Final Properties Of Nanocomposites Research Articles

Thickness, modulus and strength of interphase in clay/polymer nanocomposites

The aim of the present work is to quantify the properties of interphase between the polymer matrix and the nanoclay in clay/polymer nanocomposites (CPN). Two micromechanics models, Ji and Pukanszky, are simply used to measure the modulus, strength and thickness of interphase by mechanical properties of nanocomposites. The suggested approach is applied to calculate and evaluate the interphase properties in various samples reported in the literature. The calculations clearly demonstrate the different properties of interphase compared to matrix and nanoclay phases. It is shown that the interphase usually has a significant thickness, modulus and strength in CPN which cannot be neglected in the final properties of nanocomposites.

Effect of Processing Route on the Morphology of Thermoplastic Polyurethane (TPU) Nanocomposites Incorporating Organofluoromica

In the production of polymer nanocomposites, the processing method determines the dispersion of the nanofiller and hence, the final nanocomposite properties. In this work, the potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The potential of high energy milling of the organofluoromica to improve the platelet dispersion and exfoliation in both solvent cast and melt processed thermoplastic polyurethane (TPU)/organofluoromica nanocomposites was investigated. The applied high energy milling process has successfully reduced this nanofiller platelet length from 640 nm to 400 nm and 250 nm after 1 hour and 2 hours respectively. These lower aspect ratio milled nanofillers resulted in improved quality of dispersion and delamination when incorporated into the TPU and hence interacted more preferentially with the TPU matrix.

Structure and selected properties of polyamide 6/organophilized montmorillonite nanocomposites

The paper presents the results of a study on the nanocomposites prepared from polyamide 6 (PA 6) and montmorillonite, organophilized with two quaternary ammonium salts of different chemical structures (MO1, MO2), used as a filler at a concentration of 5 wt.%. The PA 6/organophilized montmorillonite composites were prepared using a co-rotating twin screw extruder. The test samples were made by injection or compression moulding. The structure of nanocomposites, in particular the degree of nanofiller exfoliation, was assessed using WAXS and TEM methods. The produced nanocomposites were characterized for the mechanical, rheological and thermal properties as well as flammability. It was found that the type of organically modifying agent exerts a substantial influence on the degree of nanofiller dispersion in a polyamide matrix, and in effect, on the final properties of nanocomposites.

Influence of the Botanic Origin of Starch Nanocrystals on the Morphological and Mechanical Properties of Natural Rubber Nanocomposites

AbstractThe structural and mechanical properties of natural rubber (NR) nanocomposites filled with starch nanocrystals (SNC) extracted from four different starch sources are investigated. The aim of this work is to explore the influence of botanic sources on final properties of nanocomposites and SNC reinforcing capability. A general trend seems to be that the higher the amylose content of native starch granules used for preparing SNC, the lower the water uptake and reinforcing effect (except for potato starch). It is postulated that SNC prepared from higher amylose content starch might release loosely bonded amylose chains during preparation and/or soaking in water and thus prevent SNC to participate in the formation of a reinforcing network.magnified image

Adhesive surface interactions of cellulose nanocrystals from different sources

Adhesion plays an important role in the final properties of nanocomposites. This study explored the surface interaction of cellulose nanocrystals (CNCs) and the effect of CNC sources on adhesion between individual CNCs and the Si tip of an AFM cantilever using a force mapping technique called FMap. The adhesion between CNCs and a Si tip from five different sources has been studied: cotton, Whatman filter paper, hemp, softwood chemical kraft pulp, and softwood-dissolving pulp (alistaple). Mica was used as the background substrate to act as an internal standard. This study’s findings suggest that adhesion is not the same for all CNCs. Transmission electron microscopy and atomic force microscopy were used to determine the size and shape of each CNC. The experimental quantitative data showed that adhesion between CNCs and the Si tip has a close correlation with the diameter of the CNCs. X-ray photoelectron spectroscopy confirmed the presence of sulfate groups on the surface of the CNCs and a correlation between adhesion and surface chemistry of the CNCs was observed.

Effect of layered silicate nanoclay on the properties of silane crosslinked linear low-density polyethylene (LLDPE)

In the present work, the effect of pristine layered silicate montmorillonite (MMT) nanoclay on the properties of silane-crosslinked LLDPE prepared by melt compounding is investigated. The effect of the sequence of feeding additives (nanoclay and grafting agent) into the mixer on gel content, thermal and mechanical properties were studied. Results demonstrate that the sequence of feeding additives influences the final properties of nanocomposites. For samples prepared by first grafting of silane on LLDPE followed by incorporation of nanoclay into the polymer matrix, the gel content and the rate of crosslinking increased, while the elongation at break decreased. For samples prepared by first mixing nanoclay into the LLDPE matrix followed by the grafting reaction, the rate of crosslinking and the tensile properties did not change significantly. The gel content increased with increasing content of nanoclay for both process routes due to an enhanced permeation of water molecules into the polymer matrix in the presence of polar montmorillonite particles. Wide angle X-ray scattering (WAXS) results proved the intercalation/partial exfoliation morphology of nanoclay in the silane-grafted LLDPE matrix. Differential scanning calorimetry (DSC) data showed multiple melting behaviour for crosslinked samples which is indicative for different crystalline structures of the sol and gel part of the LLDPE matrix.

Chemically Functionalized Clay Vinyl Ester Nanocomposites II - Vernonia Oil-based Surfactant

The primary objective of this study is to examine the role of reactive and nonreactive surfactants in exfoliation and dispersion of clay platelets in vinyl ester resin and evaluate the mechanical properties of final nanocomposites. The morphology of the nanocomposites was characterized using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) and the mechanical properties of the nanocomposite were determined by performing tensile measurements. When the clay was ion-exchanged with a combination of reactive and nonreactive surfactants and mixed with vinyl ester resin, a partially exfoliated vinyl ester nanocomposite was formulated. The degree of dispersion of the clay platelets in vinyl ester matrix was found to be sensitive to the chemistry associated with clay platelet modification, reactive comonomer, and processing conditions. At montmorillonite clay content of only 2.5 wt%, the modulus improved by 20% in partially reactive organoclay dispersed nanocomposite, while the modulus improved by 10% in nonreactive organoclay-dispersed nanocomposite compared to that of unfilled cured vinyl ester resin.

Metallocene‐based functionalized polyolefins as compatibilizers in polyolefin nanocomposites

AbstractThis article reports a study of some functionalized polyolefins evaluated as compatibilizers in polyethylene nanocomposites. The functionalized polymers were prepared by direct metallocene‐mediated copolymerizations of ethylene and a functional comonomer. The prepared nanocomposites were evaluated for mechanical and barrier property enhancement. A good combination of mechanical and barrier properties was obtained with the metallocene‐based functionalized polyethylene. The toughness–stiffness balance was better than or comparable to that achieved with conventional functionalized polymers such as maleic anhydride grafted polyethylene. The results also indicated that these metallocene‐based functionalized polyolefins, when used as compatibilizers, could have relatively higher molar masses and lower functionality than those of conventional post‐reactor‐modified compatibilizers, and so the drawbacks associated with the latter could be avoided. Their inherent properties could also further improve the final nanocomposite properties. This was attributed to the more homogeneous nature of metallocene‐catalyzed polymers in comparison with post‐reactor‐modified products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1094–1100, 2004