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Polymeric Composites (polymeric + composite)
Selected AbstractsPolymeric composites for use in electronic and microwave devicesPOLYMER ENGINEERING & SCIENCE, Issue 3 2004Alexandre Moulart The dielectric and conductive properties of thermoplastic (ABS) composites filled with ceramic powder (barium titanate), conductive powders (carbon black, copper) and conductive fibers (carbon, steel) were investigated for use in electromagnetic crystals and microwave devices. Barium titanate/ABS composites were produced that had dielectric constants over 8 and loss tangents of 0.01, which are the requirements for electromagnetic crystals. Carbon black/ABS and steel fiber/ABS composites were obtained with conductivities suitable for electromagnetic shielding (over 10,3 S/cm). Fused decomposition modeling was tested as a method for building electromagnetic crystals and showed promising results. Polym. Eng. Sci. 44:588,597, 2004. © 2004 Society of Plastics Engineers. [source] Fracture Properties of Wood and Wood CompositesADVANCED ENGINEERING MATERIALS, Issue 7 2009Stefanie E. Stanzl-Tschegg Wood has a complex hierarchical structure and is a kind of polymeric composite with elongated cells in an amorphous matrix. Therefore, fracturing is a complicated process that is influenced by loading mode and direction, humidity, etc. Standard linear-elastic fracture mechanics methods mostly cannot sufficiently quantify fracturing, and combining fracture mechanical with structural investigations at different levels of magnification (centimeter to nanometer levels) helps obtaining insight into the fracture mechanisms. [source] Chromatographic partitioning of cesium by a macroporous silica-calix[4]arene-crown supramolecular recognition compositeAICHE JOURNAL, Issue 10 2010Anyun Zhang Abstract A macroporous silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2 -P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene-R14 and n -octanol into the pores of the macroporous SiO2 -P particles support. n -Octanol was used to modify Calix[4]arene-R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3,7.0 M. (Calix[4]+Oct)/SiO2 -P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2 -P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2 -P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Physicochemical evaluation of silica-glass fiber reinforced polymers for prosthodontic applicationsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2005Gökçe Meriç This investigation was designed to formulate silica-glass fiber reinforced polymeric materials. Fused silica-glass fibers were chosen for the study. They were heat-treated at various temperatures (500°C, 800°C and 1100°C), silanized, sized and incorporated in two modified resin mixtures (A and B). The flexural properties in dry and wet conditions were tested and statistically analyzed, and the content of residual methyl methacrylate (MMA) monomer, dimensional changes with temperature, water sorption and solubility were determined. Woven fibers [36.9% (wt/wt)], heat-treated at 500°C, gave the highest strength values for the polymeric composites (an ultimate transverse strength of 200 Mpa and a flexural modulus of 10 GPa) compared with the fibers heat-treated at other temperatures. There was no statistically significant difference in the measured flexural properties between resins A and B regarding fiber treatment and water storage time. These fiber composites had a small quantity of residual MMA content [0.37 ± 0.007% (wt/wt)] and very low water solubility, indicating good biocompatibility. It was suggested that silica-glass fibers could be used for reinforcement as a result of their anticipated good qualities in aqueous environments, such as the oral environment. [source] Triple-Shape Polymeric Composites (TSPCs)ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Xiaofan Luo Abstract In this paper, the fabrication and characterization of triple-shape polymeric composites (TSPCs) that, unlike traditional shape memory polymers (SMPs), are capable of fixing two temporary shapes and recovering sequentially from the first temporary shape (shape 1) to the second temporary shape (shape 2), and eventually to the permanent shape (shape 3) upon heating, are reported. This is technically achieved by incorporating non-woven thermoplastic fibers (average diameter ,760 nm) of a low- Tm semicrystalline polymer into a Tg -based SMP matrix. The resulting composites display two well-separated transitions, one from the glass transition of the matrix and the other from the melting of the fibers, which are subsequently used for the fixing/recovery of two temporary shapes. Three thermomechanical programming processes with different shape fixing protocols are proposed and explored. The intrinsic versatility of this composite approach enables an unprecedented large degree of design flexibility for functional triple-shape polymers and systems. [source] Cone calorimeter testing of S2 glass reinforced polymer compositesFIRE AND MATERIALS, Issue 7 2009Alexander B. Morgan Abstract With the ever increasing demand for fuel savings on vehicles, there is a strong push to replace metal with polymeric + fiber (carbon/glass) composites. However, the replacement of metal with polymeric composites can lead to additional fire risk. Our study focused on glass fiber reinforced polymer composites meant for vehicular structural applications, and flammability performance of these composites was studied by cone calorimetery. The effects of fiberglass loading, nanocomposite use (clay, carbon nanofiber) and polymer type (epoxy, phenolic) were studied under a heat flux of 50kW/m2 to better understand the potential effects that these variables would have on material flammability. It was found that as fiberglass loading increased, flammability decreased, but at a cost to structural integrity of the residual polymer + fiber char. The use of nanocomposites has little effect on reducing flammability in this set of samples, but the use of phenolic resins in comparison with epoxy resins was found to yield the greatest improvements in flammability performance. Further, the phenolic system yielded a higher level of structural integrity to the final polymer + fiberglass char when compared with the other polymer systems of low heat release. Copyright © 2009 John Wiley & Sons, Ltd. [source] Boron Nanotube,Polymer Composites: Towards Thermoconductive, Electrically Insulating Polymeric Composites with Boron Nitride Nanotubes as Fillers (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Mater. Composites formed through embedding of high-concentration boron nitride nanotubes in polymers are reported by C. Y. Zhi et al. on page 1857. The composites possess high thermal conductivity, high break-over voltage, low coefficient of thermal expansion, and other favorable properties. These polymeric composites are promising highly thermoconductive electrically insulating materials for a range of applications. [source] Towards Thermoconductive, Electrically Insulating Polymeric Composites with Boron Nitride Nanotubes as FillersADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Chunyi Zhi Abstract Ultilizing boron nitride nanotubes (BNNTs) as fillers, composites are fabricated with poly(methyl methacrylate), polystyrene, poly(vinyl butyral), or poly(ethylene vinyl alcohol) as the matrix and their thermal, electrical, and mechanical properties are evaluated. More than 20-fold thermal conductivity improvement in BNNT-containing polymers is obtained, and such composites maintain good electrical insulation. The coefficient of thermal expansion (CTE) of the BNNT-loaded polymers is dramatically reduced because of interactions between the polymer chains and the nanotubes. Moreover, the composites possess good mechanical properties, as revealed by Vickers microhardness tests. This detailed study indicates that BNNTs are very promising nanofillers for polymeric composites, allowing the simultaneous achievement of high thermal conductivity, low CTE, and high electrical resistance, as required for novel and efficient heat-releasing materials. [source] Mechanical and thermal properties of poly(butylene succinate)/plant fiber biodegradable compositeJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Zhichao Liang Abstract Biodegradable polymeric composites were fabricated from poly(butylene succinate) (PBS) and kenaf fiber (KF) by melt mixing technique. The mechanical and dynamic mechanical properties, morphology and crystallization behavior were investigated for PBS/KF composites with different KF contents (0, 10, 20, and 30 wt %). The tensile modulus, storage modulus and the crystallization rate of PBS in the composites were all efficiently enhanced. With the incorporation of 30% KF, the tensile modulus and storage modulus (at 40°C) of the PBS/KF composite were increased by 53 and 154%, respectively, the crystallization temperature in cooling process at 10°C/min from the melt was increased from 76.3 to 87.7°C, and the half-time of PBS/KF composite in isothermal crystallization at 96 and 100°C were reduced to 10.8% and 14.3% of that of the neat PBS, respectively. SEM analysis indicates that the adhesion between PBS and KF needs further improvement. These results signify that KF is efficient in improving the tensile modulus, storage modulus and the crystallization rate of PBS. Hence, this study provides a good option for preparing economical biodegradable composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of particle size of an amorphous calcium phosphate filler on the mechanical strength and ion release of polymeric composites,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Soo-Young Lee Abstract The random clustering of amorphous calcium phosphate (ACP) particles within resin matrices is thought to diminish the strength of their polymerized composites. The objective of this study was to elucidate the effect of ball-milling on the particle size distribution (PSD) of ACP fillers and assess if improved dispersion of milled ACP in methacrylate resin sufficiently enhanced filler/matrix interactions to result in improved biaxial flexure strength (BFS), without compromising the remineralizing potential of the composites. Unmilled and wet-milled zirconia-hybridized ACP (Zr-ACP) fillers were characterized by PSD analysis, X-ray diffraction, thermogravimetric and chemical analysis, infrared spectroscopy, and scanning electron microscopy. Composite specimens made from a photoactivated, ternary methacrylate resin admixed with a mass fraction of 40% of un-milled or milled Zr-ACP were evaluated for the BFS (dry and wet) and for the release of calcium and phosphate ions into saline solutions. While having no apparent effect on the structure, composition, and morphology/topology of the fillers, milling significantly reduced the average size of Zr-ACP particulates (median diameter, dm = 0.9 ± 0.2 ,m) and the spread of their PSD. Better dispersion of milled Zr-ACP in the resins resulted in the improved BFS of the composites, even after aqueous soaking, and also gave a satisfactory ion release profile. The demonstrated improvement in the mechanical stability of anti-demineralizing/remineralizing ACP composites based on milled Zr-ACP filler may be beneficial in potentially extending their dental utility. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Hysteresis measurements and dynamic mechanical characterization of functionally graded natural rubber,carbon black compositesPOLYMER ENGINEERING & SCIENCE, Issue 5 2010S.S. Ahankari Functionally graded polymer composites (FGPCs) were prepared by construction based layering method employing natural rubber (NR) as a matrix and carbon black (CB) in graded form. CB particles were graded along the rectangular geometry polymer matrix comprising the variation of particle volume fraction along thickness direction. These FGPCs were characterized through hysteresis measurements and compared with uniformly dispersed polymeric composites (UDPCs) maintaining the same average amount of filler. Dynamic mechanical properties of these FGPCs and UDPCs were also compared. Dynamic mechanical characterization revealed that FGPCs show much higher storage modulus than the corresponding UDPCs for any given combination of stacking sequence. Loss tangent of FGPCs was also observed to be lesser when compared to UDPCs leading to less hysteretic losses followed by lesser heat buildup in the composite. Hysteresis measurements accorded with the results of dynamic mechanical characterization. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source] | ||||||||||||||||||||||