Search results for "COMPOSITE"
showing 10 items of 4584 documents
Liquid Crystalline Elastomers
1989
Today, material science is directed towards the development of multifunctional and oriented structures. One example of such supramolecular systems are liquid crystalline (LC) elastomers which combine the properties of LC phases (the combination of order and mobility) with rubber elasticity, one of the most typical polymer properties. Their most outstanding characteristic is their mechanical orientability; strains as small as 20% are enough to obtain a perfectly oriented LC monodomain. This orientability, if LC elastomers with chiral phases are used, leads, for example, to elastomers with chiral smectic C* phases which are likely to show piezo-electric behavior.
Creep and recovery experimental investigation of low oil content food emulsions
2008
Abstract Creep and recovery tests have been performed to study the viscoelastic behavior of low oil content food emulsions. Formulations of salad dressings usually include modified starch (MS) due to its low cost and the special creamy texture if affords. The combination of starch with other natural gums may improve the quality of the product. A reference emulsion containing 4% MS, and four other formulations in which the starch was partially replaced by xanthan gum (XG), locust bean gum (LBG) and two synergistic blends of these gums were formulated. Gels prior to emulsification were studied for comparative purposes. The viscoelastic behavior of all the systems was characterized by means of…
Mass spectrometrical detection of polymer particles in capsule tissue surrounding joint endoprotheses of polyethyleneterephthalate
1982
Pyrolysis mass spectrometry of synthetic high polymers is described. The method is used to detect polymer wear particles in capsule tissue surrounding endoprotheses with polyethyleneterephthalate parts. An approximation of semi-quantitative determination of the polymer wear will be discussed.
Magnetic Composite Thin Films of FexOy Nanoparticles and Photocrosslinked Dextran Hydrogels
2012
Abstract Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By util…
A Versatile Technique to Produce Porous Polymeric Scaffolds: The Thermally Induced Phase Separation (TIPS) Method
2017
Among the various scaffold fabrication techniques, thermally induced phase separation (TIPS) is one of the most versatile methods to produce porous polymeric scaffold and it has been largely used for its capability to produce highly porous and interconnected scaffolds. The scaffold architecture can be closely controlled by varying the process parameters, including polymer type and concentration, solvent/non-solvent ratio and thermal history. TIPS technique has been widely employed, also, to produce scaffolds with a hierarchical pore structure and composite polymeric matrix/inorganic filler foams.
Surface and Intercalation Chemistry of Polycarboxylate Copolymers in Cementitious Systems.
2009
International audience; The Ca–Al-layered double hydroxide, the so-called AFm phase, is a product of cement hydration. It is shown that the interaction of this phase with anionic polycarboxylate ether (PCE)-based dispersant polymers is not a simple adsorption but a more complex intercalation phenomenon leading to the transient sequestration of the PCE within the AFm crystallites. As a result, part of the PCE is immobilized, forming a layered organo-mineral composite, and does not play its role of a dispersing agent. This article presents, along general considerations on the links between cement chemistry and rheology, a detailed investigation of the formation, structure, and stability of a …
The effect of free polymer on the glass transition dynamics of microgel colloids
2002
Abstract From the phase behavior we establish that 1:10 crosslinked polystyrene microgel colloids in a good solvent can be considered as hard spheres whereas 1:50 crosslinked particles are slightly softer. Nevertheless, the glass transition dynamics of 1:10 microgels and a binary mixtures of 1:50 microgels can be described in both cases within the mode coupling theory for hard spheres. The only difference is that the increase of the polydispersity from about 7% to about 13% when going from the one-component system to the mixture is accompanied by a shift of the glass transition from ϕ g ≈0.56 to ϕ g ≈0.595. On addition of linear polystyrene to the 1:50 binary mixture we find a tremendous ac…
Impact of operation condition on temperature distribution in single cell of polymer electrolyte fuel cell operated at higher temperature than usual
2016
For improving performance of the stationary Polymer Electrolyte Fuel Cell (PEFC) system, the cell operating temperature up to 90°C will be preferred in Japan during the period from 2020 to 2030. To understand the operation of the PEFC system under relatively high temperature conditions, detail heat and mass transfer analysis is required. The main focus of this study is to analyze the PEFC performance under operational conditions, such as initial operational temperature of cell (Tini), relative humidity of supply gas, and the cathode gas type, temperature distribution in a cell of PEFC (using Nafion membrane) under relatively higher operating temperature conditions. The in-plane temperature …
Interfacial Assembly and Jamming Behavior of Polymeric Janus Particles at Liquid Interfaces
2017
The self-assembly and interfacial jamming of spherical Janus nanoparticles (JNPs) at the water/oil interface were investigated. Polymeric JNPs, made by cross-linking polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (PS-PB-PMMA), with a high interfacial activity assemble at the water/oil interface. During the self-assembly at the interface, the interfacial energy was reduced and a dynamic interlayer was observed that is responsive to the pH of the aqueous phase. Unlike hard particles, the JNPs are composed of polymer chains that can spread at the liquid-liquid interface to maximize coverage at relatively low areal densities. In a pendant drop geometry, the interfacial area of …
Preparation and mechanical characterization of polycaprolactone/graphene oxide biocomposite nanofibers
2016
Biocomposite nanofiber scaffolds of polycaprolactone (PCL) filled with graphene oxide (GO) were prepared using electrospinning technology. Morphological and mechanical properties of the scaffolds were characterized in dry and wet environment. The results showed that the successful incorporation of GO nanosheets into PCL polymer nanofibers improved their mechanical properties. Furthermore it was demonstrated the higher performance achieved when GO is filled at low concentration in the nanofibers.