• International Journal of Air-Conditioning and Refrigeration
• /
• v.10 no.1
• /
• pp.31-39
• /
• 2002

Microencapsulated pcm (MPCM) particles are mixed with distilled water and utilized to evaluate its characteristics and performance as a thermal storage medium transporting heat. For the present study, tetradecane ($C_14$$H_30$, $T_m$=5.5$^{\circ}C$) is capsulated in the core, coated with the melamine for their surface. The size of particles is well-controlled under 10$\mu$m in the process of in-situ polymerization with melamine-formaldehyde resin. For the experiment, the concentractions of slurries are prepared for 20 wt%, 30 wt%, and 40 wt%. The results are compared with those of water and 100% tetradecane oil. The pure water and tetradecane start solidifying within 20 minutes after introducing cooling water into the thermal storage tank whose flow rates are varied by 125 cc/min, 250 cc/min, and 500 cc/min. However, MPCM slurries are required relatively longer period of time for their phase change than pure phase change materials. That is, the entrained MPCM particles restrict their heat transfer in terms of natural convection and conduction to them.

• Textile Coloration and Finishing
• /
• v.15 no.5
• /
• pp.327-332
• /
• 2003

In this study, the polyurethane microcapsules for non-aqueous dyeing containing iron oxide and disperse dyes were prepared by in-situ polymerization method using hexamethylene diisocyanate(HDI) with ethylene glycol(EG). And the size, shape, and particle size distribution of microcapsules prepared were investigated. The size and shape of microcapsule were observed by optical microscope and scanning elecron microscope. The particle size distribution was analyzed by particle size analyzer. The microcapsule size and its distribution were largely effected by the existance of surface active agent in the system. When a surfactant did not exist in the system, the size distribution of microcapsules prepared was much uneven. By adding a surfactant, this phenomenon was disappeared. And the size of microcapsule was also effeced by the hydrophobicity of core material(disperse dye). It was considered due to the difference of dispersity of core materials. And the size of microcapsule prepared was inversely proportional to the stirring speed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.2
• /
• pp.80-87
• /
• 2001

Microencapsulated PCM particles are mixed with distilled water and utilized to evaluate its characteristics and performance as a thermal storage medium transporting heat. For the present study, tetradecane(C$_14H_30, T_m=5.5^{\circ}C$) is capsulated in the core with the melamine of its surface. The size of particles is well-controlled under 10${\mu}{\textrm}{m}$ in the way of in-situ polymerization with melamine-formaldehyde resin. For the experiment, the concentrations of slurries are prepared for 20wt%, 30wt%, and 40wt%. The results are compared with those of water and 100% tetradecane oil. The pure water and tetradecane start solidifying within 20 minutes after introducing cooling water into the thermal storage tank whose tank whose flow rates are varied by 125cc/min, 250cc/min, and 500cc/min. However, MicroPCM slurries are required relatively longer period of time for their phase change than pure phase change materials. That is, the entrained MicroPCM particles control its heat transfer in terms of natural convection and conducting to them.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.4
• /
• pp.357-363
• /
• 2006

Monolithic molecularly imprinted columns were designed and prepared by an in-situ thermal-initiated copolymerization technique for rapid separation of tryptophan and N- CBZ-phenylalanine enantiomers. The influence of polymerization conditions and separation conditions on the specific molecular recognition ability for enantiomers and diastereomers was investigated. The specious molecular recognition was found to be dependent on the stereo structures and the arrangement of functional groups of the imprinted molecule and the cavities in the molecularly imprinted polymer (MIP). Moreover, hydrogen bonding interactions and hydrophobic interactions played an important role in the retention and separation. Compared to conventional MIP preparation procedures, the present method is very simple, and its macroporous structure has excellent separation properties.

• Carbon letters
• /
• v.13 no.2
• /
• pp.88-93
• /
• 2012

Polypyrrole (PPy)/multi-walled carbon nanotubes (MWCNTs) composites were prepared by in situ polymerization of pyrrole on the surface of MWCNTs templates to improve the ammonia gas sensing properties. PPy morphologies, formed on the surface of MWCNTs, were investigated by field emission scanning electron microscopy. The thermal stabilities of the PPy/MWCNTs composites were improved as the content of MWCNTs increased due to the higher thermal stability of the MWCNTs. PPy/MWCNTs composites showed synergistic effects in improving the ammonia gas sensing properties, attributed to the combination of efficient electron transfer between PPy/MWCNTs composites and ammonia gas, and the reproducible electrical resistance variation on PPy during the gas sensing process.

• Textile Coloration and Finishing
• /
• v.8 no.4
• /
• pp.11-18
• /
• 1996

Natural functional compound in the textile finishing for health and amenity using fragrant material have been applied by microencapsulation method. The microcapsules containing fragrant materials as functional compound were produced by in situ polymerization using urea-formaldehyde prepolymer. The average diameter of microcapsules is 2.75$\mu$ and particle size ranges over 0.5~10$\mu$. Fragment material is extracted approximatly proportioned from microcapsule at room temperature. The adsorption of microcapsule was improved by pretreatment of cationic agent. Fragrant materials in microcapsule was revealed to have long release time.

• KSBB Journal
• /
• v.20 no.3
• /
• pp.133-141
• /
• 2005

This review presents the preparation, transport mechanism and application of molecularly imprinted membranes (MIM). Molecular imprinting has now been established as a technique which allows the creation of tailor-made binding sites for many classes of compounds. MIM have some advantages; a high capacity due to a large surface area, faster transport of substrate molecules and faster equilibrium of binding cavities compared to molecularly imprinted particles. MIM were prepared by covalent and non-covalent chemical bonding systems, by interactions between functional monomer and template. MIM can be prepared by in-situ polymerization, wet phase inversion, dry phase inversion, and surface imprinting method. MIM can continuously separate mixtures based on facilitated or retarded diffusion of the template. MIM can change their permeability in the presence of templates. MIM have a potential to be used to separate chiral compounds and materials with similar structures. However the application of MIM by the chemical industries is still in its infancy stages.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.5
• /
• pp.1097-1100
• /
• 2009

New types of conducting polyaniline-polymannuronate (PANI-PM) composites were synthesized by in situ deposition techniques in an aqueous media. By dissolving different weight percentage of polymannuronate (PM) (5, 10, 15, and 25%), the oxidative polymerization of aniline was carried out using ammonium per sulfate as an oxidant. The obtained composites were studied for their thermal stability and electrochemical behavior. The thermal stability of PANI-PM composites is lower than PANI, which supports a strong interaction between PANI and PM. However, the composites show an appreciable electrochemical behavior. Based on these observation the PANI-PM composites can be explored in different fields such as electric devices, sensors, functional coatings, etc.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.8
• /
• pp.707-712
• /
• 1996

Growth and changes of electronically conducting polypyrrole (PPy) in the form of thin films polymerized on metal electrodes were investigated by electrochemical and in situ three-parameter ellipsometry methods at the wavelength of 632.8 nm. Although the optical equations produced multiple sets of solution, it was possible to determine a unique set of thickness and the optical constants of a film by auxiliary measurements and/or physical reasoning. The changes in the thickness and the optical properties of the polymers during polymerization and electrochemical oxidation/reduction was successfully followed by the three-parameter ellipsometric technique. The optical properties of the polymers continuously changed as the film grew. The imaginary part of the refractive index of polypyrrole seemed to be dominantly determined by the existence of an absorption band around the visible range.

• Textile Coloration and Finishing
• /
• v.10 no.2
• /
• pp.37-44
• /
• 1998

In this study, the polyurethane microcapsules containing disperse dye were prepared by in-situ polymerization method using hexamethylene diisocyanate (HDI, aliphatic type) and m-xylene diisocyanate(XDI, aromatic type) with ethylene glycol (EG) And the size, shape, particle size distribution, and breaking behavior of microcapsules prepared were investigated. The size and shape of microcapsule were observed by scanning electron microscope (SEM) . The particle size distribution was analyzed by image analyzer. The breaking behavior of microcapsule was checked by measuring the optical density of solution that the disperse dye was dissolved after the microcapsule was broken by constant pressure. The particle size was inversely proportional to the stirring speed, and the size of microcapsule prepared from HDI and EG was smaller than that of microcapsule prepared from XDI and EG. Aliphatic type microcapsule was broken easily, compared with aromatic type one. It was considered due to the difference of reactivity between HDI and XDI. And the microcapsule prepared by stirring strongly was broken easily.