1,721,022 research outputs found
Rheological evidence for the microstructure of intercalated polymer/layered silicate nanocomposites
No full textThe rheological behavior of intercalated polystyrene/layered silicate nanocomposites was investigated. Both storage and loss moduli increased with silicate loading at all frequencies and showed non-terminal behavior at low frequencies which is a typical behavior of non-homogeneous systems with ordered microstructures. The rheological behavior in intercalated polystyrene/layered silicate nanocomposite depends not only on the intercalation of polymers, but also on the alignment of silicate layers. Furthermore, the real time intercalation dynamic of polystyrene into the layered silicate, monitored by rheological measurements, were also consistent with our simple quantitative analysis
Phase morphology and rheological behavior of polymer/layered silicate nanocomposites
No full textRheological behavior of polymer/layered silicate nanocomposites an strongly dependent not only upon their microstructure but also upon the interfacial characteristics. Different phase morphology (intercalated or exfoliated) of polymer/clay is obtained according to interfacial characteristics between polymer chains and clay. In intercalated structure, the presence of randomly oriented anisotropic stacks of silicate layers is responsible for the enhancement of both moduli. The PS/clay nanocomposites exhibit a slight enhancement at low frequency because of its simple intercalated structure and little interaction. On the other hand, the PS-co-ma/clay nanocomposites have a similar intercalated structure but exhibit a distinct plateau-like behavior at low frequency since the PS-co-ma has a strong attractive interaction with the silicate layers. Finally, PE-g-ma/clay nanocomposites display an exfoliated structure, which exhibit both a distinct plateau-like behavior at low frequency and enhanced moduli at high frequency. Percolation structure as well as large interfacial area between polymer chains and clay are responsible for the theological behavior
Microstructure and rheological behavior of block copolymer/clay nanocomposites
No full textOrganic/Inorganic hybrid nanocomposites based on poly(styrene-butadiene-styrene) copolymer (SBS) and clay are fabricated by melt intercalation. The degree of intercalation is dependent on the surface properties of clay and SBS. The epoxized block in epoxized SBS acts as a strong attractive site with the clay surface, which yields the increased interlayer space in the layered silicates. It is also shown that the thermal stability of clay as well as the surface properties is very important in fabricating the polymer/clay nanocomposites. The rheological behavior of the SBS/clay nanocomposites is quite different from that of SBS itself. Both storage moduli and complex viscosity of the SBSI layered silicate nanocomposites increase and show non-terminal flow behavior
Phase morphology and rheological behavior of polymer/layered silicate nanocomposites
No full textRheological behavior of polymer/layered silicate nanocomposites an strongly dependent not only upon their microstructure but also upon the interfacial characteristics. Different phase morphology (intercalated or exfoliated) of polymer/clay is obtained according to interfacial characteristics between polymer chains and clay. In intercalated structure, the presence of randomly oriented anisotropic stacks of silicate layers is responsible for the enhancement of both moduli. The PS/clay nanocomposites exhibit a slight enhancement at low frequency because of its simple intercalated structure and little interaction. On the other hand, the PS-co-ma/clay nanocomposites have a similar intercalated structure but exhibit a distinct plateau-like behavior at low frequency since the PS-co-ma has a strong attractive interaction with the silicate layers. Finally, PE-g-ma/clay nanocomposites display an exfoliated structure, which exhibit both a distinct plateau-like behavior at low frequency and enhanced moduli at high frequency. Percolation structure as well as large interfacial area between polymer chains and clay are responsible for the theological behavior
Improved electrorheological effect in polyaniline nanocomposite suspensions
No full textWe prepared polyaniline (PANI)/clay, composites that are composed of both PANI-clay nanocomposite particles and pure PANT particles. The PANI-clay nanocomposite particles were made during the polymerization process, wherein PANT particles are attached on the surface of exfoliated clay particles modified by an aminosilane group. The PANI/clay composites were used as electrorheological fluids (ERFs) by, dispersing them in silicon oil. The PANI-clay nanocomposite particles, which can form columnar structure under an electric field, strongly, enhance the mechanical rigidity of the suspensions. The maximum yield stress of the PANI/clay composite suspensions (15 wt% in silicon oil) was 1.6 kPa at 3 kV/mm, while that of pure PANT was 300 Pa at the same electric field, A mechanism to explain the yield behaviors of the PANI-based nanocomposite suspensions is proposed. (C) 2002 Elsevier Science
New approach to enhance the yield stress of electro-rheological fluids by polyaniline-coated layered silicate nanocomposites
No full textWe synthesized new polyaniline (PANI)/organoclay (aminosilane surface-treated) nano-composite particles and prepared electro-rheological (ER) thirds by dispersing the particles in silicone oil. A distinct enhancement in yield stress was observed due to the presence of PANI-coated clay particles. The effects of delaminated clay on the ER yield stress were investigated and compared with other ER fluid systems, which use PANI particles only or a simply intercalated PANI/clay nano-composite
Thermal characteristics of organoclay and their effects upon the formation of polypropylene/organoclay nanocomposites
No full textWe have examined thermal characteristics of two types of organically modified montmorillonite (OMMT) with different alkylammonium cations and their effects upon the formation of PP nanocomposite, when using a maleic anhydride grafted polypropylene oligomer (maPP) as a compatibilizer. The microstructure of the composite has been characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy and Fourier transform infrared spectroscopy. OMMT showed the decrease of the interlayer spacing at the processing temperature, due to the release of organic ion by thermal decomposition. Thermal characteristics of OMMTs depended greatly on the interlayer structure of OMMT. When the OMMT with small interlayer spacing and less organophilicity was used, PP composite resulted in the only partial exfoliation due to thermal decomposition of the clay layers
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