research article spectral and thermal degradation of melamine...

Hindawi Publishing CorporationJournal of MaterialsVolume 2013 Article ID 262094 7 pageshttpdxdoiorg1011552013262094

Research ArticleSpectral and Thermal Degradation of Melamine Cyanurate

V Sangeetha1 N Kanagathara2 R Sumathi3 N Sivakumar4 and G Anbalagan4

1 Department of Physics DGVaishnav College Arumbakkam Chennai 106 India2Department of Physics Vel Tech Multi Tech Dr Rangarajan Dr Sakunthala Engineering College Avadi Chennai 62 India3 Department of Physics Vel Tech Polytechnic College Avadi Chennai 62 India4Department of Physics Presidency College Chennai 5 India

Correspondence should be addressed to G Anbalagan anbu24663yahoocoin

Received 14 December 2012 Accepted 25 January 2013

Academic Editor Carmen Alvarez-Lorenzo

Copyright copy 2013 V Sangeetha et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Melamine cyanurate an organic crystalline complex was synthesized by evaporation of an aqueous solution containing equimolarquantities of melamine and cyanuric acid The synthesized compound has been subjected to various characterizations like PowderXRD FT-IR TG-DTG SEM and SHG The presence of sharp diffraction peaks in the XRD confirms that the products are highlycrystalline The average particle size was calculated using the Debye-Scherrer formula and it was found to be 3067120583m Thermalbehavior of the grown crystal has been studied by TG-DTG analysis From TG-DTG it is found that the title crystal possessesgood thermal stability The activation energy was calculated using the Broido Coats-Redfern and Horowitz-Metzger methods Asharp peak exothermic peak at 40540∘C was assigned as the melting point of the title material SEM reveals the morphology of thesynthesized salt No detectable signal was observed during the Kurtz-Perry technique

1 Introduction

The rapid growth in material and processing technologymakes it essential for its use in various industrial applica-tions Cyanuric acid which is also known as triazinetriol ortrihydroxy cyaniding is a polymer of cyanic acid and arisesby dry heating of urea The organic derivatives of cyanuricacid find wide industrial applications todayThe compositionof cyanurates includes the s-triazine ring formed as a result oftrimerization of the cyanato groupsThe cyanuric acid deriva-tives containing the s-triazine ring (C

3N3) are considered

to be promising compounds for the synthesis of complexes[1] The strong interaction of the 120587 electrons of the cyanuricacid with the unshared electron pair of the amine nitrogenatom imparts basic properties to themelamine amino groupsTwo forms of hydrogen bonding between melamine andcyanuric acid are suggested with a planar structure [2 3]Flame retardancy is one of the important properties inindustrial applicationMelamine cyanurate offers better ther-mal stability (up to 377∘C) than pure melamine This helpsin polymer processing steps Both melamine and cyanuricacid have got several industrial applications [4] Melamine

cyanurate is particularly effective in improving fire safety ofnitrogen-based polymers such as polyamides (nylons) andthermoplastics (polyurethane) It can be used in epoxy poly-mers and in a variety of other substrates These complexesare very promising light-emitting materials because of theirgood thermal stability [5] The thermochemical propertiesof cyanuric acid were characterized using mass spectrometrymeasurements along with computational studies was alreadyreported by Mukherjee and Ren [6] Cyanuric acid is atriazine derivative and may also be described as two struc-tural isomers the enol-like triazine-triol and the keto-liketautomer Cyanuric acid is commonly used as a componentof bleaches in swimming pools [7 8] Cyanuric acid canform hydrogen bonded self-assemblies with specific surfacestructures and these assemblies have been used as surfacetemplates in supramolecular chemistry [9] Cyanuric acid isused in the preparation of high performance magnet-wireenamels and in electrical varnishes plastics with enhancedproperties flame retardant resins and solid lubricants andcross-linking and curing agents in the manufacture plasticsand coatings Cyanuric acid is also used to reduce nitrogenoxides (NOX) in stationary diesel engine exhaust gases In

2 Journal of Materials

the present work melamine cyanurate has been synthesizedand characterized by subjecting it to various studies like XRDFT-IR and TG-DTG and results are discussed in detail

Cyanuric acid is mainly used as a precursor to N-chlorinated cyanurates which are used to disinfect waterCyanuric acid is also used in the manufacture of specialtyintermediates used in the production of plastics and coatingsThis paper discusses the structure properties analysis chem-istry manufacture and uses of cyanuric acid

(HNCO)3+ (H2NCN)

3

997888rarr (HNCO)3sdot (H2NCN)

3

cyanuric acid +melamine 997888rarr melamine cyanurate(1)

Cyanuric acid (135-triazine-246-triol) is the cyclictrimer of cyanic acid [10] It is an organic compound withthe chemical formulaC

3H3N3O3 It haswide industrial appli-

cations This triazine derivative is a stable white odorlessand hygroscopic solid at room temperature It is used as astabilizer in recreational water treatment to minimize thedecomposition of hypochlorous acid by light in outdoorswimming pools and hot tubs Chlorinated derivatives ofcyanuric acid such as trichloro-s-triazinetrione and sodiumdichloro-s-triazinetrione are used as algacides or microbio-cides in swimming pool water and large-scale water systemsin industry [11] The ring in its molecule has an aromaticcharacter and the hydroxyl groups in the triol form of themolecule take on a phenolic character becoming somewhatmore acidic than hydroxyls in an alcohol The hydrogen ofany one of cyanuric acid hydroxyls can be neutralized to forma cyanurate salt [12] Melamine cyanurate is a halogen-freeflame retardant that can be used in thermoplastic urethanes(TPUs) for electrical wire coatings [13ndash15]

2 Materials and Methods

AR grade samples of melamine and cyanuric acid were takenin 1 1 ratio and the hot solution of cyanuric acid was addeddropwise to the hot solution ofmelamineThemixed solutionwas stirred well for nearly 4 hours and then allowed to coolat room temperature During a few days the entire solventwas evaporated and thewhite colourmelamine cyanuratewasobtained which are insoluble in water and common organicsolvents like acetone chloroform benzene alcohol and soforth but soluble in strong acids or basic solutions [16] Theobtained compound was then washed with distilled water toremove the presence of impurities and dried at a constanttemperature of 80∘C

3 Characterization

The synthesized compound has been subjected to variouscharacterization studies like Powder XRD FT-IR TG-DTGSEM and SHG The synthesized compound has been char-acterized by X-ray powder diffraction technique using RichSeifert X-ray powder diffractometer with CuK120572 radiationof 120582 = 15406 A The 2120579 range was analyzed from 10∘ to70∘ by employing the reflection mode for scanning Thedetector used was a scintillation counter A Perkin Elmer

5 10 15 20 25 30 350

100

200

300

400

500

600

Inte

nsity

(cps

)

2120579 (deg)

Figure 1 Powder X-ray diffraction pattern of melamine cyanuratecomplex

Spectrum ONE FT-IR spectrometer was employed to recordthe IR spectrum to analyze the functional groups present inthe synthesized melamine cyanurate compound The samplefor this measurement was finely grounded and mixed withKBr TG-DTG spectra were recorded for the synthesizedmelamine cyanurate compound using SDTQ 600V 80 build95 thermal analyzer with a heating rate of 20∘Cmin inthe temperature up to 1000∘C in nitrogen atmosphere TheQuanta 200 FEG scanning electron microscope (SEM) wasused to know the surface morphology of the synthesizedsalt with a resolution of 12 nm gold particle separation on acarbon substrate with a magnification from a minimum of12X to greater than 100000X The nonlinear optical activityof melamine cyanurate was identified by illuminating it withan NdYAG laser In this technique sample packed in a cellwas sandwiched between two glass plates and was subjectedto the output of a Q switched NdYAG laser emitting afunctional 120582 of 1064 nm with 10 ns pulse width with a poweroutput 20mW

4 Results and Discussion

41 Powder X-Ray Diffraction Analysis Figure 1 shows thepowder XRD pattern of melamine cyanurate The presenceof sharp diffraction peaks in the XRD confirms that theproducts are highly crystalline The average grain size (119863)of the synthesized was calculated by the Debye-Scherrerformula 119863 = 09120582120573 cos 120579 where 120582 is the wavelength ofCuK120572 line (120582 = 15418 A)120573 is the full width at halfmaximumheight and 120579 is the diffraction angle From the XRD analysisthe average particle size of the title material was estimated as3067 120583m

42 FT-IR Studies Figure 2 shows the FT-IR spectrum ofmelamine cyanurate and the vibration band assignment islisted in the Table 1 Internal vibrations ofmelaminemoleculewere recently published [17 18] According to crystallo-graphic data melaminium residues often form hydrogen

Journal of Materials 3

Table 1 Vibration band assignment of melamine cyanurate

Observed wavenumber (cmminus1) Assignment References3396 NH2 symmetric stretching type of vibrations of 3 triazine NH2 groups [3]3234 NndashH symmetric stretching [4]3041 NndashHsdot sdot sdotN stretching [8]2825 NndashH deformation (cyanuric acid) [12]2698 NH2 asymmetric stretching [10]1782 Stretching vibration of the carbonyl group C=O [2]1743 NH2 scissoring [9]1667 NH2 bending vibration [4]1528 C=N symmetric stretching [2]1449 CndashN symmetric stretching [2]1036 Ring breathing type of vibration [11]924 Ring breathing type of vibration [13]808 Ring-sextant out-of-plane bending type of vibration [9]771 Ring-sextant out-of-plane bending type of vibration [9]596 Ring bending vibration [11]529 Side chain in plane CndashN bending vibration [12]

500 1000 1500 2000 2500 3000 3500 4000

0

20

40

60

80

100

2825

2179

2698

2568

1782

1743

1667

152814

4912

0910

8710

3692

480

877

159

652

9

3041

3234

Tran

smitt

ance

()

3396

Wavenumber (cmminus1)

Figure 2 FT-IR spectrum of melamine cyanurate

bonds of NndashHsdot sdot sdotN and NndashHsdot sdot sdotO type Melamine cyanuratecomplex is held together by an extensive two-dimensionalnetwork of hydrogen bonds between the two compoundsThebands observed in the measured region 4000ndash350 cmminus1 arisefrom internal vibrations of melaminium cations cyanuricacid anions and water molecules the vibrations of both NndashHsdot sdot sdotO and OndashHsdot sdot sdotO types of hydrogen bond and fromthe vibrations of lattice The three amino groups in themelamine molecule have different types of hydrogen bondsThe melamine molecules are not linked by hydrogen bondsto each other Due to this system of hydrogen bond networkthe visible modes of NH

2 OH and the six-membered ring

of melamine are expected to give unusual frequencies andintensities for the IR bands [19] A strong peak at 3396 cmminus1is due to the NH

2symmetric stretching type of vibrations of

triazine groups [3] and this band usually occurs at 3328 cmminus1

in melamine crystal [20] The difference of 68 cmminus1 is knownas blue shift Similar shift is observed in Debrus et al [21]The strong intense peak at 3234 cmminus1 and medium peak at3041 cmminus1 are due to the formations of hydrogen bondingbetween NH

2NH groups NndashH stretching vibration occurs

at 3205 cmminus1 and 3079 cmminus1 which shifted to lower wavenumbers compared with those of melamine [5 12] Themedium peak at 2825 cmminus1 is assigned to NndashH deforma-tion Usually this band appears in the range of 2828 cmminus1ndash2907 cmminus1 in the cyanuric acid spectrum [22] A mediumpeak at 2698 cmminus1 can be assigned to NH

2asymmetric

stretching of vibration [19] The stretching vibration ofthe carbonyl group C=O at 1782 cmminus1 is due to cyanateanion [4] The strong peak at 1743 cmminus1 is assigned to NH

2

scissoring [18] Several pronounced differences have beenobserved between the IR spectrum of melamine crystal andthat for melamine cyanurate in region of NH

2bending

type of vibration A weak band appears at 1667 cmminus1 andthis occurs usually at higher frequencies (1666 cmminus1) Thismay be due to intermolecular interaction through the NH

2

groups of melamine molecule This causes the rising of theirfrequencies for bending type of motion [22] The triple bondCndashN stretching frequency in the IR spectra of cyanuratesshould be assigned to a strong polarization of the cyanurateanion by melamine cation [4] The benzene ring has twointense absorption bands corresponding to the vibrationsof CndashN and C=N bonds This appears in the region of1450 cmminus1ndash1500 cmminus1 and 1530 cmminus1ndash1600 cmminus1 respectivelywhich indicates the presence of cyanuric acid Similar bandsare shifted to lower frequency of 1449 cmminus1 and 1528 cmminus1in our spectra [4] The band corresponds to C=N stretch-ing frequency vibration occurs in the range of 1590 cmminus1ndash1600 cmminus1Whichmay either be appearingweak or disappearThe medium band at 1036 cmminus1 [20] and 924 cmminus1 originatesfrom ring breathing type of vibration And the peaks at


0 200 400 600 800 1000

102030405060708090

100110

41679

334144054

TG DTG

Wei

ght (

)

0

05

1

15

2

25

3

Temperature (∘C)

Der

ived

wei

ght (

∘ C

)Figure 3 TG-DTG spectrum of melamine cyanurate

375 380 385 390 395 400 405 410 415

0

02

04

06

08

1

Temperature (∘C)

120572

Figure 4 Fraction reacted 120572 versus temperature

808 cmminus1 and 771 cmminus1 are attributed to ring-sextant out-of-plane bending type of vibration [18] and the medium peak at596 cmminus1 is due to ring bending [20] and the peak at 529 cmminus1is due to the side chain in plane CndashN bending vibration [22]

43 Thermogravimetric Analysis Figure 3 shows the TG-DTG spectra recorded for the synthesized melamine cyanu-rateTheTG curve exhibitsmass losses in a single stage whichindicates that decomposition of the grown crystals takesplace sharply Initial mass is taken as 30210mg The thermaldecomposition of melamine cyanurate is accompanied bythe detachment of ammonia and gradual linking of cyanuricrings through imide bridges [4] The initial weight loss startsat 33414∘C and ends at 41679∘Cwith about 8825 of weightloss which corresponds to liberation of ammonia and watermolecules followed by the decomposition of cyanuric acidto volatile cyanates There is a sharp weight loss which isindicated by the derivative curve as peak This suggest thatthere is no other processes of decomposition except transitionfrom solid to liquid state which is designated asmelting point

147 148 149 15 151 152 15331

32

33

34

35

36

37

38

39

1000119879 (Kminus1)

ln119896

119884 = 2493691 minus 1424534119883

119877 = 099367

SD = 001828

Figure 5 The Arrhenius plot

and this occurs at 4054∘C as indicated in Figure 3 For puremelamine this occurs at 354∘C [4]Thus it can be understoodthat melamine cyanurate offers better thermal stability thanpuremelamine (up to 320∘C)This enables its use in polymersfor processing The decomposition at 407∘C may be due todecay of cyanates The thermal decomposition of melaminecyanurate may be decomposition of melamine and cyanuricacid Above 250∘C carbonyl groups are replaced with aminegroups in cyanuric acidThe decomposition ends with a finalresidue of 02513mg

Various researchers put forward integral method whichcan be applied to TG data assuming order of reaction andfrom which the activation energy is calculated Generallymass conversion can be calculates as

120572 =119898119900minus 119898

119898119900minus 119898119891

(2)

where119898119900is the initialmass119898 is the correspondingmass and

119898119891is the final massKinetic studies assumed that the isothermal rate of

conversion 119889120572119889119905 is a linear function of reactant concen-tration loss and of temperature-independent function of theconversion 120572

119889120572

119889119905= 119896119891 (120572) (3)

where119891(120572) is reactionmodel that depends on themechanismof degradation The function 119896 is described by the Arrheniusexpression

119896 = 119860 exp(minus119864119886

119877119879) (4)

ln 119896 = ln119860 minus119864119886

119877119879 (5)

where 119860 is preexponential factor independent of temper-ature 119864

119886is activation energy and 119877 is the universal gas

constantThe linear Arrhenius plot of ln 119896 versus 1119879 is plotted from

the TG data From the slope (minus119864119886119877) the activation energy

(119864119886) was calculated


(a) (b)

(c) (d)

(e) (f)

Figure 6 (a) SEM photograph with 6518X (b) SEM photograph with 10500X (c) SEM photograph with 11010X (d) SEM photograph with15000X (e) SEM photograph with 17900X and (f) SEM photograph with 35000X

Equation (3) can be writtens as

119889120572

119889119905= 120573(

119889120572

119889119879) = 119860119891(120572) exp(minus

119864119886

119877119879) (6)

where 120573 is the heating rate (20∘Cmin) and 119891(120572) is thereaction model

Figure 4 shows the fraction reacted 120572 versus temperatureThe Arrhenius plot is shown in Figure 5

431 Broidorsquos Method Consider

ln [ln( 1120572)] = (minus

119864119886

119877119879) + [

1198771198601198792

119864119886120573

] (7)

In Broidorsquos approximation [23] the thermal degradationis considered as first-order and the calculations are doneaccordingly The value of the activation energy (119864

119886) can

be calculated from the slope of the plot of graph betweenln [ln(1119910)] and 1119879 The calculated activation energy is32521 KJmolminus1


Table 2 Kinetic parameters obtained by different methods

Method Activation energy (kJmolminus1) 119877 SDArrhenius 11844 099367 001828Broido 32521 09964 003063Coats-Redfern 39333 099939 000598Horowitz-Metzger 33657 098575 003021

432 The Coats-Redfern Method Consider

ln [minus ln (1 minus 120572)

1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)

By using the Coats-Redfern expression [24] the value ofthe activation energy (119864

119886) can be calculated from the slope

of the plot of graph between ln[minus ln(1 minus 120572)1198792

] and 1119879 Thecalculated activation energy is 39333 KJmolminus1

433 The Horowitz-Metzger Method [25] Consider

ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)

By using the expression above (9) the activation energy(119864119886) can be calculated from the slope of the plot of graph

between ln(1 minus 120572) and 1119879 The calculated activation energyis 33657 KJmolminus1 The activation energy (119864

119886) and pre-

exponential factor (119860) calculated from all the above methodswere listed in Table 2

44 Scanning Electron Microscope Analysis Scanning elec-tron microscopy was used to study the surface features ofthe synthesized salt Figures 6(a)ndash6(f) shows different typesof morphologies exhibited by synthesized salt at differentmagnifications The various types of morphologies includespherulites platelets cuboids and coalesced and rod-shapedcrystals It is seen from SEM observation that the decompo-sition takes place starting from a relevant number of nucleiwhich grow rapidly enough Melamine cyanurate formsspoke-like crystals in aqueous solutions Figures 6(a)ndash6(f)shows the SEM photograph of melamine cyanurate underdifferent magnifications with 1ndash5120583m in size

45 Kurtz Perry Technique The sample was found to beNLO inactive There is no emission of green (120582 = 520 nm)radiation which confirms that there is no production ofsecond harmonic generation

5 Conclusion

Melamine cyanurates were obtained by employing slow evap-oration solution growth technique The grown crystals are of1 120583m to 5 120583m size The Powder XRD pattern of the complexensures its crystallinity The FTIR spectrum clearly indicatesthe presence of functional groups in the complex The TG-DTG studies were used to formulate the decomposition

pattern of the complex compound and it is found thatthermal stability for melamine cyanurate is more than thatof pure melamine and hence finds applications in polymersfor processing at high temperatures From the Arrheniusexpression a linear straight line equation is obtained Acti-vation energy was calculated by four different methods theArrhenius Broido Coats-Redfern and Horowitz-Metzgermethods Among four different methods activation energyobtained by Coats-Redfern is higher And activation energyobtained by Arrhenius method 119864

119886is 1184 kJmol which is

much lower than that obtained fromothermethodsThis is sobecause the data are taken at a single heating rate (20∘Cmin)in all the cases which may not be applicable This is moreso if mechanism of decomposition is going to change andthis will be confirmed at different heating rates like 5 10 and15∘Cmin Also these complexes are very promising light-emitting materials due to their good thermal stability Thereis no emission of green signal through Kurtz-Perry techniquewhich confirms that the synthesized material is not havingsecond harmonic generation efficiency Further research hasto be carried out and can be extended to several industrialand research applications

References

[1] H Zhu Z Yu X You H Hu and X Huang ldquoThe crystaland molecular structure of bis(melamine)silver(I) perchlorateAg(C

3

H6

N6

)2

ClO4

rdquo Journal of Chemical Crystallography vol29 no 2 pp 239ndash242 1999

[2] Y Wang B Wei and Q Wang ldquoCrystal structure of melaminecyanuric acid complex (11) trihydrochlorideMCAsdot3HClrdquo Jour-nal of Crystallographic and Spectroscopic Research vol 20 no 1pp 79ndash84 1990

[3] F H Herbstein ldquoPurported ldquomelamine cyanuric acid trihydro-chloriderdquo C

3

H6

N6

sdotC3

H3

N3

O3

sdot3HCl is actually ldquodiprotonated-melamine cyanuric acid dichloride dihydraterdquo (C

3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2

Ordquo Journal of Chemical Crystallographyvol 33 no 7 pp 527ndash529 2003

[4] G R Seifer ldquoCyanuric acid and cyanuratesrdquo Russian Journal ofCoordination Chemistry vol 28 no 5 pp 301ndash324 2002

[5] Y Qiu and L Gao ldquoBlue-emitting cyanuric acid-melaminecomplexes from urea thermolysisrdquoMaterials Research Bulletinvol 40 no 5 pp 794ndash799 2005

[6] S Mukherjee and J Ren ldquoGas-Phase acid-base properties ofmelamine and cyanuric acidrdquo Journal of the American Societyfor Mass Spectrometry vol 21 no 10 pp 1720ndash1729 2010

[7] A Zaknich ldquoSwimming pool and Spa water testing pro-cessrdquo Granted innovation Pat (Australia) Application AU2009100474 8 2009

[8] V I Teichberg ldquoMethods and compositions and Devicesfor maintaining chemical balance of chlorinated waterrdquo YedaResearch and Development coLtd Israel In PCT Int ApplApplication WO 2007107981 58 2007

[9] K Damodaran G J Sanjayan P R Rajamohanan S Gana-pathy and K N Ganesh ldquoSolid state NMR of a molecularself-assembly multinuclear approach to the cyanuric acid-melamine systemrdquo Organic Letters vol 3 no 12 pp 1921ndash19242001

[10] N Kriebizsch N V Degussa-Antwerpen H Klenk and WH Degussa in Ullmannrsquos Encyclopedia of Industrial Chemistry


W Gerhartz Y S Yamamoto L Kaudy R Pfefferkorn and FRounsavaille Eds vol 8 p 191 Wiley New York NY USA 5thedition 1987

[11] G Herzberg and C I Reid ldquoInfra-red spectrum and structureof the HNCOmoleculerdquoDiscussions of the Faraday Society vol9 pp 92ndash99 1950

[12] P G Maiella and T B Brill ldquoSpectroscopy of hydrothermalreactionsrdquo Applied Spectroscopy vol 50 pp 829ndash835 1996

[13] J Zhang M Lewin E Pearce M Zammarano and J WGilman ldquoFlame retarding polyamide 6 with melamine cyanu-rate and layered silicatesrdquo Polymers for Advanced Technologiesvol 19 no 7 pp 928ndash936 2008

[14] P Gijsman R Steenbakkers C Furst and J Kersjes ldquoDiffer-ences in the flame retardant mechanism of melamine cyanuratein polyamide 6 and polyamide 66rdquo Polymer Degradation andStability vol 78 no 2 pp 219ndash224 2002

[15] Z Y Wu W Xu Y C Liu J K Xia Q X Wu and WJ Xu ldquoPreparation and characterization of flame-retardantmelamine cyanuratepolyamide 6 nanocomposites by in situpolymerizationrdquo Journal of Applied Polymer Science vol 113 no4 pp 2109ndash2116 2009

[16] R Henricus and M Kierkels ldquoPatent application titleMelamine cyanurate in crystalline form InventorsrdquoJoAnn Villiamizar Ciba CorporationPatent DepartmentEP1799655A1 2007

[17] R J Meier J R Maple M J Hwang and A T Hagler ldquoMolec-ular modeling urea- and melamine-formaldehyde resins 1A force field for urea and melaminerdquo Journal of PhysicalChemistry vol 99 no 15 pp 5445ndash5456 1995

[18] P J Larkin M P Makowski N B Colthup and L A FloodldquoVibrational analysis of some important group frequencies ofmelamine derivatives containing methoxymethyl and carba-mate substituents mechanical coupling of substituent vibra-tions with triazine ring modesrdquo Vibrational Spectroscopy vol17 no 1ndash3 pp 53ndash72 1998

[19] C Y Panicker H T Varghese A John D Philip and HI S Nogueira ldquoVibrational spectra of melamine diborateC3

N6

H6

2H3

BO3

rdquo Spectrochimica Acta A vol 58 no 8 pp1545ndash1551 2002

[20] W J Jones and W J Orville-Thomas ldquoThe infra-red spectrumand structure of dicyandiamiderdquo Transactions of the FaradaySociety vol 55 pp 193ndash202 1959

[21] S Debrus M K Marchewka M Drozd and H Rata-jczak ldquoVibrational calorimetric and nonlinear optical studiesof melaminium-bis(trichloroacetate) monohydrate molecular-ionic crystalrdquo Optical Materials vol 29 no 8 pp 1058ndash10622007

[22] E Garcıa-Lopez G Marci N Serpone and H Hidaka ldquoPho-toassisted oxidation of the recalcitrant cyanuric acid substratein aqueous ZnO suspensionsrdquo Journal of Physical Chemistry Cvol 111 no 49 pp 18025ndash18032 2007

[23] A Broido ldquoA simple sensitive graphical method of treatingthermogravimetric analysis data part Andash2rdquo Journal of PolymerScience vol 7 no 10 pp 1761ndash1773 1969

[24] A W Coats and J P Redfern ldquoKinetic parameters from ther-mogravimetric datardquoNature vol 201 no 4914 pp 68ndash69 1964

[25] HHHorowitz andGMetzger ldquoAnewanalysis of thermogravi-metric tracesrdquo Analytical Chemistry vol 35 no 10 pp 1464ndash1468 1963

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Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


the present work melamine cyanurate has been synthesizedand characterized by subjecting it to various studies like XRDFT-IR and TG-DTG and results are discussed in detail

Cyanuric acid is mainly used as a precursor to N-chlorinated cyanurates which are used to disinfect waterCyanuric acid is also used in the manufacture of specialtyintermediates used in the production of plastics and coatingsThis paper discusses the structure properties analysis chem-istry manufacture and uses of cyanuric acid

(HNCO)3+ (H2NCN)

3

997888rarr (HNCO)3sdot (H2NCN)

3

cyanuric acid +melamine 997888rarr melamine cyanurate(1)

Cyanuric acid (135-triazine-246-triol) is the cyclictrimer of cyanic acid [10] It is an organic compound withthe chemical formulaC

3H3N3O3 It haswide industrial appli-

cations This triazine derivative is a stable white odorlessand hygroscopic solid at room temperature It is used as astabilizer in recreational water treatment to minimize thedecomposition of hypochlorous acid by light in outdoorswimming pools and hot tubs Chlorinated derivatives ofcyanuric acid such as trichloro-s-triazinetrione and sodiumdichloro-s-triazinetrione are used as algacides or microbio-cides in swimming pool water and large-scale water systemsin industry [11] The ring in its molecule has an aromaticcharacter and the hydroxyl groups in the triol form of themolecule take on a phenolic character becoming somewhatmore acidic than hydroxyls in an alcohol The hydrogen ofany one of cyanuric acid hydroxyls can be neutralized to forma cyanurate salt [12] Melamine cyanurate is a halogen-freeflame retardant that can be used in thermoplastic urethanes(TPUs) for electrical wire coatings [13ndash15]

2 Materials and Methods

AR grade samples of melamine and cyanuric acid were takenin 1 1 ratio and the hot solution of cyanuric acid was addeddropwise to the hot solution ofmelamineThemixed solutionwas stirred well for nearly 4 hours and then allowed to coolat room temperature During a few days the entire solventwas evaporated and thewhite colourmelamine cyanuratewasobtained which are insoluble in water and common organicsolvents like acetone chloroform benzene alcohol and soforth but soluble in strong acids or basic solutions [16] Theobtained compound was then washed with distilled water toremove the presence of impurities and dried at a constanttemperature of 80∘C

3 Characterization

The synthesized compound has been subjected to variouscharacterization studies like Powder XRD FT-IR TG-DTGSEM and SHG The synthesized compound has been char-acterized by X-ray powder diffraction technique using RichSeifert X-ray powder diffractometer with CuK120572 radiationof 120582 = 15406 A The 2120579 range was analyzed from 10∘ to70∘ by employing the reflection mode for scanning Thedetector used was a scintillation counter A Perkin Elmer

5 10 15 20 25 30 350

100

200

300

400

500

600

Inte

nsity

(cps

)

2120579 (deg)

Figure 1 Powder X-ray diffraction pattern of melamine cyanuratecomplex

Spectrum ONE FT-IR spectrometer was employed to recordthe IR spectrum to analyze the functional groups present inthe synthesized melamine cyanurate compound The samplefor this measurement was finely grounded and mixed withKBr TG-DTG spectra were recorded for the synthesizedmelamine cyanurate compound using SDTQ 600V 80 build95 thermal analyzer with a heating rate of 20∘Cmin inthe temperature up to 1000∘C in nitrogen atmosphere TheQuanta 200 FEG scanning electron microscope (SEM) wasused to know the surface morphology of the synthesizedsalt with a resolution of 12 nm gold particle separation on acarbon substrate with a magnification from a minimum of12X to greater than 100000X The nonlinear optical activityof melamine cyanurate was identified by illuminating it withan NdYAG laser In this technique sample packed in a cellwas sandwiched between two glass plates and was subjectedto the output of a Q switched NdYAG laser emitting afunctional 120582 of 1064 nm with 10 ns pulse width with a poweroutput 20mW

4 Results and Discussion

41 Powder X-Ray Diffraction Analysis Figure 1 shows thepowder XRD pattern of melamine cyanurate The presenceof sharp diffraction peaks in the XRD confirms that theproducts are highly crystalline The average grain size (119863)of the synthesized was calculated by the Debye-Scherrerformula 119863 = 09120582120573 cos 120579 where 120582 is the wavelength ofCuK120572 line (120582 = 15418 A)120573 is the full width at halfmaximumheight and 120579 is the diffraction angle From the XRD analysisthe average particle size of the title material was estimated as3067 120583m

42 FT-IR Studies Figure 2 shows the FT-IR spectrum ofmelamine cyanurate and the vibration band assignment islisted in the Table 1 Internal vibrations ofmelaminemoleculewere recently published [17 18] According to crystallo-graphic data melaminium residues often form hydrogen




500 1000 1500 2000 2500 3000 3500 4000

0

20

40

60

80

100

2825

2179

2698

2568

1782

1743

1667

152814

4912

0910

8710

3692

480

877

159

652

9

3041

3234

Tran

smitt

ance

()

3396











2asymmetric


2


2bending


2



0 200 400 600 800 1000

102030405060708090

100110

41679

334144054

TG DTG

Wei

ght (

)

0

05

1

15

2

25

3

Temperature (∘C)

Der

ived

wei

ght (

∘ C


375 380 385 390 395 400 405 410 415

0

02

04

06

08

1

Temperature (∘C)

120572




147 148 149 15 151 152 15331

32

33

34

35

36

37

38

39

1000119879 (Kminus1)

ln119896

119884 = 2493691 minus 1424534119883

119877 = 099367

SD = 001828




120572 =119898119900minus 119898

119898119900minus 119898119891

(2)




119889120572

119889119905= 119896119891 (120572) (3)


119896 = 119860 exp(minus119864119886

119877119879) (4)

ln 119896 = ln119860 minus119864119886

119877119879 (5)







(a) (b)

(c) (d)

(e) (f)



119889120572

119889119905= 120573(

119889120572

119889119879) = 119860119891(120572) exp(minus

119864119886

119877119879) (6)




ln [ln( 1120572)] = (minus

119864119886

119877119879) + [

1198771198601198792

119864119886120573

] (7)


119886) can







1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)






ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)



119886) and pre-




5 Conclusion





References


3

H6

N6

)2

ClO4




3

H6

N6

sdotC3

H3

N3

O3


3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2




















N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






500 1000 1500 2000 2500 3000 3500 4000

0

20

40

60

80

100

2825

2179

2698

2568

1782

1743

1667

152814

4912

0910

8710

3692

480

877

159

652

9

3041

3234

Tran

smitt

ance

()

3396











2asymmetric


2


2bending


2



0 200 400 600 800 1000

102030405060708090

100110

41679

334144054

TG DTG

Wei

ght (

)

0

05

1

15

2

25

3

Temperature (∘C)

Der

ived

wei

ght (

∘ C


375 380 385 390 395 400 405 410 415

0

02

04

06

08

1

Temperature (∘C)

120572




147 148 149 15 151 152 15331

32

33

34

35

36

37

38

39

1000119879 (Kminus1)

ln119896

119884 = 2493691 minus 1424534119883

119877 = 099367

SD = 001828




120572 =119898119900minus 119898

119898119900minus 119898119891

(2)




119889120572

119889119905= 119896119891 (120572) (3)


119896 = 119860 exp(minus119864119886

119877119879) (4)

ln 119896 = ln119860 minus119864119886

119877119879 (5)







(a) (b)

(c) (d)

(e) (f)



119889120572

119889119905= 120573(

119889120572

119889119879) = 119860119891(120572) exp(minus

119864119886

119877119879) (6)




ln [ln( 1120572)] = (minus

119864119886

119877119879) + [

1198771198601198792

119864119886120573

] (7)


119886) can







1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)






ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)



119886) and pre-




5 Conclusion





References


3

H6

N6

)2

ClO4




3

H6

N6

sdotC3

H3

N3

O3


3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2




















N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 200 400 600 800 1000

102030405060708090

100110

41679

334144054

TG DTG

Wei

ght (

)

0

05

1

15

2

25

3

Temperature (∘C)

Der

ived

wei

ght (

∘ C


375 380 385 390 395 400 405 410 415

0

02

04

06

08

1

Temperature (∘C)

120572




147 148 149 15 151 152 15331

32

33

34

35

36

37

38

39

1000119879 (Kminus1)

ln119896

119884 = 2493691 minus 1424534119883

119877 = 099367

SD = 001828




120572 =119898119900minus 119898

119898119900minus 119898119891

(2)




119889120572

119889119905= 119896119891 (120572) (3)


119896 = 119860 exp(minus119864119886

119877119879) (4)

ln 119896 = ln119860 minus119864119886

119877119879 (5)







(a) (b)

(c) (d)

(e) (f)



119889120572

119889119905= 120573(

119889120572

119889119879) = 119860119891(120572) exp(minus

119864119886

119877119879) (6)




ln [ln( 1120572)] = (minus

119864119886

119877119879) + [

1198771198601198792

119864119886120573

] (7)


119886) can







1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)






ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)



119886) and pre-




5 Conclusion





References


3

H6

N6

)2

ClO4




3

H6

N6

sdotC3

H3

N3

O3


3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2




















N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)

(e) (f)



119889120572

119889119905= 120573(

119889120572

119889119879) = 119860119891(120572) exp(minus

119864119886

119877119879) (6)




ln [ln( 1120572)] = (minus

119864119886

119877119879) + [

1198771198601198792

119864119886120573

] (7)


119886) can







1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)






ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)



119886) and pre-




5 Conclusion





References


3

H6

N6

)2

ClO4




3

H6

N6

sdotC3

H3

N3

O3


3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2




















N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








1198792] = ln( 119860119877

120573119864119886

)[1 minus2119877119879

119864119886

] minus119864119886

119877119879for 119899 = 1

(8)






ln (1 minus 120572) =119864119886(119879 minus 119879

119901)

119877119879119901

for 119899 = 1 (9)



119886) and pre-




5 Conclusion





References


3

H6

N6

)2

ClO4




3

H6

N6

sdotC3

H3

N3

O3


3

H8

N6

)2+sdotC3

H3

N3

O3

sdot2Cl-sdot2H2




















N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials














N6

H6

2H3

BO3















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article spectral and thermal degradation of melamine...

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