• Membrane Journal
• /
• v.28 no.4
• /
• pp.265-270
• /
• 2018

In previous studies, a poly(ethylene oxide)(PEO)/Ag nanoparicles (AgNPs)(precursor $AgBF_4$)/p-benzoquinone (p-BQ) composite membrane was prepared for olefin/paraffin separation and the performance of this composite membrane was maintained at a selectivity of 10 and a permeability of 15 GPU. However, since the price of $AgBF_4$ precursor is high, this study used $AgNO_3$ as a precursor of Ag nanoparticles which is competitive in terms of price. As a result, it was observed that the separation performance was not obtained because the existing $NO_3{^-}$ could surround AgNPs. In this study, we fabricated PEO, poly(vinyl alcohol)(PVA), and polyether block amide-1657 (PEBAX-1657) polymer composite membrane using electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) for separation performance even when $AgNO_3$ was used as a precursor of Ag nanoparticles. As a result, it was analyzed that the performance was not observed regardless of the influence of the polymer and the electron acceptor, indicating that the anion of the precursor plays a crucial role in the separation performance.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.4
• /
• pp.461-469
• /
• 2013

This research is performed to investigate the changes in the physicochemical properties and microbial growths of seasoned anchovies with various packaging materials (PET/CPP : polyethylene terephthalate/cast polypropylene, PET/EVOH : polyethylene terephthalate/ethylene-vinyl alcohol, PET/AL/LDPE: polyethylene terephthalate/aluminum/low density polyethylene), which are stored at various temperatures (25, 35, $45^{\circ}C$) for 60 days. Generally, it is being observed that changes in physicochemical properties (i.e., moisture content, color, brown intensity, TBA value, TMA, VBN etc) of seasoned anchovies are significant when stored at higher temperatures. Particularly, the packaging materials are found to influence substantially on the physicochemical properties of seasoned anchovies. With packaging materials of high oxygen transmission rates and moisture vapor transmission rates (i.e., PET/CPP), the changes in physicochemical properties of seasoned anchovies are significant, while being low with low oxygen transmission rates and low moisture vapor transmission rates (i.e., PET/EVOH). In addition, results of microbial growths in seasoned anchovies show that significant increases in total aerobic bacteria counts (about 100-fold after 60 day of storage) are observed in samples with packaging materials of high oxygen transmission rates and moisture vapor transmission rates (i.e, PET/CPP), while with only small increases for samples of low oxygen transmission rates and low moisture vapor transmission rates (i.e., PET/EVOH). Based on the changes in the physicochemical properties and results of microbial growths, it is being concluded that PET/EVOH film is suitable for the packaging of seasoned anchovies.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.6
• /
• pp.827-832
• /
• 2013

An attempt is made to predict the shelf life of seasoned anchovies packaged with laminated film, composed of polyethylene terephthalate (PET) and ethylene vinyl alcohol (EVOH). First, a descriptive sensory analysis is carried out to determine the principal sensory quality index in seasoned anchovies. Then, the physicochemical quality index with high correlation to the principal sensory quality index is determined accordingly. Subsequently, with the physicochemical quality index, the shelf-life is estimated by using the Arrhenius equation. As for the sensory quality index, 'color' is determined as a principal sensory quality index. For all samples stored at 3 different temperatures (25, 35, $45^{\circ}C$), it is observed that the sensory score is shown to be over 2.5 until 60 days of storage period, which is the lowest acceptable level. In addition, the b-value, as a physicochemical quality index, is determined to have a high correlation to the sensory quality index. Further, the activation energy and the Q10 value for the b-value by the Arrhenius equation is found to be 11.24 kcal/mol, 1.385~2.011, respectively. Thus, it can be concluded that the shelf life of seasoned anchovies packaged with PET/EVOH film is estimated to be 279.44 days when stored at $20^{\circ}C$.

• Polymer(Korea)
• /
• v.24 no.6
• /
• pp.820-828
• /
• 2000

In this study, biaxially oriented film process was used to improve barrier property of polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends by inducing a laminar morphology of the dispersed phase in the matrix phase. In order to examine the extent of deformation during melt extrusion process, the rheological properties of the resins were measured and the viscosity ratio of the dispersed phase to the continuous phase was determined. The effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were studied. The laminar morphology of the EVOH phase with a larger area of thinner layer induced by biaxial orientation was found to result in a significant increase in oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP When both PP-g-MAH and ionomer were used as the compatibilizers, there existed an optimum level of compatibilizer content for obtaining improved barrier properties with a well developed laminar structure. In addition, higher draw ratio and draw temperature were found to be more favorable processing conditions in obtaining higher barrier blends.

• Korean Chemical Engineering Research
• /
• v.55 no.4
• /
• pp.467-472
• /
• 2017

Alkaline electrolytes consisting of 6 M KOH and polymer (PEO, PVA, and PAAK) are coated on PAN nonwoven fabrics as a separator, and the electrochemical properties of the activated carbon supercapacitor adopting them are investigated in terms of redox behavior, specific capacitance, and interfacial impedance. Although the interaction between polymer and KOH are comparatively inactive in PEO and PVA, PAAK (3 wt.%)-KOH forms a hydrogel phase by active interactions between $COO^-K^+$ in side-chain of PAAK and $K^+OH^-$ from alkaline electrolyte solution, improving ionic conduction of electrolytes and the electrochemical properties of the supercapacitor. As a result, the activated supercapacitor adopting the PAAK-KOH shows the superior specific capacitance of $46.8Fg^{-1}$ at $100mVs^{-1}$.

• Elastomers and Composites
• /
• v.49 no.3
• /
• pp.225-231
• /
• 2014

In this study, we used polypropylene grafted with itaconic acid (PP-g-IA) as a compatibilizer to prevent phase separation phenomenon which occurs upon blending polypropylene (PP) and ethylene-vinyl alcohol copolymer (EVOH). A compatibilizer was prepared using graft copolymerization of itaconic acid (IA) onto PP where input ratio of IA was 1, 2, 5, and 10 wt.%. To confirm the structure of PP-g-IA and the graft ratio of IA onto PP, we used $^1H$ NMR and FT-IR. We tested the compatibilizer which has highest graft ratio of 1% in immiscible PP/EVOH blends. The morphologies of PP/PP-g-IA/EVOH blends were analyzed by SEM. Thermal and mechanical properties of the blends were analyzed by DSC and UTM. PP-g-IA enhanced the interfacial adhesion of PP and EVOH copolymer.

• Polymer(Korea)
• /
• v.32 no.3
• /
• pp.246-250
• /
• 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)
• /
• v.33 no.2
• /
• pp.144-152
• /
• 2009

The thermal and optical properties of poly {1-(cholesteryloxycarbonylalkanoyloxy) ethylene}s (PCALEn, n=2$\sim$8,10, the number of methylene units in the spacer) were investigated. All of the homologues formed monotropic cholesteric phases with left-handed helical structures. PCALEn with n=2 or 10, in constrast with PCALEn with $3{\leq}n{\leq}8$, did not display reflection colors over the full cholesteric range, suggesting that the helical twisting power of the cholesteryl group highly depends on the length of the spacer connecting the cholesteryl group to the polyethylene chain. The glass transition temperatures decreased with increasing n. The isotropic-cholesteric phase transition temperatures decreased with increasing n up to 7 and showed an odd-even effect. However it became almost constant when n is more than 7. This behavior is rationalized in terms of the change in the average shape of the side chain on varing the parity of the spacer. This rationalization also accounts for the observed variation of the entropy gain for the clearing transition. The thermal stability and degree of order in the mesophase and the temperature dependence of the optical pitch observed for PCALEn were significantly different from those reported for cellulose tri(cholesteryloxycarbonyl)alkanoates. The results were discussed in terms of the differences in the chemical structure and flexibility of main chain and the number of the mesogenic units per repeating unit.

• Polymer(Korea)
• /
• v.32 no.5
• /
• pp.489-496
• /
• 2008

The thermotropic liquid crystalline behavior of a homologous series of poly[1-{4-(4' nitrophenylazo) phenoxycarbonylalkanoyloxy}ethylene]s (NAPEn, n = $2{\sim}8$,10, the number of methylene units in the spacer) have been investigated. All of the homologues formed monotropic nematic phases. The glass transition temperatures decreased with n. This is attributed to a plasticization of the backbone by the side chains. The isotropic-nematic phase transition temperatures decreased with increasing n up to 7 and showed the odd-even effect. However it became almost constant when n is more than 7. This behavior was rationalized in terms of the change in the average shape of the side chain on varing the parity of the spacer. This rationalization also accounts for the observed variation of the entropic gain for the clearing transition. The mesophase properties of NAPEn were entirely different from those reported for the polymers in which the azobenzene groups are attached to polyacrylate, polymathacrylate, and polystyrene backbones through polymethylene spacers. The results indicate that the mode of chemical linkage of the side group with the main chain plays an important role in the formation, stabilization, and type of mesophase.

• Journal of Yeungnam Medical Science
• /
• v.12 no.1
• /
• pp.96-104
• /
• 1995

The transarterial embolization has been widely used to control bleeding. It has a variety of clinical utility; to reduce bleeding on the surgical field, to reduce the size of malignant tumor as a preopearative treatment, to treat arteriovenous malformation or arterial aneurysm as a curative method and to promote life quality of patient with diffuse or multiple hepatocellular carcinoma as a palliative treatment, etc. With the advance of modem technology, various embolic materials have been also developed. However, it has not been fully investigated of histopathologic changes of the embolized organs according to the embolic materials used. This study was undertaken to investigate the histopathologic changes of embolized renal artery in rabbit by various embolic materials, according to each embolic material and to time passed by after embolization. Of the 5 arteries embolized by ethylene vinyl alcohol copolymer(EVAL), one showed abscess formation in embolized kidney. The other 4 allowed to perform further pathologic study: within a week after embolization there was no any specific change in vessels, however, minimal endothelial hypertrophy was observed following 2 weeks of embolization. Of the 8 renal arteries embolized by N-buthyl-2-cyanoacrylate(Histoacryl), 4 showed total occlusion of the main renal arteries as well as renal infarction, which reflects the strong adhesiveness of Histoacryl to vascular wall. The other 4 showed fibrinoid degeneration in vascular wall within a week. However, further change was not observed thereafter. In all the 5 renal arteries embolized by polyvinyl alcohol(Ivalon), there were infiltration of inflammatory cells along the vessel walls, within one week, which represents vasculitis. They showed some fibrosis with appearance of giant cells in the vessel wall two weeks after embolization and also showed marked fibrosis of connective tissues surrounding vessels two months after embolization, respectively. The results suggest that EVAL is useful for the embolization of hypervascular lesion with limited arteriovenous fistula, Histoacryl for the curative treatment of the lesion with high blood flow or severe arteriovenous fistula, and Ivalan for palliative treatment of malignant tumor or arteriovenous malformation, respectively.