Degradation Behaviour of Zeolite Filled Polyurethanes under In Vitro Aging Process

2015 ◽  
Vol 812 ◽  
pp. 83-88
Author(s):  
Peter Kaali ◽  
György Czél
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Artificial Aging ◽  
Surface Pattern ◽  
Degradation Behaviour ◽  
Total Exposure Time ◽  
Polyurethane Composites ◽  
Over Time ◽  
Release Processes

In this study the degradation and ion/zeolite release processes of in vitro aged zeolite loaded polyurethane composites were evaluated. Two in vitro artificial aging solutions were used; artificial lysosomal fluid (ALF) and Gamble ́s solution and the total exposure time was 12 weeks. Periodically, SEM micrographs were taken of the surface of polyester type polyurethane-zeolite composites. After exposure to ALF solution the samples showed round holes and a rougher surface in general over time. Micrographs of the samples immersed in Gamble’s solution exhibited different signs of degradation with damage features on the surfaces, understood as black holes and a rougher surface pattern. In addition varying amount of salt was also observed on the surfaces that might influence the ion/zeolite release. Furthermore, the zeolite filler caused remarkable changes in mechanical properties after the aging process, which could not be discerned.

Investigation on the Stress Relaxation Aging Behavior of 2195 Al-Li Alloy

2021 ◽  
Vol 315 ◽  
pp. 37-42
Author(s):  
Hai Long Liao ◽  
Li Hua Zhan ◽  
Yuan Gao ◽  
Xue Ying Chen ◽  
Ming Hui Huang
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
High Performance ◽  
Aging Process ◽  
Artificial Aging ◽  
Ageing Time ◽  
High Strength ◽  
Aging Behavior ◽  
Stress Corrosion Resistance ◽  
Scanning Electron

2195 Al-Li alloy is famous for high strength, excellent fatigue strength and good stress corrosion resistance, which is widely used in the manufacture of high-performance aerospace components. The aim of this study is to validate how the stress relaxation aging behavior effect on the mechanical properties of 2195 Al-Li alloy. Through mechanical property test, the research was found that the performance after stress relaxation aging is higher than artificial aging (AA). In addition, the analysis of scanning electron microscopy SEM and TEM revealed that dislocations should be introduced by the stress relaxation aging process, which is more conducive to the precipitation of the T1 phase and strengthened the material with prolong ageing time. The results show that stress relaxation aging can significantly promote the precipitation of the T1. Therefore, this paper sheds new light on how SRA can improve mechanical properties and that SRA make better improve the distribution of precipitates in the grain boundary.

scholarly journals Effects of Pre-Stretching on Creep Behavior, Mechanical Property and Microstructure in Creep Aging of Al-Cu-Li Alloy

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 333 ◽  
Author(s):  
Jin Zhang ◽  
Zhen Jiang ◽  
Fushun Xu ◽  
Mingan Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Dislocation Density ◽  
Creep Behavior ◽  
Aging Process ◽  
Artificial Aging ◽  
Dislocation Motion ◽  
Nucleation And Growth ◽  
Blocking Effect ◽  
Creep Stage

The effects of pre-stretching on creep behavior, mechanical properties and microstructure during the creep aging process of Al-Cu-Li alloy were investigated. AA2195 was taken as the representative of Al-Cu-Li alloys. It is found that the total creep strain and strength property of creep aged AA2195 specimens can be improved through effective pre-stretching. Unlike with artificial aging, yield strength increased increasing by 47%. The TEM images show that the constitution of aging precipitates in the creep-aged specimens are obviously changed by pre-stretching. Precipitates in the 2% pre-stretched specimen are mainly composed of T1 phase, while a great amount of θ’ phase accompanied with a few T1 phase were found in the non-pre-stretched specimen. Moreover, pre-stretching introduces many dislocations which benefit the creep deformation, but the increasing dislocation density also accelerates the nucleation and growth of the precipitates as well. The premature T1 phase has a great blocking effect to the dislocation motion, creating a lower decrease rate but a longer duration in the early creep stage. Except for the initial dislocations, the dislocation motion in the creep aging process is also a favorable factor to precipitate the T1 phase.

Surface Changes of Fluoride-Releasing Composites: a Comparison of in Vivo and in Vitro Results

1995 ◽  
Vol 9 (4) ◽  
pp. 348-354 ◽  
Author(s):  
G.E.H.M. Dijkman ◽  
J. De Vries ◽  
W.L. Jongebloed ◽  
J. Arends
Keyword(s):  
Mechanical Properties ◽  
Outer Surface ◽  
Tap Water ◽  
Surface Microhardness ◽  
Vitro Experiment ◽  
In Vitro Experiment ◽  
Over Time ◽  
Surface Changes

Fluoride-releasing composites lose fluoride very slowly over time. An interesting question is the possible change in mechanical properties related to the F release. If this happens, it might be expected that the mechanical properties of the outer surface of a fluoridating composite are affected first. The purpose of this study was to investigate in vivo and in vitro the changes in surface microhardness and surface structure of three fluoride-releasing composites and a non-F-containing control after 28 days. In the in vitro experiment, the composites were stored in tap water at 37°C. The results show that all composites stored in water were significantly softened after 28 days. In vivo, however, a very different picture emerged: The surface microhardness of the fluoride-releasing composites did not change significantly. In vitro, the data indicate that the amount of softening of the fluoridating composites is related to the amount of fluoride released. No relation was found between the amount of F released in one month in vitro and the microhardness changes in vivo. SEM micrographs of fluoridating composites do not reflect the microhardness changes mentioned.

Effect of Artificial Aging on Aluminum Extrusion Alloy for Automobile Bumper

2011 ◽  
Vol 695 ◽  
pp. 190-193
Author(s):  
Sun Dae Kim ◽  
Hoon Cho ◽  
Do Hyang Kim
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Volume Fraction ◽  
High Strength ◽  
Atomic Ratio ◽  
Aluminum Extrusion ◽  
Extrusion Alloy ◽  
Processing Factors

The heat-treatable, precipitation-hardening, aluminum alloys are of special interest for automobile where high strength and dent resistance are required, and for bumpers, where good strength and shock absorption are needed. In both cases, good formability is also an important requirement. The heat-treatable 6000-series Al-Mg-Si alloys have been the material of choice for automobile. Despite the high strengthening potential of Al-Mg-Si alloys, processing factors such as the artificial aging processes, as well as the duration of artificial aging, can seriously impede the strengthening process. The highest tensile strength of A6082 alloy was obtained when Mg/Si atomic ratio is set to 1.1 due to the biggest volume fraction of intermetallic compound containing Mg and Si. It was to determine how aging process affected the microstructure and mechanical properties of the A6082 alloy as different ratio between Mg and Si.

Microstructure and Mechanical Properties of ZK60 Alloy Sheets during Aging

2007 ◽  
Vol 558-559 ◽  
pp. 159-164 ◽  
Author(s):  
Jae Hyung Cho ◽  
Y.M Jin ◽  
Hyoung Wook Kim ◽  
Suk Bong Kang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aging Time ◽  
Solution Heat Treatment ◽  
Aging Process ◽  
Artificial Aging ◽  
Warm Rolling ◽  
Microstructure And Mechanical Properties ◽  
Zk60 Alloy

Variations in microstructure and mechanical properties of ZK60 alloy sheets were investigated with aging time. ZK60 alloy sheets with a thickness of 1mm were prepared from a casting ingot followed by homogenization and warm-rolling. Artificial aging process after solution heat treatment (T6) affected both hardness variations and precipitates distributions with aging time. Hardness variations were related to precipitates, i.e. rod-shaped ( 1 β ′ ) or disc shaped ( 2 β ′ ) particles. Rod-shaped ( 1 β ′ ) precipitates mainly consist of Mg and Zn without Zr.

MECHANICAL PROPERTIES OF ELECTROSPUN PCL SCAFFOLD UNDER IN VITRO AND ACCELERATED DEGRADATION CONDITIONS

2014 ◽  
Vol 26 (03) ◽  
pp. 1450043 ◽  
Author(s):  
Alexandra Løvdal ◽  
Jakob Vange ◽  
Lene Feldskov Nielsen ◽  
Kristoffer Almdal
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Molecular Weight ◽  
Elastic Modulus ◽  
No Reduction ◽  
Biodegradable Scaffold ◽  
Accelerated Degradation ◽  
Degradation Time ◽  
Over Time

Within recent years, researchers have looked into using polycaprolactone (PCL) as a synthetic biodegradable scaffold for tissue engineering purposes. This study investigated the mechanical properties of an electrospun PCL, while being exposed to physiological fluids at 37°C (in vitro conditions) with and without the influence of cell in-growth. The molecular weight and mechanical properties were monitored during the degradation. Incubation in physiological fluids for 3–16 weeks showed an improvement in mechanical properties and no reduction in molecular weight. It was also shown that cells did not deteriorate the mechanical properties of PCL after 16 weeks. The viability of the cells decreased over time, however, without influencing the mechanical properties of the scaffold. A relation between reduction in molecular weight and the mechanical properties of electrospun PCL was seen between 2–29 days in buffer (pH 12). The accelerated study showed a linear decrease in both elastic modulus and yield stress as a function of degradation time.

Effects of Aging Process in Hot Forming with Synchronous Cooling on Properties of AA2024

2016 ◽  
Vol 725 ◽  
pp. 706-710
Author(s):  
Ming He Chen ◽  
Guo Liang Chen ◽  
N. Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Aging Process ◽  
Artificial Aging ◽  
Natural Aging ◽  
Performance Testing ◽  
Hot Forming ◽  
Elongation Ratio ◽  
Subsequent Performance

Aging treatment is an important process of a new hot forming technology with synchronous cooling (HFSC) for heat-treatable, high-strength aluminum alloys. In this paper, it were carried out respectively experimental research both the artificial aging and natural aging, and subsequent performance testing and microstructure analysis were implemented to investigation the effect of different aging process on the final mechanical properties of AA2024. Research results show that, under the condition of forming temperature range from 475°C to 495°C, the mechanical properties of AA2024 which made by HFSC and after nature aging for 96 hours: yield strength, tensile strength and elongation ratio was up to 499.0MPa, 306.5 MPa and 19.1% respectively; For the artificial aging, at aging temperature of 190°C, aging time of 4～8 hour, its yield strength, tensile strength and elongation ratio was up to 515.0MPa, 398.0 MPa and 11.1% respectively.

scholarly journals Engineering and Monitoring 3D Cell Constructs with Time-Evolving Viscoelasticity for the Study of Liver Fibrosis In Vitro

2021 ◽  
Vol 8 (8) ◽  
pp. 106
Author(s):  
Ludovica Cacopardo ◽  
Arti Ahluwalia
Keyword(s):  
Mechanical Properties ◽  
Liver Fibrosis ◽  
Progressive Increase ◽  
Cell Stress ◽  
Matrix Proteins ◽  
Hepatic Tissue ◽  
3D Microenvironment ◽  
Mechanical Microenvironment ◽  
Over Time

Liver fibrosis is generally associated with an over-production and crosslinking of extracellular matrix proteins, causing a progressive increase in both the elastic and viscous properties of the hepatic tissue. We describe a strategy for mimicking and monitoring the mechano-dynamics of the 3D microenvironment associated with liver fibrosis. Cell-laden gelatin hydrogels were crosslinked with microbial transglutaminase using a purpose-designed cytocompatible two-step protocol, which allows for the exposure of cells to a mechanically changing environment during culturing. A bioreactor was re-engineered to monitor the mechanical properties of cell constructs over time. The results showed a shift towards a more elastic (i.e., solid-like) behaviour, which is likely related to an increase in cell stress. The method effectively mimics the time-evolving mechanical microenvironment associated with liver fibrosis and could provide novel insights into pathophysiological processes in which both elastic and viscous properties of tissues change over time.

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