• Membrane Journal
• /
• v.9 no.2
• /
• pp.114-125
• /
• 1999

Dense polymer membranes were made from vanous silicone polymers such as poly(1-trimethylsilyl-1-propyneHPTMSP), poly(dimethylsiloxaneHPDMS), PTMSP- g-PDMS. These membranes were evaluated in terms of the removal of chlorinated organic hydrocarbons such as chloroform, trichloroethylene(TCE), perchloroethylene(PCE) from water by pervaporation. It was possible for membranes used in this study to remove PCE selectively which is dissolved small quantity in water among other separable solutes. PTMSP membranes exhibited a remarkable decay in permeability with time because of the free volume decreases. However, PTMSP-g-PDMS membrane underwent no physical aging and showed the stable flux behavior. From the results of the contact angle measurement, polymeric membranes used in this study showed affinity with solutes for separation and no affinity with water. The relative swelling degree was directly related to the selectivity, while it has no influence on the flux.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.233-237
• /
• 1991

In the study, samples were made on the electrode in internal glass bell jar by the radio frequency discharge polymerization. The polymerization rate of samples was observed as a function of r.f. discharge power. The characteristics of polymers obtained from TMDSO and HMDSO were analyzed by FT-IR and TGA, and their electrical properties were examined on insulation resistivity, breakdown voltage, dielectric constant, and tan ${\delta}$. (1) There was no difference between PPTMDSO and PPHMDSO in a polymerization rate and thermal and electrical properties. (2) The growing rates of thin film with discharge powers were from $0.42{\mu}/h$ to $1.2{\mu}m/h$. (3) According to IR spectra analysis, discharge power did not effect polymer structure due to polyermization mechanism and effected only polymerization rate. (4) PPTMDSO and PPHMDSO were thermally resistive polymers which did not decompose to $300^{\circ}C$.

• Journal of the Korean Chemical Society
• /
• v.39 no.1
• /
• pp.76-80
• /
• 1995

Polydimethylsiloxane(PDMS)-co-poly(2-hydroxyethyl methacrylate)(PHEMA) was prepared and the degree of swelling of solvents into the polymers was examined. It was confirmed that the solubility parameter of PHEMA homopolymer is 26 (J/cm3)1/2. Ethanol was significantly absorbed into copolymers containing large amount of PHEMA, while tetrahydrofuran was effectively absorbed into copolymers containing large amount of PDMS. Absorption of polar solvents into the copolymers were increased with the increase of PDMS content. The model drug, crystal violet (CV), was more absorbable into PDMS-HPEMA copolymers than PHEMA homopolymer. Absorption of CV was decreased with the increase of PDMS content of the copolymers.

• Fibers and Polymers
• /
• v.4 no.4
• /
• pp.210-214
• /
• 2003

Siloxylated polypropylene fibers composed of polypropylene (PP) and aluminosiloxane (AS) were prepared by melt blending followed by spinning. The effects of blend compositions on the thermal behaviors, surface and tensile properties of PP/AS blend fibers were investigated by DSC, WAXD, SEM, static honestometer, etc. The heat of fusion of PP/AS blends decreased with increasing AS contents. In addition, the peak intensity of PP/AS blends in X-ray diffraction patterns decreased with increasing AS contents. It was observed that the silicone molecules exist and well distribute on the surface of siloxylated polypropylene fibers. From the results of the half-life period measurements, the anti-static properties of PP fibers siloxylated with AS was found to be significantly modified.

• Macromolecular Research
• /
• v.9 no.4
• /
• pp.197-205
• /
• 2001

Platelet adhesion onto elastic polymeric biomaterials was tested in vitro by perfusing human whole blood at a shear rate of 100 sec$\^$-1/ for possible verification of mechanisms of initial platelet adhesion perfusion of blood on the polymeric substrates was performed after treatments either with or without pre-adsorption of 1% blood plasma, and either with or without residence of the protein-preadsorbed substrate in phosphate buffered solution. The surfaces employed were elastic polymers such as poly(ether urethane urea), poly(ether urethane), silicone urethane copolymer, silicone rubber and poly(ether urethane) with the anti-calcifying agent hydroxyethane bisphosphate. Each polymer surface treated was exposed in vitro to the dynamic, heparinized whole blood perfused for upto 6 min and the surface area of platelets initially adhered was measured by employing in situ epifluorescence video microscopy. The blood perfusion was performed on the surfaces treated at the following three different conditions: directly on the bare surfaces, after protein pre-adsorption and after residence in buffer for 3 days of the surfaces protein pre-adsorbed for 2 h. The effects of blood plasma pre-adsorption on the initial platelet adhesion was surface-dependent. The amount of the adsorbed fibrinogen and the surface coverage area of the adhered platelets were dependent on the surface conditions whether substrates were bare surfaces or protein pre-adsorbed ones. To test an effect of possible morphological (re)orientations of the adsorbed proteins on the initial platelet adhesion, the polymeric substrate pre-adsorbed with 1% blood plasma was immersed in phosphate buffered solution for 3 days and then exposed to physiological blood perfusion. The surface area of the platelets adhered on these surfaces was significantly different from that of the surfaces treated with protein pre-adsorption only. These results indicated that platelet adhesion was dependent on the surface property itself and pre-treatment conditions such as blood perfusion without any pre-adsorption of proteins, and blood perfusion either after protein pre-adsorption or after subsequent substrate residence in buffer of the substrate pre-adsorbed with proteins. Understanding of these results may guide for better designs of blood-contacting materials based on protein behaviors.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.26 no.3
• /
• pp.262-272
• /
• 2023

A polymer-based mechanical low-pass filter(m-LPF) for high-g accelerometers makes it possible to remove high-frequency transient noises from acceleration signals, thus ensuring repeatable and reliable measurement on high-g acceleration. We establish a prediction model for performance of m-LPF by combining a fundamental vibration model with the fractional derivative standard linear solid(FD SLS) model describing the storage modulus and loss modulus of polymers. Here, the FD SLS model is modified to consider the effect of m-LPF shape factor (i.e., thickness) on storage modulus and loss modulus. The prediction accuracy is verified by comparing the displacement transmissibility(or cut-off frequency) estimated using our model with that measured from 3 kinds of polymers(polysulfide rubber(PSR), silicone rubber(SR), and polydimethylsiloxane(PDMS)). Our findings will contribute a significant growth of m-LPF for high-g accelerometers.

• Elastomers and Composites
• /
• v.44 no.1
• /
• pp.76-83
• /
• 2009

The purpose of this study was to investigate the effects of combined use of several types of silicone polymers on the physical properties of the dental polyvinylsiloxane impression materials (PVS). Four types of silicone prepolymers having different molecular weight and vinyl group position, and two types of cross-linkers having differently located silyl hydride functional groups were used in various combinations for the formulation. The samples containing bimodal or trimodal prepolymers showed higher tensile strength, elongation at break, and elastic deformation than those containing only one type of prepolymer. The samples using CR210 cross-linker which has side- and terminal-silyl hydride groups showed higher elastic deformation and elongation at break than those using CR101 cross-liker which has side-only silyl hydride group. High vinyl content prepolymer having side vinyl group delayed setting even though it enhanced tensile strength. Further studies are needed to clarify the specific role of this component on setting time and to find appropriate controlling methods for making improved PVS with optimum workability.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.5
• /
• pp.489-495
• /
• 2009

A novel technique to measuret of viscoelastic properties of polymers is proposed to investigate complex Poisson's ratio as a function of frequency. The forced vibration responses for the samples under the normal and the shear deformation are to be measured with varying load masses. The measured data were used to obtain the viscoelastic properties of the material based on an accurate 2D numerical deformation model of the sample. The 2D model enabled us to exclude data correction by the empirical form factor used in 1D model. Comprehensive measurements of viscoelastic properties of two slightly varied silicone RTV rubber ($Silastic^{(R)}$ S2) compositions were performed. Standard composition (90% PDMS polymer + 10% catalyst) and modified composition (92.5% polymer + 7.5% catalyst) were tested in temperature range from $30^{\circ}C$ to $70^{\circ}C$. Shear modulus, modulus of elasticity, loss factor, and both the real and the imaginary parts of the Poisson's ratio were determined for frequencies from 50 to 400Hz in the linear deformation regime (at relative deformations $10^{-4}{\sim}10^{-3}$).

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.36 no.2
• /
• pp.93-97
• /
• 2010

In this study, cationic guar polymer was selected from many cationic polymers currently using in shampoo and then was newly developed having 0.7 % above of nitrogen content and 190~200 cps of viscosity through various performance measurements. Wet combing ability, polymer substantivity, silicone deposition and panel test were evaluated for performance measurements. Cationic guar polymer that was invented from this study can optimize conditioning effects in shampoo.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1999.07a
• /
• pp.27-30
• /
• 1999

Poly(phenylene oxide)s were used to prepare flat, integrally skinned self-supporthed asymmetric membranes by dry-wet phase separption. The intrinsic ideal gas selectivity of poly- (2,6-dimethy-1,4-phenylene oxide) (PMPO) was retained in the membranes, and improved by a coating with silicone rubber. Polymers of the same class were coated of UF supports with a silicon rubber gutter layer, yielding composite membranes with high flux but lower selectivity. The effect of th glutaraldehyde cross-linking of sodium alginate (SA) membranes on the mobility of water and ethanol has been studied with pfg nmr. Crosslinking reduces water self-diffusion, and does not seem to be stable on the timescale of weeks.