selvi full corrected

Upload: rajrudrapaa

Post on 04-Jun-2018

231 views

Category:

Documents


0 download

TRANSCRIPT

  • 8/13/2019 Selvi Full Corrected

    1/31

    LIST OF ABBREVIATIONS:

    1. AN-Acrylonitrile2.

    AA-Acrylicacid

    3. AAm-Acrylamide4. PAN-Polyacrylonitrile5. MA-Methylacrylate6. MMA-Methyl Methacrylate7. PEG-Polyethylene Glycol8. NCTB-N-Cetyl-Trimethyl Ammonium Bromide9. CTAB-Cetyl-Trimethyl Ammonium Bromide10.CAN-Ceric Ammonium Nitrate11.CAS-Ceric Ammonium Sulphate12.CA-Citric Acid13.CS-Ceric (IV) Sulphate14.LA-Lactic Acid15.CMC-Critical Micelle Concentration16.SDS-Sodium Dodecyl Sulphate17.[ ]Concentration18.I-Ionic Strength19.oC-Temperature In Degree Celcius20.K-Degrees of Kelvin21.Rp-Rate of Polymerisation22.Ri-Rate of Initiation

  • 8/13/2019 Selvi Full Corrected

    2/31

    CHAPTER-I

    1.Introduction

    Macromolecules or polymers are very high molar mass compounds

    consisting of several structural units inter-connected by covalent bonds. The

    molar mass of a polymer may vary from 5,000 to several millions.

    Fundamentals research in polymer chemistry was done from 1920 to 1950 by

    the German chemist,Hermann Staudinger who won the 1953 chemistry Nobel

    prize. Karl Ziegler,Giulio Natta and Paul J.Flory also made signifigant

    contributions to the polymer chemistry. Flory was awarded the 1974 chemistry

    Nobel prize. P.G.de Gennes, the French physicist was awarded the 1991

    physics Nobel Prize for studying polymer liquid crystals and developing the

    scaling concept in polymer dynamics.

    A polymer consists of a large number of simple monomeric structural

    un which are repeated over and over again to form a giant molecule called a

    macromolecule. The simple unit is called the repeat unit. In the polymers -A-A-A-A-A-A- and -A-B-A-B-A-B- for instance, the repeat units are A and A-B

    respectively. A high polymer is one in which the number of repeating units is

    in excess of about 1000. This number is termed as Degree of

    polymerization.

    Polymers find immense use in glass and ceramics industries. They

    are also being employed for rocket constructions polymer engineering deals

    with the splitting up of natural high molar mass compounds to produce

    valuable food stuffs. The hydrolysis industry, for instance,produces ethyl

    alcohol by hydrolysis of wood.

  • 8/13/2019 Selvi Full Corrected

    3/31

    2. Types of polymer and polymerization

    One classification based on polymer structure and divides polymers into

    condensation and addition polymers. The other classification is based on

    polymerizations mechanism and divides polymerization into step and chain

    polymerizations. The condensation addition classifications is based on the

    composition or structure of polymers. The step-chain classification is based on

    the mechanism of polymerization.

    Vinyl monomers can be made to react with themselves to form polymers

    by conversion of their double bonds into saturated linkages.

    nCH2=CHY ( CH2CHY ) n

    Where Y can be any substituent group such as hydrogen, alkyl, aryl,

    nitrile, ester, acid, ketone, ether and halogen.

    Condensation polymer and its synthesis involve the elimination of small

    molecules, or it contains functional group as part of the polymer chain its

    repeating units locks certain atoms. That is present in the monomer to which it

    can be degraded.

    2.1 Radical chain polymerization

    It consisting of a sequence of three steps initiation, propagation, and

    termination. The homolytic dissociation of an initiator species I to yield a pair

    of radicals R.

    KdI 2 R

    Kd rate constants for catalytic dissociation. Then the addition of this

    radical to the first monomer molecule to produce the chain initiating radicalM1.

  • 8/13/2019 Selvi Full Corrected

    4/31

    K1

    R+ M M1

    M-monomer molecule, k1- rate constant for initiation step. Propagation

    consist of the growth M1

    by successive additions of large number of monomer

    molecules

    Kp

    M1+ M M2

    Kp

    M2+ M M3

    etc.

    Kp

    Mn

    + M Mn+1

    Kp rate constant for propagation. Termination occurs by a combination

    of coupling and disproportionation.

    Ktc

    Mn+ Mm

    Mn +

    m

    KtcMn

    + Mm

    Mn

    +Mm

    Ktc & Ktd are the rate constant for termination by coupling and

    disproportionation respectively.

    2.2 Initiators

    The initiation of the polymer chain growth is brought about by free

    radicals produced by the decomposition of compounds called initiators. The

    term chain growth represents a process involving a continuous and very rapid

    addition of the monomer units to form polymer molecules or polymer chains.

    As more and more monomer units are added, the length of the polymer chains

    increases continuously and the chain growth rapidly.

    A variety of initiators system can be used to bring about the

    polymerization radicals can be produced by a variety of thermal,

  • 8/13/2019 Selvi Full Corrected

    5/31

    photochemical & redox methods. [Banford, 1998; Denisova et.al., 2003;

    Eastmond., 1976 a, b, c; Moad et.al., 2002]1.

    2.3 Thermal Decomposition of Initiators :

    Types of Initiators :

    The thermal, homolytic dissociation of initiator is the most widely used

    mode of generating radicals to initiate polymerization. Polymerizations

    initiated in this manner are often referred to as thermal initiated or thermal

    catalyzed polymerizations.

    The number of different types of compounds that can be used as thermal

    initiators is rather limited one is usually limited to compounds with bound

    dissociation energies in the range 100-170 KJ Mol-1

    .

    Compounds with higher or lower dissociation energies will dissociate

    too slowly or too rapidly. Several different types of peroxy compounds are

    widely used [Sheppard]2 these are peroxides such as acetyl and benzoyl

    peroxides.

    O O O

    CH3-C-O-O-C-CH3 2CH3- C-O ----------------1

    O O O

    -C-O-O-C- 2-C-O ----------------2

    The value of decomposition rate constant Kdvaries in the range 10-4

    -10-9

    S-1

    , depending on the initiator temperature [East Mond, 1976, a,b,c]3. Most

    initiators are used at temperature where Kdis usually 10-4

    -10-6

    S-1

    .

    Kd is larger for acetyl peroxides than for alkyl peroxides since the

    RCOO radical is more stable than the RO

    radical and for R-N=N-R, Kd

    increases in the order R=allyl, benzyl > tertiary > secondary > primary

    [Koenig, 1973]4.

  • 8/13/2019 Selvi Full Corrected

    6/31

  • 8/13/2019 Selvi Full Corrected

    7/31

    2.5 Types of Redox initiators:

    Peroxides in combination with a reducing agent are a common source of

    radicals; for example; The reaction of hydrogen peroxide with ferrous ion

    H2O2+ Fe2+ HO+ HO+ Fe3+.

    Ferrous ion also promotes the decomposition of a variety of other

    compounds including various types of organic peroxides.

    Fe2+

    ROOR RO+ RO

    ----------------- 6

    Fe2+

    ROOH HO

    + RO

    ----------------- 7

    O O

    Fe2+ROOCR RCO

    + RO

    ----------------- 8

    Other reductants such as Cr2+

    , V2+

    , Ti3+

    , Co2+

    and Cu2+

    can be employed

    in place of ferrous ion in many instances most of these redox systems are

    aqueous or emulsion systems.

    The combination of a variety of inorganic reductants and inorganic

    oxidants initiates radical polymerization, for example,

    -O3S-O-O-SO3+ Fe

    2+ Fe

    3+ + SO4

    2 + SO4

    -O3S-O-O-SO3+ S2O3

    2 SO4

    2 + SO4

    + S2O3

    Other redox systems include reductants such as HSO3, SO3

    2, S2O3

    2in

    combination with oxidants such as Ag+, Cu

    2+, Fe

    3+, ClO3

    and H2O2.

    OrganicInorganic redox pairs initiate polymerization, usually but notalways by oxidation of the organic component, for example for oxidation of an

    alcohol by Ce4+

    .

    R-CH2-OH + Ce4+

    Ce3+

    + H+ + R-

    CH-OH (Or)

    By V5+

    , Cr6+

    , Mn3+

    [Fernandez and guzman 1989; Misra and Bajpai,

    1982; Nayak and Lenka, 1980]6.

  • 8/13/2019 Selvi Full Corrected

    8/31

    There are some initiator systems in which the monomer itself acts as one

    component of the redox pair. Examples are thiosulphate plus acrylamide or

    methacrylic acid and N,N-dimethylaniline plus methyl methacrylate

    [Manickam et.al., 1978; Tsuda et.al., 1984]7

    .

    2.6 Photochemical initiation:

    Photochemical or photoinitiated polymerizations occurs when radicals

    are produced by ultraviolet and visible light irradiation of a reaction system

    [Oster and yang., 1968; pappas, 1988]8.

    In general, light absorption results in radical production by either of two

    pathways;

    Some compound in the system undergoes excitation by energyabsorption and subsequent decomposition into radicals.

    Some compound undergoes excitation and excited species interacts witha second compound to form radicals derived from the latter and / or

    former compound.

    2.7 Metal ion Oxidants in Redox Initiation:

    Numerous reduction agents like alcohols, thiols, ketones, aldehydes,

    acids, amines and amides have been used in combination with oxidizing metal

    ions to participate in general singleelectron transfer reaction for free radical

    polymerization, metal ion used mainly for this purpose are Mn(III) and

    Mn(VII), Ce(IV), V(V), Co(III), Cr(VI) and Fe(III).

    2.8 Cerium (IV) and electro induced polymerization

    Cerium (IV) ion has been used for the oxidation of many organic

    compounds, in the form of ceric(IV) ammonium nitrate (CAN), Ceric(IV)

    ammonium sulphate (CAS), Ceric(IV) Sulphate (CS) and cericperchlorate and

    the mechanism of such cericperchlorate and the mechanism of such reactions

    has been well established.

    Reducing agents, combined with Cerium(IV) and alcohols, aldehydes,

    acids and amines. The rate of vinyl monomers were in the order of Ceric

  • 8/13/2019 Selvi Full Corrected

    9/31

    perchlorate > Ceric nitrate > Ceric sulphate. Which is in the order of oxidation

    power of mentioned species.

    Ceric ions forms complexes with amines such as sulfate, nitrate and

    hydroxyl in aqueous solution whose relative concentrations have been found to

    be function of hydrogen ion, respective anion concentration and ionic strength.

    Increase of ligand concentration X = SO42

    and NO3depress the rate of

    polymerization due to formation of less reactive cerium (IV) species, CeXn

    than Ce4+

    and Ce(OH)n.

    The mechanism and kinetics of polymerization involving ceric ion alone

    [Ananthanarayan and santappa et.al]9 and also in combination with reducing

    substrates such as alcohols10

    , diols11

    , polyols12

    , aldehydes13

    , ketones14

    and

    amines15

    etc. with different monomers acrylonitrile, acrylamide and methyl

    methacrylate etc.

    2.9 Redox Polymerization:

    The kinetics of redox polymerization in terms of the propagation and

    termination steps. Termination is by biomolecular reaction of propagating

    radicals; The initiation and polymerization rates will be given by the

    expressions.

    Ri= Kd[reductant] [Oxidant] -----------------9

    Kd[Reductant] [Oxidant] 1/2

    Rp= Kp[M] ----------10

    2Kt

    In the alcoholCe4+

    system termination occurs according to

    Mn+ Ce

    4+ Ce

    3++ H

    +dead polymer ------------11

  • 8/13/2019 Selvi Full Corrected

    10/31

    At high ceric ion concentrations. the propagating radical losses a

    hydrogen to form dead polymer with C=C and group.

    Ri = Kd[Ce4+

    ] [alcohol] --------------12

    Rt = Kt[Ce4+] [alcohol] ---------------13

    Steady state assumption (Ri= Rt) one obtains the polymerization rate as

    KdKp[M] [alcohol]

    Rp= ----------14

    Kt

    Rpwill show a higher dependence on [M] in these cases then indicated

    by the equation 2 and 5. The first dependence of Rion [M] results, in 3/2 and 2-

    order dependence of Rp on [M] for biomolecular and monomolecular

    terminations respectively. Organic inorganic redox pair initiate

    polymerization, usually but not always by the oxidation of organic component.

    For example : Ce4+

    , V5+

    , Cr6+

    , Mn3+

    , Ag+, Cu

    2+ and Fe

    3+ are used as the

    initiator of the redox systems. There are some initiator systems in which

    monomer itself act as a one component of redox pair. Examples, thiosulphate

    plus acrylamide or metharylic acid and N, N- dimethylaniline plus methyl

    methacrylate.

    Initiation :

    K1

    M + R

    M1

    ---------------15

    Propagation :

    Kp

    M1+ M M2

    ----------------16

    Kp

    Mn-1

    + M Mn

  • 8/13/2019 Selvi Full Corrected

    11/31

    Termination

    Kt

    Mn + Ce(IV) Mn+ Ce (III) + H

    + ---------17

    Oxidative Termination :

    KpR

    + Ce(IV) oxidation product + Ce (III) + H

    + ---------18

    In the methyl methacrylate polymerization by cerium(IV) (CAN)

    primary alcohol in nitric acid under nitrogen, by the application of Tafts

    correlation. It was suggested that the mechanism is free radical mechanism

    (* =0, P= -0.2).

    Kd

    Ce(IV) + RCH2OH R-CH-OH+ Ce(III) + H

    + ----------19

    In the polymerization of methyl methacrylate by Cerium(IV) [CAS]-

    diol (propane 1, 2-diol16

    and butane 1,4 diol17

    ) system in aqueous sulfuric

    acid and under nitrogen, for the primary radical production step, complex

    formation was not reported between cerium(IV)18

    and diol.

    In addition of kinetic results, the infrared spectrum of the isolated

    polymers showed the presence of hydroxyl group along with those of the

    homopolymer, indicating that the polymer contains the diol as an end-group

    which envisages the initiation by primary radicals formed from the reaction of

    Ceric ion with diol and termination by metal ions.

    In the cases rate of polymerization was found to be directly proportional

    to the concentration of diol and inversely proportional to the ceric ion

    concentration but shows square dependence to the concentration of monomer.

    The rate of ceric ion disappearance is directly proportional to the initial

    concentration of ceric ion and diol.

  • 8/13/2019 Selvi Full Corrected

    12/31

    For the polymerization of methyl methacrylate with Cerium(IV) (CAS)-

    glycerol ion aqueous sulfuric acid the termination step is postulated to mutual

    at lower concentration of Ce(IV)0.5

    where the rate of monomer disappearance

    was found to be proportional to [Ce(IV)] and [Glycerol].

    The termination step for the same system at high concentrations of

    Ce(IV) termination step was proposed to be linear showing that the rate of

    polymerization is proportional to [M]2[Glycerol].

    The rate of ceric ion disappearance was found to decrease with increase

    sulfuric acid concentration and increasing ionic strength by addition of

    NaHSO4to constant sulfuric acid concentration.

    Probably due to formation of neutral disulfate complexes of Ce(IV)

    [Ce(SO4)2] according to following equilibrium.

    Ce4+

    + HSO4

    Ce(SO4)2+

    + H+

    Ce(SO4)2+

    + HSO4

    Ce(SO4)2+ H+

    Ce(SO4)2+

    + HSO4

    Ce(SO4)32

    + H+

    In the polymerization methyl methacrylate (MMA) by Ce(IV) benzyl

    alcohol [BA] system in nitric acid, the first order dependence of Rp on

    (MMA) observed and the rate of Ce(IV) disappearance was proportional to first

    powers of [Ce(IV)] and [BA]. The reaction of Ce(IV) benzyl alcohol

    produces the free radical C6H5CH2OH which may partly be oxidized by

    [Ce(IV)] to give benzaldehyde. The growing polymer chains get terminated by

    the mutual annihilation of polymer radicals as evidenced by the dependence of

    rate of polymerization over square roots of [Ce(IV)] and BA.

    2.10 Dependence of polymerization rate on Initiator:

    The polymerization rate to be dependent on the square root of the

    initiator concentration. This dependence has been abundantly confirmed formany different monomer initiator concentrations over wide ranges of

  • 8/13/2019 Selvi Full Corrected

    13/31

    monomer and initiator concentrations. [East mond, 1976, a,b,c, : Kamatchi

    et.a;., 1978 : Santee et.al., 1964; Schuez and Blaschke., 1942; V.Ranchan and

    smets., 1959]19

    The order of dependence of Rpon [I] may be observed to be less than

    one-half at very high initiator concentrations.

    The termination mode may change from the normal bimolecular

    termination between propagating radicals to primary termination which

    involves propagating radicals relating with primary radicals. [Perger et.al.,

    1977; David et.al; 2001: Ito., 1980]20

    .

    Ktp

    Mn

    + R

    Mn-R ---------------21

    This occurs if primary radicals are produces at too high a concentration

    and / or in the presence of too low a monomer concentration to be completely

    and rapidly scavenged by monomer.

    If termination occurs exclusively by primary termination the

    polymerization rate is given by

    KpKi[M]2

    RP= --------------------- ----------------22

    Ktp

    Lower than one-half order dependence of Rpon Ri is also expected if

    one of the two primary radicals formed by initiator decomposition has low

    reactivity for in initiation, but is still active in termination of propagating

    radicals [Kaminsky et.al., 2002]21

    2.11 Dependence of Polymerization Rate of Monomer :

    The initiator rate can be monomer dependent in several ways. The

    initiator efficiency may vary directly with the monomer concentration.

    F = f [M]

    Which would lead to firstorder dependence of Rion [M] and 3/2 order

    dependence of Rpon [M], the equivalent result arises if the second step of the

  • 8/13/2019 Selvi Full Corrected

    14/31

    initiation reaction were to become the rate determining step. This occurs when

    Kd> Kior when [M] is low.

    The initiation reaction may be written as,

    M + I M

    + R

    And results in a 3/2 order dependence of Rp on [M]. This initiation is

    probably best considered as an example of redox initiation.

    2.12 Kinetics of Initiation and Polymerization :

    The rate of producing primary radicals by thermal homolysis of an

    initiator Rdand is given by

    Rd = 2 fKd[I] -------------23

    Where,

    [I] is the concentration of initiators and f is the initiator efficiency. The

    initiator efficiency is defined as the fraction of radicals produced in the

    homolysis reaction that initiate polymer chains, the value of f is usually less

    then unity due to wastage reactions, radicals that initiate polymer chains. The

    value due to wastage reactions.

    The normalizes of the initiator is the rate-determining step in the

    initiation sequence, and the rate of initiation is then given by

    Ri = 2 fKd[I] -------------24

    Substitution of Eq 7 into Rp

    fKd[I] 1/2

    Rp = Kp[M] --------------------- ----------------25

    Kt

  • 8/13/2019 Selvi Full Corrected

    15/31

    CHAPTER-II

    3. REVIEW OF LITERATURE

    Studies on kinetics of polymerization of methyl methacrylate initiate by

    Ce(IV) redox systems are available in the literature. Some of them are as

    follows.

    C.M.Patra etal.,(1994)22

    was investigated the influence of N-

    acetylglycine on the kinetics of graft copolymerization of acrylonitrile (AN)

    and methyl methacrylate (MMA) onto chemically modified jute fibers was

    studied in the temperature range 40-600C. The optimum conditions for grafting

    have been determined by the effects of concentrations of monomers, Ce(IV),

    and N-acetylglycine on the rate of grafting. The effect of time, temperature, and

    concentration of the acid, the amount of jute fibers and some organic solvents

    and inorganic salts on the rate of grafting has been reported. On the basis of

    experimental results findings out, a kinetic scheme has been proposed. Infrared

    spectra of chemically modified jute and grafted jute have been investigated.

    More than 185% graft yield could be achieved with the present system.

    Grafting has improved the thermal stability of jute fibers.

    M.Patra etal.,(1996)23

    studying the polymerization of acrylonitrile

    (AN) the Ce(IV) Citric Acid (CA) redox system as an initiator in aqueous

    nitric acid solution, in the presence of an anionic surfactant, sodium dodecyl

    sulfate (SDS) has been kinetically reported at a temperature range of 25-450C.

    The rate of polymerization (Rp) and disappearance of Ce(IV) (-Rce) increase

    with increasing concentration of SDS above its critical micelle concentration

    (CMC) when the surfactant molecules are organized, Rp was found to be

    proportional to [AN]1.5

    and [CA]0.5

    with other organic substrates Rp follows

    the increasing order of sorbitol > mannitol > glycerol > CA. It was found to

    decrease considerably in the presence of cationic surfaetant (CTAB), and

    nonionic surfactant (Trition - X100) had no effect on the rate.Rce variouslinearly with [Ce(IV)] and [CA]. Both Rp and Rce increase with increasing

  • 8/13/2019 Selvi Full Corrected

    16/31

    temperature. The overall activation energy was found to be 18.31 and 13.72

    k.cal mol in the absence and presence of 0.015 MSDS, respectively. The chain

    length of the polyacrylonitrile has also increased with increasing SDS

    concentration.

    R.Chandragandhi etal.,(1997)24

    was investigating the polymerizations,

    of methyl methacrylate (MMA) and acrylonitrile (AN) were carried out in

    aqueous nitric acid at 300C with the redox initiator system ammonium ceric

    nitrateethyl cellulose (EC). A short induction period was observed as well as

    the attainment of a limiting conversion for polymerization reactions. The

    consumption of ceric ion was first order with respect to CE(IV) concentrationin the concentration range (0.20.4) x 10

    -2M, and the points deviations from a

    linear fit. The plots of the inverse of pseudo first order rate constant for ceric

    ion consumption, (K1)-1

    vs [EC]-1

    gave straight lines for both the monomer

    systems with non zero intercepts supporting complex formation between

    Ce(IV) and EC. The rate of polymerization increases regularly with [Ce(IV)]

    upto 0.003M, yielding an order of 0.41, then falls to 0.0055M and again shows

    a rise at 0.00645M for MMA polymerization for AN polymerization Rp shows

    a steep rise with [Ce(IV)] up to 0.001M and beyond this concentration Rp

    shows a regular increase with [Ce(IV)], yielding an order of 0.48. In the

    presence of constant [NO3-] MMA and AN polymerization yield orders of 0.36

    and 0.58 for [Ce(IV)] variation respectively. The rate of polymerization

    increased with an increase in EC and monomer concentration, only at a higher

    concentration of EC and [0.5M] was a steep fall in Rp observed for both

    monomer systems. The orders with respect to EC and monomer for MMA

    polymerization were 0.19 and 1.6 respectively. The orders with respect to EC

    and monomer for AN polymerization were 0.2 and 1.5, respectively. A kinetic

    scheme involving oxidation of ECCe(IV) via complex formation, whose

    decomposition gives rise to a primary radical initiation, propagation, and

    termination of the polymeric radicals by biomolecular intervation the

    polymeric radicals by biomolecular interaction is proposed. An oxidativetermination of primary radicals by Ce(IV) is also included.

  • 8/13/2019 Selvi Full Corrected

    17/31

    Novel block copolymers of poly (ethylene glycol) (PEG) with

    various vinyl monomers namely acrylonitrile (AN), acrylamide (AAm), methyl

    methacrylate(MMA) and methacrylic acid(MAA) were synthesized using Ce4+

    -

    PEG and Mn3+

    -PEG redox system in aqueous acidic medium. The

    polymerization proceeded via a macroradical generation, which was

    substantiated by ESR spectroscopy. This macroradical acted as a redox

    macroinitiator for the block copolymerization of vinyl monomers. The

    formation of the block copolymers was confirmed by chemical test and

    fractional precipitation, as well as by FT-IR,1H and

    13C FT-NMR

    spectroscopy. These polymerizations have been studied by S.Nagarajan etal.,

    (1998)25.

    C.Erbil etal.,(1998)26

    was synthesized the polyacrylamides (PANMS)

    polyacrylonitriles (PANS) and polymethyl methacrylates (PMMAS) by using

    Ce(NH4)2 (NO3)6, Ce(SO4)2 4H2O and KMno4 in combination with

    nitrilotriacetic acid (NTA) and diethylenetriamine penta acetic acid (DTPA)

    which have strong chelating properties, as redox initiations, polymerizations,

    were carried out in the aqueous acidic solutions at 250C and 550C in the

    presence of air. The chain structures of the resulting products were studied by

    fourier transform infrared (FTIR) spectroscopic measurements form the

    comparison of the spectroscopic results with gravimetric and viscometric data

    it was concluded that both the difference between he solubility behaviour in

    aqueous solutions of MMA, AN, AAM, and their polymers and catalyst-

    activator-monomer combinations were important parameters effecting the

    polymerization mechanism, conversions and the structures of the polymers.

    The FTIR and viscosity results indicated that PAAMS obtained in our

    experimental conditions formed cross linked structures with sulphated

    complexes of Ce (III) and Mnso4 produced by the redox reactions between

    catalyst [Mno4

    and Ce(IV)] NTA and AAM. The observed and PAN chains

    were terminated by hydrated and sulphated complexes of Ce(III) while the

    termination of PMMA radicals took place by primary radicals becausePMMAS were formed by emulsion polymerization kinetics.

  • 8/13/2019 Selvi Full Corrected

    18/31

    Nesrin Oz etal.,(2001)27

    was investigating the Ethoxylated nonyl phenols,

    ethoxylated fatty alcoholos, and ceric ammonium nitrate redox systems were

    used for the polymerization of vinyl and acrylic monomers such as

    acrylonitrile, styrene, and acrylic acid. The initiating radical was formed on

    reducing organic compound which in turn initiated polymerization to give

    polymers containing chain ends of ethoxylated nonyl phenols and ethoxylated

    fatty alcohols that showed much higher water absorption. The effects of the

    concentration of Ce4+

    salt, ethoxylated nonyl phenols, and monomers on both

    the yield and the molecular weight of corresponding polymers were studied.

    V.S.Jamal Ahmed etal.,(2001)

    28

    studied the kinetics of radical freepolymerization of methyl methacrylate using potassium peroxomonosulfate as

    initiator in the presence of benzyl tributylammonium chloride (BTBAC) as

    phase transfer catalyst was studied. The polymerization reactions were carried

    out under nitrogen atmosphere and unstirred conditions at a constant

    temperature of 60oC in ethyl acetate /water bi-phase system. The rate of

    concentrations of monomer, initiator, catalyst, temperature, acid and ionic

    strength on the rate of polymerization (Rp) as certained. The orders with

    respect to monomer, initiator and phase transfer catalyst were found to be 1.5,

    0.5 and 0.5 respectively. The rate of polymerization (Rp) is independent of

    ionic strength and PH.

    Kavitha sankar etal.,(2002)29

    investigated the kinetics and

    mechanism of free radical polymerization of methyl methacrylate (MMA)

    using water soluble initiator viz., potassium peroxydisulfate (PDS) in the

    presence of newly synthesized 1,4-dihexadecylpyrazine-1,4-diium dibromide

    as multi-site phase transfer catalyst(MPTC) has been investigated in ethyl

    acetate/water two phase system at constant temperature 50+1oC under nitrogen

    atmosphere. The effect of variation of [MMA],[PDS],[MPTC] ,and volume of

    fraction of aqueous phase, solvent polarity and temperature on the rate of

    polymerization (Rp) was ascertained. The order with respect to monomer,

    initiator and multi-site phase transfer catalyst were found to be 1.0, 0.5 and 0.5

  • 8/13/2019 Selvi Full Corrected

    19/31

    respectively. The rate of polymerization of is independent of ionic strength and

    PH.

    A.K.Srivastava etal., (2003)30

    investigated the homo polymerization of

    methyl methacrylate(MMA) was carried out in the presence of triphenyl

    stibonium 1,2,3,4- tetraphenyl- cyclopentadienylide as an initiator in dioxane at

    65oC+0.1

    oC. The system follows non-ideal radical kinetics (Rp [M]

    1.4[I]

    0.44)

    due to primary radical termination as well as degradative chain-transfer

    reaction. The overall activation energy and average value of Kp2/Ktwere 64 KJ

    mol-1

    and 0.173X10-3

    /mol-1

    S-1

    respectively.

    S.V.Subramanian etal.,(2004)31investigated the polymerization of

    the monomer, methyl methacrylate (MMA) was carried out in sulfuric acid

    medium at 15oC. With the redox initiator system, ceric ammonium sulfate-

    malonic acid. There was no induction period, and a steady state was attained in

    a short time. There was found to be no polymerization even after 1hr, in the

    absence of the reducing agent R. The initiation was by the radical produced

    from the Ce4+

    -malonic acid reaction. The rate of monomer disappearance was

    proportional to [M]1.5

    , [R]0.5

    and [Ce]0.3-0.5

    , and the rate of ceric disappearance

    was proportional to [R] and [Ce4+

    ]. Chain lengths of the polymers were directly

    proportional to [M] and inversely to [R]1/2

    and [Ce4+

    ]1/2

    .

    M.Dharmendira kumar etal.,(2004)32

    studied the kinetics of free

    radical polymerization of methyl methacrylate(MMA) using potassium

    peroxydisulfafe as initiator in the presence of propiophenone benzyl

    dimethylammonium chloride as phase transfer catalyst were studied. The

    reactions were carried out under inert and unstirred conditions at constant

    temperature of 60oC in cyclohexanone/water biphase media. The dependence

    of the rate of polymerization on various experimental conditions, such as

    different concentrations of monomer, initiator and phase transfer catalyst (PTC)

    and different ionic strength, temperature and volume fraction of aqueous phase

    was studied. The order with respect to monomer, initiator and phase transfercatalyst was found to be 1, 0.5 and 0.5 respectively. The rate of polymerization

  • 8/13/2019 Selvi Full Corrected

    20/31

    (Rp) is independent of ionic strength and PH. However, an increase in the

    polarity of solvent and volume fraction of aqueous phase has slightly increased

    the Rp value.Ye.S.Garina etal.,(2005)33

    The kinetics of polymerization of methyl methacrylate initiated by

    cerium (IV)-lactic acid redox system was studied in an aqueous medium in the

    temperature range of 25-50oC. The rate of polymerization (Rp) and the rate of

    Ce(IV) disappearance have been measured. The effects of some water-miscible

    organic solvents, cationic, anionic, nonionic surfactants, and complexing

    agents on the rate of polymerization were investigated. The temperature

    dependence of the rate was studied, and the activation parameters werecomputed using the Arhenius and Eyring plots. The effects of inorganic and

    organic solvents polymerization were also investigated by Mahadevaiah etal.,

    (2006)34

    .

    The polymerization of methyl methacrylate initiated by the ceric

    ammonium nitrateD-glucose redox system has been studied in aqueous nitric

    acid under nitrogen in the temperature range 20.5 to 35oC.The initial rate of

    polymerization was determined gravimetrically whereas the initial rate of ceric

    ion disappearance was determined by titration of ceric ion. The relationships

    between conversion and D-glucose, Ce(IV), and monomer concentrations were

    determined. The dependence of the rates on D-glucose,

    Ce(IV), and monomer concentrations was evaluated. The effect of temperature

    was studied byM.D.Fernandez etal., (2007)35

    .

    M.D.Fernandez etal.,(2007)36

    investigated the polymerization of

    methyl methacrylate initiated by ceric ammonium nitrate-maltose has been

    investigated in aqueous nitric acid under nitrogen in the temperature range

    20.5-35Co.The dependence of the initial rate of polymerization and the initial

    rate of ceric ion consumption on maltose, Ce(IV),and monomer concentrations

    has been determined. The reaction orders were found to depend on ceric ion

    concentration. At a moderately high Ce(IV) concentration (1X10

    -3

    mol litre

    -1

    )the orders were 1/2 and 3/2 with respect to maltose and monomer

  • 8/13/2019 Selvi Full Corrected

    21/31

    concentration, respectively and independent of Ce(IV) concentration. But a low

    Ce(IV) concentration (4X10-4

    mol litre-1

    ) the orders with respect to monomer

    and Ce(IV) changed to 1 and 1/2 respectively.

    Femeozturk etal.,(2007)37

    was studying the comprehensive account on

    the synthesis of block copolymers via redox initiating systems. Redox

    polymerization systems for the synthesis of block copolymers have been

    reported. The mechanism of initiation by a radox process is a method which is

    used to obtain block copolymers by various transition metals, such as Ce(IV),

    Mn(III), Cu(II), and Fe(III) redox polymerization has found wide applications

    in initiating polymerization reactions in initiating polymerization reactions andhas been specifically of industrial importance. As it follows from the

    Contents in addition to the above mentioned metals other redox

    polymerization systems such as hydrogen peroxide and vanadium are described

    as well.

    The free radical terpolymerization of indene (In) methyl methacrylate

    (MMA) and acrylonytrile (AN) has been investigated by Naguib, Hala.F

    etal.,(2009)38

    . The rate of polymerization of all the binary systems involved

    dilatometrically for the homogeneous polymerization. The reactivity ratios of

    the three binary systems were calculated and were found to be equal to 0.031

    and 0.397 for In/AN copolymers and 0.02 and 3.82 for In/MMA copolymers

    and finally 0.152 and 1.20 for AN/MMA copolymers. The rate of

    terpolymerization in bulk has been measured as well as the relationship

    between the monomer mixture composition and the obtained terpolymer in

    order to construct the compositional triangle. Also the effect of initiator

    concentration on the rate of terpolymerization was investigated.

    Sunilkumar Banyal etal.,(2011)39

    was studied the mulberry silk fibre

    was graft copolymerized with binary mixtures of acrylic acid, methylacrylates

    as the principal monomer in aqueous medium by using CAN as redox initiator.

    The binary vinyl monomers were graft co polymerized by using the graftingconditions like reaction time, temperature, concentration of MMA and CAN as

  • 8/13/2019 Selvi Full Corrected

    22/31

    reported earlier for optimum percent grafting (74.40) of MMA alone onto the

    same backbone. Graft copolymers were characterized by FTIR, SEM swelling

    studies, moisture absorbance and chemical resistance in acidic and alkaline

    medium. Dye uptake (Gention Violet) on graft copolymers were studied photo

    calorimetrically at 420nm. The dying capabilities of the graft copolymers

    with binary mixture is more that the reference graft copolymers of methyl

    methacrylate.

    P.L.Nayak etal.,(2011)40

    was studying the grafting of acryonitrile onto

    chitosan was studied using ceric ammonium nitrate as the redox initiation in

    aqueous media. The percentage of grafting and the efficiency of the processwere calculated as function of the concentration of initiator and monomer the

    reaction time and temperature. The percentage of grafting was found to depend

    on the relative amount of monomer to chitosan, initiator and volume of the

    aqueous phase as well as the reaction temperature. By using optimized

    combinations of the reaction variables a grafting efficiency up 88% and a

    percentage of grafting of nearly 20% were reached. Evidence of grafting was

    obtained from comparison of SEM, XRP, and FTIR of the grafting and non-

    grafted chitosan as well as solubility characteristics of the product. The

    antibacterial and angifungal activities of the grafted polymer have also been

    investigated.

    M.Palanivelu etal., (2011)41

    investigated the kinetics of polymerization

    of methyl methacrylate initiated by Ce(IV)-Vanillin redox system in aqueous

    solution of sulfuric acid at 40o

    C. The rate of polymerization (Rp) and the

    reaction orders with respect to monomer, initiator and ligand have been

    determined and found to be 1.5, 0.5 and 0.5 respectively. The effect of

    concentration of sulfuric acid on the polymerization was also studied. The rate

    of polymerization was found to increase with increasing temperature 30-60o

    C

    and decreases at higher temperature (>600C). The overall activation energy

    (Ea) was found to be 36.7 KJ/mol.

  • 8/13/2019 Selvi Full Corrected

    23/31

    4. SCOPE OF THE PRESENT WORK

    Metal ions such as Cr6+

    , V5+

    , Fe3+

    , Ce4+

    , Co3+

    , Mn3+

    etc., coupled with

    certain have been reported to be useful redox system for initiating vinyl

    polymerization. For instance CE4+

    have been found to be an active oxidant in

    the vinyl polymerization, hence Ce4+

    (Ceric ammonium sulphate) is chosen as

    the oxidizing agent for the present investigation then also lactic acid

    (CH3CHOHCOOH) reducing agent for the present work.

    Detailed survey of literature reveals that an extensive study can be

    carried out on methyl methacrylate, acrylamide, methyl acrylate, acrylic acid

    and its derivatives with organic reducing agent like alcohols, aldehydes,

    ketones, acids, amides, amines etc., which in combination with a oxidizing

    agent constitute a redox pair to initiate the Vinyl polymerization.

    Earlier, the redox polymerization of methyl methacryalate initiated by

    various redox system has been investigated. Based on the kinetic studies of

    polymerization of methyl methacrylate (MMA) initiated by ceric ammonium

    sulphte (CAS) lactic acid (LA) redox system have been studied with a suitable

    experimental methods. Hence the system is choosen for the present work.

  • 8/13/2019 Selvi Full Corrected

    24/31

    CHAPTER-III

    5.EXPERIMENTAL PART

    5.1 Polymerization Reaction Vessel

    The reaction tubes used for the experiments were pyrex glass tubes

    closed by B-24 cones in which nitrogen inlet and outlet tubes were fused. The

    longer tube was used as inlet for puring nitrogen gas through the solution and

    the shorter one was used as outlet for nitrogen. After passing nitrogen for the

    specified time, the tubes were sealed with rubber gaskets to ensure maintenance

    of an inert atmosphere.

    5.2 Thermostat

    The thermostat used was a rounded vessel with a heater, stirrer and

    thermometer. The temperature range used for all the experiments reported were

    300C and 35

    0C controlled to an accuracy of 0.1

    0C.

    5.3 Deaeration Technique

    The nitrogen gas used to deaerate the experimental system was free from

    oxygen by passing through several columns of fisher solution. The gas after

    passing through fisher solution was free from hydrogen sulphide, sulfur dioxide

    etc, by passing it through a wash bottle containing saturated lead acetate

    solution and then washed free of all vapours by passing it through a wash bottle

    containing double distilled water. Before passing the purified nitrogen through

    the reaction tube, it was passed through a wash bottle containing the same

    concentration of monomer solution in order to avoid the loss of monomer

    during deaeration. For all the experiments the deaeration time was 20 minutes.

    5.4 Preparation of Fisher Solution

    Fisher solution was prepared by dissolving 20g of sodium hydroxide in

    100ml of water and adding 16g of sodium dithionate (N2S2O4) and 2g of

  • 8/13/2019 Selvi Full Corrected

    25/31

    anthroquinone sulphonate (silver salt) to the warm solution. The mixture

    was stirred well until a clear blood red colour solution was obtained. It was

    cooled of room temperature and then used. The fisher solution was changed for

    every ten runs.

    5.5 Reagents

    All chemicals used were of the purest quality mostly BDH, E.Merck,

    SDs fine (analar or G.R. Grade), SRL, products. Glasswares and the reaction

    vessels were cleaned with warm solutions of chromic acid, rinsed frequently

    with double distilled water and dried in air oven at 900C.

    5.6 Water

    Water was distilled in all glass cornery vessel, the second distillation

    being from potassium permanganate and the double distilled water was used

    throughout the study.

    5.7 Monomer

    CH3

    Methyl Methacrylate [CH2 = C COOCH3] was recrystallised twice

    from methanol and dried in vacuo.

    5.8 Reducing Agent

    The reducing Agent used in the present work is lactic acid

    5.9 Acid

    All experiments were conducted in sulphuric acid solution. Solution of

    sulphuric acid were prepared by suitable dilution of concentrated acid with

    double distilled water and standardized against sodium hydroxide solution.

  • 8/13/2019 Selvi Full Corrected

    26/31

    5.10 Purification of Reagents

    To obtain reproducible results and to minimize experimental errors a

    high degree of purity of the solvents and reagents were used. Therefore only a

    analytical grade chemicals were used. Commercial sample and laboratory grade

    reagents were carefully purified by standard procedure and then purity was

    checked by melting point measurements.

    5.2 Estimations

    5.2.1 Initiator

    Ceric ammonium sulphate was used as initiator. The Ce(IV) ion

    concentration were determined by cerimetry. For this, an aliquot of Ce(IV)

    stock solution was run into a known excess of standard ferrous ammonium

    sulphate solution using ferroin indicator.

    5.2.2 Ferroin Indicator

    The ferroin indicator was prepared by dissolving 1.485g of 1,10-

    phenantheroline monohydrate (C12H8N2H2O) in 100 ml of 0.025 ferrous

    ammonium sulphate solution.

    5.2.3 Rate of Polymerization (Rp)

    The rate of polymerization (Rp) of methyl methacrylate was determined

    by Iodimetry. The weight of polymer obtained in each experiment was

    substituted in the equation given below to get Rp.

    Rp = (1000 x W) / (V x T x M)

    Where W = Weight of the polymer

    T = Temperature

    V = Total Volume of the reaction mixture.

    M = Molecular weight of the monomer.

  • 8/13/2019 Selvi Full Corrected

    27/31

    R = Reaction time in seconds.

    5.2.4 Rate of Ce(IV) Disappearance

    Rate of Ce(IV) disappearance (-d[Ce(IV)]/dt) was determined asdescribed below. At the end of the reaction time, the reaction was arrested with

    definite amount of ferrous ammonium sulphate on the excess ferrous ion was

    determined by cerimetry. From the amount of unreacted ferrous ion, the Ce(IV)

    consumed was evaluated and hence the rate of Ce (IV) disappearance was

    computed.

    5.2.5 Oxidation experiment

    A typical oxidation experiment is described below. A reaction mixture

    containing lactic acid, sulphuric acid, sodium bisulphate (to maintain the ionic

    strength) and water (to maintain total volume constant) were taken in the

    reaction tube. Nitrogen free from oxygen by passing through fisher solution by

    bubbled through the solution for 20 minutes and the system was thermostated

    at the desired temperature. The Ce(IV) stock solution was added and the tube

    was sealed with rubber gaskets to ensure maintenance of an inert atmosphere.

    The total volume of the reaction mixture was usually 20ml. At the end of the

    reaction time (20 min), the reaction was arrested by the addition of a known

    excess of ferrous ammonium sulphate solution, when the remaining Ce(IV)

    was instantly reduced to Ce(III) state. The unreacted Fe(II) was estimated by

    titrating with a standard ceric ammonium sulphate solution using ferroin

    indicator. The rate of Ce(IV) disappearance was evaluated from the titre value.The rate of Ce(IV) disappearance was followed at different substrate

    concentration, Ce(IV) concentration and sulphuric acid concentration keeping

    the constant ionic strength.

    5.2.6 Polymerization Experiment

    In a typical kinetic run, a reaction mixture containing methyl

    methacrylate, lactic acid, sulphuric acid, sodium bisulphate and water taken in

  • 8/13/2019 Selvi Full Corrected

    28/31

    the reaction tube was interposed between the nitrogen cylinder and the reaction

    tube (to avoid loss of monomer during deaeration) nitrogen, free from oxygen

    by passing through fisher solution, was bubbled through the solution for 20

    minutes and the system was thermostated at the desired temperature. The

    Ce(IV) stock solution was added and the tube was sealed with rubber gaskets to

    ensure maintenance of an inert atmosphere. Polymerization started without any

    induction period. At the end of the reaction time (20 min), the reaction tube

    was opened and quenched with excess of ferrous ammonium sulphate

    solution.The aliquot was done by iodimetry titration.From this titre value we

    can determined the rate of polymerization (Rp)

  • 8/13/2019 Selvi Full Corrected

    29/31

    8.REFERENCES

    1. Bamford, CH., G.C.Eastmond and D.Whittle, Polymer, 10,771(1969b). Denisova, E.T., T.G.Denisova and T.S.Pokidova, Handbook

    of Free Radical Initiators, Wiley, New York (2003), Moad, G., J.Chiefari, R.T. A. Mayadunne, C.L.Moad, A.Postma, E.Rizzardo, and

    S.H.Thang, Macromol. Symp., 182, 65 (2002).

    2. Sheppard C.S., Peroxy Compounds, pp. 1-21 in Encyclopedia ofPolymer Science and Engineering, Vol.11, H.F. Mark, N.M. Bikales,

    C.G. Overberger, and G.Menges eds., Wiley Interscience, NewYork, (1988).

    3. Eastmond G.C., The Kinetics of Free Radical Polymerization ofVinyl Monomers in Homogeneous Solutions, Chap. 1 in

    Comprehensive Chemical Kinetics, Vol. 14A, C.H. Bamford and

    C.F.H. Tipper, eds., American Elsevier, New York, (1976a.)

    4. Koenig. T., The Decomposition of Peroxides and Azoalkanes,Chap.3 in Free Radicals, Vol.I, J.K.Kochi, ed., Wiley, New York,

    (1973).

    5. Sarac, A.S., Prog, Polym. Sci., 24, 1149 (1999).6. Fernandez, M.D. and G.M. Guzman, J.Polym. Sci. Polym. Chem.. Ed.,

    27, 2427 (1989). Misra, G.S. and U.D.N. Bajpai, Prog. Polym, Sci., 8,

    61 (1982). Nayak, P.L. and S.Lenkla, J.Macromol. Sci. Rev.

    Macromol. Chem., C19, 83 (1980).

    7. Manickam, S.P., K.Venkatarao, U.c. Singh, and N.R.Subbaratnam,J.Polym, Sci. Polym. Chem.. Ed., 16, 2701 (1978).

    8. Oster, G and N.L. Yang, Chem. Rev., 68, 125, (1968), Pappas, S.P.,Photopolymerization, pp 186-212 in Encyclopedia of Polymer

    Science and Engineering, Vol. 11, H.F. Mark, N.M.Bikales, C.G.

    Overberger, and G.Menges, eds., Wiley Interscience, New York,

    (1988).

    9. Ananthanarayan V.S. Santappa M.J. Appl Polym Sci; 9:2347 (1969).10.Hanna SB, Carool WR, Attiga S, Webb WH, Z.Naturforsch, B. Anorg

    Chem: 30:409, (1975), Renders G, Broze G, Jerome R, Teyssie Ph. J

    Macromol Sci Chem A : 16 (8) : 1399, (1981).

    11.Mohanty N. Pradhan B, Mohanta MC. Eur Polym J; 15:743 (1979).12.Rout A, Rout Sp, Singh BC, Santappa M. Makromol Chem; 178:639;

    (1977).

  • 8/13/2019 Selvi Full Corrected

    30/31

    13.Subramanian SV, Santappa M, Makromol Chem : 112: (1968)14.Subramanian SV, Santappa M, J Polym Sci, Part A-1; 6:493: (1968).15.Saha SK, Chaudhuri AK, J Polym Sci, Polym Chem Ed : 10:797:

    (1972).

    16.Mohanty N, Pradhan B, Mohanta MC, Eur Polym J : 15:743(1979).17.S. Mohanty N, Pradhan B, Mohanta MC, J Macromol Sci A :

    19(2):283:(1981).

    18.Sarac, AS. Int Chem Kinet 1985: 17 : 1333. Sarac AS, Goc, men A.J.Soln Chem : 19:901(1990).

    19.Kamatchi M., J Satoh, and S.-I Nozakura, J. Polym, Sci, Polym.Chem. Ed., 16, 1789 (1978); Santee, G.F., R.H.Marchessault, H.G.

    Clark, J.J. Kearny, and V.Stannett, Makromol. Chem., 73 177 (1964);

    Schulz, G.V. and F.Blaschke, Z. Physik Chem. (Leipzig), B51, 75

    (1942).

    20.David G., J.J. Robin, and B.Boutevin, J. Polym. Sci. Polym. Chem.Ed., 39, 2740 (2001); Sarac, A.S., Prog. Polym. Sci., 24, 1149 (1999);Ito, K., J. Polym. Sci. Polym. Chem.. Ed., 18, 701 (1980);

    Macromolecules, 13, 193, (1980).

    21.Kaminsky, V., M.Buback, and M.Egorov, Macromol, Theory Simul.,11, 128 (2002).

    22.C.M.Patra, B.C. Singh : Journal of Applied Polymer Science, 52,1557-

    1568 (1994).

    23.M.Patra, A.K.Pandigrathi, and B.K.Sinha, Journal of Polymer Science

    (1996).

    24.Chandraganthi, K.Vasanthi and R.Sriram; J.M.S. Pure Appl. Chem,

    A32(12), 1997-2015 (1995).

    25.S.Nagarajan, S.Sudhakar, K.S.V. Srinivasan: Pure and Appl. Chem.,70(6), 1245-1248(1998).

    26.E.Erbil : E.Heximaglu, A.S.Sarac; Polymer; 40, 7409-7415 (1998).

    27.Nesrin OZ; Ahmet Akar; J.Am. Chem. Soc. 82, 301-313 (2001).

    28. V.S.Jamal Ahamed, H.Thajudeen, T.K.Shabeer. Eur polym J(2001)

    29.Kavitha Sankar, Venugopal Rajendran, Journal of Applied Polymer

    Science.(2002)

    30.A.K.Srivastava and Ajay Kumar Chaurasia : J.Chem Sci., 116, 55-59(2003).

  • 8/13/2019 Selvi Full Corrected

    31/31

    31.S.V.Subramanian, M.Santappa: Journal of Polymer Science, (2004).

    32.Dharmendira Kumar, M., ; Konguvel Thehazhnan, P.; Umapathy, M.;

    Rajendran, M.; International Journal of Polymeric Materials 53,95-

    103(2004).

    33.Ye.S.Garina, A.V.Olenin, v.P.Zubov, V.a.Kabanov; Journal of

    Polymer Science.(2005)

    34. Mahadevaian T.Demappa : Journal of Applied Polymer Science,m

    103 (6) : 34983505(2006).

    35. M.D. Fernandez, G.M.Guzman : British Polymer Journal 21 (5): 413-

    419 (2007)

    36. M.D.Fernandez, G.M. Guzman : British Polymer Journal (2007).

    37.Temel Ozturk and Ismail Cakmak, Iraniarr Polymer Journal 16 (8),

    561-581, (2007).

    38.Naguib, Hala F.; Makhtar, Samia M.; Khalil, NEsren Z.; Elsabee,

    Maher Z (2009).

    39.Sunil Kumar Banyal, Balbir Singh Knith, Rajeev Kr.Sharma; Adv.

    Appl. Sci. Res. 2(1), 193-207, (2011).

    40.P.L.Nayak, Manojkumar Pati, Advances in Polymer Science and

    Technology; An International Journal 1(2); 14-21; (2011).

    41. M.Palanivelu, K.E.N. Nalla Mohamed, T.Hidayathulla Khan and

    M.Prem Nawaz (2011).