.M. Sadek, M.M.B. Awad, A.F. El-Din, J. Appl. Polym. Sci. 67

(1998) 577.37] G.T. Howard, Int. Biodeter. Biodegr. 49 (2002) 245.38] A. Zlantanic, C. Lava, W. Zhang, Z.S. Petrovic, J. Polym. Sci. Part B: Polym. Phys.

42 (2004) 809.

40] K.J. Saunder, Organic Polymer Chemistry: An Introduction to the Organic Chem-istry of Adhesives, Fibers, Paints, plastic and rubber, second ed., Chapman andHall, New York, 1973, p. 358.

41] S. Ahmad, F. Naqvi, K. Verma, S. Yadav, J. Appl. Polym. Sci. 72 (1999) 1679.42] I. Janvi, Z.S. Petrovic, A. Guo, R. Fuller, J. Appl. Polym. Sci. 77 (2000) 1723.