Search results for "LONG"
showing 10 items of 3969 documents
“Compatibilization” through Elongational Flow Processing of LDPE/PA6 Blends
2018
Polyamide/polyolefin blends have gained attention from the academia and the industry for several years. However, in order to optimize their properties, some drawbacks such as chemical incompatibility must be adequately overcome. This can be done by adding suitable compatibilizers. On the other hand, it is less known that suitable processing techniques may also lead to significant results. In a previous work on a low-density polyethylene/polyamide 6 (LDPE/PA6) blend, we found that the orientation due to elongational flow processing conditions could lead to an unexpected brittle&ndash
Elucidating the Effect of Bimodal Grain Size Distribution on Plasticity and Fracture Behavior of Polycrystalline Materials
2020
The refinement of grains in a polycrystalline material leads to an increase in strength but as a counterpart to a decrease in elongation to fracture. Different routes are proposed in the literature to try to overpass this strength-ductility dilemma, based on the combination of grains with highly contrasted sizes. In the simplest concept, coarse grains are used to provide relaxation locations for the highly stressed fine grains. In this work, a model bimodal polycrystalline system with a single coarse grain embedded in a matrix of fine grains is considered. Numerical full-field micro-mechanical analyses are performed to characterize the impact of this coarse grain on the stress-strain const…
Thickness sensitivity of ultrasound velocity in long bone phantoms
2004
One approach to bone disease diagnosis such as osteoporosis is to measure the velocity of ultrasound propagating axially along long bones. In this study, the variation in velocity as a function of radial position was assessed using two polyvinyl chloride (PVC) bone phantoms with cross-sectional geometry similar to the human tibia but differing in medullary cavity diameter. Two ultrasonometers were used: these were a commercial device operating at a relatively high frequency (HF) of 1.25 MHz and a prototype low frequency (LF) device operating at approximately 200 kHz. The LF measurements showed a larger variation with radial position, with changes in velocity of up to 20% occurring around th…
Assessment of root canal enlargement using Mtwo and BioRace rotary files.
2014
Objective. To evaluate root canal enlargement following mechanical shaping using 2 nickel titanium rotary systems.Material and Methods. Forty single-rooted teeth were immersed in resin and sectioned perpendicular to the long axis at 4, 8, and 12 mm from the apex. Digital capture of sections was performed before and after canal instrumentation using Mtwo and BioRace instruments. The area increase of endodontic space was calculated by subtraction.Results. The use of both instruments has allowed the removal of great amounts of dentin from the canal walls, even when the endodontic morphology is characterized by awkwardness to reach recesses.Conclusions. Both procedures seem to be valid and no d…
Quantification of Plasma Sprayed Coating Adhesion Using Pulsed Laser Induced Decohesion Technique
2001
Abstract The aim of the present study is to compare a laser ultrasonic technique with a conventional indentation test for the determination of intrinsic properties and the adhesion of alumina coatings, of different thicknesses (30–350 µm), deposited on stainless steel substrates by atmospheric plasma spraying (APS). For this purpose, a pulsed Nd:YAG laser is used to irradiate the coated specimens, and the ultrasonic waves generated by the laser are recorded at the epicenter using a laser interferometer. In the thermoelastic regime, the good agreement between the experiment and computation allows determination of the longitudinal wave velocity as well as the Young's modulus of the oxide coat…
Mechanical characterization of rose bengal and green light crosslinked collagen scaffolds for regenerative medicine
2021
Abstract Collagen is one of the most important biomaterials for tissue engineering approaches. Despite its excellent biocompatibility, it shows the non-negligible disadvantage of poor mechanical stability. Photochemical crosslinking with rose bengal and green light (RGX) is an appropriate method to improve this property. The development of collagen laminates is helpful for further adjustment of the mechanical properties as well as the controlled release of incorporated substances. In this study, we investigate the impact of crosslinking and layering of two different collagen scaffolds on the swelling behavior and mechanical behavior in micro tensile tests to obtain information on its wearin…
Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging
2021
It is well known that the need for more environmentally friendly materials concerns, among other fields, the food packaging industry. This regards also, for instance, nets used for agricultural product (e.g., citrus fruits, potatoes) packaging. These nets are typically manufactured by film blowing technique, with subsequent slicing of the films and cold drawing of the obtained strips, made from traditional, non-biodegradable polymer systems. In this work, two biodegradable polymer systems were characterized from rheological, processability, and mechanical points of view, in order to evaluate their suitability to replace polyethylene-based polymer systems typically used for agricultural prod…
Using the single-ring infiltrometer method to detect temporal changes in surface soil field-saturated hydraulic conductivity
2004
Abstract Determining temporal changes in field-saturated hydraulic conductivity ( K fs ) is important for understanding and modelling hydrological phenomena at the field scale. Little is known about the sensitivity of temporal change estimates to the method used for measuring K fs . The objective of this study was to compare temporal changes in K fs obtained in the surface layer of a clayey soil using two application procedures of the single-ring infiltrometer method. Rings installed permanently at the beginning of a 1.5-year study period (permanent sites, PSs, sample size N =16) and rings installed immediately before conducting the infiltrometer measurement (non-permanent sites, NPSs, N =1…
Interfacial tension of the isotropic-nematic interface in suspensions of soft spherocylinders.
2005
The isotropic to nematic transition in a system of soft spherocylinders is studied by means of grand canonical Monte Carlo simulations. The probability distribution of the particle density is used to determine the coexistence density of the isotropic and the nematic phases. The distributions are also used to compute the interfacial tension of the isotropic--nematic interface, including an analysis of finite size effects. Our results confirm that the Onsager limit is not recovered until for very large elongation, exceeding at least L/D=40, with L the spherocylinder length and D the diameter. For smaller elongation, we find that the interfacial tension increases with increasing L/D, in agreem…