• Textile Coloration and Finishing
• /
• v.15 no.5
• /
• pp.321-326
• /
• 2003

In order for disperse dye based ink to be fitted with the critical requirements of ink jet printing, this study was undertaken to investigate the effects of 6 different dispersants on the milling efficiency of insoluble dye particles and dispersion stability of the final ink. It was found that a polystyrene dispersant with high molecular weight exerted relatively better dispersion stability which may be associated with its steric stabilization effect in the ink solution.

• Journal of the Korean institute of surface engineering
• /
• v.25 no.4
• /
• pp.165-172
• /
• 1992

Filler, popularly used in the polymer materials, was dispersed randomly and irregularly. For the study of dispersed behavior, the specimen which have two particles in polystyrene was prepared. And the tensile strength, modulus and SEM picture were measured. When the distance between particles increased, the tensile strength and modulus increased, but particle size did not affect the values. And when the am-bient temperature increased, the tensile strength and modulus decreased, but the distance did not affect the tensile strength and modulus.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2002.11a
• /
• pp.68-69
• /
• 2002

대기 중에 존재하는 에어로졸 입자의 특성을 이해하기 위해서는 입자의 크기뿐만 아니라 질량 밀도에 대한 정보를 아는 것이 매우 유용하다. 본 연구에서는 광산란과 동시에 입자의 동력학적 속도를 측정함으로써 밀도에 대한 정보도 동시에 알 수 있는 측정방법에 대하여 연구하였다. 이를 위하여 크기가 0.5$\mu\textrm{m}$-3.15$\mu\textrm{m}$이고 굴절률이 1.59이며, 질량 밀도가 1.05g/mL인 구형의 PSL(polystyrene Latex) 표준입자를 사용하여 광산란 및 동력학적 속도를 측정하였다. (중략)

• Journal of the Korean Graphic Arts Communication Society
• /
• v.20 no.1
• /
• pp.65-78
• /
• 2002

The suspension polymerization of styrene was carried out to obtain the narrow-size distribution of particle by using poly(vinyl alcohol) (PVA) as suspension stabilizer according to the degree of hydrolysis and the molecular weight. The stabilizing properties of suspension are also dependent on the interfacial tension of aqueous solution when PVA is added. When the polymerization process was carried out with low hydrolyzed PVA, it gave single, well-defined particles, while high hydrolyzed PVA gave clusters. The size of particle produced in this study ranged between 5${\mu}{\textrm}{m}$ and 10${\mu}{\textrm}{m}$. The suspending agent, PVA, influences on the drop size and drop stability, When the molecular weight of PVA is increased, the drop size decreases and the drops become more stable toward coalescence. An increase in the PVA concentration decreases the mean drop size and narrows the drop size distribution.

• Macromolecular Research
• /
• v.15 no.5
• /
• pp.403-411
• /
• 2007

Monodisperse micron-sized polystyrene (PS) spheres were successfully obtained using a single stage soap-free emulsion method in aqueous media mixed with ethanol (co-solvent) containing NaCI as the electrolyte. The optimum conditions for preparing the monodisperse PS microspheres, using soap-free emulsion polymerization in a water/ethanol mixture with an electrolyte, were studied. The presence of the co-solvent and electrolyte controlled the particle dispersion stability during the polymerization. The microspheres formed using PS, with a weight-average diameter of $2.6{\mu}m$, coefficient of variation of 5.3% and zeta potential of -15.1 eV, were successfully obtained in the presence of 0.1 wt% NaCI, 10 wt% monomer, 0.1 wt% initiator and 95/5 (g/g) of a water/ethanol mixture reacted at $70^{\circ}C$ for 24 h.

• Bulletin of the Korean Chemical Society
• /
• v.8 no.5
• /
• pp.403-405
• /
• 1987

A dynamic laser light scattering system has been constructed using a personal computer. The intensity of the scattered light was detected with a photomultiplier tube and a photon counter. The BCD output of the photon counter which is proportional to the intensity of scattered light is fed into a personal computer via an interface card. The personal computer was programmed as an autocorrelator in machine language. The data acquisition rate of the system was about 600 samples/s which is adequate for studies on the molecular dynamics of concentrated polymer solutions, polymer latices with large particle size, and polymer glass systems. The constructed system was tested with polystyrene latex and the measured diameter of the latex particle agrees well with the supplier's value.

• Journal of Adhesion and Interface
• /
• v.4 no.1
• /
• pp.35-42
• /
• 2003

Polystyrene nanocapsules containing octadecane as a core material were prepared by miniemulsion polymerization. The morphology and size of the nanocapsules were measured with varying the surfactant concentration, content of initiator, core/shell ratio and content of comonomer. The morphologies of the prepared nanoparticles were examined by a scanning electron microscope, a transmission electron microscope and the core material was confirmed by a differential scanning calorimeter. The particles below 70 nm in diameter were formed at a high surfactant concentration. The size of the nanoparticles was not significantly affected by the initiator content. With increasing the core/shell ratio and polar comonomer content, the particle size and its distribution were increased.

• Journal of Sensor Science and Technology
• /
• v.20 no.5
• /
• pp.357-362
• /
• 2011

This paper demonstrates a novel electrodynamic technique to remove particles from the wall of microchannels. Dielectrohporesis(DEP) is generated by applying alternating electric potentials to the interdigitated electrodes integrated at the bottom of the micro-channel. The proposed technique is applied to a general microfluidic channel as a feasibility test. To examine the wall loss reduction efficiency, 10 ${\mu}m$ diameter Polystyrene latexes(PSL) were supplied to the inlet of the device. Then, the concentration of collected particles through devices was measured. In the experiment for 10 ${\mu}m$ diameter PSL particles, the concentration of the injected particles was $174.25{\times}10^4$ particles/ml. However, the concentration of collected particles at the outlet was $52.25{\times}10^4$ particles/ml. Only 30 % of particles had arrived at the outlet and 70 % of particles had adhered to the wall of the microfluidic channel. By applying alternating electric potentials from 0 to 20 $V_{pp}$ at 3 MHz, the concentration of injected particles was 135.00${\times}10^4$ particles/ml, the concentration of collected particles was increased as $105.25{\times}10^4$ particles/ml at 20 $V_{pp}$ at the outlet. When the electric potential was 20 $V_{pp}$, the particle loss was decreased by 39 % (initial loss: 70 %, loss at 20 Vpp: 31 %) with 10 ${\mu}m$ particle. The particle loss was decreased along to the incensement of electric potentials and the enlargement of the diameter of particles. According to these measured results, it was confirmed that the proposal of using DEP technique could be a good candidate for particle loss reduction in micro-particle processing chip application. Moreover, it is expected that the proposed technique could enhance performance of microfluidic and biochip devices.

• Journal of Adhesion and Interface
• /
• v.13 no.3
• /
• pp.109-115
• /
• 2012

Monodisperse blue-colored poly(styrene-co-acrylic acid) latices were successfully prepared by seeded emulsion polymerization. Blue-colored latices with carboxyl anionic charge on the surface were synthesized at the second stage with the introduction of Blue 606 dye, acrylic acid, and 0.21 ${\mu}m$-polystyrene seed. All the blue-colored latices synthesized in this study were in the size range of 0.25~0.42 ${\mu}m$ and all uniform with less than 1.01 in PSD. The particle size increased with the addition of acrylic acid being delayed and colloidally stable latices were obtained over 30 min after its addition. The blue-colored latex with 20 wt% acrylic acid showed -145 mV of zeta-potential and $-9.4{\times}10^{-6}\;cm^2/Vs$ of electrophoretic mobility, and with 25 wt% of DVB showed high $T_g$ at 396.7 K.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.281-281
• /
• 2010

Very low refractive index (<1.4) materials have been proved to be the key factor improving the performance of various optical components, such as reflectors, filters, photonic crystals, LEDs, and solar cell. Highly porous SiO2 are logically designed for ultralow refractive index materials because of the direct relation between porosity and index of refraction. Among them, ordered macroporous SiO2 is of potential material since their theoretically low refractive index ~1.10. However, in the conventional synthesis of ordered macroporous SiO2, the time required for the crystallization of organic nanoparticles, such as polystyrene (PS), from colloidal solution into well ordered template is typical long (several days for 1 cm substrate) due to the low interaction between particles and particle - substrate. In this study, polystyrene - polyacrylic acid (PS-AA) nanoparticles synthesized by miniemulsion polymerization method have hydrophilic polyacrylic acid tails on the surface of particles which increase the interaction between particle and with substrate giving rise to the formation of PS-AA film by simply spin - coating method. Less ordered with controlled thickness films of PS-AA on silicon wafer were successfully fabricated by changing the spinning speed or concentration of colloidal solution, as confirmed by FE-SEM. Based on these template films, a series of macroporous SiO2 films whose thicknesses varied from 300nm to ~1000nm were fabricated either by conventional sol - gel infiltration or gas phase deposition followed by thermal removal of organic template. Formations of SiO2 films consist of interconnected air balls with size ~100 nm were confirmed by FE-SEM and TEM. These highly porous SiO2 show very low refractive indices (<1.18) over a wide range of wavelength (from 200 to 1000nm) as shown by SE measurement. Refraction indices of SiO2 films at 633nm reported here are of ~1.10 which, to our best knowledge, are among the lowest values having been announced.