• Macromolecular Research
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• v.10 no.5
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• pp.282-285
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• 2002

In this paper, we report a modified technique for the production of oriented continuous nanofibers instead of non-woven mats using a rapidly rotating collection device. We are interested in retaining physical properties such as electrical conductivity of fiber bundles in their axial direction. The experiments were performed using polyethylene oxide (PEO) and its blend with polyaniline (PANI). According to the results, a typical fiber with a uniform diameter of about 100 nanometer was produced. The fibers from the PEO/ CHCl$_3$ solution show high crystallinity and good orientation whereas the fibers from the blend solution of PEO/PANI/m-cresol and CHCl$_3$ show no preferred orientation. However, the fibers of the blend exhibit high electrical conductivity of 33 S/cm for a fiber bundle at a PANI level of 50 %.

• Elastomers and Composites
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• v.28 no.4
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• pp.283-292
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• 1993

The morphology and impact strength of alloys of high density polyethylene(HDPE) and nylon-6(PA) with modified $ethylene-{\alpha}-olefin$ copolymer(OCP) as compatibilizer and impact modifier were measured by the scanning electron microscope(SEM) and the notched Izod impact test(and the high rate impact test), respectively. HDPE is incompatible with PA and specimens obtained from simple mechanical mixing show the inferior properties. However, it was indicated that OCP played roles of not only impact modifier but also compatibilizer. High rate impact test results were different from those of the notched Izod impact test, but in both tests OCP was effective for HDPE/PA blends. From SEM observation, the size of the dispersed phase in alloys prepared with OCP is much smaller than that of alloys without OCP and the interfacial adhesion of alloys prepared with OCP is also better. Toughening mechanism of polymer blends was discussed by combining the morphology analysis with mechanical and thermal properties.

• Food preservation and processing industry
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• v.3 no.1
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• pp.42-46
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• 2004

Quality of fresh-cut tomato slices was compared during cold storage under various modified atmosphere packaging conditions. Chilling injury of slices in containers sealed with Film A was higher than with Film B; these films had oxygen transmission rates of 87.4 and 60.0 ml h-1 m-2 nun-1 at $5^{\circ}C$ and $99\%$ RH, respectively. While slices in containers with an initial atmospheric composition of air, $4\%$ CO2 + 1 or $20\%\;O_2, \;8\%\;CO_2+1$ or $20\%\;O_2$, or $12\%\; CO_2+\;20\%\;O_2$ showed fungal growth, slices in containers with $12\%\;CO_2 +\;1\%\;O_2$ did not. Low ethylene in containers enhanced chilling injury. Modified atmosphere packaging provided good quality tomato slices with a shelf-life of 2 weeks or more at $5^{\circ}C$. Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill. 'Sunbeam') fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at $5^{\circ}C$ under a modified atmosphere. Slices were analyzed for firmness, soluble solids content (SCC), titratable acidity (TA), pH, electrolyte leakage, fungi, yeasts, and chilling injury. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch (Vicia villosa Roth) mulch were firmer than those from tomato fruit grown with black polyethylene mulch after 12 days storage. Ethylene Production of slices from fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from WF and NF fungicide treatments after 12 days, respectively. The percentage of water-soaked areas (chilling injury) for slices from tomato fruit grown.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.61-66
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• 2012

Bismuth(Bi) nanoparticles were synthesized at room temperature by a modified polyol process using bismuth(III) carbonate basic as precursor. In addition, some characteristics of the synthesis with respect to the exchange of a capping agent/surface stabilizer and solvent type were observed. When polyvinylpyrroldone was added, the finest Bi nanoparticles were synthesized in diethylene glycol(DEG), while the coarsest nanoparticles were formed in polyethylene glycol(PEG). The particle size immediately after synthesis was proportionate to final particle size which was determined by particle growth through coalescence and aggregation during drying. As a result, the finest Bi particles with the diameter range of several tens of nanometers - 300 nm were finally obtained in DEG. Regardless of the type of capping agent/surface stabilizer, extensive coalescence and aggregation behavior occurred in PEG, resulting in final products agglomerated with coarse particles.

• Food Science and Preservation
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• v.11 no.4
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• pp.478-484
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• 2004

Freshness maintenance of polyethylene packaging film containing surface-modified zeolite was investigated depending on the nature of substituted cations and cationic surfactants. Freshness maintenance was designed to work by cation or cationic surfactant adsorbed onto the zeolite surface by ion-exchange method. Cationic surfactants such as DODAB (n-dodecyltrimethylammonium bromide), CTAB (n-cetyltrimethylammonium bromide), and DHAB (n-dihexadecyldime-thylammonium bromide), and cations ($Ce^{3+},\;Al^{3+},\;Mg^{2+},\;Ca^{2+},\;Ag^{3+},\;Na^{1+}\;and\;Cu^{3+}$) were used. Surface-modified zeolite powder was compounded with LDPE to produce $20\;wt\%$ zeolite masterbatch (M/B), and the M/B was again blended with LDPE to get zeolite-containing LDPE films with 3, 5, $10\;wt\%$ of zeolite (width: 40 cm, thickness: $40\;{\mu}m$). Mechanical properties of zeolite-containing LDPE films generally decreased with increasing zeolite content. However, cationic surfactant-modified zeolite film showed the better mechanical properties compared to cation-modified zeolite film. As for the freshness maintenance, the zeolite-containing films modified with cationic surfactants or cations ($Al^{3+},\;Ag^{3+}$) showed the best performance.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.5
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• pp.104-105
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• 1999

This study was performend to examine Poisson's ration of polymer-modified asphalt concrete due to temperature variatino . Asphalt binder used in this study was an AC85-100, penetration grade of 85-100, and polymer for modifying asphalt were domestic LDPE(Low-density polyethylene) and SBS(Styrene-butadiene-styrene). Aggregate was a crushed gneiss which was most widely used in the middle part of Korea. Using these materias, asphalt mixture slab(340mm$\times$240mm$\times$80mm) with optimum asphalt content from mix design was made and cut into square pillar (80mm$\times$80mm$\times$160mm). Poisson's ration was measured in various temperture (-15$^{\circ}C$, -1$0^{\circ}C$, -5$^{\circ}C$,$0^{\circ}C$,5$^{\circ}C$,1$0^{\circ}C$ and 2$0^{\circ}C$) under the load of one axis repeated compression mode. Poisson's ration of normal asphalt polymer modified asphalt mixtures in normal temperatures. This indicated that AP mixture was more susceptible to temperature effects. From regression aalysis of experimental results, the difference of Poisson's ration between normal and low temperature showed that polymer modified asphalt mixture were lower than AP mixture except for SBS modified asplat mixture.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.215-222
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• 1994

As a toughness modifier for plastics chlorosulfonated polyethylene(CSM) can be used. CSM has a good resistance to oxygen and ozone. CSM has a crosslinkable functional group(sulfonyl chorid) with sulfur and metal oxide. Polyvinylchloride(PVC) is widely used industrial plastics because of its balanced properties and low cost. But it has some disadvantages such as low impact strength, light, ozone and oxygen degradation. In order to improve these properties of PVC, CSM was blended with PVC. The toughening effect appeared at about 10wt% and there is no additional effect above 30wt% of CSM. The weatherability, ozone resistance and mechanical properties of PVC were improved by blending with CSM. The toughening mechanism is studied by SEM.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.62-67
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• 2012

This study calculated kinetic parameters of Escherichia coli O157:H7 and developed a probabilistic model to estimate growth probabilities of E. coli O157:H7 on polyethylene cutting boards as a function of temperature and time. The surfaces of polyethylene coupons ($3{\times}5$ cm) were inoculated with E. coli O157:H7 NCCP11142 at 4 Log $CFU/cm^2$. The coupons were stored at 13 to $35^{\circ}C$ for 12 h, and cell counts of E. coli O157:H7 were enumerated on McConkey II with sorbitol agar every 2 h. Kinetic parameters (maximum specific growth rate, Log $CFU/cm^2/h$; lag phase duration, h; lower asymptote, Log $CFU/cm^2$; upper asymptote, Log $CFU/cm^2$) were calculated with the modified Gompertz model. Of 56 combinations (temperature${\times}$time), the combinations that had ${\geq}$0.5 Log $CFU/cm^2$ of bacterial growth were designated with the value of 1, and the combinations that had increases of <0.5 Log $CFU/cm^2$ were given the value 0. These growth response data were fitted to the logistic regression to develop the model predicting probabilities of E. coli O157:H7 growth. Specific growth rate and growth data showed that E. coli O157:H7 cells were grown at $28-35^{\circ}C$, but there were no obvious growth of the pathogen below $25^{\circ}C$. Moreover, the developed probabilistic model showed acceptable performance to calculate growth probability of E. coli O157:H7. Therefore, the results should be useful in determining upper limits of working temperature and time, inhibiting E. coli O157:H7 growth on polyethylene cutting board.

• Polymer(Korea)
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• v.36 no.2
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• pp.137-144
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• 2012

The surface of polyethylene (PE) was modified through Ar atmospheric pressure plasma treatment and subsequent grafting of glycidyl methacrylate (GMA). Optimum plasma treatment conditions were determined through analyzing the surface free energies calculated from the contact angles between PE samples and three probe liquids, which were RF-power of 200 W, plasma treatment time of 600 sec, Ar flow rate of 5 LPM, and sample-holder moving speed of 20 mm/sec. To introduce the maximum amount of GMA on PE surface treated under the conditions, graft copolymerization conditions such as GMA concentration, temperature, and time were carefully controlled. Grafting degree (GD) was obtained through weight difference analysis of PE film before and after graft copolymerization. A maximum GD was achieved at the GMA concentration of 20 vol%, the temperature of $80^{\circ}C$, and the treatment time of 4 hr.

• Journal of Pharmaceutical Investigation
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• v.38 no.2
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• pp.127-134
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• 2008

Peroral administration is the most convenient one for the administration of pharmaceutically active compounds. Most of poorly water-soluble drugs administered via the oral route, however, remain poorly available due to their precipitation in the gastrointestinal (GI) tract and low permeability through intestinal mucosa. In this study, one of drug delivery carriers, lipid nanoparticles (LNPs) were designed in order to reduce side effects and improve solubility and stability in GI tract of the poorly water soluble drugs. However, plain LNPs are generally unstable in the GI tract and susceptible to the action of acids, bile salts and enzymes. Accordingly, the surface of LNPs was modified with polyethylene glycol (PEG) for the purpose of improving solubility and GI stability of paclitaxel (PTX) in vitro. PEG-modified LNPs containing PTX was prepared by spontaneous emulsification and solvent evaporation (SESE) method and characterized for mean particle diameter, entrapping efficiency, zeta potential value and in vitro GI stability. Mean particle diameter and zeta potential value of PEG-modified LNP containing PTX showed approximately 86.9 nm and -22.9 mV, respectively. PTX entrapping efficiency was about 70.5% determined by UV/VIS spectrophotometer. Futhermore, change of particle diameter of PTX-loaded PEG-LNPs in simulated GI fluids and bile fluid was evaluated as a criteria of GI stability. Particle diameter of PTX-loaded PEG-LNPs were preserved under 200 nm for 6 hrs in simulated GI fluids and bile fluid at $37^{\circ}C$ when DSPE-mPEG2000 was added to formulation of LNPs above 4 mole ratio. As a result, PEG-modified LNPs improved stability of plain LNPs that would aggregate in simulated GI fluids and bile solution. These results indicate that LNPs modified with biocompatible and nontoxic polymer such as PEG might be useful for enhancement of GI stability of poorly water-soluble drugs and they might affect PTX absorption affirmatively in gastrointestinal mucosa.