Papers by Keyword: Materials Testing

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Authors: Mohd Zharif Ahmad Thirmizir, Muhammad Dzulakmal Hazahar, Zainal Arifin Mohd Ishak
Abstract: Poly(butylene succinate)/Poly(hydroxybutyrate-co-hydroxyhexanoate) (PBS/PHBHH) blends were prepared using melt blending in an internal mixer at 160°C. Mechanical and morphological properties of the blends, with ratios of 10/90, 20/80, 30/70, 40/60 and 50/50, are studied by tensile test and microscopy analysis. The effects of maleated PHBHH (PHBHHgMA) compatibiliser on the blend’s mechanical and morphological properties are also investigated. The compatibiliser is prepared by melt grafting maleic anhydride (MA) onto PHBHH at 160°C, in the presence of dicumyl peroxide (DCP) initiator. In this study, the purified compatibiliser is added to the blends. The highest tensile strength was achieved by the 10/90 blend, with a value of 24.83MPa; which is slightly higher than the neat PBS. The tensile modulus of the blends decreased with increasing PBS ratio, and approximately followed the Rule of Mixtures. Meanwhile, the elongation at break achieved its optimum value at 10wt. % PBS loading. The addition of PHBHHgMA at 5wt. % improved the tensile properties of all blends; with the highest value being achieved by the 10/90 blend ratio. Morphological observation via SEM was conducted to observe phase morphology and compatibility between the blend’s components.
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Authors: J.A. Cortês, Elena Mavropoulos, Moema Hausen, Alexandre Rossi, J.M. Granjeiro, Gutemberg Alves
Abstract: Cell adhesion, proliferation and differentiation are important specific parameters to be evaluated on biocompatibility studies of candidate biomaterials for clinical applications. Several different methodologies have been employed to study, both qualitative and quantitatively, the direct interactions of ceramic materials with cultured mammal and human cells. However, while quantitatively evaluating cell density, viability and metabolic responses to test materials, several methodological challenges may arise, either by impairing the use of some widely applied techniques, or by generating false or conflicting results. In this work, we tested the inherent interference of different representative calcium phosphate ceramic surfaces (stoichiometric dense and porous hydroxyapatite (HA) and cation-substituted apatite tablets) on different tests for quantitative evaluation of osteoblast adhesion and metabolism, either based on direct cell counting after trypsinization, colorimetric assays (XTT, Neutral Red and Crystal Violet) and fluorescence microscopy. Cell adhesion estimation after trypsinization was highly dependent on the time of treatment, and the group with the highest level of estimated adhesion was inverted from 5 to 20 minutes of exposition to trypsin. Both dense and porous HA samples presented high levels of background adsorption of the Crystal Violet dye, impairing cell detection. HA surfaces also were able to adsorb high levels of fluorescent dyes (DAPI and phalloidin-TRITC), generating backgrounds which, in the case of porous HA, impaired cell detection and counting by image processing software (Image Pro Plus 6.0). We conclude that the choice for the most suitable method for cell detection and estimation is highly dependent on very specific characteristics of the studied material, and methodological adaptations on well established protocols must always be carefully taken on consideration.
325
Authors: Ichiro Shimizu
Abstract: New rotary to linear conversion mechanism named "reverse-type differential rotary to linear conversion mechanism (RDRLCM)" was invented for simultaneous achievement of large load capacity and precise displacement control, for compression test devices and press forming machines. The new mechanism was developed and incorporated as loading systems into an original biaxial compression test device, and thus, its fundamental performance was investigated. The results revealed that the loading system by the new rotary to linear conversion mechanism were able to generate compression force of about three times larger than that by a conventional feed-screw mechanism for the same input torque. In addition, the generated compressive force was maintained while the compressive motion was interrupted. These facts confirm the advantage to use RDRLCM for compression test devices as well as for press forming machines.
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Authors: Eduard Schenuit, Rainer Bolkart, Thomas Becker, Oliver Spinka
Abstract: Progresses in developments of high resolution digital cameras and processors power as well enable the use of optical systems for axial and biaxial strain measurements. The main benefit of these systems is a contact free measurement on the sample surface without any influence to the sample. The commonly used optical systems based on following markings attached to sample surface which have to be applied before testing. This paper presents an alternative optical measuring system using the speckle-correlation-technique. The laser based method does not need any special sample markings before testing. The speckle correlation in the presented extensometer measures up to two-dimensional surface strains in tensile as well as in compression tests; original gauge lengths down to 1.5 mm are supported.
237
Authors: Fei Zhong, Wei Zhang, Biao Qiang Jiao, Yue Xian Zhong
Abstract: In this paper, ultrasonic materials testing researches are reviewed. The latest progress of ultrasonic testing technology is introduced, including water-squirting ultrasonic C-scan testing, laser ultrasound, ultrasonic feature scan imaging, signal processing and pattern recognition technology in the application of ultrasonic testing.
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Authors: Kay André Weidenmann, Lisa Baumgärtner, Benedikt Haspel
Abstract: The interlaminar shear strength is a characteristic value describing the mechanical behavior of composite materials such as laminates. Several methods for the determination of the interlaminar shear strength are described in open literature by several authors. Among these methods, the ILSS test (DIN EN ISO 14130) measuring the apparent interlaminar shear strength by using a modified bending test is the state of the art technique, as both the necessary testing equipment and the sample geometry are quite common. However, the ILSS tests implements shear loads indirectly by bending often leading to sample failure which is then not solely initiated by shear loads. Particularly for ductile matrices or those showing pronounced elastic behavior under bending, no interlaminar shear failure can be implemented and the interlaminar shear strength can not been determined or – if the user is not sensitized to the identification of non-shear failure behavior – the determined value is not correct.Up to now, alternative methods for determining the interlaminar shear strength implementing a shear load directly to the sample are quite elaborate regarding the test equipment to be used or the specimen preparation and geometry. In this contribution the authors present a novel test setup for an edge shear test which allows both a direct shear load and at the same time a reduced complexity of the specimen geometry which is comparable to those used in the ILSS test. The authors present results based on this novel testing method in comparison to conventional ILSS tests.
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