• Polymer(Korea)
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• v.33 no.4
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• pp.284-289
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• 2009

The morphology and mechanical properties of epoxy/polyamide/MPD reactive blends with various amount of polyamide were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of high soluble polyamide in epoxy ranged from 0 to 30 phr, and the cure reaction occurred at $170^{\circ}$ for 30 min. The start and maximum exothermic temperature in heat flows during cure reactions appeared at almost same temperature, indicating that soluble polyamide could rarely hinder the cure reactions. From the SEM images, it was found that the size of separated-phase was very fine about 100-300 nm, and at 20 phr of polyamide the boundary of separated-phase was unclear and the phase revealed co-continuous. By AP plasma treatment of specimen surface, the adhesion strength was increased by 20% due to enhanced surface free energy. By blending 20 phr of polyamide with epoxy, the adhesion strength was increased by 50% due to co-continuous phase in morphology. By considering the surface treatment of specimen and morphological tuning of the blends, it can be expected that the improvement in toughness and excellent adhesion strength can be achieved in structural adhesive systems.

• Polymer(Korea)
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• v.32 no.3
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• pp.246-250
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• 2008

Colloidal stability of the biodegradable nanoparticle was characterized by measuring the variation of particle size with time using photon correlation spectroscopy. Three kinds of polymers, namely, poly(D,L-lactide-co-glycolide)(PLGA), PLGA/poly(L-lactide) blends, and PLGA/poly(L-lactide)-g-poly(ethylene glycol) blends were used as matrix material for nanoparticle preparation. Nanoparticles were prepared with or without using poly(vinyl alcohol)(PVA) as suspension stabilizer to evaluate the condition of preparation. Nanoparticles from the blend of amphiphilic graft copolymer with short poly(ethylene glycol) chain and PLGA maintained suspension for 1 day when protein stock solution was introduced. This is somewhat improvement in colloidal stability against protein adsorption compared with that of nanoparticles without PEG moiety. Suspension stabilizer, PVA, had a significant effect on the colloidal stability against freezing and protein adsorption which led to coagulation of nanoparticles. It is important to consider effect of suspension stabilizer as well as materials used to prepare nanoparticle on the colloidal stability.

• Polymer(Korea)
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• v.37 no.4
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• pp.420-430
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• 2013

Polymer blends were prepared by solution blending poly(amic acid) (PAA) and poly(o-hydroxy amide) (PHA) having imide groups in the main chain. The polymers and their blends were characterized by using FTIR, FT NMR, DSC, TGA, SEM, XRD, UTM, and LOI. The solubility study revealed that the blends were readily soluble in aprotic solvents such as DMF, DMAc, DMSO, and NMP. The maximum weight loss of the blends occurred in the range of $578-645^{\circ}C$, and the maximum weight loss temperature increased with increasing the PHA content. The PBO/PI blends showed relatively high char yields (i.e. 56-69 wt%). The LOI values of the blends were in the range of 24.5-28.1% and increased with increasing the PHA content. The initial modulus and tensile strength of the blends increased by 57 to 121% and by 67 to 107%, respectively, compared to the values of PAA. Especially the initial modulus and tensile strength of the PHA/PAA=2/8(wt/wt) showed the highest values of 4.87 GPa and 108 MPa, respectively. The PHA domains of $0.03-0.1{\mu}m$ in their size were more or less uniformly dispersed. The interfacial adhesion between PAA and PHA was found to be good.

• Korean Journal of Food Science and Technology
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• v.7 no.4
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• pp.187-193
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• 1975

A supplemental effect of Undaria Pinnatifida extract on the composite flour prepared from a blend of wheat, barley, sweet potato, potato, and defatted soybean flours was studied in terms of binding properties, cooking test, and sensory analysis. Dry noodle of the composite flour was made by the conventional method and air dried. Instant noodle was prepared in a hot vegetable oil bath after the noodle was made. The standard was made of wheat flour only. 1. The noodle prepared with composite flour (wheat flour : barley flour, 5 : 5) and Undaria Pinnatifida extract (1 or 2%) showed same results of cooking and sensory tests as well as properties of texture as the standard. 2. The mixture of wheat, barley and defatted soybean flour (10%) had a less efficient binding capacity with Undaria Pinnatifida extract. The binding effect was, however, significantly improved with the wheat and barley flour mixture with either sweet potato or potato flour. 3. The instant noodle prepared with the composite flour (either barley, or sweet potato, or potato was mixed with wheat flour up to 70% separately) and hydroxypropyl methyl cellulose (1% as final) showed the higher oil absorption and the sensory results were the same as the standard. Nevertheless, the binding properties and cooking quality were less efficient.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.13-20
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• 2007

Leachates resulting from the waste landfill of waste can possibly cause the second pollution, such as the underground water and environmental pollution. Accordingly, Liner layer has been installed in the reclaimed land of waste to block and purify permeation water to and prevent this second pollution. The material used as Liner layer should have water resistance and be less than permeability coefficient of $1{\times}10^{-7}$ cm/sec. As it is very difficult to get this kind of natural clay with low permeability around the field, the suitable way to get the low permeable material is to use blend with good watertighness by mixing it with natural soil which is spread in the site. While this mixed soil, which can resist water, is commonly used in the site, namely, bentonite and MCG cementious mateiral mixed soil, which is widely used as Liner layer in the reclaimed land of waste, is recognized in Liner and durability. The study was performed to find the effect of additive of the bottom liner in the waste landfill. The aim of this paper is to explain of the field application examples as well as the data of experimental research with the engineering properties of Liner layer of the reclaimed land.

• Journal of Pharmaceutical Investigation
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• v.34 no.2
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• pp.147-153
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• 2004

The purpose of the present study was to evaluate the bioequivalence of two glimepiride tablets, $Amaryl^{\circledR}$ (Handok/Aventis Pharm. Co., Ltd.) and Glimed (Kuhn II Pharm. Co., Ltd.), according to the guidelines of Korea Food and Drug Administration (KFDA). The glimepiride release from the two glimepiride formulations in vitro was tested using KP VIII Apparatus II method with a variety of dissolution media (pH 1.2, 4.0, 6.8 buffer solution, water and blend of PSB 80 into each dissolution medium). Twenty six healthy male subjects, $22.65{\pm}2.19$ years in age and $66.55{\pm}8.85$ kg in body weight, were divided into two groups and a randomized $2\;{\times}\;2$ cross-over study was employed. After one tablet containing 2 mg as glimepiride was orally administered, blood was taken at predetermined time intervals and the concentrations of glimepiride in serum were determined using HPLC method with UV detector. The dissolution profiles of two formulations were similar at all dissolution media. Besides, the pharmacokinetic parameters such as $AUC_t$, $C_{max}$ and $T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters using logarithmically transformed $AUC_t$, $C_{max}$ and untransformed $T_{max}$. The results showed that the differences between two formulations based on the Amaryl were -3.70, -8.28 and 0.61% for $AUC_t$, $C_{max}$ and $T_{max}$, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance range of log(0.8) to log(1.25) (e.g., $log(0.84){\sim}log(1.04)$ for $log(0.82){\sim}log(1.03)$ for $AUC_t$ and $C_{max}$, respectively). Thus, the criteria of the KFDA guideline for the bioequivalence were satisfied, indicating Glimed tablet and Amaryl tablet were bioequivalent.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.539-544
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• 1998

A study was conducted to investigate the effects of Poria cocos powder on dough rheology and wet noodle quality. Poria cocos powder had considerably lower content of crude protein, crude fat and crude ash than those of wheat flour. Poria cocos powder had also much bigger particle size $(74.62\;{\mu}m)$ and larger surface area $(3884.13\;cm^2/g)$ than those of wheat flour. The peak, final viscosities and setback in amylograph increased with the increase of Poria cocos powder concentration. The water absorption and dough stability in farinograph increased with the increase of Poria cocos powder concentration. With the increase of Poria cocos powder, the L values decreased in wheat flour-Poria cocos powder blend and dough, but increased in wet noodles. The cooked weight and volume of cooked noodles decreased, but the turbidity of soup increased with the increase of Poria cocos powder concentration. The hardness, cohesiveness, chewiness and springiness of cooked noodles had the biggest values at 3% addition of Poria cocos powder, but the values decreased above that concentration. The sensory evaluation of cooked noodles showed that the wet noodles with high quality could be produced by $5{\sim}7%$ addition of Poria cocos powder.

• Polymer(Korea)
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• v.28 no.5
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• pp.404-411
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• 2004

The microcapsules containing triphenyl phosphate (TPP), a flame retardant, were prepared by phase-inversion emulsification technique using the epoxy resin (Novolac type) with excellent physical properties and network structure. This microencapsulation process was adopted for the protection of TPP evaporation and wetting of polymer composite during the polymer blend processing. The TPP, epoxy resin and mixed surfactants were emulsified to oil in water (O/W) by the phase inversion technology and then conducted on the crosslinking of epoxy resin by in-situ polymerization. The capsule size and size distribution of TPP capsules was controlled by mixed surfactant ratio, concentration and TPP contents, The formation and thermal property of TPP capsules were measured by differential scanning calorimetry and thermogravimetric analysis. The morphology and size of TPP capsules were also investigated by scanning and transmission electron microscopies. As the surfactant concentration increased, the TPP capsules were more spherical and mono-dispersed at the same weight ratio of mixed surfactants (F127: SDBS).

• Polymer(Korea)
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• v.24 no.3
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• pp.314-325
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• 2000

Thermal degradation of thermoplasitc polyurethane modified polycarbonate has been investigated by means of DSC, GPC and FT-IR techniques. The polyurethanes used in this study are TPU-35 and TPU-53 containing 35.5 and 53.4 wt% of hard segments, respectively. The more content of hard segment, the higher the glass transition temperature (T$_{g}$) of TPU was observed. On the other hand, the T$_{g}$ of the TPU modified PC decreased with the content of TPU and the annealing temperature regardless of the hard segment contents. The latter behavior nay arise from the thermal degradation of TPU upon annealing process: the observed thermal degradation temperatures were at 240 and 25$0^{\circ}C$ for the PC/TPU-35 and PC/TPU-53, respectively. The molecular weight, molecular weight distribution and viscosity agree well with the DSC measurement, which implicates a thermal degradation of TPU. In addition, thermal stability of the TPU modified PC linearly decreased with an incorporation of TPU. Transesterification or any interaction was not observed using FT-IR: the evidence was no frequency shift or any variance betwere the carbonyl stretching and NH group. For the specimens prepared below the degradation temperature, the enhancement of the thickness dependent impact strength of the PC/TPU blend was observed, and the morphology of the two blends was compared.d.

• Polymer(Korea)
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• v.37 no.6
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• pp.744-752
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• 2013

The miscibility between poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was investigated using thermal analyses for the purpose of developing birefringence-free material at oriented state. The effect of methyl acrylate (MA) units as comonomer of PMMA on the miscibility was also studied. All the blends prepared in this study show composition-dependent single $T_g$'s between those of blend components and high transparency over the visible region, indicating the miscibility at molecular level and no discernible effect of MA units on it. No phase separation was observed at elevated temperature of $280^{\circ}C$, higher than the degradation of PLLA and PMMA. The interaction energy density in PLLA/PMMA blends with 17 mol% of MA was measured to be $-0.74J/cm^3$ from the equilibrium melting temperature depression based on the Hoffman-Weeks method. The blends show zero-${\Delta}$n behavior at a specific mixing ratio and the drawing ratio of 3 due to compensation of intrinsic orientation birefringence. Birefringence dispersion of PLLA/PMMA5 blends was also measured to examine the possibility for quarter-wave plates or polarizer protective films.