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Interfacial Strength (interfacial + strength)
Selected AbstractsInterfacial strength in short glass fiber reinforced acrylonitrile-butadiene-styrene/polyamide 6 blendsPOLYMER COMPOSITES, Issue 3 2010Nihat Ali Isitman The purpose of this study is to derive the apparent interfacial shear strength of short glass fiber reinforced acrylonitrile-butadiene-styrene/polyamide 6 (PA6) blends with different PA6 contents. Tensile stress-strain curves and fiber length distributions are utilized within a continuum micromechanics approach which involves a unified parameter for fiber length distribution efficiency represented as a function of strain. The unique combination of predicted micromechanical parameters is capable of accurately reproducing the mechanical response of the composite to applied strain. In this way, the influence of PA6 on interfacial zone is revealed by outcomes of the predictive method and validated by scanning electron microscopy observations. Favored intermolecular interactions in presence of PA6 chains result in the formation of a PA6 sheathing layer on glass fiber surfaces which in turn causes a drop in the apparent interfacial shear strength. The reason behind is shown to be the shift of the fracture zone from fiber/matrix interface to sheathing layer/matrixinterphase. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Increased Interface Strength in Carbon Fiber Composites through a ZnO Nanowire InterphaseADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Yirong Lin Abstract One of the most important factors in the design of a fiber reinforced composite is the quality of the fiber/matrix interface. Recently carbon nanotubes and silicon carbide whiskers have been used to enhance the interfacial properties of composites; however, the high growth temperature degrade the fiber strength and significantly reduce the composite's in-plane properties. Here, a novel method for enhancing the fiber/matrix interfacial strength that does not degrade the mechanical properties of the fiber is demonstrated. The composite is fabricated using low-temperature solution-based growth of ZnO nanowires on the surface of the reinforcing fiber. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113%, and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. This novel interface could also provide embedded functionality through the piezoelectric and semiconductive properties of ZnO. [source] Effect of quasi-carbonization processing parameters on the mechanical properties of quasi-carbon/phenolic compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Donghwan Cho Abstract In this work, quasi-carbon fabrics were produced by quasi-carbonization processes conducted at and below 1200°C. Stabilized polyacrylonitrile (PAN) fabrics and quasi-carbon fabrics were used as reinforcements of phenolic composites with a 50 wt %/50 wt % ratio of the fabric to the phenolic resin. The effect of the quasi-carbonization process on the flexural properties, interfacial strength, and dynamic mechanical properties of quasi-carbon/phenolic composites was investigated in terms of the flexural strength and modulus, interlaminar shear strength, and storage modulus. The results were also compared with those of a stabilized PAN fabric/phenolic composite. The flexural, interlaminar, and dynamic mechanical results were quite consistent with one another. On the basis of all the results, the quasi-static and dynamic mechanical properties of quasi-carbon/phenolic composites increased with the applied external tension and heat-treatment temperature increasing and with the heating rate decreasing for the quasi-carbonization process. This study shows that control of the processing parameters strongly influences not only the mechanical properties of quasi-carbon/phenolic composites but also the interlaminar shear strength between the fibers and the matrix resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Enhancing the mechanical integrity of the implant,bone interface with BoneWelding® technology: Determination of quasi-static interfacial strength and fatigue resistanceJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006Stephen J. Ferguson Abstract The BoneWelding® technology is an innovative bonding method, which offers new alternatives in the treatment of fractures and other degenerative disorders of the musculoskeletal system. The BoneWelding process employs ultrasonic energy to liquefy a polymeric interface between orthopaedic implants and the host bone. Polymer penetrates the pores of the surrounding bone and, following a rapid solidification, forms a strong and uniform bond between implant and bone. Biomechanical testing was performed to determine the quasi-static push-out strength and fatigue performance of 3.5-mm-diameter polymeric dowels bonded to a bone surrogate material (Sawbones solid and cellular polyurethane foam) using the BoneWelding process. Fatigue tests were conducted over 100,000 cycles of 20,100 N loading. Mechanical test results were compared with those obtained with a comparably-sized, commercial metallic fracture fixation screw. Tests in surrogate bone material of varying density demonstrated significantly superior mechanical performance of the bonded dowels in comparison to conventional bone screws (p < 0.01), with holding strengths approaching 700 N. Even in extremely porous host material, the performance of the bonded dowels was equivalent to that of the bone screws. For both cellular and solid bone analog materials, failure always occurred within the bone analog material surrounding and distant to the implant; the infiltrated interface was stronger than the surrounding bone analog material. No significant decrease in interfacial strength was observed following conditioning in a physiological saline solution for a period of 1 month prior to testing. Ultrasonically inserted implants migrated, on average, less than 20 ,m over, and interfacial stiffness remained constant the full duration of fatigue testing. With further refinement, the BoneWelding technology may offer a quicker, simpler, and more effective method for achieving strong fixation and primary stability for fracture fixation or other orthopaedic and dental implant applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Creep Resistant Polymer Nanocomposites Reinforced with Multiwalled Carbon NanotubesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 8 2007Jinglei Yang Abstract Poly(propylene) (PP) nanocomposites filled with shorter- and longer-aspect-ratio multiwalled carbon nanotubes (MWNTs) were compounded using a twin-screw extruder and an injection moulding machine. It is shown that with only 1 vol.-% of MWNTs, creep resistance of PP can be significantly improved with reduced creep deformation and creep rate at a long-term loading period. Additionally, the creep lifetime of the nanocomposites has been considerably extended by 1,000% compared to that of a neat PP. Three possible mechanisms of load transfer were considered that could contribute to the observed enhancement of creep resistance, which are: (1) fairly good interfacial strength between MWNTs and polymer matrix, (2) increasing immobility of amorphous regions due to nanotubes acting as restriction sites, and (3) high aspect ratio of MWNTs. DSC results showing crystallinity changes in the specimens before and after creep deformation present evidence to confirm these mechanisms. Our results should lead to improved grades of creep resistant polymer nanocomposites for engineering applications. [source] Dependence of interfacial strength on the anisotropic fiber properties of jute reinforced compositesPOLYMER COMPOSITES, Issue 9 2010J.L. Thomason The upsurge in research on natural fiber composites over the past decade has not yet delivered any major progress in large scale replacement of glass fiber in volume engineering applications. This article presents data on injection-molded jute reinforced polypropylene and gives a balanced comparison with equivalent glass reinforced materials. The poor performance of natural fibers as reinforcements is discussed and both chemical modification of the matrix and mercerization and silane treatment of the fibers are shown to have little significant effect on their level of reinforcement of polypropylene in comparison to glass fibers. A hypothesis is proposed to explain the poor performance of natural fibers relating their low level of interfacial strength to the anisotropic internal fiber structure. POLYM. COMPOS., 31:1525,1534, 2010. © 2009 Society of Plastics Engineers [source] Interfacial adhesion and molecular diffusion in melt lamination of wood sawdust/ebonite NR and EPDMPOLYMER COMPOSITES, Issue 3 2009W. Yamsaengsung Adhesion mechanisms and peel strengths of wood/ebonite NR-EPDM laminates were investigated. Three different chemical coupling agents: namely; N-(, aminoethyl)-,-aminopropyl-triethoxysilane (AAS), 3-methacryloxypropyl trimethoxysilane (ACS), and Bis-(3-triethoxylpropyl) tetrasulfan (Si69) were introduced into the wood/NR composites to enhance an interaction between wood sawdust (SD) particles and NR molecules, and to improve the adhesion strength between the SD/NR and EPDM layers. The quantitative evidences were given to explain the changes in the adhesion or peel strengths of the SD/NR-EPDM laminates through scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). The experimental results indicated that the suitable cure time and cure temperature for SD/NR-EPDM melt-laminates were the tc90 of SD/NR composites and 140°C, respectively. The Si69 coupling agent was found to be the most effective coupling agent as compared with AAS and ACS coupling agents. The Si69 of 0.5 wt% was recommended for the optimizations of the tensile modulus of the SD/NR composites and the peel strength of the SD/NR-EPDM laminates. The diffusion level between the SD/NR and EPDM layers could be quantitatively substantiated by determining the sulfur content transfer from the SD/NR layer to the EPDM layer. The diffusion and entanglement of molecular chains from the SD/NR to the EPDM layer initiated the co-crosslinking reaction which played an important role on the changes in the interfacial strength in the SD/NR-EPDM melt-laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Characterization and design of interphases in glass fiber reinforced polyproplyenePOLYMER COMPOSITES, Issue 3 2000E. Mäder Bond strength between reinforcing fibers and polymer matrices can be controlled in two ways: 1) by intensification of molecular interaction at the interface and 2) by creation of a strong transition layer (interphase) between the components. In this paper, we consider the possibilities of controlling interfacial strength by means of target-oriented variation of structure, thickness and strength of the interphase artificially created between the glass fiber and the polypropylene matrix. The bond strength was measured using a continuously monitored microbond test, including recording the crack length as a function of the load applied. The measured interfacial strengths correlated to the macromechanical properties of glass fiber reinforced polypropylene. The interphase design provided simultaneous increase in the tensile strength and the impact toughness of the composites. [source] Melt processing effects on the structure and mechanical properties of PA-6/clay nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 8 2006Nitin K. Borse Polyamide-6 nanocomposites were prepared using two organoclays, Cloisite 30B and Cloisite 15A, and Cloisite Na+, which is unmodified sodium montmorillonite (Na-MMT) clay. Nanocomposites were prepared using two twin-screw extrusion systems: System B employing conventional mixing and residence time conditions, while System A was modified to achieve longer residence time and higher mixing efficiency. The work considers the effects of mixing conditions, residence time, and interactions between the polymer and clay surface on the structure and mechanical properties of polyamide-6 (PA-6)/clay nanocomposites. Furthermore, a comparison was made between experimental data and the predictions of composite models usually employed to predict mechanical properties of nanocomposites. The melt processing of Cloisite 30B in System A produced the highest degrees of exfoliation and the largest enhancement of mechanical properties. The aspect ratios of the filler particles in the nanocomposites were estimated from TEM micrographs and from composite models. Yield stress data were employed to calculate the values of parameter B in Pukanszky's equation, which incorporates the effects of the interfacial interaction, interfacial strength, and specific surface area of the filler particles. POLYM. ENG. SCI. 46:1094,1103, 2006. © 2006 Society of Plastics Engineers [source] Some important aspects in designing high molecular weight poly(L -lactic acid),clay nanocomposites with desired propertiesPOLYMER INTERNATIONAL, Issue 12 2008Subhendu Ray Chowdhury Abstract BACKGROUND: The main aim of the work reported here was to investigate the effect of clay aspect ratio and functional edge group on the dispersion, degree of order of clays and interfacial strength of high molecular weight poly(L -lactic acid) (PLLA),clay amorphous nanocomposites and consequently their properties. Three kinds of clays (two montmorillonites (SMMTC18 and NMMTC18) and one fluoro-mica (MC18) with the same surfactant) were used to synthesize three amorphous nanocomposites. Thermomechanical properties, permeability, etc., were compared among composites and with pure PLLA. RESULTS: From X-ray diffraction and transmission electron microscopy, both MMTs with lower aspect ratio showed better dispersion and greater degree of disorder, which led to stronger interfacial strength and consequently higher storage modulus than MC18-based composites. All composites showed better properties than pure PLLA. The oxygen barrier efficiencies of SMMTC18- and NMMTC18-based composites were higher than that of the MC18-based composites. Due to the highest exposed area and probably stronger interactions, SMMTC18 had the highest nucleating efficiency. CONCLUSIONS: Along with aspect ratio, dispersion and degree of intercalation, the interfacial strength of composites and degree of order of clays are also important issues for property development. Compared to reported results in the literature, our amorphous composites showed less of an improvement of thermomechanical properties as real reinforcement was solely from clays. Copyright © 2008 Society of Chemical Industry [source] Recycled PCB flour reinforced linear low-density polyethylene composites enhanced by water cross-linking reactionASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Chen-Feng Kuan Abstract Recycled printed circuit board (PCB) flour reinforced linear low-density polyethylene (LLDPE) composites were prepared successfully. Water cross-linking technique was adopted to improve the physical characteristics of the composites. Composites were compounded using a twin-screw extruder and treated with a coupling agent (vinyltrimethoxysilane, VTMOS) and a compatibilizer (polyolefin elastomer grafted with melaic acid, POE-g-MA). They were then moisture-cross-linked in hot water. The composite that was cross-linked in water exhibited better mechanical properties than the noncross-linked composite because of strong chemical bonding between the filler and the polyolefin matrix. When the PCB flour content reaches 60 wt% following 4 h of water cross-linking, the tensile strength and the flexural strength are increased by 18.8% (12.8,15.2 MPa) and 13.2% (21.9,24.8 MPa) respectively. Scanning electron microscopy (SEM) images of the fracture surfaces of water cross-linked composites indicated that good interfacial strength existed between the filler and the polyolefin matrix. Thermal analyses of water cross-linked composites indicated that the thermal degradation temperature and the heat deflection temperature (HDT) of the composite increased with the increasing of water cross-linking time. The HDT of the composite rose from 55.8 to 83 °C. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||