Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

Chaudhary, Deeptangshu; Prasad, Ranjit; Gupta, Rahul; Bhattacharya, S. N.

doi:10.1016/j.tca.2005.02.031

Cited by 79 publications

(71 citation statements)

References 11 publications

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“…Such influence may be the result of grafting between the polymer and clay, or crosslinking of the polymer. Although it is known [1] that clay exfoliates better into higher vinyl acetate (VA) containing EVA, we used 9% VA containing EVA so that any effect of the peroxide will not be overshadowed by a strong interaction between the EVA and clay modifier. Dicumyl peroxide (DCP) was used as crosslinking initiator at a temperature well below its optimum decomposition temperature (1 h halflife at 136°C), while dibenzoyl peroxide (DBP) was used at a temperature above its optimum decomposition temperature (1 h half-life at 91°C).…”

Section: Resultsmentioning

confidence: 99%

“…Organic-inorganic hybrids based on layered inorganic compounds, such as clays, and organic polymers have been studied because of exceptional properties like increased modulus [1][2][3], reduced gas permeability [4,5], and enhanced thermal stability [6,7]. Dispersion of the silicate particles in the polymer matrix is improved by replacing the metal cations with ions bearing an aliphatic chain for compatibilizing the silicate.…”

Section: Introductionmentioning

confidence: 99%

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Effect of organic peroxides on the morphological, thermal and tensile properties of EVA-organoclay nanocomposites

Mishra¹,

Luyt²

2008

Express Polym. Lett.

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Abstract. Nanocomposites were prepared using an ethylene vinyl acetate copolymer (EVA) and organically modified Cloisite ® 93A clay in the absence and presence of dicumyl peroxide (DCP) and dibenzyl peroxide (DBP) as cross-linking agents. The results clearly show differences in the EVA-clay morphology of nanocomposites prepared in the absence of organic peroxides, and of those prepared in the presence of respectively DCP and DBP. It seems as if DCP may initiate grafting between the polymer and the clay, which results in an exfoliated morphology. The presence of clay seems to inhibit the initiation of EVA crosslinking by the DBP free radicals. These free radicals probably initiate hydroxylated edge-edge interaction between the clay layers, which gives rise to a flocculated morphology and reduced polymer-clay interaction. There is a good correlation between these morphologies and the thermal stabilities and total crystallinities of the nanocomposites. Clay incorporation and peroxide treatment did not significantly change the tensile properties.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of organic peroxides on the morphological, thermal and tensile properties of EVA-organoclay nanocomposites

Mishra¹,

Luyt²

2008

Express Polym. Lett.

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“…Chaudhary et al 24 found that a higher vinyl acetate (VA) content in EVA improved the polymerclay interaction, which gave rise to an increase in the rigid amorphous phase and significantly changed the mechanical properties of the nanocomposites. Gupta et al 25 found predominantly exfoliated morphologies for nanocomposites of EVA with organically modified bentonite clay.…”

Section: Introductionmentioning

confidence: 99%

Effect of ethylene glycidyl methacrylate compatibilizer on the structure and mechanical properties of clay nanocomposites modified with ethylene vinyl acetate copolymer

Guduri

Luyt

2006

J of Applied Polymer Sci

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ABSTRACT:The structure and mechanical properties of clay modified with ethylene vinyl acetate copolymer in the presence of ethylene glycidyl methacrylate (EGMA) were investigated as a function of compatibilizer and clay contents. The structure and properties were determined by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis (TGA). The presence of EGMA caused strong exfoliation of the clay in the polymer matrix, although at higher clay contents, some clay layers still existed. The more effective exfoliation, however, did not seem to substantially influence the tensile properties of the nanocomposites because the EGMA itself had a much stronger influence, which overshadowed any possible influence that the EGMA-clay interaction may have had on these properties. The thermal stability of the nanocomposites (as studied by TGA) improved in the presence of EGMA.

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“…This is different from plasticization (such as by xylitol) as the amorphous fraction influences the mechanical properties of composites mainly by development of an organized crystalline structure. 25,26 A final observation of maltodextrin samples indicates that it failed to shown any significant improvement in degree of elongation even at 15% addition. As seen from Table III, maltodextrin samples equilibrated with significantly lower amount of water.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Understanding polymeric amylose retrogradation in presence of additives

Chaudhary

Adhikari

2009

J of Applied Polymer Sci

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Polymeric aging in starch is an important equilibrating process leading to long-chain amylose recrystallization and anisotropic properties of material made from starch. Investigations into a number of plasticizers and hydrocolloids showed that their water retention/binding capability influence the starch polymer's crystallinity. Addition of up to 8 wt % glycerol and 3 wt % xylitol acted as an antiplasticizer and apparently increased the total crystalline phase, which reduced the degree of elongation of amylose matrix by 15%. Maltodextrin and xanthan gum also reduced matrix elongation capability but X-ray diffraction (XRD) analysis showed samples with varying crystallinity, and the extent of crystallinity did not correlate with respective tensile properties. Additives such as maltodextrin, with similar molecular structure as amylose, were ineffective in increasing degree of elongation even at 15 wt % addition rate, because of formation of pockets of crystalline region, as observed by XRD analysis. Both xylitol and xanthan gum samples showed similar tensile strength and elongation properties, but the water retention capability of xylitol-filled starch samples was about 27% lower than xanthan gum samples, at their respective higher concentrations. A dynamic structural unit is proposed to satisfy the isotropic increase in tensile strength and degree of elongation in oriented starch matrix.

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Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

Cited by 79 publications

References 11 publications

Effect of organic peroxides on the morphological, thermal and tensile properties of EVA-organoclay nanocomposites

Effect of organic peroxides on the morphological, thermal and tensile properties of EVA-organoclay nanocomposites

Effect of ethylene glycidyl methacrylate compatibilizer on the structure and mechanical properties of clay nanocomposites modified with ethylene vinyl acetate copolymer

Understanding polymeric amylose retrogradation in presence of additives

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