barrier performance
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2022 ◽  
Author(s):  
Manareldeen Ahmed ◽  
Yan Li ◽  
Wenchao Chen ◽  
Erping Li

Abstract This paper investigates the diffusion barrier performance of 2D layered materials with pre-existing vacancy defects using first-principles density functional theory. Vacancy defects in 2D materials may give rise to a large amount of Cu accumulation, and consequently, the defect becomes a diffusion path for Cu. Five 2D layered structures are investigated as diffusion barriers for Cu, i.e., graphene with C vacancy, hBN with B/N vacancy, and MoS2 with Mo/2S vacancy. The calculated energy barriers using climbing image - nudged elastic band show that MoS2-V2S has the highest diffusion energy barrier among other 2D layers, followed by hBN-VN and graphene. The obtained energy barrier of Cu on defected layer is found to be proportional to the length of the diffusion path. Moreover, the diffusion of Cu through vacancy defects is found to modulate the electronic structures and magnetic properties of the 2D layer. The charge density difference shows that there exists a considerable charge transfer between Cu and barrier layer as quantified by Bader charge. Given the current need for an ultra-thin diffusion barrier layer, the obtained results contribute to the field of application of 2D materials as Cu diffusion barrier in the presence of mono-vacancy defects.


2021 ◽  
Author(s):  
Andreas Fall ◽  
Marielle Henriksson ◽  
Anni Karppinen ◽  
Anne Opstad ◽  
Ellinor Bævre Heggset ◽  
...  

Abstract Cellulose nanofibrils, CNFs, show a great potential in many application areas. One main aspect limiting the use of the material is the slow and energy demanding dewatering of CNF suspensions. Here we investigate the dewatering with a piston press process. Three different CNF qualities, two laboratory grades (high and low charge) and one industrial grade (low charge) were tested. The chemical conditions were varied by changing salt concentration (NaCl) and pH. For the original suspensions, the dewatering rate is substantially slower for the high charge CNFs. However, by changing the conditions it dewatered as fast as the two low charge CNFs, even though salt/acid additions also improved dewatering rate for these two CNFs. Finally, by tuning the conditions fast dewatering could be obtained with only minor effect on strength and barrier performance of films prepared from the CNFs.


Author(s):  
Israel Sifuentes-Nieves ◽  
Roberto Yáñez Macías ◽  
Guadalupe Neira Velázquez ◽  
Gonzalo Velázquez ◽  
Zureima Garcia Hernandez ◽  
...  

2021 ◽  
Author(s):  
Khadijeh Aboutalebi ◽  
Pariya Yardani Sefidi ◽  
Mir ghasem Hosseini ◽  
Solen Kinayyigit ◽  
Armin Ghouchi

Abstract The 2-mercaptobenzimidazole-polyaniline-ceria (MBI-PANI-CeO2) ternary nanocomposite synthesized and used as pigment into epoxy (EP) to improve protection properties of coating on mild steel. The MBI-PANI-CeO2 nanocomposite was prepared using layer by layer assembly. Initially, the PANI layer was polymerized on the surface of CeO2 nanoparticles. Then, the MBI inhibitor was adsorbed on PANI with opposite electrostatic charges. The anticorrosive performance of EP coatings was investigated using electrochemical impedance spectroscopy, salt spray test, and scanning electron microscopy by incorporating various amounts (0.5, 1, and 2 wt. %) of the MBI-PANI-CeO2 nanocomposite. The EP coating containing 1 wt. % of nanocomposite showed the highest corrosion resistance and minimum agglomeration. This coating indicated the coating resistance of 19.1 MΩ cm2, which is greater than EP and EP/CeO2 coatings. The EP/MBI-PANI-CeO2 (1 wt. %) coating showed water uptake percentage (2.09 %) about two times lower than EP/CeO2 coatings (4.56 wt. %), indicating appropriate barrier performance of inhibitor incorporated EP.


2021 ◽  
pp. 138960
Author(s):  
Réka Lilla Kovács ◽  
Szilvia Gyöngyösi ◽  
Gábor Langer ◽  
Eszter Baradács ◽  
Lajos Daróczi ◽  
...  

TAPPI Journal ◽  
2021 ◽  
Vol 20 (9) ◽  
pp. 583-595
Author(s):  
BEKO MESIC ◽  
MATHEW CAIRNS ◽  
JAMES JOHNSTON ◽  
MEETA PATEL

An aqueous styrene-butadiene latex dispersion coating containing in-situ processed tetraethyl orthosilicate (TEOS) applied on paperboard demonstrated improved water barrier performance. Coatings containing TEOS equivalent to 0.8% silicon dioxide (SiO2; dry basis) exhibited water vapor performance of < 25 g/m2/day (23°C, 50% relative humidity [RH]) and liquid water barrier performance Cobb 1800 s of < 6 g/m2, when applied as a single-layer 18 g/m2 coating. Cobb 1800 s barrier performance was still good (< 11 g/m2) at coat weights of 7–10 g/m2. The use of filler materials such as kaolin improved the vapor barrier properties of the coating, but this was not critical to the liquid water barrier properties.


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