• Corrosion Science and Technology
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• 제18권6호
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• pp.232-242
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• 2019

In this study, hydrophobically modified fumed silica was added to the PVDF coating to improve corrosion protection performance. Two types of silane modifiers, trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ), were used for hydrophobic modification of the fumed silica. The composition of modified fumed silica was analyzed by Fourier transform infrared, X-ray photoelectron spectroscopy, and elemental analysis. The dispersion of modified fumed silica in the PVDF coating was observed by the transmission electron microscopy, and the hydrophobicity of PVDF coating was analyzed by the water contact angle. Surface properties were examined by the field emission scanning electron microscopy and scanning probe microscopy. Potentiodynamic polarization was conducted to confirm corrosion protection performance of PVDF coating in terms of hydrophobically-modified fumed silica contents. As a result, the average surface roughness and the water contact angle of the PVDF coating increased with modifier contents. The results of the potentiodynamic polarization test showed an increase of the E_corr values with increase of the hydrophobicity of PVDF coating. Thus, it clearly indicates that the corrosion protection performance of PVDF coating improved with the addition of the hydrophobic-modified fumed silica that prevents the penetration of moisture into the PVDF coating.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.129-136
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• 2006

Although cleaner and cheaper deinking of ONP could be performed at the neutral or low alkaline condition excessive loss from froth-flotation is unavoidable and so reduction of alkali or caustic soda dosage sacrifices recycling yield. Now the new trade-off regarding alkali dosage versus flotation yield is urgently required in order to set the optimized neutral or low alkaline deinking process of ONP. Lipase from Thermomyces Lanuginosus has an effect on desizing and deacetylation reaction and it could be applied to the stock of pre flotation secondary stage in order to reduce the flotation reject without the sacrifice of optical properties of flotation accepts. Instead of inorganic base, lipase could be applied as a biochemical catalyst for the selective modification of valuable hydrophobic particles in deinking stock, for example cellulose fines and inorganic fillers covered by hydrophobic additives or contaminants. When the enzymatic hydrolysis of ester bond could be made on the surface of hydrophobic particulates, unwanted float of fine particles could be prevented. Now the enhancement of flotation selectivity or the modification of the hydrophobicity of deinking stock is expected to be promoted by the enzymatic pre treatment. And the reduction of recycling cost with the saves of raw material, recovered paper would be possible as a result.

• Textile Coloration and Finishing
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• 제13권3호
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• pp.172-179
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• 2001

In order to improve dye uptime and wash fastness on dyeing of cotton fabrics with Amur cork tree, twitter ionic groups, acid groups, hydrophobic groups or cross linkage were introduced into cotton fabrics. Results obtained were as follows, 1 The optimum modification of cotton fabrics was carbosy methylation in the water solution containing 15% sodium chloroacetate and 15% sodium hydroxide and then introducing hydrophobic groups by treating in the solution containing $30m\ell$ DMSO and $3m\ell$ 2,4-TDI 2. Numbers of carbon, diisocyanate group than monoisocyanate group and aromatic compound than aliphatic compound in introduced hydrophobic groups were effective. 3. The dye uptake and wash fastness wore enhanced significantly by treating only with 2,4-TDI. 4. The wash fastness seems to correlate to the degree of swelling of the fabric during washing and also depend on the Interaction between dyes and acid groups as well as hydrophobic groups.

• Tribology and Lubricants
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• 제20권5호
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• pp.237-244
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• 2004

Micro/nano tribological characteristics of PTFE coating films were experimentally studied. PTFE (polytetrafluoroethylene) modified polyethylene and low molecular weight PTFE were used as a coating materials. These films were deposited on Si-wafer (100) by IBAD (ion beam assisted deposition) method. The Ar ion beam sputtering was performed to change the surface topography of films using a hollow cathode ion gun under different Ar ion dose conditions in a vacuum chamber. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribotester, SPM (scanning probe microscope), contact anglemeter and profilometer, respectively. The durability of the films were measured with macro tribotester. Results showed that the PTFE coating surfaces were converted to hydrophobic. The water contact angle of coated surfaces and surface roughness increased with the coating thickness. Adhesion and friction in micro and nano scale were governed by magnitude of normal load in soft material such as PTFE films. As the increase of sputtering time on low molecular weight PTFE films, the surface roughness was increased and nano adhesion and friction were decreased. The nano tribological characteristics of surfaces are mainly improved by chemical modification such as PTFE coating and given a synergy effect by the physical modification such as topographic modification.

• Journal of the Korean institute of surface engineering
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• 제45권4호
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• pp.151-154
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• 2012

A hydrophobic surface has been fabricated on aluminum by two-step surface treatment processes consisting of structure modification and surface coating. Nature inspired micro nano scale structures were artificially created on the aluminum surface by a blasting and Ar ion beam etching. And a hydrophobic thin film was coated by a trimethylsilane ($(CH_3)_3SiH$) plasma deposition to minimize the surface energy of the micro nano structure surface. The contact angle of micro nano structured aluminum surface with the trimethylsilane coating was $123^{\circ}$ (surface energy: 9.05 $mJ/m^2$), but the contact angle of only trimethylsilane coated sample without the micro nano surface structure was $92^{\circ}$ (surface energy: 99.15 $mJ/m^2$). In the hydrophobic treatment of aluminum surface, a trimethylsilane coated sample having the micro nano structure was more effective than only trimethylsilane coated sample without the micro nano structure.

• Tribology and Lubricants
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• 제37권5호
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• pp.189-194
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• 2021

A straightforward, yet effective surface modification method of stainless steel mesh and its interesting anti-wetting characteristics are reported in this study. The stainless steel mesh is electrochemically etched, and the specimen has both micro and nano-scale structures on its surface. This process transforms the two types of mesh specimens known as the regular and dense specimens into hydrophobic specimens without applying any hydrophobic chemical coating process. The fundamental wettability of the modified mesh is analyzed through a dedicatedly designed experiment to investigate the waterproof characteristics, for instance, the penetration threshold. The waterproof characteristics are evaluated in a manner that the modified mesh resists as high as approximately 2.7 times the pressure compared with the bare mesh, i.e., the non-modified mesh. The results show that the penetration threshold depends primarily on the advancing contact angles, and the penetration stop behaviors are affected by the contact angle hysteresis on the surfaces. The findings further confirm that the inexpensive waterproof meshes created using the proposed straightforward electrochemical etching process are effective and can be adapted along with appropriate designs for various practical applications, such as underwater devices, passive valves, and transducers. In general, , additional chemical coatings are applied using hydrophobic materials on the surfaces for the applications that require water-repelling capabilities. Although these chemical coatings can often cause aging, the process proposed in this study is not only cost-effective, but also durable implying that it does not lose its waterproof properties over time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.49-52
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• 2004

New hydrophobic alumina nanoparticles were synthesized from alumina powders which were hydrophilic nano-agglomerates with diameters from ${\mu}m$ to mm by surface modification. The synthesized hydrophobic alumina nanoparticles which were retreated with Oleic acid were analyzed by Fourier transform infrared spectrophotometer and transmission electron microscopy. Then transformer oil containing surface-modified alumina naonparticles were synthesized. The synthesized hydrophobic alumina nanoparticles were well-dispersed in transformer oil. The coefficient of viscosity and dielectric strength of the Nano-transformer oil were investigated with viscometer and high voltage experiment device. In this study, the thermal conductivity of Nano-transformer oil was investigated to reduce the oil temperature of transformer by transient hot-wire method.

• Journal of the Korean Society of Food Culture
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• 제14권5호
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• pp.467-476
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• 1999

We studied to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Soybean protein isolate was acylated rapidly up to 80% modification and more of 80% modification was proceed slowly. Electrophoretic analysis showed that more changes in modified protein. Also, modification of soybean protein produced more ionizable tyrosines and exposed more hydrophobic groups, while modified protein exhibited a loss of reactive sulfhydryl groups. Spectrophoretic studies demonstrated that the shift was occurred at the UV 278nm and fluorescence 333nm, respectively, and the intensity decreased as the degree of modification was increased.

• Textile Coloration and Finishing
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• 제4권4호
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• pp.110-116
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• 1992

For the modification of PET surface, Perfluoropropene and Methyl alcohol were LT-plasma polymerized on the PET fabrics as thin films by means of 13.56 MHz radio frequency generator. The surface properties of PET fabrics were modified from hydrophobic to hydrophilic by application of the postplasma reaction of thin films. The evidence of the modification was identified by observation of the presence of hydroxy group in IR spectrum and the evaluation of degree of hydrophilicity was performed by measuring frictional static voltage of PET fabric with cotton fabric. For the case of modification by PFP, the result performed at the condition of 25 W, 70 m torr has shown to be effective, and for MeOH, result performed at the condition of 25 W, 100 m torr effective. The effect of hydrophilic surface modification of MeOH plasma polymer was superior to that of PFP-plasma polymer.

• Journal of the Korean Applied Science and Technology
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• 제31권1호
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• pp.92-100
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• 2014

Hydrophobic magnesium hydroxide [$Mg(OH)_2$] was modified by hydrothermal method using non-ionic sorbitol surfactant with Span series. Mganesium chloride [$MgCl_2$] and sodium hydroxide [NaOH] were used for synthesis of $Mg(OH)_2$. Also non-ionic surfactant were added as a stabilizer, dispersant and surface modifier. Addition of non-ionic surfactant was favourable to obtain small sized $Mg(OH)_2$ particles with better dispersibility and hydrophobic property of $Mg(OH)_2$ particles. The obtained product were characterized by particle size analysis(PSA), scanning electron microscope(SEM), energy dispersive spectroscopy(EDS), x-ray diffraction(XRD) and fourier transform infrared spectroscopy(FT-IR). The results show that the product are prepared with this method has a well hydrophobic properties and dispersity compared with unmodified $Mg(OH)_2$ particles. The improve properties of surface modified $Mg(OH)_2$ particles were also verified by similarity synthesizing under slightly different conditions.