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Composite Containing (composite + containing)
Selected AbstractsEffects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001Kathleen R. McDonald Effects of matrix cracks and the attendant interface debonding and sliding on both the longitudinal and the transverse thermal diffusivities of a unidirectional Nicalon/MAS composite are investigated. The diffusivity measurements are made in situ during tensile testing using a phase-sensitive photothermal technique. The contribution to the longitudinal thermal resistance from each of the cracks is determined from the longitudinal diffusivity along with measurements of crack density. By combining the transverse measurements with the predictions of an effective medium model, the thermal conductance of the interface (characterized by a Biot number) is determined and found to decrease with increasing crack opening displacement, from an initial value of ,1 to ,0.3. This degradation is attributed to the deleterious effects of interface sliding on the thermal conductance. Corroborating evidence of degradation in the interface conductance is obtained from the inferred crack conductances coupled with a unit cell model for a fiber composite containing a periodic array of matrix cracks. Additional notable features of the material behavior include: (i) reductions of ,20% in both the longitudinal and the transverse diffusivities at stresses near the ultimate strength, (ii) almost complete recovery of the longitudinal diffusivity following unloading, and (iii) essentially no change in the transverse diffusivity following unloading. The recovery of the longitudinal diffusivity is attributed to closure of the matrix cracks. By contrast, the degradation in the interface conductance is permanent, as manifest in the lack of recovery of the transverse diffusivity. [source] Preparation and Properties of Natural Sand Particles Reinforced Epoxy CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2007Gang Sui Abstract An epoxy composite using Cancun natural hydrophobic sand particle as filler material was fabricated in this study. Three point bending tests demonstrated an enhancement of 7.5 and 8.7% in flexural strength and flexural modulus, respectively, of epoxy composite containing 1 wt.-% sand particles without any chemical treatment involved, compared to the pristine epoxy. Scanning electron microscopy (SEM) studies revealed that the fracture toughness of the epoxy matrix was enhanced owing to the presence of sand particles in an epoxy/sand composite. Through dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) methods, it was found that the storage modulus (E,), glass transition temperature (Tg) and dimensional stability of the sand particles/epoxy composites were increased compared to the pristine epoxy. The friction behavior of epoxy/sand system reflected that the microstructure of epoxy composites was steady. These experimental results suggest that Cancun sand, as a freshly found natural micron porous material, may find promising applications in composite materials. [source] Studies on Molecular Composites of Polyamide 6/Polyamide 66MACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2004Yulin Li Abstract Summary: A series of molecular composites of PA 6/PA 66 was synthesized via in situ polymerization. The impact resistance of PA 6 was improved dramatically by incorporating a minor amount of PA 66 (2,10 wt.-%), without decreasing the tensile strength. Inserting PA 66 macromolecules at a molecular level into a PA 6 matrix may interfere with the arrangement of the hydrogen bonds of PA 6, in turn changing the crystalline structure and impeding the crystallization of PA 6. SEM micrograph of the fractured surface of a PA 6/PA 66 composite containing 10 wt.-% PA 66. [source] Simultaneously improving the toughness, flexural modulus and thermal performance of isotactic polypropylene by ,-, crystalline transition and inorganic whisker reinforcementPOLYMER ENGINEERING & SCIENCE, Issue 2 2010Yewen Cao Magnesium salt (M-HOS) whisker and ,-nucleating agent were introduced into polypropylene and their effects on the crystalline structures, morphologies, mechanical properties, and thermal resistance of polypropylene (PP) were investigated. The results of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and polar optical microscopy (POM) examinations suggested that the presence of the whisker did not cause any negative effect on the occurrence of ,-modification, and ,-phase became absolutely dominant form in ,-nucleated samples. The mechanical and thermal properties tests demonstrated that there is an excellent synergy between the ,-nucleating agent and the whisker. For PP composite containing 0.1 wt% of the ,-nucleating agent and 10 wt% of the whiskers, the Izod notched impact strength, elongation at break, flexural modulus, and heat deflection temperature were increased by 108, 194, 31, and 40%, respectively, compared with those of neat PP. By combining the toughening effect of ,,, transition with the reinforcing effect of the whisker, simultaneous improvement in toughness, flexural modulus, and thermal performance of PP was successfully achieved. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Oxidation behaviour of particle reinforced MoSi2 composites at temperatures up to 1700°C.MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 3 2005Part II: Initial screening of the oxidation behaviour of MoSi2 composites Abstract In the first part of this paper a literature survey on the oxidation behaviour of MoSi2 and MoSi2 composites has been given. The present second part reports about the experimental results from oxidation tests with several MoSi2 composites containing 15 vol.-% Al2O3, Y2O3, ZrO2, HfO2, SiC, TiB2, ZrB2, or HfB2, respectively, from different development stages. The tests were conducted at 1600°C in air for 100 hours. It was shown that the production route of the powders has a significant influence on the performance of the materials at high temperatures. This was attributed to contaminations. Additionally, the results indicated that only the composites with SiC, ZrO2 or HfO2, respectively, are suitable for application above 1500°C. A more detailed report about the optimised material will follow in the third part of this paper. [source] Characterization and properties of activated nanosilica/polypropylene composites with coupling agentsPOLYMER COMPOSITES, Issue 11 2009Ong Hui Lin In this work, nanosilica/polypropylene composites containing 1 wt% of silica nanoparticles were prepared by melt mixing in a Thermo Haake internal mixer. Prior compounding, nanosilica was subjected to surface activation using sodium hydroxide (NaOH) solution. The effectiveness of the activation process was evaluated by measuring the amount of hydroxyl groups (OH) on the surface of nanosilica via titration method and supported by FTIR analysis. Two coupling agents namely 3-aminopropyl triethoxysilane (APTES) and neopentyl (diallyl)oxy, tri(dioctyl) phosphate titanate (Lica 12) were used for surface treatment after activation process. The mechanical properties of polypropylene matrix reinforced with silica nanoparticles were determined by tensile and impact test. Hydroxyl groups on the nanosilica surface played an important role in enhancing the treatment with silane coupling agents. To increase the amount of hydroxyl groups on the nanosilica surface, the optimum concentration of NaOH is 1 mol%. Tensile strength, tensile modulus, and impact strength of nanosilica/PP composites improved with activation process. As the coupling agent is concerned, APTES coupling agent is more pronounced in enhancing the mechanical properties of the composites when compared with Lica 12 coupling agent. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Properties of polypropylene/aluminum trihydroxide composites containing nanosized organoclayPOLYMER ENGINEERING & SCIENCE, Issue 12 2005Noora Ristolainen Montmorillonite is a promising substitute for aluminum trihydroxide in flame-retardant polypropylene/aluminum trihydroxide (PP/ATH) composites. Study was made of the partial substitution of organoclay for ATH in PP/ATH composites. The total concentration of filler was kept at 30 wt%. The composites were compatibilized with two types of compatibilizer: commercial maleic anhydride functionalized polypropylene (PP- g -MA) and hydroxyl-functionalized polypropylene (PP- co -OH) prepared with metallocene catalyst. The effect of compatibilization on the morphology was studied by the transmission electron microscopy and the scanning electron microscopy. Mechanical properties were characterized by tensile and impact measurements, and flammability properties with a cone calorimeter. Addition of compatibilizer and stearic acid (SA) treatment of the ATH particles contributed to the dispersion of the fillers. Both compatibilizers produced organoclay with exfoliated structure and improved adhesion between the fillers and the matrix. Toughness improved and decomposition and flammability were reduced. POLYM. ENG. SCI. 45:1568,1575, 2005. © 2005 Society of Plastics Engineers [source] Barrier and mechanical properties of injection molded montmorillonite/polyesteramide nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 1 2005M. Krook Properties of injection-molded biodegradable polyesteramide composites containing 5 and 13 wt% octadecylammonium-treated montmorillonite clay have been studied. Oxygen transmission rates and mechanical properties were measured. X-ray diffraction was used to assess the degree of intercalation of the clay layer stacks, and transmission electron microscopy (TEM) was used to assess the morphology and degree of layer delamination. A substantial reduction in oxygen permeability was observed when clay was added to the composites. The oxygen permeability of the 13 wt% clay sample was only 20% of that of the pure polymer. The in-plane stiffness and in-plane strength of the sheets were greatly improved without any embrittlement. These beneficial effects were probably due to the high degree of clay layer exfoliation and orientation observed by TEM. Heat shrinkage, toughness analysis, and cutting operations suggested that the polymer chains and the clay layers were oriented parallel to the plane of the sheet. TEM and X-ray showed that stacked layers were still present but that these were significantly intercalated. The clay-layer periodic spacing increased from 25 Å to approximately 35 Å during processing. POLYM. ENG. SCI. 45:135,141, 2005. © 2004 Society of Plastics Engineers [source] | ||||||||||