On the characterization of tensile creep resistance of polyamide 66 nanocomposites. Part II: Modeling and prediction of long-term performance

Aging has a significant effect on performance of asphalt materials. Reliable characterization of asphalt binder properties with aging is crucial to improving asphalt binder specifications as well as modification and formulation methods. The objective of this study is to correlate the laboratory conditioning methods with field aging using evolution of binder rheological parameters with time and pavement depth. Loose mixtures are aged in the lab (5 and 12 days aging at 95°C, and 24 h at 135°C) and recovered binder rheological properties are compared with those from different layers of field cores. The virgin binder results with 20 h pressure aging vessel (PAV) aging are also included. Binder testing is conducted using a dynamic shear rheometer with a 4 mm plate over a wide range of frequencies and temperatures. Rheological parameters calculated from the master curves, performance grade system, and binder Christensen–Anderson–Marasteanu model are used to evaluate changes with aging. The field aging gradient is evaluated, and the laboratory conditioning durations corresponding with the field aging durations at different pavement depths are calculated. The results show that 5 days of aging can simulate around 8 years of field aging (in New Hampshire) for the top 12.5 mm pavement, and 12 days’ aging can simulate approximately 20 years; 20 h PAV binder aging is not adequate to capture the long-term performance of the pavement. This study provides a way to optimize the laboratory conditioning durations and evaluate the performance of asphalt material with respect to pavement life (time) and depth (location) within the pavement structure.

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Characterization of the Charging and Long Term Performance of Cytop Electret Layers for MEMS Applications

MRS Proceedings ◽

10.1557/proc-1134-bb08-17 ◽

2008 ◽

Vol 1134 ◽

Cited By ~ 2

Author(s):

Ulrich Bartsch ◽

Joao Gaspar ◽

Oliver Paul

Keyword(s):

Corona Discharge ◽

Silicon Substrates ◽

Charging Station ◽

Corona Charging ◽

Initial Charge ◽

Charge Stability ◽

Long Term Performance ◽

Term Performance

AbstractThis paper reports on the characterization of the charge stability of an amorphous fluoropolymer electret called Cytop. Cytop is a dissolved polymer material, compatible with standard micromachining fabrication technologies. In this study, Cytop layers are deposited and patterned on Pyrex and silicon substrates, followed by the electrical poling of the material by corona discharge using a customized charging station. The long-term performance of Cytop as an electret material is evaluated as a function of several relevant charging parameters. The results reveal highly stable layers, able to keep at least 92% of the initial charge 143 days after the corona charging stored at 23°C.

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On the characterization of tensile creep resistance of polyamide 66 nanocomposites. Part I. Experimental results and general discussions

Polymer ◽

10.1016/j.polymer.2006.02.065 ◽

2006 ◽

Vol 47 (8) ◽

pp. 2791-2801 ◽

Cited By ~ 89

Author(s):

Jing-Lei Yang ◽

Zhong Zhang ◽

Alois K. Schlarb ◽

Klaus Friedrich

Keyword(s):

Creep Resistance ◽

Experimental Results ◽

Tensile Creep ◽

Polyamide 66

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Long-term performance and characterization of microbial desalination cells in treating domestic wastewater

Bioresource Technology ◽

10.1016/j.biortech.2012.06.054 ◽

2012 ◽

Vol 120 ◽

pp. 187-193 ◽

Cited By ~ 65

Author(s):

Haiping Luo ◽

Pei Xu ◽

Zhiyong Ren

Keyword(s):

Domestic Wastewater ◽

Long Term Performance ◽

Term Performance

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Characterization of selective laser-sintered hydroxyapatite-based biocomposite structures for bone replacement

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2007.1854 ◽

2007 ◽

Vol 463 (2084) ◽

pp. 1857-1869 ◽

Cited By ~ 16

Author(s):

L Hao ◽

M.M Savalani ◽

Y Zhang ◽

K.E Tanner ◽

R.J Heath ◽

...

Keyword(s):

Surface Morphology ◽

Porous Structure ◽

Cell Attachment ◽

Selective Laser Sintering ◽

Bone Implant ◽

Powder Particles ◽

Long Term Performance ◽

Term Performance

Integration of the bone into the implant is highly desirable for the long-term performance of the implant. The development of a bone–implant interface is influenced by the surface morphology and roughness, surface wettability and porosity of the implants. This study characterizes these important properties of a hydroxyapatite-based biocomposite structure fabricated by selective laser sintering (SLS) with a comparison to a moulded specimen. The sintered specimens exhibited a rougher surface with open surface pores and a highly interconnected internal porous structure. It was shown that the characteristics of the powder particles used in the SLS provided a more influential means to modify the surface morphology and the features of the internal pores than laser parameter variation. The correlation of wettability and porous structure shows that although surface open pores could help cell ingrowth and bone regeneration, they resulted in a poorer wettability of the materials, which may not encourage initial cell attachment and adhesion. The potential solution to improve the wettability and cell anchorage is discussed.

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Characterization of Turbulent Flow Behind a Transcatheter Aortic Valve in Different Implantation Positions

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.804565 ◽

2022 ◽

Vol 8 ◽

Author(s):

Leonardo Pietrasanta ◽

Shaokai Zheng ◽

Dario De Marinis ◽

David Hasler ◽

Dominik Obrist

Keyword(s):

Aortic Valve ◽

Flow Field ◽

Turbulent Flow ◽

Aortic Root ◽

Flow Topology ◽

Transcatheter Aortic Valve ◽

Long Term Performance ◽

Term Performance

The development of turbulence after transcatheter aortic valve (TAV) implantation may have detrimental effects on the long-term performance and durability of the valves. The characterization of turbulent flow generated after TAV implantation can provide fundamental insights to enhance implantation techniques. A self-expandable TAV was tested in a pulse replicator and the three-dimensional flow field was extracted by means of tomographic particle image velocimetry. The valve was fixed inside a silicone phantom mimicking the aortic root and the flow field was studied for two different supra-annular axial positions at peak systole. Fluctuating velocities and turbulent kinetic energy were compared between the two implantations. Velocity spectra were derived at different spatial positions in the turbulent wakes to characterize the turbulent flow. The valve presented similar overall flow topology but approximately 8% higher turbulent intensity in the lower implantation. In this configuration, axial views of the valve revealed smaller opening area and more corrugated leaflets during systole, as well as more accentuated pinwheeling during diastole. The difference arose from a lower degree of expansion of the TAV's stent inside the aortic lumen. These results suggest that the degree of expansion of the TAV in-situ is related to the onset of turbulence and that a smaller and less regular opening area might introduce flow instabilities that could be detrimental for the long-term performance of the valve. The present study highlights how implantation mismatches may affect the structure and intensity of the turbulent flow in the aortic root.

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The Electrochemical Characterization of Rebar Passivation Film in Simulated Concrete Media

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.539 ◽

2011 ◽

Vol 255-260 ◽

pp. 539-545 ◽

Cited By ~ 1

Author(s):

Wei Zhong Gan ◽

Wei Liang Jin ◽

Jian Ping Shao

Keyword(s):

Concrete Structure ◽

Chloride Ion ◽

Dynamic State ◽

Reinforcing Bar ◽

Passivation Film ◽

Active Transition ◽

Long Term Performance ◽

Term Performance

Based on the fundamental theory of electrochemical anodic polarization, simulated concrete is doped with corrosion inhibitor to prevent corrosion by chloride ion in the marine environment. Thus, with reference to the potential-time curves obtained in different concrete environments and construction conditions, the early dynamic state of active transition of rebar passive films in concretes can be quickly characterized. According to the experiments, the characteristics of passive active transition are synchronous with rebar corrosion. This helps to systematically study the influence of different components of concrete and external media on the durability of the concrete structure. The strong alkaline environment of the concrete is useful in controlling corrosion rate of reinforcing bar. As one of the additional protective measures of the durability of the concrete structure, corrosion inhibitor’s long-term performance contains uncertainty.

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