scholarly journals Prediction of loss of barrier properties in cracked thin coatings on polymer substrates subjected to tensile strain

2021 ◽  
Vol 426 ◽  
pp. 127746
Author(s):  
Marcus Vinícius Tavares da Costa ◽  
E. Kristofer Gamstedt
Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 688 ◽  
Author(s):  
Baljinder K. Kandola ◽  
Katherine V. Williams ◽  
John R. Ebdon

Thin coatings of crosslinked poly(vinylphosphonic acid), PVPA, display good adhesion and excellent intumescent, fire-retardant barrier properties when applied to the surfaces of a typical thermoplastic, such as poly(methyl methacrylate), but perform relatively poorly in water-soak tests. To strengthen and further improve the barrier properties of the intumescent char and to make the coating more hydrophobic, PVPA has been complexed with various inorganic and organic species. The chars formed from coatings of some of these hybrid materials are less friable than chars from coatings synthesized from crosslinked PVPA alone, and show higher levels of water tolerance with no significant reduction in dry adhesion to the substrate.


1984 ◽  
Vol 40 ◽  
Author(s):  
Hani L. Rizkalla ◽  
Stephen T. Wellinghoff

AbstractAmorphous, anodic Ta2O5 films of 400 A thickness deposited on deformable polymer substrates deformed by microshear banding even at 5–10% tensile strain. Electron beam evaporated Ta2O5 (EBE) were considerably more brittle in tension on the same substrates, fracturing at strains less than 1%. Even though both films were amorphous to electron diffraction the EBE vibrational spectrum in the Ta2O5 region (900 cm-1 - 400 cm-1) was more reminiscent of thermally oxidized material that appears to have greater microstructural order. A significant dynamic mechanical peak was observed at 60–90°C for both Al and Ta foils coated with either anodic or EBE Ta2O5 films. This process was assigned to relaxation of interfacial stresses induced by atomic motion in the oxide in this temperature range. In the face of the rather similar dynamic mechanical spectra we suspect that the presence of a greater Packing heterogeneity might explain the greater brittleness of the EBE films.


2009 ◽  
Vol 517 (10) ◽  
pp. 3075-3080 ◽  
Author(s):  
John Fahlteich ◽  
Matthias Fahland ◽  
Waldemar Schönberger ◽  
Nicolas Schiller

2020 ◽  
Vol 62 ◽  
pp. 152-164
Author(s):  
V. V. Bobkova ◽  
S. N. Konovalov

In vegetative experiment has been studied the infl uence of adsorbents on the basis of mineral and polymer substrates Bentonite, Arpolit, Supradit, Agronit on the accumulation of heavy metals (HM) of strawberry plants plant variety Troitskaya in the artificial contamination of sod-podzolic soil at the level MAC (maximum allowable concentration) of total content of TM: Cd 2 mg/kg, Cr 100 mg/kg (MAC missing), Pb 130 mg/kg, Zn 220 mg/ kg. It was found that the use of adsorbents based on mineral and polymer substrates helps to reduce the content of mobile forms of Cr, Cd, Pb in the soil. Their content is reduced to the greatest extent when the adsorbents Supradit M are added to the soil (by 78.5 % for Cd and 40.1 % for Pb, compared with the control) and Agronite (by 79.0 % for Cd and 48.9 % for Pb, compared with the control). For mobile Cr, the downward trend in soil content was statistically unreliable. The content of mobile Zn in the variants with all adsorbents, on the contrary, increased in comparison with the contaminated control, to the greatest extent when the adsorbent Supradit M was added – by 26.1 %, compared with the control. The use of adsorbents led to a decrease in the content of Cd and Pb in the roots of strawberry plants. The greatest decrease in their content in the roots was when adding adsorbents Supradit M (65.2 % for cadmium and 76.8 % for lead, compared with the control) and Agronite (65.7 % for cadmium and 78.2 % for lead, compared with the control). The content of Zn in the roots in the variants with the introduction of adsorbents, except for Bentonite, increased in comparison with the contaminated control, to the greatest extent with the introduction of the adsorbent Supradit M – by 45.2 %. The content of Cr in the roots when using all adsorbents, except Agronite, also tended to increase, to the greatest extent when applying Arpolite – by 105.9 %, compared with the control. When applying the adsorbents Supradit M and Agronit to the soil, the content of Cd in the leaves decreased: when applying the adsorbent Supradit M by 52.9 %, Agronit – by 41.2 %, compared to the control. The content of Zn, Cr, and Pb in the leaves in the variants with adsorbents increased in comparison with the contaminated control, to the greatest extent when adding the adsorbent Arpolite: by 63.7 % – for Zn, by 71.2 % – for Cr, and by 46.3 % – for Pb. When using this adsorbent, the content of Cd in the leaves also increased – by 105.9 % higher than the contaminated control. The content of Cd, Cr, Pb, Zn in the berries of strawberry when using adsorbents less than in the roots and leaves, depended on the content of the corresponding heavy metals in the soil and was not statistically significant. When adding the adsorbents Supradit M and Agronit to the soil, the content of Cd in berries tended to decrease: when using the adsorbent Supradit M – by 30.0 %, Agronit – by 40.0 %, compared with the control. When adding the adsorbent Arpolite to the soil, the Cd content in berries tended to increase by 30.0 %, Pb – by 111.8 % from the control. The Cr content in the berries in the variants with adsorbents increased in comparison with the contaminated control, to the greatest extent with the introduction of Bentonite adsorbent – by 180.0 %. For the content of Zn in berries, there was no pronounced natural tendency for adsorbents to act. The closest relationship between the content of TM in the organs of strawberry plants and the content of mobile forms of heavy metals in the soil was observed for roots and leaves. There was no such dependency for Cr. At the studied levels of mobile TM content in the soil, the barrier properties of strawberry plants play an important role in the accumulation of heavy metals. The translocation coefficients of heavy metals were higher in the experiment variants, in which a decrease in the content of mobile forms of TM in the soil was observed when adding adsorbents. For Cd in the variant using the adsorbents Supradit M and Agronit, the TM translocation coefficients were higher than the control value by 98.0 and 72.5 %, respectively. For Pb, the values of translocation coefficients increased with the use of these adsorbents, compared to the control, by 300 % and 350 %, respectively. With an increased content of mobile forms of TM in the soil in the variants with the introduction of adsorbents Supradit M and Agronit, the translocation coefficients for Zn, compared to the control, were lower by 33.3 % and 33.3 %, respectively.


2021 ◽  
Author(s):  
Yun Li ◽  
Di Wen ◽  
Yinghao Zhang ◽  
Yuan Lin ◽  
Kun Cao ◽  
...  

Polymer substrates with superior barrier properties are of great importance for the development of highly-stable flexible displays. Atomic layer infiltration (ALI) method has been utilized to integrate nanoscale inorganic materials...


2011 ◽  
Vol 117-119 ◽  
pp. 743-746
Author(s):  
Zue Chin Chang ◽  
C. B. Lin ◽  
Wen Hua Yang ◽  
Jin Shin Ho

Abstract: The polydimethylsiloxane (PDMS) film was applied a tensile strain, next the following steps was should be done: fixing the tensile strain, sputtering the gold film on the surface of PDMS film, and then releasing the tensile strain, a large-scale area ripple structure was formed. The ripple dislocations, the cracks and the oriented surface cracks appeared simultaneously during the forming of the ripple structure. This study also discussed the wavelengths of ripple structures resulted from the amount of tensile strain (30%, 50%, 70%, 90% and 110%) and gold thickness (4Å and 10Å). The wavelengths of ripple structures decreased as the tensile strains increased and gold thickness decreased.


Author(s):  
B. Van Deurs ◽  
J. K. Koehler

The choroid plexus epithelium constitutes a blood-cerebrospinal fluid (CSF) barrier, and is involved in regulation of the special composition of the CSF. The epithelium is provided with an ouabain-sensitive Na/K-pump located at the apical surface, actively pumping ions into the CSF. The choroid plexus epithelium has been described as “leaky” with a low transepithelial resistance, and a passive transepithelial flux following a paracellular route (intercellular spaces and cell junctions) also takes place. The present report describes the structural basis for these “barrier” properties of the choroid plexus epithelium as revealed by freeze fracture.Choroid plexus from the lateral, third and fourth ventricles of rats were used. The tissue was fixed in glutaraldehyde and stored in 30% glycerol. Freezing was performed either in liquid nitrogen-cooled Freon 22, or directly in a mixture of liquid and solid nitrogen prepared in a special vacuum chamber. The latter method was always used, and considered necessary, when preparations of complementary (double) replicas were made.


Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.


Author(s):  
R. R. Warner

Keratinocytes undergo maturation during their transit through the viable layers of skin, and then abruptly transform into flattened, anuclear corneocytes that constitute the cellular component of the skin barrier, the stratum corneum (SC). The SC is generally considered to be homogeneous in its structure and barrier properties, and is often shown schematically as a featureless brick wall, the “bricks” being the corneocytes, the “mortar” being intercellular lipid. Previously we showed the outer SC was not homogeneous in its composition, but contained steep gradients of the physiological inorganic elements Na, K and Cl, likely originating from sweat salts. Here we show the innermost corneocytes in human skin are also heterogeneous in composition, undergoing systematic changes in intracellular element concentration during transit into the interior of the SC.Human skin biopsies were taken from the lower leg of individuals with both “good” and “dry” skin and plunge-frozen in a stirred, cooled isopentane/propane mixture.


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