scholarly journals Surface Modification of Electrospun PVDF/PAN Nanofibrous Layers by Low Vacuum Plasma Treatment

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Fatma Yalcinkaya ◽  
Baturalp Yalcinkaya ◽  
Adam Pazourek ◽  
Jana Mullerova ◽  
Martin Stuchlik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Plasma Treatment ◽  
Water Remediation ◽  
High Porosity ◽  
Vacuum Plasma ◽  
Hydrophobic Membranes ◽  
Small Pore ◽  
Hydrophilic Membranes ◽  
Water Treatments

Nanofibres are very promising for water remediation due to their high porosity and small pore size. Mechanical properties of nanofibres restrict the application of pressure needed water treatments. Various PAN, PVDF, and PVDF/PAN nanofibre layers were produced, and mechanical properties were improved via a lamination process. Low vacuum plasma treatment was applied for the surface modification of nanofibres. Atmospheric air was used to improve hydrophilicity while sulphur hexafluoride gas was used to improve hydrophobicity of membranes. Hydrophilic membranes showed higher affinity to attach plasma particles compared to hydrophobic membranes.

Surface Modification of Cellulose Membrane by Air Plasma Treatment

2013 ◽  
Vol 770 ◽  
pp. 112-115
Author(s):  
Nawal Binhayeeniyi ◽  
Adinan Jehsu ◽  
Mancharee Sukpet ◽  
Safitree Nawae
Keyword(s):  
Surface Modification ◽  
Plasma Treatment ◽  
Surface Modifications ◽  
Contact Angles ◽  
Cellulose Membrane ◽  
Air Plasma ◽  
Before And After ◽  
Cellulose Membranes ◽  
Hydrophilic Membranes ◽  
Air Plasma Treatment

Low-temperature air plasma was used to treat the cellulose membranes by varying the period of time from 10 to 30 minutes. The surfaces of membranes were changed from hydrophobic to hydrophilic membranes. The contact angles of treated membranes were increased when increasing time to treat. The surface modifications of membrane before and after treated were characterized by SEM. It is shown that air plasma treatment is used to improve the roughness. The dielectric property was also studied.

scholarly journals A Study on the Effect of Plasma Treatment for Waste Wood Biocomposites

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
MiMi Kim ◽  
Heung Soo Kim ◽  
Joong Yeon Lim
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Plasma Treatment ◽  
Atmospheric Pressure ◽  
Plasma Polymerization ◽  
Atmospheric Pressure Plasma ◽  
Single Species ◽  
Wood Powder ◽  
Waste Wood ◽  
Pressure Plasma

The surface modification of wood powder by atmospheric pressure plasma treatment was investigated. The composites were manufactured using wood powder and polypropylene (wood powder: polypropylene = 55 wt% : 45 wt%). Atmospheric pressure plasma treatment was applied under the condition of 3 KV,17±1 KHz, 2 g/min. Helium was used as the carrier gas and hexamethyl-disiloxane (HMDSO) as the monomer to modify the surface property of the waste wood biocomposites by plasma polymerization. The tensile strengths of untreated waste wood powder (W3) and single species wood powder (S3) were about 18.5 MPa and 21.5 MPa while those of plasma treated waste wood powder (PW3) and plasma treated single species wood powder (PS3) were about 21.2 MPa and 23.4 MPa, respectively. Tensile strengths of W3 and S3 were improved by 14.6% and 8.8%, respectively. From the analyses of mechanical properties and morphology, we conclude that the interfacial bonding of polypropylene and wood powder can be improved by atmospheric pressure plasma treatment.

scholarly journals Effects of Surface Modification of MWCNT on the Mechanical and Electrical Properties of Fluoro Elastomer/MWCNT Nanocomposites

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Tao Xu ◽  
Jinghui Yang
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Electrical Properties ◽  
Plasma Treatment ◽  
Polyvinylidene Fluoride ◽  
Composite Films ◽  
Mechanical Tests ◽  
Dielectric Behavior ◽  
Acid Oxidation ◽  
Multiwalled Carbon

Surface modification is a good way to improve the surface activity and interfacial strength of multiwalled carbon nanotubes (MWCNTs) when used as fillers in the polymer composites. Among the reported methods for nanotube modification, mixed acid oxidation and plasma treatment is often used by introducing polar groups to the sidewall of MWCNT successfully. The purpose of this study is to evaluate the effect of different surface modification of MWCNT on the mechanical property and electrical conductivity of Fluoro-elastomer (FE)/MWCNT nanocomposites. MWCNTs were surface modified by mixed oxidation and CF4plasma treatment and then used to reinforce the fluoro elastomer (FE, a copolymer of trifluorochloroethylene and polyvinylidene fluoride). FE/MWCNT composite films were prepared from mixture solutions of ethylacetate and butylacetate, using untreated CNTs (UCNTs), acid-modified CNTs (ACNTs), and CF4plasma-modified CNT (FCNTs). In each case, MWCNT content was 0.01 wt%, 0.05 wt%, 0.1 wt%, and 0.2 wt% with respect to the polymer. Morphology and mechanical properties were characterized by using scanning electron microscopy (SEM), Raman spectroscopy, as well as dynamic mechanical tests. The SEM results indicated that dispersion of ACNTs and especially FCNTs in FE was better than that of UCNTs. DMA indicated mechanical properties of FCNT composites were improved over ACNT and UCNT filled FE. The resulting electrical properties of the composites ranged from dielectric behavior to bulk conductivities of 10-2 Sm-1and were found to depend strongly on the surface modification methods of MWCNTs.

Tuning the Mechanical Properties of Poly-silicon Film by Surface Modification Using Plasma Treatment

2004 ◽  
Vol 820 ◽  
Author(s):  
Wang-Shen Su ◽  
Weileun Fang ◽  
Ming-Shih Tsai
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Elastic Modulus ◽  
Plasma Treatment ◽  
Vacuum Annealing ◽  
Silicon Film ◽  
Mems Devices ◽  
Poly Silicon ◽  
Plasma Treatments ◽  
Surface Modified

AbstractThe mechanical properties of thin film are very critical for the performance of MEMS devices. Since Poly-silicon film is of great use in MEMS, this study investigates the surface modification by various plasma treatments to finely tune the chemical and mechanical properties of poly-silicon film. Various plasma treatments, including H2, O2, and NH3, were implemented to modify the original Si-Si film bonding, Young's modulus, and hardness of poly-silicon film. These were significant Si-O, Si-OH/Si-H and Si-NH2/Si-N bonds formed after O2, H2 and NH3 plasma treatment, respectively. According to the H analysis from SIMS depth profile of, the thickness of surface modified layer would be ranged from 50 to 120 nm. In summary, the surface modification with H2 plasma can reduce the elastic modulus of poly-silicon film for about 32.3%; moreover, the following vacuum annealing will further reduce the elastic modulus for about 60.2%. Therefore, surface modification with an adequate plasma treatment would be an effective method to change the chemical and mechanical properties of poly-silicon film.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

scholarly journals Fabrication of Hybrid Nanofibers from Biopolymers and Poly (Vinyl Alcohol)/Poly (ε-Caprolactone) for Wound Dressing Applications

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2104
Author(s):  
Sibusiso Alven ◽  
Blessing Atim Aderibigbe
Keyword(s):  
Mechanical Properties ◽  
Wound Healing ◽  
Vinyl Alcohol ◽  
Wound Dressing ◽  
Chronic Wounds ◽  
Cellular Adhesion ◽  
Wound Dressings ◽  
Poly Vinyl Alcohol ◽  
High Porosity ◽  
Hybrid Nanofibers

The management of chronic wounds is challenging. The factors that impede wound healing include malnutrition, diseases (such as diabetes, cancer), and bacterial infection. Most of the presently utilized wound dressing materials suffer from severe limitations, including poor antibacterial and mechanical properties. Wound dressings formulated from the combination of biopolymers and synthetic polymers (i.e., poly (vinyl alcohol) or poly (ε-caprolactone) display interesting properties, including good biocompatibility, improved biodegradation, good mechanical properties and antimicrobial effects, promote tissue regeneration, etc. Formulation of these wound dressings via electrospinning technique is cost-effective, useful for uniform and continuous nanofibers with controllable pore structure, high porosity, excellent swelling capacity, good gaseous exchange, excellent cellular adhesion, and show a good capability to provide moisture and warmth environment for the accelerated wound healing process. Based on the above-mentioned outstanding properties of nanofibers and the unique properties of hybrid wound dressings prepared from poly (vinyl alcohol) and poly (ε-caprolactone), this review reports the in vitro and in vivo outcomes of the reported hybrid nanofibers.

scholarly journals Strategies to Reduce Porosity in Al-Mg WAAM Parts and Their Impact on Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 524
Author(s):  
Maider Arana ◽  
Eneko Ukar ◽  
Iker Rodriguez ◽  
Amaia Iturrioz ◽  
Pedro Alvarez
Keyword(s):  
Mechanical Properties ◽  
Gas Flow ◽  
Bottom Layer ◽  
Local Heat ◽  
High Porosity ◽  
Shielding Gas ◽  
Heat Accumulation ◽  
High Mechanical Property ◽  
Building Conditions ◽  
Static Tensile

With the advent of disruptive additive manufacturing (AM), there is an increasing interest and demand of high mechanical property aluminium parts built directly by these technologies. This has led to the need for continuous improvement of AM technologies and processes to obtain the best properties in aluminium samples and develop new alloys. This study has demonstrated that porosity can be reduced below 0.035% in area in Al-Mg samples manufactured by CMT-based WAAM with commercial filler metal wires by selecting the correct shielding gas, gas flow rate, and deposition strategy (hatching or circling). Three phase Ar+O2+N2O mixtures (Stargold®) are favourable when the hatching deposition strategy is applied leading to wall thickness around 6 mm. The application of circling strategy (torch movement with overlapped circles along the welding direction) enables the even build-up of layers with slightly thicker thickness (8 mm). In this case, Ar shielding gas can effectively reduce porosity if proper flow is provided through the torch. Reduced gas flows (lower than 30 Lmin) enhance porosity, especially in long tracks (longer than 90 mm) due to local heat accumulation. Surprisingly, rather high porosity levels (up to 2.86 area %) obtained in the worst conditions, had a reduced impact on the static tensile test mechanical properties, and yield stress over 110 MPa, tensile strength over 270 MPa, and elongation larger than 27% were achieved either for Ar circling, Ar hatching, or Stargold® hatching building conditions. In all cases anisotropy was lower than 11%, and this was reduced to 9% for the most appropriate shielding conditions. Current results show that due to the selected layer height and deposition parameters there was a complete re-melting of the previous layer and a thermal treatment on the prior bottom layer that refined the grain size removing the original dendritic and elongated structure. Under these conditions, the minimum reported anisotropy levels can be achieved.

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