View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Defence Science Journal Defence Science Journal, V 01 47, ~o 3, July I ~97, pp. 401-409 Q 1997, DESIDO~ , , ~ I Structure-Properties \ Methacrylate , Correlation & Alkyl Seema Defence Researc,h & DevelJpment in Copolymers Methacrylates of Methyl Agarwal Establishment. Gwalior-474 002. and Veena Indian Institute Choudhary of & Technology, I.K. New Varrna Delhi-110 016 ABSTRACT I The resul~ o~ a study on the copolymerisation of methyl methacrylate (MMA) with varying mol fractions of octyl m~thacrylate, decyl methacrylate (DMA), lauryl methacrylate (LMA) and stearyl methacrylate (SMA~ by free radical polymerisation using benzoyl peroxide as the initiator are presented. It was hnticipated that ~ncorporation of alkyl methacrylate (AMA) having a long alkyl side chain in poly(methyl methadrylate) (PMMA) backbone may lead to an improvement in the toughness I of the cast sh~ets. Such copolymers can be u~ed for low temperature applications in defence. I The glas.s transition temperature of the polymers determined using differential scanning calorimetry was found to decrease with increase in length 9f the alkyl side chain and the comonomer content. A significant increase in percent!lge elongation and decrease in tensile strength, modulus anQ . per cent transmittance was observed on incorporation of AMA in PMMA backbone. In the copolymers of SMA and MMA, significant opacity was observed. I I. INTRODUCTION i Varma and coworkersl-8 sation and thermaf behaviour (MMA) with several vinyl reported of methyl monomers. plasticisation due to the presence of long alkyl copolymeri- chain would lead to an improvement methacrylate of the fast sheets without The effect of useful optical alkyl groupt and structure of the side chain! on physico-met:hanical properties of cast acrylic sheets was als() studied6. I. t The present systematically in alkyl composition st~dy was aimed At , investigating the effect of length qf the side chain mcthacr}\late I on (AMA) the bnd properties Rcccivcd25 July 1996,rc:!viscd~8January1997 in toughness affecting properties. the Such cast sheets may be used for low temperature applications in defence. Several copolymer sheets were therefore prepared by copolymerising 0.05-0.25 mol (OMA), fractions decyl copolymer meihacrylate of (SM~) MMA significantly and mechanical side of octyl methacrylate (I.MA) I with MMA. and methacrylate (DMA), stearyl lau~yl methacrylate The effect of I~ngth of the alkyl I 401 DEF SCI J, VOL 47, NO 3, JULY 1997 transmittance, mechanical properties and softening temperature was evaluated. 2 I.:X I.I~ It IM I.:NT A I.. D I~T A 11..S 2.1 M a terials Methyl methacrylate (MMA, Aldrich) was purified by washing with 10 per cent NaOH solution followed by water. MMA was left overnight over anhydrous Na2S04 and diJtilled under reduced pressure. OMA, DMA, LMA and SMA were synthesised in the laboratory by esterifying methacrylic acid with corresponding alcohol using p-toluene sulfonicl acid as catalyst. Benzoyl peroxide (BPO) was tecrystalli'sed from chloroform solution. I bath and the temperature 4 hr. The assembly maintained was then ) at 15 °c for removed , a~d placed in an air oven ~t 90 °c for 90 min and then at 120 °c fur ullutl,cr 90 mill. 011 tllc CUillplctiull uf polymerisation. tpe mold was cooled and solidified , I 3 acrylic sheets of 18 x 24 x 0.2 cm were taken out by p~ssing a stream of w~ter. I , I copolymer Twenty taking different comonomers initial sheets mol (OMA, were fractions DMA, or voids. by of t ~MA and SMA) feed. All fabricated'sheets bubbles Ifepared I (0.05-0.25) in the were free from air sheets have been , designated as OMS, OMS, LMS and SMS, respec~ively. A. suffix indicating the mol per cent of .comonomers These taken in the initial feed has been , appended to the generic nam,e. For example, a sheet 2.2 Preparation or Prepolymer Syrup To fabricate sheets, a prepolymer syrup was prepared by taking requisite quantities of MMA and comonomers in a round bottom flask fitted with prepared by using 5 pr 25 mol per cent of OMA a nitrogen inlet and a reflux condenser. Nitrogen gas was bubbled through the solution and then are given 1 per cent (w/w) BPO was added. The temperature was then raised to 75 °C. When the extent of conversion was -15 per cent, the flask was be,en designated respectively. designation as IOMS-5 or in Table I. ~~sidual monomer release agent. A polyvinyl chloride (PVC) gasket of 2 mm diameter was placed in between the plates which were held together by ~sing steel clamps. One side of the n1old was kept 9Pen for pouring the prepolymer syrup. 2.4 Fabrication of Sheets 1 f About 100 ml of monomer-polymer syrupwas used for fabricating sheets, because it reduces the amount of heat to be dissipated, reduces tthe probability of trapped air bubbles, shrinkage and also lowers the initiation temperature. After filling the glass mold with the prepolymer syrup, the opening was closed using a metal plate and clamps. The filled mold was placed in a preheated water 402 content Table I. Characteristics of:lkyl methacrylate copolymer sheets fabricated , Density at 28+0.1 °c (g/cm3) 1.176 or Mold Two-toughened glass plates (21.5 x 29.0 cm2) were cleaned thoroughly and sprayed with a silicon OMS-25, The feed, cbmposition, sample and 'thickness of the fabricated sheets removed and the reaction was arrested by quenchcooling the contents of the flask in ice water. 2.3 Preparation has OMS-5 . OMS-IO OMS-15. OMS-20 OMS-25 , DM~-5 DMS-IO DMS-15 DMS-20 DMS-25 LMS-5 LMS-IO LMS-15 LMS-20 L~S-25 SMS-S' SMS-IO SMS-1S SMS-20 0.9510 0.9008 0.8528 0.8016 0.7523 1.88 0.9501 0.9012 0.8510 0.8001 0.7540 1.80 1.88 1.92 1.89 1.88 1.82 1.8~ 1.89; 1.89t 0.9517 1.79 0.901~ 0.851i 0.8031 0.7514 1.8b 0.9540 0.9011 0.8516 1.80 0.80231 1.88 2.05, 1.95' 1.65 2.70 1.94 1.80 1.8~ 1.89 1.157 1.131 1.111 1.102 2.65 2.90 2.05 2.45 , 2.50 \ 1.162 1.'51 1.131 1.122 1.101 2.75 2.20 1.160 1.153 1.130 1.109 1.018 1.86 1.82 1.164 2.95 , 3.55 2.85 2.00 2.15 1.158 1.149 1.140 1.128 AGARWAL, et al : STRUCTURE-PROPERTIES I was determined sheets by with exttacting methanol a small fer apparatus. ThF residual in all the coPflymers. 36 hf portion using of I moJ1omer was -1.5 I the CORRELATION recording Soxhlet function per cent I I which IN COPOLYMERS moduli of temperature. measure solar CHARACT~RISATION The intrinsic & TESTING I viscosity in chloroform was I at 30 :t Ubbelohde copolymer suspension level. viscometer. The ( I samples in po\\\der form were used for evaluati?g T g using DSC t4chnique. of were obtained sheets polymer excess °c the\ polymers . determined samples I of in chloroform by dropwise of analyser by dissolving and ~ddition methanol.' A using The powdered small pifces precipitating of th:is solution DuPont having ;a 910 ~SC module 1090 were used in each ~xperiment. To keep the thermal history same, of samples all th~ were . copolymers heated bnd this temperature for 2 min. The samples pNere allowed at a was to cool and then DSC traces wdre recorded in a second I heating cycle. To characterise the glass transition I region, three chara~teristic temperatures were T on Temperature at which deviation from the base line starts. It was obtained by extrapolating the base line and drawing tangent at the .steep portion of the curvet . TI Tg Post-transition temperature becomes straight; It extrapolation,' and I TempefatureJ at the at which the base line was obtained by according tester to ASTM point of the mm, Dyna~ic copolymer mechanical measJrements sheets 'werc carried o~t using of the P.olymcr mm) sirze of j frequencies 30 x ,10 x of I ahd 10 Hz and a 2 mm3 were used for determined narrow tensile conditions. For I specimens (length section 12.5 mm, were used. The edges of the us~d full using for a fine sand paper. testing were: Gauge scale load = 500 kg, chart of five samples were tested for each composition. 4. RESULTS All & DISCUSSION the fabricated colourless sheets were transparent except SMS-20. The intrinsic which composition. (TI) of the copolymers 1.65-3.5 dl/g I). The TI trend with copolymer formed for copolymers Isolated at low per cent), indicating that the were of higher molecular This can be attributed to a reduction at high conversion due t() viscosity effect), weight thereby homopolymerisation9. in Table to high A gel effect density sheets was determined summarised per cent, leading has been reported The weight. in the termina- ( -98.5 copolymers. 15 per cent conversion are (Table These values were higher than that of the values obtained conversio'n 7 ( -12 polymers and was opaque. viscosity values showed no systematic copolymers mechanical was speed = 100 mm and cross head speed = 1 mm!min. of 5 °C/ll1in, dynarhic ambient were polished = 50 mm, copolymer sample df conditions length I.thermal analyser model Mk II in the range 50-150 °~. A heati~g rate Laboratories sheets. on an Instron dumb bell-shaped -2 specimens The I at width thickness molecular transitil!>n. the were 0-638 model-1121 tion reaction inflection of spectrophotometer properties was in the range noted: was used to Properties tensile A minimum powdered in I?SC pan to 120 °c heating rate of 10 °C/min maintained the The 165 the transition temperatures. A sample size I of 5.9 :t 0.9 mg' a.nd a heating rate of 10 °C/min transmittance 3.1 J Mechanical into evaluate as a used to measure transmittance of the sheets in the I wavelength range 300-800 nm. tensile testing, was used to pyranometer, UV -visible j the thermal and loss modulus) The D and S alphatometer is a miniaturised Hitachi-330 3. (storage I. above in MMA of the and the results Density of the decreased with increase in mol fraction I of the comonomers having long alkyl side. 403 DEF SCI J, VO~ 47, NO 3, JULY 1997 Table 2. Solar transmittance sheets and turbidity values for copolymer The solar/ transmittance summarised Sample designation Solar transmittan(!e Turbidity solar transmitla?ce ('t) ti on of PMMA 0.91 0.052 increasing OMS-2S 0.90 0.89 0.88 0.87 0.87 0.056 0.062 0.066 0.073 0.074: DMS-5 DMS-IO DMS-15 DMS-20 DMS-25 0.88 0.88 0.87 0.86 0.85 0.071 0.070 0.076 0.080 0.086 LMS-5 LMS-IO LMS-15 LMS-20 LMS-25 0.88 0.84 0.071 0.077 0.081 0.083 0.097 SMS-S 0.86 0.82 0.70 0.25 0.081 0.107 0.189 0.737 OMS-S OMS-IO OMS-1S OMS-20 SMS-IO SMS-1S SMS-20 0.87 0.86 0.86 Table 80.0 3. Percent 15 LMS-5 LMS-IO LMS-15 LMS-20 LMS-25 78.2 79.5 74.0 78.0 78.0 82.5 82.5 79.0 78.2 82.0 80.0 73.0 fraction when mol per cent wl1ich ~nd LMA. On in the case of MMA-SMA significant "and in of comonomers, a , of copolymer sheets in turbi~ity decrease I increase low of in in mol percentage turbidity fractions '~MA had was reduced 70 was of SMA A copolymer ,when 20 mol per cent df SMA having per cent to 25 per cent was incorporated in poly(methyl fethacry,late) (PMMA) backbone. Decrease in transmittance on the addition of higher I mol fractions ofl SMA could be due to incompatibility ofl methacrylate), which chain. PMMA with Ihds a non-polar poly(stearyl alkyl side , The percentage transmittance of the copolymer sheets at different wavelengt~ values for copolymer 83.2 8~.2 82.0 85.0 78.0 77.5 even transmittance, 81.5 84.0 80.5 83.5 76.5 78.5 82.5 76.0 77.5 76.0 404 obs~rved 77.0 '1.0 77.0 70.0 71.5 71.0 OMS-20 mol data are decrease on copolymerisa- DMA "were present in the backbone. 86.5 DMS-5 DMS-IO DMS-15 DMS-20 DMS-25 OMS-15 a transmittance 85.5 80.2 the OMA, was seen. However, 83.0 OMS-25 OMS-IO was obser~ed with increase copolymers, " lIght transmittance 67.0 75.0 72.0 74.0 67.5 OMS-5 MMA marginal ~nd turbidity in Table 12. A inarginaf 83.0 84.5 85.0 86.0 80.0 81.5 81.0 82.5 80.0 82.0 84.5 85.0 85.5 83.5 86.0 85.0 84.5 82.5 83.0 84.4 sheets at different 87.0 Was also measured wavelength's 87.0 87.5 88.0 87.0 88.0 84.0 87.5 81.0 84.0 86.0 86.5 86.2 87.0 87.5 82.2 83.0 84.0 86.0 86.5 87.5 79.0 79.5 81.0 85.5 87.0 83.0 83.5 83.0 86.0 84.0 87.0 87.1 85.0 85.0 83.2 84.~ 87.0 88.0 85.0 86.0 85.0 85.8 86.0 86.5 85.0 86.8 86.0 86.0 87.0 85.5 87.0 86.5 87.5 88.0 86.0 87.0 86.5 86.2 84.5 86.5 86.0 87.0 83.5 \ ~ AGARWAL, Table I. values 4. Turbidity ro~ et al : STRUCTURE-PROPERTIES copolymer sheets at different CORRELATION IN COPOLYMERS Table 5. Glass transition temperaturesjror copolymer sheets wavelengths OMS-S OMS-IO OMS-IS OMS-20 OMS-2S DMS-5 DMS-IO DMS-15 DMS-20 DMS-25 0.0788 I 0.0756 0.0694 0.1390 0.1173 0,1327 0~1180 0~1673 6.0978 0.08(> I 0.1093 0.085~ 0.1329 0.0802 0.07'40 0.0970 0.0767 9.122d 0..0740 0.0679 0.0908 0.0706 0.11 to 0.1341 0.1056 0.1491 p.1348 0.1452 0.0935 0.0815 0.1111 0.1017 0.1050 0.0837 0.0766 0.0773 0.1074 0.090' LMS-S LMS-IO LMS-lS LMS-20 LMS-2S 0.1372 SMS-S 0.1380 SMS-IO 0.1760 SMS-lS 0.4201 SMS-20 Opaque 0.1 d68 0.087p 0.096~ 0.0828 0.0902 0.1267 0.1351 0..0902 9.1206 0.2529 I 0.098p 0.0922 0.0973 0.0702 0.0883 0.0798 0.0859 0.0842 0.0805 0.0859 0.0777 !>.0837 0.0778 0.0710 0.0798 0.0765 0.0805 0.090~ 0.1206 0.2529 0.0837 0.1072 0.2118 (Table 3). It was lowl at lower wavelength The turbidity increase PMMA 0.1012 of in 'the I mol. (Table 4). The showed higher copolymers fraction J ;MMA:SMA values other copolymer the DMS-5 DMS-I0 DMSI-15 DMS-20 DMS-25 LMS~5 LMS-I0 LMS-20 LMS-25 SMS-5 97.2 (105) 83.3 (95.3) 76.9 (86.5) 58.1 (77.6) 56.6 (69.3) 97.0 (99.7) 80.0 (85.5) 71.0 (72.4) 62.0 (60.,0) 55.0 (48.9) 90.8 (98.9) 74.3 (84.4) 55.9 (57.0) 52.8 (45.0) 86.9 (-) lEMPERATURE ~ C) 80 100 ro with 120 DMS-5 l~ comonomer copolymer of turbidityl sheets. I OMS-5 OMS-I0 OMS-15 OMS-20 OMS-25 (400 nm). increased of I 114.8 sheets as compared to 1-< LM S- 5 I I ""' The DSC scans of I various shown in Fig. I. A shift in'base in the range the alkyl of 45-120 are the line wa~ observed °C, depending I fabricated The glass copolymers o'n the length characteristic tran'&ition are tabulated PMMA of of even low in Table comonomers in PMMA mol temperatures range sheet was found Incorp.oration for all 5. The ~ T$ of fraction backbone (0.05) resulted of in a decrease in' incorporation of AMA in PMMA backbone can be I onl the basis of internal plasticisation the alkyl side chain. I In MMA-SMA glass having Figures within trhnsition ~igher I mol parenth~ses represent ---SMS-5 -T to. be 114.8' °C. decrease in T 01\" T, and Tr values. copolymers ~ the significant explained effect of ~ '-' side chain of Afv1A and the mol fraction comonomers. defining copolymers temperature fra~tion on of SMA T g values calculated ~MS.5 The ro .80 100 120 TEMPERA1URE~C) Figure using Fox equation I. DSC scans orcopolymers, OMS, DMS, LMS and SMS in Table 5, 405 DEF ~CI J, VOL 47, NO 3, JULY 1997 I Table 6. Storage modulus copolymer sheets and softening temperatures 6.5 Log E'(Pa) at OOC Sample for Softening 6.0 temperature designation I lOHi Hz «1C) --~ PMMA 5.5451 5.5694 OMS-5 OMS-IO OMS-20 OMS-25 5.5347 5.7010 5.2961 5.2694 5.5625 5.7291 5.3543 5.6041 87.0 DMS-5 DMS-25 5.5138 5.5243 5.7568 5.5069 5.5313 5.5347 5.5555 5.7916 5.5416 5.5763 78.0 66.0 52.0 50.5 51.0 LMS-5 LMS-IO LMS-15 LMS-20 LMS-25 5.6527 5.5208 5.4236 5.5624 5.5763 5.6805 5.5486 5.4652 5.5832 5.6180 76.0 68.0 56.0 52.0 48.0 The values for storage modulu~ SMS-5 SMS-IO SMS-15 SMS-20 5.5555 5.5486 5.5555 5.2768 5.5833 5.5833 5.5972 5.3324 74.0 copolymer 59.6 temperature (0.10-0.20), the DMS-IO DMS-15 DMS-20 shift in base I 102.0 s-~.~ 66.0 § 58.0 S.O 55.4 4.5 Figure 49.0 the 41.0 line was not sharp in DSC scans. Therefore, glass transition temperature could not be determined for Jhese copolymers. The glass transition copolymers can also be predicted = wIIT;1 theoretically wl and w2 are the fractions of monomer 1 and 2 and T81and T82 are the glass transition temperatures of homopolymer 1 and 2, respectively. Similar calculation was done in the present work by taking T8 of PMMA as 115 °c and of polyOMA, poly , ° ° DMA and poly LMA as -20 C, -60 C and The calculated values are (E') with at temperature portion temperature of in 'the AMA variation in storage for OMS-5 1 Hz. Comparison of copolymer composition showed lof the' tangent at modulus curve. PMMA 'backbone. It was also observed that increase in comonomer content leads t to a decrease in softening temperature of the copolymers. This cquld be due to Idecreased intermolecular intera~tions in PMMA throuFh incorporation backbone. elon'gation ,nd results summarisf1d are modulus modulus copolyme~ cal~ulated Table in the t.1ase of copolymer having per 5 increase mol' cent in comonomer failure. A elongation significant was observed long , and the 4~ .Brittle . chain AMA. cdntent resulted I increase if on adding failure samples Further in ductile per cent 151-20 mol per such as OMA, DMA and LMA. Percentage elonga~tion Iwas much higher in SMS-lO, SMS-15 I and SMS-20. N°l significant sheet E' ,as a function no definite were in was observed of trend. change changing in per cent elongation the crmonomer , 406 6. Softcning by prawing decreasec! on incorporation cent long chain of AMA,t given in Table ~. 2 shows steepest at 1 Hz at O °c for different il\ Table was determined Softening ! !famples otOMS The stress-strain' curves for sMs copolymers , are shown in' Fig. -3. From the stress-strain curves, I tFnsile strength at break and fat yield, per cent where Figure traces sheets are given of AMA + W21Tg2 -65 °C, respectivelyl0. 2. DMTA 100 temperatures of random using the Fox equation: llTg 0 150 TEMPERATURE ~ C) .50 was ~bserved on I from OMA to LMA up to ~ I AGARWAL, Table 7. Tensile I properties , e,lal I I : STRUCTURE-PROPERTIES or c!polymer CORRELATION IN COPOLYMERS sheets 600Sample ~ designa/ion Strain at Modulus Ibreak (%) (MPa) Work of rupture (MPa) 6116 07.6 2100 262 41.0 56.4 .4 2,4.5 .5 05.6 12.0 1670 1280 151 367 OMS-15 OMS-20 OMS-25 32.0 23.0 17.9 1.7.0 .0 Ip.o.0 8.00 30.4 33.1> 35.0 j 780 530 470 I 616 439 420 DMS-5-5 DMS-10 -10 .51.71 43.4 35.0 1080 1020 177 44tj DMS-15 -15 DMS-20 -20 DMS-25 43.1 26.4 17.21 15.8 11.2 5.0 06.4 06 10.0 10 29.7. 29 39.4 39 54.4 54 PMMA Tensile strength (MPa) at Yield I B~eak I OMS-5 OMS-10 I -25 LMS-5-5 LMS-10 -10 ' 54.4 1 48.0 LMS-15 28.8 44.4 16.0 LMS-20 -20 LMS-25 -25 19.2 14)4 9.5 6.0 SMS-5 SMS-Ib SMS-15 SMS-20 34.4 19.6 12.6 52.2 20.0 10.0 6.2 -15 I 720 690 370 ~/V\ .JVU 400 636 152~ 321 \ 1410 111 I 30.0 ~ 1300 I 1000 460 564 63.5 66.6 520 240 446 426 04.7 18.7 57.9 75~0 1400 1040 500 290 161 428 742 419 I SMS.5 5 ~ :; 300 SMS.15 ~ VJ II ! 200 \ A . 100 - , ,\\ \ I. .I 15 mol per cent, whereas a marked increase in LMS-20 aslcompared to OMS-20. I copolymer sa":,ples showed higher per strength as c~mpared to other at yie:ld and at break samples. SMS cent 0 0 Tensile and modulus 10 wit,h comonomers. increase in mol per cent calculated on stress-strain comonomer curve inbreased with increase in the content up tq 15 molI per cent. These strain-to-failure prepared DMA 3-~ times by using or LMA pl~stics that bf PMMA 10-115 mol as.co~onome1rs having a & are I Non-Conventional India, for I. can be curves Establishment, extended Anal., 1990, 36, 617. MMA. Sources, Government -samples due to Dr R. V. .Swamy, Director, Defence Research the methacrylate. J. Thermal and thermal characterisation of methyl acrylate polymers. Eur. Polym. J., 199~, 28, 1433. of are also for Patnaik, M.; Choudhary, V. & Vanna, I.K. Strucmethacrylate/alkyl of Thanks Gwalior, mal behaviour of copolymers of methyl methacry- along with De{Jartment or SMS Varma, I.K.; Patnaik, M. & Choudhary, V. Therlate and 2-ethylhexyl the 90 to them. per cent of OMA, fellowship. , providin~ Energy to 70 60 REFERENCES tural grateful 50 (%) ~ 2.1 authors 3. Stress-strain Development cooperation ACKNOWLEDGEMENTS The 40 of of t,qe copolymer sheets I b,sis of area under the studies thus show that transparent 30 value Toughness the 20 SmAIN Figure decreased, -I was observed elongation SMS.10 !~ SMS-20 05.4 I N'-.. 3. Varma, I.K.; Nair, M.V.; D.S. Thermal Karan, V.K. & Varrna, characterisation of methyl 407 DEF SCI J, VOL 47, NO 3, JULY 1997 methacrylate -alkyl methacrylate Ther.:him. Acta, 1989, 142, 189. Varma, 4 I.K.; behaviour Nair, M.V. & of copolymers and iso-octyViso-decyl Karan, methacrylate/alkyl copolymers. Die V.K. 7, Thermal I of methyl methacrylate methacrylate. J. Thermal Angew (metry) Makromol. acrylate Chemie, copolymers. 1993, 205, 47. Agarwal. S.; Choudhary. V. & Varma. I.K. Struc:Jure-property re\ationship in copolymers of methacrylic acid ester~. I: Thermal behaviour. J. Appl. Polym. Sci.. 1?94.53. 1525. Anal., 1989, 35, 989. 8, Agarwal, ~.; ChoudharY, V. & Varrna, I.K. Effect of cai'danyl acrylate on thermal behaviour of , Bharel, R.; Choudhary, 5 methyl methacrylate copolymers. J. Appl. Polym. Sci., 1992, 46, 1707. V. & Varma, I.K. Thermal and mechanical properties of copoymers of methyl methacrylate with N-phenyl maleimide. J. Appl. 9, Polym. Sci., 1993, 49, 31. Odian, G. .Princi~le~ of polymerisation. Wiley & Sdns, New York, 1~91, Chap. 3. 10. Kine, 6. Patnaik, M.; Choudhary, T .1.M. Effect V .; Varma, I.K. & Sinha, of structure physico-mechanical and composition properties of on methyl B.B, & Novak, R. W .Acrylic and methacrylic ester polyme~s. In Encyc. Polym Sci,& Engg" edited by J"L, Kroschwitz, Ed.2 John Wiley & Sons, New York, 1986. Contributors MB Veena Choudhary obtained her PhD from Indian Institute of Technology, ~elhi, in 1977, and is working there as Professor. She worked as Res~arch Professor at Polytechnic University, New York, during 1992- f1993. She was Indp-US Scie\1ce and Technology Fellow (1992- 1993) and Alexander Yon Humbo1dt Fellow, rest Germany ( 1985 -1986). She ha~ published 96 papers in various international J"ournals. I' -1 Ms IK Varma obtained her PhD from Glasgow University, Scotland, U.K., in 19~. She is working at Indian Institute of Technology, Delhi, as Joint Professo!:in the Department bf Chemistry and Centre for Polymer Science and Engineering. The areas of her interest include ,hermally stable polymers, alkyl methacrylates, urethane acrylate resins, vinyl est~r resins, electrically conducting , polymers, modifications of polymers, structure-property relatiohship in polymers, mechanistic studies on thermal degradation of vinyl polymers and polymer compJsites (both particulate and fibre reinfor~ed). She has more than 250 scientific publications and four US pate~ts to her credit. She ,was awarded National Research Council, Senior Resident Research Associa~eship (1979-81) at NASA-Ames Resea,rch Centre, Moffett field, Cali~ornia, USA. She received sevbral cash awards and certificates of recognition from NASA for her ~ioneering work in the area of name retardant polyimides. 408 She received DSc in thermal behavlour of polymeric materials from Glasgow AGARWAL, et J, : STRUCTU~E-PROPERTIES I Univer.sity analysis. in 1986 and She is a fellow Analy~s (Wiley, Polymer Society UK) IN COPOLYMERS DuPont Internationa/ Award of National Academy of Sciences, India; Regional (Hungary). She is currently and of India. CORRELATION Akademial Kiado for polymer characterisation Editor, the by thermal Journal Thermal President of the I. 409