scholarly journals Studying some mechanical properties of maxillofacial silicone elastomer before and after incorporation of intrinsic pigments and artificial aging

2018 ◽  
Vol 4 (2) ◽  
pp. 244-252
Author(s):  
Noor M. Shihab ◽  
Faiza M. Abdul-Ameer
Keyword(s):  
Mechanical Properties ◽  
Artificial Aging ◽  
Silicone Elastomer ◽  
Before And After

scholarly journals Microstructure and Mechanical Properties of Composite Resins Subjected to Accelerated Artificial Aging

2013 ◽  
Vol 24 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Andrea Candido dos Reis ◽  
Denise Tornavoi de Castro ◽  
Marco Antonio Schiavon ◽  
Leandro Jardel da Silva ◽  
Jose Augusto Marcondes Agnelli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Artificial Aging ◽  
Thermal Analyses ◽  
Surface Hardness ◽  
Composite Resins ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

scholarly journals A Facile Way to Prolong Service Life of Double Base Propellant

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2236 ◽  
Author(s):  
Shixiong Sun ◽  
Song Ma ◽  
Benbo Zhao ◽  
Guangpu Zhang ◽  
Yunjun Luo
Keyword(s):  
Mechanical Properties ◽  
Service Life ◽  
Storage Time ◽  
Artificial Aging ◽  
Mechanical Performance ◽  
Diffusion Characteristics ◽  
Actual Service ◽  
Before And After ◽  
Double Base ◽  
And Diffusion

The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation and diffusion characteristics of nitroglycerin (NG) in propellant were evaluated by thermogravimetry analysis (TGA). The results showed that mechanical properties of propellant were improved due to PTFE, especially for elongation at −40 °C, which was greatly increased by 115%. Moreover, the results of TGA showed that NG migration was reduced due to PTFE, which delayed the decline of propellant mechanical performance during aging. The reduction in elongation at −40 °C caused by aging was decreased by 68.5% for PTFE modified DBP. Enhanced mechanical properties and reduced NG migration could potentially prolong propellant service life.

Evaluation of Hydroxyapatite Film by Powder Jet Deposition after Artificial Aging

2012 ◽  
Vol 529-530 ◽  
pp. 229-232
Author(s):  
Ryo Akatsuka ◽  
Ken Matsumura ◽  
Miyoko Noji ◽  
Chihiro Nishikawa ◽  
Kei Sato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Cycling ◽  
Vickers Hardness ◽  
Bonding Strength ◽  
Artificial Aging ◽  
Three Dimensional ◽  
Human Tooth ◽  
Significant Difference ◽  
Before And After ◽  
New Type

This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.

The Effect of Microstructure and Mechanical Properties of Aluminium Aa6061 before and after Heat Treatment Using TIG

2013 ◽  
Vol 465-466 ◽  
pp. 881-885
Author(s):  
Rosli Ahmad ◽  
Samir Sani Abdulmalik
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
Vickers Microhardness ◽  
Testing Machine ◽  
Post Weld Heat Treatment ◽  
Microstructure Characteristics ◽  
Microhardness Testing ◽  
Before And After

This work studies the effect of a post-weld heat treatment (PWHT) on the mechanical and microstructure properties of an AA6061 sample welded using Tungsten Inert Gas (TIG) method. TIG method is comparatively flexible and has good economy. The welded samples were divided into as-welded and PWHTs samples. The PWHTs samples were solution heat treatment, water quenching and artificial aging. Both welded samples were cut according to the ASTM E8M-04 standard to obtain the tensile strength and the elongation of the joints. The failure pattern of the tensile tested specimens was analysed using scanning electron microscopy (SEM). A Vickers microhardness testing machine was used to measure the hardness across the joints. From the results, the PWHTs were able to enhance the mechanical properties and microstructure characteristics of the AA6061 joints welded by the TIG method.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

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