Sodium montmorillonite clay loaded novel organic–inorganic hybrid composites: Synthesis and characterization

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  • Progress in Organic Coatings 75 (2012) 33 37

    Contents lists available at SciVerse ScienceDirect

    Progress in Organic Coatings

    jou rn al h om epage: www.elsev ier .com

    Sodium anSynthe

    Kishore K outa Organic Coati 7, Indib Research, Dev

    a r t i c l

    Article history:Received 28 OReceived in reAccepted 9 MaAvailable onlin

    Keywords:CoatingThermomechaSandwich struDynamic mech(DMTA)Heat treatmen

    ed wpolyiml scand to uopertompoith puld be ntencrease

    1. Introduction

    Polyimides have been used in a wide variety of applicationssuch as coadhesives, aexcellent mresistance [materials ising researchybrid comthermal [4]also show wcoatings [9]

    Recentlymaterials inmance coatto develop ganic particand mechanpore size anlonite clay provide the

    CorresponGroup, Ijmuide

    E-mail add

    drug delivery and membrane separations [12,13]. One of the mostwidely used llers in such applications is montmorillonite (MMT).Montmorillonite is one of the clay minerals, whose structure is like

    0300-9440/$ doi:10.1016/j.atings, microelectronic packaging, high temperaturend composites owing to their good thermal stability,echanical strength, dielectric insulation, and chemical1,2]. Combination of organic polymers and inorganic

    an exciting subject that has been receiving increas-h attention during recent decades. Organicinorganicposites show novel properties such as mechanical [3],, optical [5,6], electrical [7], and magnetical [8]. Theyide potential applications in various areas such as in, catalysis [10] and biotechnology [11]., clay particles are continued to be interesting llerto polymers in developing cost-effective high perfor-ings. Particularly, extensive research has been devotedpolymer-layered nanocomposites, wherein ller inor-les in a polymer matrix could exhibit improved physicalical properties of the base polymers. The easily tailoredd compositional variability available with montmoril-particles when embedded into polymer network will

    versatile range of applications such as in coatings,

    ding author at: Research, Development and Technology, Tata-Corusn-1760, The Netherlands. Tel.: +31 611 623435; fax: +31 251 448706.ress: (T.K. Rout).

    sandwich type with one octahedral Al2O3 sheet between two tetra-hedral SiO2 sheets. To make an organophilic clay intercalated withswelling agent, it is necessary to use clay that swells into water. Inthis aspect, synthetic mica, montmorillonite, saponite, and hectriteare appropriate for hybrid synthesis.

    In this article, we report synthesis and properties ofpolyimideclay hybrid lms with various concentration of clayto investigate the properties of the hybrids. It was found thatthe higher concentration of the clay was much more effective toimprove the properties of polyimide. In order to investigate thecoating properties, the hybrid formulations were applied on totin foil and then imidized by a thermal procedure. The thermal,mechanical and coating properties with different clay content werecharacterized.

    2. Materials and experimental

    2.1. Materials

    Untreated sodium montmorillonite (Na+MMT) clay particles,3,3,4,4-biphenyltetracarboxylic dianhydride (BTDA), benzene-1,3-diamine (BDA) and 3,3-oxydianiline (ODA) were obtained fromAldrich and used as received. 1-Methyl-2-pyrrolidone (NMP) andcetyl trimethyl ammonium bromide (CTAB) were obtained from

    see front matter 2012 Elsevier B.V. All rights reserved.porgcoat.2012.03.005 montmorillonite clay loaded novel orgsis and characterization

    . Jenaa, K.V.S.N. Rajua, Ramanuj Narayana,b, T.K. Rngs and Polymers Division, Indian Institute of Chemical Technology, Hyderabad-50060elopment and Technology, Tata-Corus Group, Ijmuiden-1760, The Netherlands

    e i n f o

    ctober 2011vised form 2 March 2012rch 2012e 10 April 2012

    nical propertiescturesanical thermal analysis


    a b s t r a c t

    Polyimide based organic matrix loadclay particles, i.e. (polyimideclay-1, mal imidization method. Differentiamechanical thermal analysis were useused to study mechanical strength prtransition temperature of the hybrid cobviously improved, in comparison wshowed that the tensile strength couclay particles to the matrix. The gel cotance and abrasion resistance were in/ locate /porgcoat

    icinorganic hybrid composites:



    ith 1, 3 and 5 wt.% of sodium montmorillonite (Na+MMT)ideclay-3 and polyimideclay-5), were developed by ther-

    ning calorimetry, thermogravimetric analysis and dynamicnderstand thermal properties. Universal testing machine wasies. The results from thermal analysis indicated that the glasssite was increased by about 10 C and its thermal stability wasre polyimide. The investigation on the mechanical propertiesobviously increased by adding 1 wt.% (by weight) (Na+MMT)t, adhesive strength, Impact strength, water absorption resis-d with increasing the clay concentration in polyimide matrix.

    2012 Elsevier B.V. All rights reserved.

  • 34 K.K. Jena et al. / Progress in Organic Coatings 75 (2012) 33 37

    Fluka Chemicals (Osaka, Japan). The solvents were freed from mois-ture using 4 A molecular sieves before use.

    2.2. Preparation of organo-montmorillonite

    The orgaconcentratetion to quatused to incrclay. Approin deionizeMalvern MaThe organiing Na-monThis techniand high shparticles. Inication, thesonication cation-exchsubsequentto ensure ttitrated witproduct wadried produ

    2.3. Synthe

    A 150 mheated forremove wawith (0.5 m(0.5 mol) ansolution anfor 16 h toused as a pmontmorillin oven at 2steps for thshown in Sc

    2.4. Organi

    A thin diving applpriate propbefore castiair-circulat

    2.5. Instrum

    The thermogravimeheating ratesamples wasition tempDMTA IV inat a frequenlms from 2of temperatwas recordples were hunder nitrostrength waun-notchedis a measur

    as a vertical cantilevered beam and is impacted by a pendulum.The pendulum that swings and breaks the samples, the distancecovered by the pendulum after breaking the sample is measured.The machine is calibrated, so that if there is no sample, the dis-

    he pendulum swings will read on the indicator. This is the why Izod Impact is expressed in Torque. The torque is thend by the sample thickness and is expressed as J/m (joules per. For the adhesion test the metal discs were pretreated witheaning (chemical pickling), washed with distilled water ande before application of coatings with spin coater. The adhe-rength of polymers on the metal surface was determined byf test (Microtech Tensiometer, UK). A known amount of the

    lms was placed in a Soxhlet apparatus and extracted withe for 6 h. The extracted lm was then dried for 80 C to con-eight. The nal weight of the extracted dry lm, expressed

    centage of the initial weight, was assumed as the gel con-he degree of polymerization). Water resistance of the lmseasured by calculating % swelling by weight. To do this, pre-d dry lms were immersed in deionized water for 50 h tothe water resistance at room temperature. After removingples from the immersion bath, these were blotted with soft

    paper and weighed to calculate swelling ratio using

    g ra[ ]

    Wdollening the rer, i.e.

    of c for ed.


    A an


    belos NM

    coatre twat abably

    Fignier was dissolved in deionized water at 60 C andd HCl was added drop by drop into the organier solu-ernize the amine group. The swelling agent CTAB wasease the compatibility and inter layered spacing of thepriate amount of Na-mont was preliminarily dispersedd water at 60 C by using ultrasound probe attached tostersizer 2000 (UK) particle size analyzer (20 W/cm2).er solution was poured in to the suspension contain-t and the mixture was vigorously sonicated for 2 h.que is commonly employed when both high speedear are required to create colloidal dispersion of ne

    order to avoid the excess heat generated during son- sonication was repeatedly carried out in an alternateand cooling cycle of around 30 s. After sonication, theanged clay particles were collected by centrifuge andly washed repeatedly with deionized water. In orderhe complete removal of chloride ions, the ltrate wash 0.1 N AgNO3 until no further AgCl precipitated. Thes then placed in a vacuum oven at 80 C for 12 h. Thect was ground to get the organo-montmorillonite.

    sis of polyimideclay hybrid

    L one-neck ask equipped with a nitrogen inlet was 10 min with a heat gun under nitrogen ow toter and oxygen from the ask. The ask was chargedol) (benzene-1,3-diamine (98%) and a 3,3-oxydianilined 100 g of NMP. (1 mol) of BTDA was added to thed the reaction mixture stirred under N2 condition

    form a polyamic acid intermediate (PAA). PAA wasrecursor for the subsequent composite synthesis usingonite-clay and directly casted on the tin foil and cured50 C for 5 min to form a solid lm. Different synthetice preparation of polyimideclay hybrid composites areheme 1.

    cinorganic hybrid lm preparation

    lm of formulation was cast onto tin foil using a manualicator to make 10 m solid lms for testing the appro-erties. The tin foil were washed with acetone and driedng a formulation. The wet thin lms were cured usinged oven at 250 C for 5 min.

    ental characterization

    mal properties of the lms were measured using ther-tric analysis (TGA) Q500 (TA Instruments, Inc.) with a

    of 10 C/min under a N2 atmosphere. The weight of thes ranged from 510 mg. The modulus and glass tran-erature (Tg) of hybrid samples were measured usingstrument (Rheometric Scientic, USA) in tensile modecy of 1 Hz with a heating rate of 3 C/min by scanning the5 to 250 C. Storage modulus (E) and tan as a functionure at a constant frequency were observed. DSC analysised on a Mettler Toledo DSC 821e, Switzerland. Sam-eated from 25 to 200 C at a heating rate of 20 C/mingen atmosphere at a ow rate of 30 mL/min. The impacts determined using Izod Impact tester (PSI, India) for

    specimens conforming to ASTM D 256 specication. Ite of brittleness of coating. Un-notched sample is held

    tance treasondividemeter)acid clacetonsion stPull-ofhybridtoluenstant was pertent (twas mweighestudy the samtissue


    wherethe swaccordmine tabrasoweightrubbedrecord

    3. Res

    3.1. TG

    TGApolyimFig. 1. occurssuch ahybridthere astarts is probtio(%) = (Ws Wd)Wd

    100 (1)

    is the weight of dry sample and Ws is the weight of sample. The abrasion resistance test was carried outo ASTM D 4060-01. This test method was used to deter-sistance of coatings to abrasion produced by the Taber

    wheel CS 10 on coatings applied to a metal panel. Theoated panel before rub was recorded. Then lm wasabout 250 and 500 cycles and again the weights were

    and discussion


    urves of the polyimide, polyimideclay (1%),clay (3%) and polyimideclay (5%) are shown in

    Fig. 1, one can see that no appreciable weight lossw 200 C for all the samples. This indicates that solvents,P, and moisture are almost perfectly removed from theings during imidization. For a pure polyimide sample,o remarkable weight loss temperatures. The rst one

    out 270 C and corresponds to 5 wt.% weight loss. This due to the degradation of the polymer. The second one

    . 1. TGA thermograms of polyimideclay hybrid coatings.

  • K.K. Jena et al. / Progress in Organic Coatings 75 (2012) 33 37 35

    starts at abof the protcauses a sliincreases wdue to the volatile proclay. As shotemperaturcontent of also noted

    Table 1Thermal-analy

    Sample code

    PolyimidePolyimidecPolyimidecPolyimidecScheme 1. Different synthetic steps for the preparation of polyi

    out 350 C which is associated with the degradationected polymer. The introduction of clay to Polyimideght weight loss above 358 C and the thermal stabilityith increasing the clay content. This might be observedthermal insulator and mass transport barrier to theducts generated during decomposition behavior of thewn in Fig. 1 and Table 1, the maximum decompositione of the samples increases with the increasing claythe hybrids [14,15]. From the weight loss curves, it isthat the degradation of Polyimide is largely reduced

    with incorpof the hybr

    3.2. Dynam

    The gladata of popolyimideimide has and 169.9

    sis data for the polyimideclay hybrid coatings.

    Ton (C) Tend (C) % Wt. remaining at

    271.6 420.9 83.16 lay (1%) 273.2 425.7 85.24 lay (3%) 286.1 449.6 86.89 lay (5%) 302.6 469.8 88.34 mideclay hybrid composites.

    oration of clay layer. Furthermore, the char yield valuesid materials increase with increasing clay content.

    ic mechanical thermal analysis (DMTA)

    ss transition temperature and storage moduluslyimide, polyimideclay-1%, polyimideclay-3% andclay-5% hybrid coatings are reported in Table 2. Poly-a Tg of118.4 C, which was shifted to 123.2, 130.6C after incorporation of clay particles into polyimide,

    Ton % Wt. residue remaining at

    450 C 550 C 600 C

    19.43 9.32 9.1123.16 18.31 18.1627.91 21.33 20.3132.18 24.19 23.71

  • 36 K.K. Jena et al. / Progress in Organic Coatings 75 (2012) 33 37

    Table 2Glass transition temperature and storage modulus data for the polyimideclay hybrid coatings.

    Sample code Tg (C) DSC Tg (C) tan max E at 50 C [dyn/cm2] E at (Tg + 5 C) [dyn/cm2]

    Polyimide 106.8 118.4 0.69 4.66 108 0.52 108Polyimideclay-1% 117.1 123.2 0.51 4.97 108 0.72 108Polyimideclay-3% 121.8 130.6 0.49 1.71 109 1.99 108Polyimideclays-5% 156.4 169.9 0.44 4.79 109 5.91 108


    suggesting to intercala

    3.3. Differe

    The glas1%, polyimfrom DSC sglass transiviz., 117.1, Na+MMT-lois due to innature.

    3.4. Tensile

    The tensclay contenFig. 3. It wasimide incresamples haThis might in polyimidever, whenabruptly de

    Table 3Tensile proper

    Sample code

    Polyimide PolyimidecPolyimidecPolyimidec

    the clay size affect the tensile strength and elongation because clayaggregations would lead to stress concentrations on the interfaces[16].

    pact strength

    Izod impact strength of the polyimide, polyimideclay (1%),ideclay (3%) and polyimideclay (5%) hybrid coatings areed in Table 3.Table shows that the impact strength of the

    coatings increases with increasing clay concentration. Thisor might be observed due to presence of inorganic networkssystem. Theses network structures stop the crack propaga-d increase the Impact strength [16].

    hesive strength

    adhidele 4. nicalide a123.7trengh hiinkeasedbe ace [1

    l con. 2. DSC thermograms of polyimideclay hybrid coatings.

    a restricted segmental motion of polyimide chains duetion [14].

    ntial scanning calorimetry (DSC)

    s transition temperature of polyimide, polyimideclay-ideclay-3% and polyimideclays-5% hybrid coatings

    3.5. Im

    Thepolyimreporthybridbehaviin the tion an

    3.6. Ad

    Thepolyimin TabmechaPolyim191.2, sion sis muccross-lis incremight interfa

    3.7. Getudy is reported in Table 2 and shown in Fig. 2. Thetion temperature has shifted to higher temperatures,121.8 and 156.4 C, respectively, for 1, 3 and 5 wt.%aded polyimide. However, increase in Tg of polyimidecreasing amount of clay particles that are inorganic in


    ile properties of polyimideclay hybrid lms with thets of 1, 3 and 5 wt.% are reported in Table 3 and shown in

    found that the incorporation of clay particles into poly-a...


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