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Henglong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Effect of organic Layered Silicate on microstructures and aging properties of styrene–butadiene–styrene copolymer modified bitumen
Construction and Building Materials, 2014Co-Authors: Henglong ZhangAbstract:Abstract A new approach to determine the microstructures of organic Layered Silicate/SBS modified bitumen was adopted by combining the results from X-ray diffraction analysis of organic Layered Silicate/SBS modified bitumen and the dissolving–filtrating procedure. The effect of thin film oven test (TFOT) and ultraviolet (UV) aging on the morphology of binders was characterized by using optical microscopy. The results show that organic montmorillonite/SBS modified bitumen and organic rectorite/SBS modified bitumen form the semi-exfoliated nanostructure, while organic expanded vermiculite/SBS modified bitumen forms the exfoliated nanostructure. The high temperature properties of SBS modified bitumen and the compatibility between SBS and bitumen are improved with the introduction of organic Layered Silicate. Compared with SBS modified bitumen, organic Layered Silicate/SBS modified bitumen shows the lower viscosity aging index and the higher retained ductility after TFOT and UV aging. Aging influences the morphology of SBS modified bitumen significantly. There is a single phase trend of SBS modified bitumen during TFOT, which is accelerated by UV radiation. However, the morphological changes are prevented obviously with the introduction of organic Layered Silicate, indicating the good aging resistance of organic Layered Silicate/SBS modified bitumen. Additionally, the influence of organic Layered Silicate on these physical properties of SBS modified bitumen before and after aging depends on its nature.
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effect of organic Layered Silicate on microstructures and aging properties of styrene butadiene styrene copolymer modified bitumen
Construction and Building Materials, 2014Co-Authors: Henglong Zhang, Chongzheng Zhu, Caiju ShiAbstract:Abstract A new approach to determine the microstructures of organic Layered Silicate/SBS modified bitumen was adopted by combining the results from X-ray diffraction analysis of organic Layered Silicate/SBS modified bitumen and the dissolving–filtrating procedure. The effect of thin film oven test (TFOT) and ultraviolet (UV) aging on the morphology of binders was characterized by using optical microscopy. The results show that organic montmorillonite/SBS modified bitumen and organic rectorite/SBS modified bitumen form the semi-exfoliated nanostructure, while organic expanded vermiculite/SBS modified bitumen forms the exfoliated nanostructure. The high temperature properties of SBS modified bitumen and the compatibility between SBS and bitumen are improved with the introduction of organic Layered Silicate. Compared with SBS modified bitumen, organic Layered Silicate/SBS modified bitumen shows the lower viscosity aging index and the higher retained ductility after TFOT and UV aging. Aging influences the morphology of SBS modified bitumen significantly. There is a single phase trend of SBS modified bitumen during TFOT, which is accelerated by UV radiation. However, the morphological changes are prevented obviously with the introduction of organic Layered Silicate, indicating the good aging resistance of organic Layered Silicate/SBS modified bitumen. Additionally, the influence of organic Layered Silicate on these physical properties of SBS modified bitumen before and after aging depends on its nature.
Chenggang Chen - One of the best experts on this subject based on the ideXlab platform.
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Processing—Morphology regulation of epoxy/Layered-Silicate nanocomposites
Journal of Applied Polymer Science, 2008Co-Authors: Chenggang Chen, Tia Benson-tolle, Jeffery W. Baur, S. PutthanaratAbstract:Polymer/Layered-Silicate nanocomposites have unique and hierarchical structures that can provide improvements to the properties of polymeric materials. Controlling the dispersion of the nanomaterials through processing greatly influences the resulting morphology and the resulting properties of the nanocomposite. In this article, the dispersion behavior of organic Layered Silicates (OLS) as a function of the processing procedure is reported. The behavior of the OLS in all stages of processing—in the solvent, the epoxy prepolymer, and in the epoxy through cure—is discussed. On the basis of understanding of the dispersion behavior of the OLS in the epoxy resin at each stage of processing, a different processing procedure can be designed and used so that the morphology of the epoxy/Layered-Silicate nanocomposite can be regulated. Mild low-shear processing resulted in an intercalated nanocomposite with large-size aggregates (> 10 μm), and high-shear processing resulted in an intercalated nanocomposite with relatively small-size aggregates (0.5–3 μm), whereas the high-shear and ultrasonication processing procedures gave rise to an exfoliated nanocomposite. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
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Fully exfoliated Layered Silicate epoxy nanocomposites
Journal of Polymer Science Part B: Polymer Physics, 2004Co-Authors: Chenggang Chen, Tia Benson TolleAbstract:Fully exfoliated Layered Silicate epoxy nanocomposites are reported in this article. The processing route that resulted in these fully exfoliated Layered Silicate epoxies is based on a combination of high-shear mixing in the presence of acetone and ultrasonication. Homomogeneous and random dispersion of the individual Silicate nanolayers in the epoxy is confirmed through transmission electron microscopy images spanning low to high magnification as well as by X-ray diffraction. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3981–3986, 2004
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Control of the Morphology of the Layered-Silicate Epoxy Nanocomposite
MRS Proceedings, 2004Co-Authors: Chenggang Chen, Tia Benson TolleAbstract:ABSTRACTPolymer Layered-Silicate nanocomposites have attracted great attention due to their unique nanostructure and properties. The property of the nanocomposite is determined by the morphology of the nanocomposite. The typical morphologies of the nanocomposite are the intercalated and exfoliated nanostructures. In this study, the Layered-Silicate epoxy nanocomposite with different morphology can be controlled and achieved. The different morphology could include the intercalated nanostructure with the 15 Å increase of the interplanar spacing, the intercalated one with ∼150 Å increase of the gallery and fully exfoliated nanostructure.
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Epoxy Layered-Silicate nanocomposites
Progress in Organic Coatings, 2003Co-Authors: Chenggang Chen, M. Khobaib, David CurlissAbstract:Polymer Layered-Silicate nanocomposites have attracted a lot of attention because of impressive enhancements of polymeric properties. In this research, both commercially available and synthesized organoLayered Silicates, which are compatible with the epoxy resins, were used to make epoxy nanocomposites. The epoxy resin used in this research includes Epon 862/curing agent W (the aerospace epoxy resin), the Epon 828/Epi-Cure curing agent 8290-Y-60 (used as the primer layer for corrosion prevention in aircraft coating), and Epon 828/Jeffamine D400. The morphology of the nanocomposites was characterized using wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The morphology development for the aerospace epoxy-organoclay nanocomposite was monitored through in situ SAXS and analyzed. The solvent absorption of the exfoliated aerospace epoxy-organoclay nanocomposite in acetone was examined, and the diffusion coefficients of solvent in the nanocomposites were reduced. The organoclay/Epon 828/Y-60 and organoclay/Epon 828/D400 nanocomposite were used to make coatings on an Al surface. The anticorrosion properties of the nanocomposite coating were evaluated and discussed.
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Self-Passivation of Polymer-Layered Silicate Nanocomposites
Chemistry of Materials, 2001Co-Authors: Hao Fong, Richard A Vaia, J.h. Sanders, Derek M. Lincoln, Andrew J. Vreugdenhil, Weidong Liu, And John Bultman, Chenggang ChenAbstract:Nanoscale dispersion of only a few weight percentage of Layered Silicate (montmorillonite) in nylon 6 and epoxy results in the formation of a uniform passivating and self-healing inorganic surface region upon exposure to oxygen plasma. The enrichment of inorganic is compositionally graded with respect to the surface and is due to the preferential oxidation of the polymer from the nanocomposite and the corresponding enhancement of the nanoscale Layered Silicate on the surface. The structure of the inorganic region is turbostratic, with an average distance between Layered Silicates of 1−4 nm. This ceramic-like Silicate layer provides an overcoat to the nanocomposite and can significantly retard the penetration of oxygen plasma. Thus, Layered Silicate containing nanocomposites may enhance the survivability of polymeric materials in aggressive oxidative environments, such as atomic oxygen in low earth orbit (LEO). The formed inorganic region was characterized chemically and morphologically by X-ray photoelect...
Masami Okamoto - One of the best experts on this subject based on the ideXlab platform.
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new polylactide Layered Silicate nanocomposites 6
Macromolecular Materials and Engineering, 2003Co-Authors: Masami OkamotoAbstract:The measurement of rheological properties of any polymeric material under molden state is crucial to gain fundamental understanding of the processability of that material. In the case of polymer/Layered Silicate nanocomposites, the measurements of rheological properties are not only important to understand the knowledge of the processability of these materials, but it also helpful to find out the strength of polymer-Layered Silicate interactions and the structure-property relationship in nanocomposites. This is because rheological behaviors are strongly influenced by their nanoscale structure and interfacial characteristics. In order to get this knowledge in the case of polylactide/montmorillonite nanocomposites, we have studied melt rheological properties of these materials in detail. On the basis of rheological data, we have conducted foam processing of pure polylactide and one representative nanocomposite by a newly developed pressure cell technique using carbon dioxide as a physical-blowing agent.
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polymer Layered Silicate nanocomposites a review from preparation to processing
Progress in Polymer Science, 2003Co-Authors: Suprakas Sinha Ray, Masami OkamotoAbstract:Abstract A review is given of the academic and industrial aspects of the preparation, characterization, materials properties, crystallization behavior, melt rheology, and processing of polymer/Layered Silicate nanocomposites. These materials are attracting considerable interest in polymer science research. Hectorite and montmorillonite are among the most commonly used smectite-type Layered Silicates for the preparation of nanocomposites. Smectites are a valuable mineral class for industrial applications because of their high cation exchange capacities, surface area, surface reactivity, adsorptive properties, and, in the case of hectorite, high viscosity and transparency in solution. In their pristine form they are hydrophilic in nature, and this property makes them very difficult to disperse into a polymer matrix. The most common way to remove this difficulty is to replace interlayer cations with quarternized ammonium or phosphonium cations, preferably with long alkyl chains. A wide range of polymer matrices is covered in this review, with special emphasis on biodegradable polymers. In general, polymer/Layered Silicate nanocomposites are of three different types, namely (1) intercalated nanocomposites , for which insertion of polymer chains into a Layered Silicate structure occurs in a crystallographically regular fashion, with a repeat distance of few nanometers, regardless of polymer to clay ratio, (2) flocculated nanocomposites , for which intercalated and stacked Silicate layers flocculated to some extent due to the hydroxylated edge–edge interactions of the Silicate layers, and (3) exfoliated nanocomposites , for which the individual Silicate layers are separated in the polymer matrix by average distances that depend only on the clay loading. This new family of composite materials frequently exhibits remarkable improvements of material properties when compared with the matrix polymers alone or conventional micro- and macro-composite materials. Improvements can include a high storage modulus, both in solid and melt states, increased tensile and flexural properties, a decrease in gas permeability and flammability, increased heat distortion temperature, an increase in the biodegradability rate of biodegradable polymers, and so forth.
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new polylactide Layered Silicate nanocomposites 5 designing of materials with desired properties
Polymer, 2003Co-Authors: Kazunobu Yamada, Masami Okamoto, Akinobu Ogami, Youhei Fujimoto, Kazue UedaAbstract:Understanding the structure/property relationship in polymer/Layered Silicate nanocomposites is of great importance in designing materials with desired properties. In order to understand these relations, a series of polylactide (PLA)/organically modified Layered Silicate (OMLS) nanocomposites have been prepared using a simple melt extrusion technique. Four different types of OMLS have been used for the preparation of nanocomposites, three were modified with functionalized ammonium salts while fourth one was a phosphonium salt modified OMLS. The structure of the nanocomposites in the nanometer scale was characterized by using wide-angle X-ray diffraction and transmission electron microscopic observations. Using four different types of Layered Silicates modified with four different types of surfactants, the effect of OMLS in nanocomposites was investigated by focusing on four major aspects: structural analysis, thermal properties and spherulite morphology, materials properties, and biodegradability. Finally, we draw conclusions about the structure/property relationship in the case of PLA/OMLS nanocomposites.
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crystallization behavior and morphology of biodegradable polylactide Layered Silicate nanocomposite
Macromolecules, 2003Co-Authors: Masami Okamoto, Masami OkamotoAbstract:An intercalated polylactide (PLA)/Layered Silicate nanocomposite was prepared by simple melt extrusion of PLA and organically modified montmorillonite. The detailed crystallization kinetics and morphology of neat PLA before and after nanocomposite preparation were studied by using polarized optical microscopy, light scattering, differential scanning calorimetric, and wide-angle X-ray diffraction analyses. The overall crystallization rate and spherulitic texture of pure PLA were strongly influenced in the presence of montmorillonite particles.
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structure property relationship in biodegradable poly butylene succinate Layered Silicate nanocomposites
Macromolecules, 2003Co-Authors: Suprakas Sinha Ray, Kazuaki Okamoto, Masami OkamotoAbstract:Understanding the structure−property relationship in polymer/Layered Silicate nanocomposites is of fundamental importance in designing materials with desired properties. To understand these relations in the case of poly(butylene succinate) (PBS)/organically modified Layered Silicate (OMLS) nanocomposites, we studied the rheological properties of these materials in detail, because the rheological behavior of polymer/OMLS nanocomposites is strongly influenced by their nanostructure and the interfacial characteristics. For this reason, a series of PBS/OMLS nanocomposites were prepared using a simple melt intercalation technique. Two different types of OMLS, montmorillonite (mmt) modified with octadecylammonium chloride and saponite (sap) modified with quaternary hexadecyl tri-n-butylphosphonium bromide, were used for the nanocomposite preparations. The structure of nanocomposites in the nanometer scale was characterized using wide-angle X-ray diffraction (WAXD) analyses and transmission electron microscopy (...
Caiju Shi - One of the best experts on this subject based on the ideXlab platform.
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effect of organic Layered Silicate on microstructures and aging properties of styrene butadiene styrene copolymer modified bitumen
Construction and Building Materials, 2014Co-Authors: Henglong Zhang, Chongzheng Zhu, Caiju ShiAbstract:Abstract A new approach to determine the microstructures of organic Layered Silicate/SBS modified bitumen was adopted by combining the results from X-ray diffraction analysis of organic Layered Silicate/SBS modified bitumen and the dissolving–filtrating procedure. The effect of thin film oven test (TFOT) and ultraviolet (UV) aging on the morphology of binders was characterized by using optical microscopy. The results show that organic montmorillonite/SBS modified bitumen and organic rectorite/SBS modified bitumen form the semi-exfoliated nanostructure, while organic expanded vermiculite/SBS modified bitumen forms the exfoliated nanostructure. The high temperature properties of SBS modified bitumen and the compatibility between SBS and bitumen are improved with the introduction of organic Layered Silicate. Compared with SBS modified bitumen, organic Layered Silicate/SBS modified bitumen shows the lower viscosity aging index and the higher retained ductility after TFOT and UV aging. Aging influences the morphology of SBS modified bitumen significantly. There is a single phase trend of SBS modified bitumen during TFOT, which is accelerated by UV radiation. However, the morphological changes are prevented obviously with the introduction of organic Layered Silicate, indicating the good aging resistance of organic Layered Silicate/SBS modified bitumen. Additionally, the influence of organic Layered Silicate on these physical properties of SBS modified bitumen before and after aging depends on its nature.
Emmanuel P Giannelis - One of the best experts on this subject based on the ideXlab platform.
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New biodegradable polyhydroxybutyrate/Layered Silicate nanocomposites.
Biomacromolecules, 2007Co-Authors: Pralay Maiti, Carl A. Batt, Emmanuel P GiannelisAbstract:Poly(hydroxybutyrate) (PHB)/Layered Silicate nanocomposites were prepared via melt extrusion. The nanostructure, as observed from wide-angle X-ray diffraction and transmission electron microscopy, indicates intercalated hybrids. The extent of intercalation depends on the amount of Silicate and the nature of organic modifier present in the Layered Silicate. The nanohybrids show significant improvement in thermal and mechanical properties of the matrix as compared to the neat polymer. The Silicate particles act as a strong nucleating agent for the crystallization of PHB. The biodegradability of pure PHB and its nanocomposites was studied at two different temperatures under controlled conditions in compost media. The rate of biodegradation of PHB is enhanced dramatically in the nanohybrids. The change in biodegradation is rationalized in terms of the crystallization behavior of the nanohybrids as compared to that of the neat polymer.
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new biodegradable polyhydroxybutyrate Layered Silicate nanocomposites
Biomacromolecules, 2007Co-Authors: Pralay Maiti, Carl A. Batt, Emmanuel P GiannelisAbstract:Poly(hydroxybutyrate) (PHB)/Layered Silicate nanocomposites were prepared via melt extrusion. The nanostructure, as observed from wide-angle X-ray diffraction and transmission electron microscopy, indicates intercalated hybrids. The extent of intercalation depends on the amount of Silicate and the nature of organic modifier present in the Layered Silicate. The nanohybrids show significant improvement in thermal and mechanical properties of the matrix as compared to the neat polymer. The Silicate particles act as a strong nucleating agent for the crystallization of PHB. The biodegradability of pure PHB and its nanocomposites was studied at two different temperatures under controlled conditions in compost media. The rate of biodegradation of PHB is enhanced dramatically in the nanohybrids. The change in biodegradation is rationalized in terms of the crystallization behavior of the nanohybrids as compared to that of the neat polymer.
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On The Origins of Silicate Dispersion in Polysiloxane/Layered‐Silicate Nanocomposites
Advanced Functional Materials, 2006Co-Authors: Daniel Schmidt, Florence Clement, Emmanuel P GiannelisAbstract:We report the first multi-system study of a Layered-Silicate dispersion in polysiloxane/Layered-Silicate nanocomposites. A variety of Layered Silicates (montmorillonite, synthetic fluoromica, laponite, and fluorohectorite) and cationic modifiers (single-, twin-, and triple-tailed surfactants with tails of varying lengths and both primary and quaternary head-groups) are combined to form organically modified Layered Silicates, which are then screened for compatibility with low-molecular-weight silanol-terminated poly(dimethylsiloxane) (PDMS). Promising combinations are then selected and studied in greater depth with respect to both molecular weight and polysiloxane end-group and substituent chemistry. We find that the PDMS backbone is generally incompatible with the Layered Silicates, regardless of modification type, and that dispersion in PDMS systems results from the presence of polar end-groups, a result unprecedented in the field of polymer nanocomposites. We go on to quantify the substituent effect, not only with respect to end-group chemistry, but taking into account changes in the polysiloxane backbone itself. For instance, in the absence of polar end-groups we observe dispersion in the case of poly(methylphenylsiloxane) but not poly(3,3.3-trifluoropropylmethylsiloxane). Finally, we apply a new epoxy/amine PDMS curing chemistry to PDMS-nanocomposite production and show higher levels of Layered-Silicate dispersion than observed in comparable silanol-terminated PDMS-based systems. Our findings serve as an indication of what is necessary to achieve a Layered-Silicate dispersion in polysiloxane/ Layered-Silicate nanocomposites, and may indicate a more general approach for improving dispersion in systems where the polymer backbone is otherwise incompatible with the Layered Silicate.
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Flammability properties of polymer - Layered-Silicate nanocomposites. Polypropylene and polystyrene nanocomposites
Chemistry of Materials, 2000Co-Authors: Jeffrey W. Gilman, Catheryn L. Jackson, Melanie Wuthenow, Dawn Hilton, Alexander B Morgan, Evangelos Manias, Richard Harris, Emmanuel P Giannelis, Shawn H. PhillipsAbstract:Our continuing study of the mechanism of flammability reduction of polymer−Layered-Silicate nanocomposites has yielded results for polypropylene-graft-maleic anhydride and polystyrene−Layered-Silicate nanocomposites using montmorillonite and fluorohectorite. Cone calorimetry was used to measure the heat release rate and other flammability properties of the nanocomposites, under well-controlled combustion conditions. Both the polymer−Layered-Silicate nanocomposites and the combustion residues were studied by transmission electron microscopy and X-ray diffraction. We have found evidence for a common mechanism of flammability reduction. We also found that the type of Layered Silicate, nanodispersion, and processing degradation have an influence on the flammability reduction.
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rheology of end tethered polymer Layered Silicate nanocomposites
Macromolecules, 1997Co-Authors: Ramanan Krishnamoorti, Emmanuel P GiannelisAbstract:The rheology of end-tethered polymer Layered Silicate nanocomposites is investigated using linear viscoelastic measurements in oscillatory shear with small strain amplitudes. Two systems consisting of poly(e-caprolactone) and nylon-6 with varying amounts of Layered Silicate (montmorillonite) are examined. The storage (G‘) and loss (G‘‘) moduli increase at all frequencies with increasing Silicate loading, consistent with previous findings with conventionally filled polymer systems. However, the power-law dependence of G‘ and G‘‘ in the terminal zone is different from that observed in homopolymers and decreases with increasing Silicate loading. At low frequencies the rheological response becomes almost invariant with frequency, suggestive of a solid-like response. Comparisons are drawn with rheology of other intrinsically anisotropic materials, and an attempt is made to explain phenomenologically their rich-rheological behavior.