• Polymer(Korea)
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• v.36 no.5
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• pp.599-605
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• 2012

The physicochemical properties such as surface hardness, solvent mechanical wear resistance, and resistance to scratch properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin film prepared by vapor phase polymerization (VPP) was effectively improved by post-treatment of various metal alkoxide sol solutions. Metal oxide layer derived from sol-gel process of metal alkoxide was generated on the PEDOT thin film layer by VPP, resulting in improving mechanical properties of the conductive thin films without any deterioration of their original surface resistance. Several kinds of silicone and titanium alkoxide derivatives with various functional groups were used as metal alkoxide sol sources. Among them, PEDOT-metal oxide composite thin film derived tetraethyl orthosilicate showed the best performance in the terms of surface resistance, transmittance, and various physicochemical properties. The effect of metal alkoxide content in washing solution, oxidant content and drying temperature have been investigated in order to optimize the various properties of PEDOT-metal oxide composite thin film.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.343-348
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• 2003

To elucidate the effect of gamma-irradiation on the physicochemical properties of zein films, the molecular and mechanical properties of the films were examined after irradiation at various irradiation doses. Gamma-irradiation of zein solutions caused the disruption of the ordered structure of the zein molecules, as well as degradation, cross-linking, and aggregation of the polypeptide chains based on an SDS-PAGE study. Gamma-irradiation increased the solubility of zein and decreased the viscosity due to cleavage of the polypeptide chains. Protein solubility of the zein films in urea/2-mercaptoethanol also increased with increasing irradiation doses. Alterations of the zein molecules by irradiation decreased water vapor per-meability by 12% and increased the elongation of zein films. However, mean tensile strength of the zein films was decreased by gamma-irradiation treatment. Measurement of Hunter color values indicated that irradiation caused a destructive effect on yellow pigments, resulting in a significant decrease in Hunter b values. The microstructure as observed by scanning electron microscopy showed that irradiated zein film had a smoother and glossier surface than the non-irradiated films.

• Journal of Pharmaceutical Investigation
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• v.40 no.spc
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• pp.9-17
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• 2010

Polymorphism has been recognized to be a critical issue throughout the drug product development process. Most of solid phase drugs have polymorphism, which has generated a great deal of interest and the field has been evolving rapidly. Preferably, thermodynamically most stable form of a drug substance is selected to obtain consistent bioavailability over its shelf life and various storage conditions. Moreover, it has the lowest potential for conversion from one polymorphic form to another. However, metastable or amorphous forms may be used intentionally to induce faster dissolution rate for rapid drug absorption and higher efficacy. For pharmaceutical industry, polymorphism is one of the key activities in form selection process together with salt selection. This article introduces the main features in the investigation of solid form selection especially polymorphic behavior with thermodynamic backgrounds, physicochemical properties with solubility, dissolution, and mechanical properties, and characterization techniques for proper analysis. The final form can be recommended based on the physicochemical and biopharmaceutical properties and by the processability, scalability and safety considerations. Pharmaceutical scientists especially in charge of formulation need to be well aware of the above issues to assure product quality.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.25-28
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• 2001

Polymer blending constitutes a most useful method for the improvement or modification of the physicochemical properties of polymeric materials. Some of the polymer blends exhibit unusual properties, unexpected from homopolymers. An important property of a polymer blend is the miscibility of its component, because it affects the mechanical properties, the morphology, its permeability and degradation [1, 2]. (omitted)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.85-87
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• 2004

Radiation technology is an effective way for regulating polymeric materials to physicochemical and mechanical properties. New polymeric hydrogels based on vinyl ethers have been synthesized by the ${\gamma}$-initiated polymerization method. In this paper, we have studied the effect of radiation on mechanical and electrochemical properties of new rubber-like polymeric composite materials based on poly (vinyl ether of ethyleneglycol: PVEEG).

• Composites Research
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• v.36 no.4
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• pp.264-269
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• 2023

Spent coffee grounds (SCG) are a ubiquitous byproduct of coffee consumption, representing a significant waste management challenge, as well as an untapped resource for economic development and sustainability. Improper disposal of SCG can result in environmental problems such as methane emissions and leachate production. This study aims to investigate the physicochemical properties of SCG and their potential as a reinforcement material in polypropylene (PP) to fabricate an eco-friendly composite via extrusion and injection molding, with SCG filler ratios ranging from 5-20%. To evaluate the effect of SCG on the morphological and mechanical properties of the bio- composite, thermogravimetric analysis, SEM, tensile, flexural, and impact tests were conducted. The results demonstrated that the addition of SCG lead to a slight increase in brittleness of the composite but did not significantly affect its mechanical properties. Impressively, the presence of a significant organic component in SCG contributed to the enhanced thermal performance of PP/SCG composites. This improvement was evident in terms of increased thermal stability, delayed onset of degradation, and higher maximum degradation temperature as compared to pure PP. These findings suggest that SCG has potential as a filler material for PP composites, with the ability to enhance the material's properties without compromising overall performance.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.4
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• pp.567-574
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• 2010

This study was performed to evaluate the physicochemical and quality characteristics of dried noodles when different concentrations of Enteromorpha intenstinalis powder (EIP) were added to the wheat flour, thereby determining which noodle recipe was preferred. The cooking quality, mechanical texture properties, and viscosity of the prepared with noodles were measured, and then a sensory evaluation was conducted on them. The gelatinization points of the composite Enteromorpha intenstinalis powder-wheat flour were shown to have an increased viscosity at $95^{\circ}C$ after 15 minutes. As measured via amylograph, the maximum viscosity values of those samples decreased with increasing EIP content. Also, when increased amounts of EIP were added, both the L and b values were reduced, whereas the a value was increased. The color values, weight and volume of the cooked noodles increased, as did the turbidity of the soup. With regard to the textural characteristics, the EIP additive increased hardness and reduced adhesiveness, cohesiveness and springiness. Overall, according to the results of our sensory evaluations, the noodles prepared with 5% EIP were preferred over other noodles.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.3-6
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• 2003

In this work, poly(ethylene oxide) nanofibers were fabricated by electrospinning to prepare nanofibers-reinforced composites. And the PEO powders-impregnated composites were also prepared to compare with physicochemical properties of nanofibers-reinforced composites. Morphology and fiber diameter of PEO nanofibers were determined by SEM observation. Mechanical interfacial properties of the composites were investigated in fracture toughness tests and interlaminar shear strength (ILSS) test. As a result, the fiber diameter decreased in increasing applied voltage. However the optimum condition for the fiber formation was 15 ㎸, resulting from increasing of jet instability at high voltage and the prepared PEO nanofibers were useful in fiber reinforced composites. The PEO-based nanofibers-reinforced composites showed an improvement of fracture toughness factors ($K_{IC} and G_{ IC}$) and ILSS, compared to the composites impregnated with PEO powders. These results were noted that the nanofibers had higher specific surface area and larger aspect ratio than those of the powder, which played an important role in improving the mechanical interfacial properties of the composites.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.527-533
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• 2011

CNFs had been well addressed due to numerous promising applications in science and technology. Besides the same physicochemical properties of ordinary carbon materials such as active carbons and carbon black, they exhibit specific, e.g., tubular or fibrous structures, a large surface area, high electrical conductivity stability, as well as extremely high mechanical strengh and modulus, which make them a superior material for electrochemical capacitors. In this study, CNFs were pretreated by mechanical milling with different time in mortar and pestle. The milled CNFs were used as active material of electrode whose electrochemical property was tested to find physicochemical characterization variation. CNF electrode milled for 5 min has the highest electric capacitance. XPS spectrum were employed to explore changes in functional group induced from mechanical milling. Crystal size was calculated to analyze change of peak from different milling time by XRD. The CNF milled for 5 min has the largest crystal size and the highest electric capacitance.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.54-61
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• 2013

This paper reports mild steel(SPHC) and stainless steel(STS304) sheets commonly used for railroad cars or commercial vehicles such as in the automobile and shipbuilding industries. The sheets are used in these applications, which are mainly fabricated using the shielded metal arc welding(SMAW) of dissimilar materials. It also reports an interesting application of Laser Induced Breakdown Spectroscopy(LIBS) in order to determine the elemental composition diffusion of SPHC and STS304. Arc blow produced by magnetic force during the electric arc welding prevents the formation from a sound weldment. In particular, the mechanical properties of the joint are influenced by not only by geometrical and mechanical factors but also the welding conditions for the arc welded joint. Therefore, the mechanical properties and performance are evaluated by performing a physicochemical component analysis. And they increase in accordance with content of elements and microstructure in mild steel. As results, appropriate range for magnetic fields could be achieved. Therefore, the effect of magnetic force in a butt weld of mild steel plates was investigated by comparing to the measured data.