• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.735-742
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• 2012

This study tried to find a suitable method for enhancing the foam stability of cationic surfactants that normally generate less foam or no foam. Several trials were made to enhance the foam stability: addition of anionic surfactant, colloids and polymer. Cationic starch (CA-ST) did not form foam at all, while the foam stability of two other cationic surfactant also showed low levels; methyl triethanol ammonium methyl sulfate distearyl ester (CEQ90) for 46 sec. and Cetyl trimethyl ammonium chloride (CM29) for 31 seconds. Foam stability of cationic surfactants were significantly affected by addition of anionic surfactant, sodium dodecyl sulfate (SDS). Foam stability of CA-ST was significantly enhanced by addition of SDS, while those of CEQ90 and CM29 were decreased. Addition of colloids ($SiO_2$, kaolin) and polyvinyl alcohol (PVA) enhanced foam stabilities of CEQ90 and CM29. However, CA-ST did not form foam even in the presence of colloids or PVA. Effect of simultaneous addition of colloids and anionic surfactant on foam stability of cationic surfactant showed that foam stability of cationic surfactant was more influenced by addition of anionic surfactant than colloids. Effect of simultaneous addition of PVA and anionic surfactant on the foam stability of cationic surfactant also showed that presence of anionic surfactant significantly affect the foam stability of cationic surfactant. Foam stability of CA-ST was greatly increased to 8,780 seconds by addition of SDS 0.14% and PVA 2.5%. The foam stability of CA-ST was 8 times higher than CEQ 90. This study suggested that cationic surfactants not forming foam can generate foam by addition of anionic surfactant and its stability can be additionally increased by addition of colloids and PVA. The study results showed that enhancement in foam stability of cationic surfactant was prominently affected by the concentration of anionic surfactant added.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.98-105
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• 2017

In this study, the fiber blending ratio and strain rate effect on the tensile behavior of hybrid fiber reinforced cement composite was evaluated. Hooked steel fiber and polyvinyl alcohol fiber were used for reinforcing fiber. The fiber blending ratio of HSF+PVA were 1.5+0.5, 1.0+1.0 and 0.5+1.5vol.%. As a results, the tensile strength, strain capacity and fracture toughness of the hooked steel fiber reinforced cement composites were improved by the increase of the bond strength of the fiber and the matrix according to increase of strain rate. However, the tensile stress sharply decreased after the peak stress because of the decrease in the number of straightened pull-out fibers by micro cracks in the matrix around hooked steel fiber. On the other hand, PVA fiber showed cut-off fracture at strain rate $10^{-6}/s$ with multiple cracks. However, at the strain rate $10^1/s$, the multiple cracks and strain capacity were decreased because of the pull-out fracture of PVA fiber. The HSF1.5PVA0.5 shown the highest tensile strength because the PVA fiber suppressed the micro cracks in the matrix around the hooked steel fiber and improved the pull-out resistance of hooked steel fiber. Thus, DIF of strain capacity and fracture toughness of HSF1.5PVA were greatly improved. In addition, the synergistic response of fracture toughness was positive because the tensile stress was slowly decreased after the peak stress by improvement of the pull-out resistance of hooked steel fiber at strain rate $10^1/s$.

• Journal of the Korea Institute of Building Construction
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• v.15 no.4
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• pp.383-389
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• 2015

The objective of this study is to develop mixture proportioning approach of crack controlled lightweight foamed concrete without using high-pressure steam curing processes, as an alternative to autoclaved lightweight concrete blocks (class 0.6 specified in KS). To control thermal cracks owing to hydration heat of cementitious materials, 30% ground granulated blast-furnace slag (GGBS) was used as a partial replacement of ordinary portland cement (OPC). Furthermore, polyvinyl alcohol (PVA) and polyamid (PA) fibers were added to improve the crack resistance of foamed concrete. The use of 30% GGBS reduced the peak value of hydration production rate measured from isothermal tests by 28% and the peak temperature of foamed concrete measured from semi-adiabatic hydration tests by 9%. Considering the compressive strength development, internal void structure, and flexural strength of the lightweight foamed concrete, the optimum addition amount of PVA or PA fibers could be recommended to be $0.6kg/m^3$, although PA fiber slightly preferred to PVA fiber in enhancing the flexural strength of foamed concrete.

• Korean Journal of Veterinary Research
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• v.59 no.2
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• pp.81-88
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• 2019

This study was performed to examine the effects of various macromolecules in in vitro growth (IVG) media on the growth, maturation, and parthenogenesis (PA) of pig oocytes derived from small antral follicles (SAF). Immature oocytes were cultured for two days in IVG medium supplemented with 10% (v/v) fetal bovine serum (FBS), 10% (v/v) pig follicular fluid (PFF), 0.4% (w/v) bovine serum albumin (BSA), or 0.1% (w/v) polyvinyl alcohol (PVA) and then maintained for 44 h for maturation. After IVG, the mean diameters of the SAF treated with FBS, PVA, and no IVG-MAF ($113.0-114.8{\mu}m$) were significantly larger than that of no IVG-SAF ($111.8{\mu}m$). The proportion of metaphase II oocytes was higher in PFF (73.6%) than in BSA (43.5%) and PVA (53.7%) but similar to that in the FBS treatment (61.5%). FBS and PFF increased cumulus expansion significantly compared to PVA and BSA while the intraoocyte glutathione content was not influenced by the macromolecules. Blastocyst formation of PA oocytes treated with FBS (51.8%), PFF (50.4%), and PVA (45.2%) was significantly higher than that of the BSA-treated oocytes (20.6%). These results show that the PFF and FBS treatments during IVG improved the growth, maturation, and embryonic development of SAF.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.1
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• pp.67-74
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• 2023

In this study, for a natural cosmetics market, we sought to explore alternatives that can replace polyvinyl alcohol (PVA) of peel-off packs. A peel-off type pack was prepared by combining pullulan, a water-soluble polysaccharide, and other polysaccharides (sodium hyaluronate, cellulose gum, hydroxyethyl cellulose, sodium alginate, corn starch), and the pH, viscosity, and stability against temperature of each peel-off type pack were confirmed. The thickness and tensile strength of the manufactured film were measured for comparison with the PVA peel-off type pack, and applicability, drying speed, and removal degree were measured. Among them, the pullulan-sodium hyaluronate peel-off type pack showed excellent film formation ability to replace the peel-off type pack containing PVA with 5.12% thin film thickness and 4.23% high film tensile strength. When applied to actual skin, the degree of spread of the pack, the usability that can be uniformly applied, and the formation and removal strength of the film when removed after drying were also similar to the peel-off type pack containing PVA. Therefore, it was confirmed that the film formed of pullulan-sodium hyaluronate showed enough physical properties to replace the PVA of the peel-off type pack as a natural peel-off type pack.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.2
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• pp.129-138
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• 2012

The aim of this in vitro study was to evaluate the effectiveness of experimental 2.26% fluoride-polyvinyl alcohol (F-PVA) tape in inhibition of enamel demineralization using enamel surface microhardness (SMH) analysis and scanning electron microscopy (SEM) examination. Enamel specimens (n=60) randomly assigned to four groups: control group, F-PVA tape group, fluoride varinish (F-varnish) group, casein phosphopeptide-amorphous calcium phosphate (CPP-ACFP) group. After topical application, pH-cycling was processed. Then, SMH was measured and the percentage loss of surface microhardness (%SML) was calculated. For the SEM examination, five sample specimens in each group were treated and the morphologic character was evaluated. After pH-cycling, the SMH values of the enamel specimens of F-PVA tape and F-varnish group were significantly higher than that of CPP-ACFP group, there was no significant difference between F-PVA tape and Fvarnish group. With SEM examination, enamel surfaces in the F-PVA tape group and F-varnish group showed numerous spherical and ovoid crystals formed on the enamel surface were also observed. The density of crystals was higher than that of both control group and CPP-ACFP group. F-PVA tape is effective in inhibition of enamel demineralization. Also, F-PVA tape's inhibition of enamel demineralization is comparable to that of F-vanish and greater than that of CPP-ACFP.

• Journal of the Korean Wood Science and Technology
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• v.48 no.5
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• pp.755-764
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• 2020

Due to pronounced mechanical performance and being environmental friendly, aqueous polymer isocyanate adhesive (API) has been widely applied in the production of formaldehyde-free wood products. In this study, flame retardant formaldehyde-free plywood was prepared by incorporation of flame retardants into the API adhesive. Partially phosphorylated poly (vinyl alcohol) (PPVA) which was prepared by reacting poly (vinyl alcohol) with phosphoric acid was used to replace PVA in API formula. In addition, Mg-Al layered double hydroxides (LDH) was chosen as additive flame retardant, replacing traditional filler CaCO₃ in API adhesive formula. And then, the flame retardant API adhesive with main agent (PPVA replacing PVA70wt.%, SBR emulsion 30wt.%), curing agent 10wt.% (accounts for of the main agent), and 20wt.% LDHs (accounts of the main agent) was used to prepare flame retardant plywood. The effect of application of PPVA and Mg-Al LDH on bonding strength of plywood was investigated. The flammability characteristics of the plywood were determined by cone calorimeter test (CCT). The results revealed that compared with the plywood prepared with API adhesive, the use of PPVA and LDH enhanced the flame retardancy of plywood without negatively affecting bonding strength. The CCT tests indicated that the heat release and smoke production flame retardant API plywood were lower than those of the ordinary API glued plywood. Promising developments for flame retardant API adhesive were expected in future applications of flame retardant formaldehyde-free plywood.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.8-15
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• 2004

Seedling mechanization of lettuce is known to be difficult due to the small seed size and the irregular seed shape. The purpose of seed pelleting is to make seedling mechanization possible by enlarging the seed size. After that, it can reduce seedling and thinning labours and can also save seeds. According to the results, there were significant differences on the percent germination and day to 50% final germination in accordance with the pelleting polymer. Among the pelleting polymer, gemination of seeds using polynimyl alcohol (PVA) was generally smooth, and followed by polyvinyl pyrrolidone (PVP), hydroxyethyl cellulose (HEC), methyl cellulose (MC), and wteen 80. The germination rate was also different according to the pelleting particulate matters. Generally, percent germination and speed of seed using the mixture of diatomaceous earth, talc and calcium carbonate were higher and faster than using other polleting materials, respectively. Thus, it should be suitable pelleting particulate matter for the pelleting of lettuce seeds. On the other hands germination of seeds using limestone, calcium oxide and benonite were low. The seed size of lettuce after pelleting was 33 times as large as the raw seed size. During the process of seed pelleting, netrient addition induced the decrement on the germination and the delay of germination speed. Also, there was differences in the germinability of pelleted seeds in accordance with the addition of nutrient sources. MS medium was generally lower than monosodium phosphate in inhibition of seed germination. Germination of pelleted seeds after priming was higher than the seeds without the treatment, and also showed the trend of early germination.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.648-653
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• 2006

As an alternative for the traditional materials packed in biofilters treating gaseous VOCs, a novel packing material has been developed and tested. In the packing material(named as Hydrogel Bead, HB), pollutant-degrading microorganisms were immobilized in hydrogel consisted of alginate, polyvinyl alcohol(PVA), and powdered activated carbon. A closed-bottle study showed that the HB rapidly removed gaseous styrene without the losses of adsorption and biodegradation capacity. Biofilter column experiments using the HBs also demonstrated that greater than 95% of removal efficiencies were found at an inlet styrene loading rate of $245g/m^3/hr$, which was higher biofilter performance than other elimination capacity reported earlier. Furthermore, when the inlet styrene concentration increased stepwise, the adsorption played an important role in overall styrene removals. The absorbed styrene was found to be biodegraded in the following low inlet loading condition. Consequently, the new HB material is able to successfully minimize the drawbacks of activated carbon(necessity of regeneration) and biological processes(low removal capacity at dynamic loading conditions), and maximize the overall performance of biofilter systems treating VOCs.

• Korean Journal of Medicinal Crop Science
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• v.14 no.3
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• pp.130-133
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• 2006

This study was conducted to select Codonopsis lanceolata seed's new pelleting particulate materials and adhesives. Different adhesives (Polyvinyl alcohol (PVA), Carboxymethyl cellulose (CMC), Polyvinyl pyrrolidone (PVP), Xanthan gum (XG), Arabic gum (AG)) and particulate materials (Illite, Diatomite, Pyrophyllite + Illite + Diatomite (PID), Pyrophyllite + Illite + Talc (PIT), Bentonite + Talc (BT)) were tested for seed pelleting. PID for Codonopsis lanceolata seed pelleting appeared to be the best particulate material. Among the pelleting adhesives, PVP was the best adhesive for seed pelleting, and the optimum concentration for germination of pelleting seed was 1 %. Germination rate of the pelleted seeds treated with PID particulate material and PVP adhesive was higher (86.8%) than those of raw seeds (85.5%). $T_{50}$ and MDG of pelleted Codonopsis lanceolata seed required five and eight days at soil moisture content of 50%, respectively.