• Fibers and Polymers
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• v.7 no.2
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• pp.89-94
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• 2006

Ionic conductivity and mechanical properties of a mixed polymer matrix consisting of poly(ethylene glycol) (PEG) and cyanoresin type M (CRM) with various lithium salts and plasticizer were examined. The CRM used was a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) with a molar ratio of 1:1, mixed plasticizer was ethylene carbonate (EC) and propylene carbonate (PC) at a volume ratio of 1:1. The conductive behavior of polymer electrolytes in the temperature range of $298{\sim}338\;K$ was investigated. The $PEG/LiClO_4$ complexes exhibited the highest ionic conductivity of ${\sim}10^{-5}S/cm$ at $25^{\circ}C$ with the salt concentration of 1.5 M. In addition, the plasticized $PEG/LiClO_4$ complexes exhibited improvement of ionic conductivity. However, their complexes showed decreased mechanical properties. The improvement of ionic conductivity and mechanical properties could be obtained from the polymer electrolytes by using CRM. The highest ionic conductivity of PEG/CRM/$LiClO_4$/(EC-PC) was $5.33{\time}10^{-4}S/cm$ at $25^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.385-388
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• 2006

In this study, I examined hardening and non-hardening of the DFRCC (Ductile Fiber Reinforced Cementitious Composites) according to maximum size of coarse aggregate and the diameter of PVA (Poly Vinyl Alcohol) to develope PVA fiber reinforced concrete with the feature of DFRCC. As a result of this study, the fresh properties is similar regardless of maximum size of coarse aggregate. The bending stress and bending stress-displacement of DFRC showed big differences according to maximum size of coarse aggregate and diameter.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.405-408
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• 2006

The purpose of this study was to determine the optimum length distribution of hybrid PVA(Poly vinyl alcohol) fiber. To produce blended PVA fiber length, first the length distribution of PVA fiber in the cement composites were identified in an experimental study based on simplex lattice design. Among the different length distributions investigated, fiber length was found to have statistically significant effect on plastic shrinkage cracking of cement composites. Subsequently, Complex analysis techniques were used to devise an experimental program that helped determine the optimum combinations of the selected fiber length distribution based on plastic shrinkage crack. The optimum blended PVA length ratio was 0.0146% 4mm fiber, 0.0060% 6-mm fiber, 0.0285% 8-mm fiber, and 0.0209% 12-mm fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.337-340
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• 2006

Utilize several kinds of reinforcement fibers to control workability and surface crack in occasion of mortar used in dilapidated concrete section repair public law. Polypropylene or poly vinyl alcohol that is hydrophilic fiber etc. is used much usually with this reinforcement fiber. Reinforcement fiber does important action that control crack that enhances coherence between material and happens at dry contraction. In this study, wished to use Sepiorite that inorganic materials and affinity such as cement are excellent nature inorganic world fiber and improve repair mortar performance. In this study, as reinforcement fiber, wished to grasp physical characteristics that uses Sepioraiteu and happens this time and grasp application possibility of concrete's repair mortar.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.3
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• pp.512-518
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• 1996

Microcapsules containing 2, 4, 4'-trichloro-2-hydroxydiphenyl ether and perfumes were prepared by the coacervation using poly (vinyl alcohol) and crosslinking agents. Effects of dispersing agents, core materials, agitating speed and crosslinking agents on microcapsule size were investigated. The mean and deviation of microcapsule diameters decreased with increasing agitation speed. The diameters of m;crocapsules decreased with increasing dispering agent concentration at 6, 000 rpm of agitation speed, but it was not changed at 10, 000 rpm. The dispering effect of PVA is better than that of gum arabic. The slight increase in the diameter of microcapsule was observed when the amount of core material was increased. As the amount of crosslinking agent was increased, the diameter of microcapsule was decreased.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.1
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• pp.25-32
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• 2009

It is now widely recognized that the disposal of packaging waste is an increasing environmental concern. Recent interest in polymer waste management of packaging materials has added incentive to the research. Poly(vinyl alcohol) is a readily biodegradable water-soluble polymer. However, this polymer cannot be processed by conventional extrusion technologies because the melting point of PVA is close to its decomposition temperature. Therefore, PVA films have been mostly prepared by solvent casting from water. Applications of PVA include sizing, binders, fibers, and films for agricultural chemicals and hospital laundry bags. A better understanding of PVA films, which also play important roles in the degradation of plastics, will expand the usage of PVA. Composite films based on PVA generally exhibit better mechanical and thermal properties than pure PVA. The aim of this review article is to review types, formation, and properties of PVA films and PVA based composite films used in packaging related researches.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.661-664
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• 2006

Recently, various concrete reinforcing fibers have been used to reduce the plastic shrinkage cracking which occurs before the concrete hardens. In this study, the physical properties of nylon fiber reinforced concrete such as slump, air content, compressive strength and tensile strength were investigated. In addition, the performance of nylon fiber in the plastic shrinkage cracking reduction of concrete has been estimated in comparison with polypropylene, poly vinyl alcohol fiber and cellulose fiber. Nylon fiber showed considerable advantages in terms of the workability of concrete and the plastic shrinkage cracking reduction of concrete compared with polypropylene fiber and cellulose fiber.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.5
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• pp.870-876
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• 1996

Microcapsules containing 2,4,4'-trichloro-2-hydroxydiphenyl ether (DP) and perfumes were prepared by the coacervation using poly (vinyl alcohol) and crosslinking agents. Internal phase content, percent releasing of core materials, antimicrobial activities of microcapsules and fabrics treated with them were investigated. The internal content of microcapsules containing perfumes and DP are increased with increasing perfumes. The internal content of cacharia in the microcapsue was higher than that of lemon and its maimum value was 93%. The microcapsules containing perfumes and DP did not release cacharia and lemon at roonl temperature. But the amount of perfumes released from microcapsules were increased with temperature and time of microcapsules containing DP and perfumes showed 100% reduction percentage of bacteria. The size of obstruction of fabrics treated with microcapsule containing DP and perfumes were increased with DP content in microcapsules.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.11
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• pp.1297-1308
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• 2011

This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.3
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• pp.372-385
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• 2014

Lignin is an abundant natural polymer in the biosphere and second only to cellulose; however, it is under-utilized and considered a waste. In this study, lignin was fabricated into nanofibers via electrospinning. The critical parameters that affected the electrospinnability and morphology of the resulting fibers were examined with the aim to utilize lignin as a resource for a new textile material. Poly(vinyl alcohol) (PVA) was added as a carrier polymer to facilitate the fiber formation of lignin, and the electrospun fibers were deposited on polyester (PET) nonwoven substrate. Eleven lignin/PVA hybrid solutions with a different lignin to PVA mass ratio were prepared and then electrospun to find an optimum concentration. Lignin nano-fibers were electrospun under a variety of conditions such as various feed rates, needle gauges, electric voltage, and tip-to-collector distances in order to find an optimum spinning condition. We found that the optimum concentration for electrospinning was a 5wt% PVA precursor solution upon the addition of lignin with the mass ratio of PVA:lignin=1:5.6. The viscosity of the lignin/PVA hybrid solution was determined as an important parameter that affected the electrospinning process; in addition, the interrelation between the viscosity of hybrid solution and the electrospinnability was examined. The solution viscosity increased with lignin loading, but exhibited a shear thinning behavior beyond a certain concentration that resulted in needle clogging. A steep increase in viscosity was also noted when the electrospun system started to form fibers. Consequently, the viscosity range to produce bead-free lignin nanofibers was revealed. The energy dispersive X-ray analysis confirmed that lignin remained after being transformed into nanofibers. The results indicate the possibility of developing a new fiber material that utilizes biomass with resulting fibers that can be applied to various applications such as filtration to wound dressing.