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Uniaxial Tensile Tests (uniaxial + tensile_test)
Selected AbstractsMultilayer Diffusion Barrier Coatings on Poly(propylene) with Improved Temperature DurabilityPLASMA PROCESSES AND POLYMERS, Issue S1 2009Lutz Körner Abstract The improvement of temperature durability for autoclaving of silicon oxide (SiOx) diffusion barrier coatings on poly(propylene) (PP) by deposition of thin amorphous hydrogenated carbon-nitrogen (a-C:N:H) intermediate layers was investigated. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy revealed terminating amino and nitrile groups responsible for low compressive stress in a-C:N:H. Uniaxial tensile tests showed a higher crack onset strain (COS) for a-C:N:H of 2.7% compared to 0.7% for SiOx. Best temperature durability was achieved by a three-layer coating from a-C:N:H, an intermediate layer deposited by a mixture of N2, C2H2, hexamethyldisiloxane (HMDSO), and a SiOx layer. The oxygen transmission rate (OTR) was only increased from 6 to 22 cm3·m,2·d,1·bar,1 after exposure to 140,°C for 30 min, whereas for single SiOx barrier coatings, severe loss of barrier properties of 1,040 cm3·m,2·d,1·bar,1 was evidenced due to the formation of cracks. [source] Tensile creep behaviour of polymethylpentene,silica nanocompositesPOLYMER INTERNATIONAL, Issue 6 2010Andrea Dorigato Abstract For the first time, poly(4-methyl-1-pentene) (PMP) nanocomposites were prepared by melt compounding 2 vol% of fumed silica nanoparticles, in order to study the role of the nanofiller surface area and functionalization on the tensile mechanical response of the material, with particular focus on its creep behaviour. The high optical transparency of the polymer matrix was substantially preserved in the nanocomposites, while the mechanical properties (in particular the creep stability) were improved. Dynamic mechanical thermal analysis showed an improvement of the storage modulus, more evident above the glass transition temperature of the polymer matrix. Uniaxial tensile tests evidenced that the elastic modulus of the material was positively affected by the presence of silica nanoparticles, even if a slight reduction of the strain at break was detected. The reduction of the tensile creep compliance was proportional to the surface area of the nanofiller, being more evident at high stresses and elevated temperatures. Findley's law furnished a satisfactory fitting of the creep behaviour of the composites, even at high temperatures. It clearly emerges that the incorporation of fumed silica nanoparticles in PMP can be an effective way to overcome the problem of the poor creep stability of polyolefins, especially at high temperatures and high stresses. Moreover the possibility of retaining the original transparency of the material is fundamental for the production of completely transparent PMP components. Copyright © 2010 Society of Chemical Industry [source] Radiopaque, barium sulfate-filled biomedical compounds of a poly(ether-block-amide) copolymerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Xiaoping Guo Abstract Various radiopaque compounds of a poly (ether- block -amide) copolymer resin filled with fine barium sulfate particles were prepared by melt mixing. Material properties of the filled compounds were investigated using various material characterization techniques, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic rheometry, uniaxial tensile test, and dynamic mechanical thermal analysis (DMTA). The effects of the filler and its concentration on the measured material properties are evaluated. It has been found that in addition to its well-known X-ray radiopacity, the filler is quite effective in reinforcing some mechanical properties of the copolymer, including modulus of elasticity and yield strength. More interestingly, it has been observed that at low loading concentrations near 10 wt %, the filler may also act as a rigid, inorganic toughener for the copolymer by improving the postyield material extensibility of strain hardening against ultimate material fracture. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Prediction of the Elastic Properties of Polycrystalline Microcomponents by Numerical HomogenizationADVANCED ENGINEERING MATERIALS, Issue 3 2009Katja Jöchen Polycrystalline microcomponents made of Stabilor®G, a dental alloy mainly consisting of gold, are examined in terms of their elastic properties. Finite element calculations of uniaxial tensile tests are carried out with ABAQUS so as to identify the characteristic parameters of the distribution of Young's modulus. It is shown that the statistics of mechanical properties observed experimentally can be estimated by using the finite element method. The findings are generalized to microcomponents consisting of crystals with a cubic symmetry. [source] Effect of long-term natural aging on the thermal, mechanical, and viscoelastic behavior of biomedical grade of ultra high molecular weight polyethyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010H. Fouad Abstract In the total joint prostheses, Ultra High Molecular Weight Polyethylene (UHMWPE) may undergo an oxidative degradation in the long term. The overall properties of UHMWPE are expected to be altered due to the oxidative degradation. The goal of this study is to investigate the effects of natural aging up to 6 years in air on the thermal, mechanical, and viscoelastic properties of UHMWPE that was used in total joint replacement. The changes in UHMWPE properties due to aging are determined using Differential Scanning Calorimetry (DSC), uniaxial tensile tests, and Dynamic Mechanical Analysis (DMA). The DSC results show that the lamellar thickness and degree of crystallinity of UHMWPE specimens increase by 38% and 12% due to aging. A small shoulder region in the DSC thermograms is remarked for aged specimens, which is an indication of formation of new crystalline forms within their amorphous region. The tensile properties of aged and nonaged UHMWPE specimens show a significant decrease in the elastic modulus, yield, fracture stresses, and strain at break due to aging. The DM testing results indicate that the storage modulus and creep resistance of UHMWPE specimens decrease significantly due to aging. Also, it is remarked that the , relaxation peak for aged UHMWPE specimens occurs at lower temperature compared to nonaged ones. The significant reduction in the strength and creep resistance of UHMWPE specimens due to aging would affect the long-term clinical performance of the total joint replacement and should be taken into consideration during artificial joint design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] | ||||||||||