Preparation and Characterization of Polymer-Grafted Montmorillonite-Lignocellulose Nanocomposites by In Situ Intercalative Polymerization

Lignocellulose-clay nanocomposites were synthesized using an in situ intercalative polymerization method at 60°C and a pressure of 1 atm. The ratio of the montmorillonite clay to the lignocellulose ranged from 1 : 9 to 1 : 1 (MMT clay to lignocelluloses, wt%). The adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). FTIR results showed that the polymers were covalently attached to the nanoclay and the lignocellulose in the nanocomposites. Both TEM and XRD analysis showed that the morphology of the materials ranged from phase-separated to intercalated nanocomposite adsorbents. Improved thermal stability, attributable to the presence of nanoclay, was observed for all the nanocomposites. The nanocomposite materials prepared can potentially be used as adsorbents for the removal of pollutants in water treatment and purification.

Preparation and characteristics of polypropylene-clay nanocomposite fibers

The objective of this work was to find a possible engineering application for polypropylene (PP) by preparing fibers filled with nanoclay particles. Unfilled and nanoclay filled (0–5 wt%) PP fibers were continuously drawn and examined. The surface morphology and topographic studies of fibers were carried out using a scanning electron microscope (SEM). It was observed that unfilled PP fibers possess poor density distribution with the nonuniform diameter across the fiber length affecting structural integrity. However, PP fibers filled with ≥2 wt% nanoclay had shown improvement in structural integrity. The structure and morphology of fibers were examined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, and the result indicated good dispersion of nanolayers of clay in PP matrix with exfoliated nanocomposite structure up to 2 wt% nanoclay and above 2 wt% showing intercalated nanocomposite structure. Improved tensile, thermal and water barrier properties of nanoclay filled PP were also observed.

Influence of clay organic modifier on morphology and performance of poly(ε-caprolactone)/clay nanocomposites

Two series of poly(e-caprolactone) nanocomposites with different organo-modified clays (1 to 8 wt%) were prepared by the solution casting method. Organoclays with polar (Cloisite?C30B) and nonpolar (Cloisite?C15A) organic modifier and with different miscibility with poly(e-caprolactone) matrix, were chosen. Exfoliated and/or intercalated nanocomposite?s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite?C30B, which had better miscibility with poly(e-caprolactone) matrix. Differences in spherulites? sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone) and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young?s modulus with experimentally obtained ones in tensile tests.

Effect of the organic groups of difunctional silanes on the preparation of coated clays for olefin polymer modification

Sodium montmorillonite (MMT) was organically modified with hexadecyltrimethyl-ammonium ions and subsequently treated with dichlorosilanes and water, aimed at in situ silane condensation polymerization and modification of clay platelets by polysiloxane coatings. Dimethyldichlorosilane, methylphenyldichlorosilane, and diphenyldichlorosilane were used to produce three siloxane-modified organoclays. The structure and morphology of the clay materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric studies (TG) and scanning electron microscopy (SEM). XRD results showed that the silanes were effectively polymerized in the clay galleries, forming a nanocomposite of intercalated particles. A fraction of the siloxane formed is bonded to the clay surface by covalent siloxane bonds. Strong structural differences in both morphology and thermal stability of the materials may occur when changing methyl or phenyl groups in the siloxane structure. The formation mechanism of these intercalated nanocomposite particles is considered. Finally, these modified clays were incorporated in an olefin polymer and morphological analyses using transmission electron microscope (TEM) images were carried out.

Kaolinite–poly(methacrylamide) intercalated nanocomposite via in situ polymerization

The preparation and characterization of a kaolinite–methacrylamide intercalation compound was achieved by a guest-displacement method, the direct treatment of a dimethylsulfoxide (DMSO) pre-intercalate with an aqueous solution of methacrylamide under mild conditions, giving intercalation ratios up to 92% and an expansion of 0.53 nm of the interlayer space. The DMSO molecules were fully displaced from the interlayer space by methacrylamide. Only partial intercalation could be obtained with N-methylformamide (NMF) pre-intercalate. After intercalation, the monomer was thermally polymerized at 100 or 150 °C with various heating times. XRD, FTIR, 13C CP/MAS NMR, and thermogravimetric analysis confirmed that polymerization was partially achieved in the interlayer spaces, while the layered structure of kaolinite was maintained, constraining the polymer in an interlayer space of 0.57 nm in the c-direction. In good agreement with the TG data, elemental analysis gave a stoichiometry of Al2Si2O5(OH)4·(C4H7NO)0.52 for the thermally treated methacrylamide intercalate, corresponding to a ratio of one methacrylamide unit per two kaolinite structural units. The thermal stability of the methacrylamide intercalate was increased after thermal treatment and polymerization.Key words: kaolinite, intercalation, nanocomposites, aluminosilicates, layered materials, interlayer polymerization, poly(methacrylamide).