• 제목/요약/키워드: pulp density

검색결과 250건 처리시간 0.025초

Development of Environment-friendly Cushioning Materials by Pulping of Waste Residual Woods (폐잔재의 펄프화를 통한 환경친화적 완충소재의 개발)

  • Lee, Young-Min;Kim, Chul-Hwan;Kim, Jae-Ok;Kim, Gyeong-Yun;Shin, Tae-Gi;Song, Dae-Bin;Park, Chong-Yawl
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제38권2호
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    • pp.61-71
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    • 2006
  • Environment-friendly shock-absorbing (cushioning) materials were made using a vacuum forming method from waste wood collected from local mountains in Korea. The waste wood was pulped by thermomechanical pulping. The TMP cushions showed superior shock-absorbing properties with lower elastic moduli compared to EPS(Expanded Polystyrene) and pulp mold. Even though the TMP cushions made using at different suction times had many free voids in their inner fiber structures, their apparent densities were a little higher than EPS and much lower than pulp mold. The addition of cationic starch improved elastic modulus of the TMP cushions without increasing the apparent density, which was different from surface sizing with starch. The porosity of the TMP cushions was a little greater than EPS and much less than pulp mold. Finally, the TMP cushions have great potential to endure external impacts occurring during goods distribution.

Antimicrobial and cytotoxic properties of calcium-enriched mixture cement, Iranian propolis, and propolis with herbal extracts in primary dental pulp stem cells

  • Mohammad Esmaeilzadeh;Shirin Moradkhani;Fahimeh Daneshyar;Mohammad Reza Arabestani;Sara Soleimani Asl;Soudeh Tayebi;Maryam Farhadian
    • Restorative Dentistry and Endodontics
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    • 제48권1호
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    • pp.2.1-2.12
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    • 2023
  • Objectives: In this study, natural substances were introduced as primary dental pulp caps for use in pulp therapy, and the antimicrobial and cytotoxic properties of these substances were investigated. Materials and Methods: In this in vitro study, the antimicrobial properties of calcium-enriched mixture (CEM) cement, propolis, and propolis individually combined with the extracts of several medicinal plants were investigated against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Then, the cytotoxicity of each substance or mixture against pulp stem cells extracted from 30 primary healthy teeth was evaluated at 4 concentrations. Data were gathered via observation, and optical density values were obtained using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) test and recorded. SPSS software version 23 was used to analyze the data. Data were evaluated using 2-way analysis of variance and the Tukey test. Results: Regarding antimicrobial properties, thyme alone and thyme + propolis had the lowest minimum inhibitory concentrations (MICs) against the growth of S. aureus, E. coli, and P. aeruginosa bacteria. For E. faecalis, thyme + propolis had the lowest MIC, followed by thyme alone. At 24 and 72 hours, thyme + propolis, CEM cement, and propolis had the greatest bioviability in the primary dental pulp stem cells, and lavender + propolis had the lowest bioviability. Conclusions: Of the studied materials, thyme + propolis showed the best results in the measures of practical performance as a dental pulp cap.

The Effect of Precipitated Calcium Carbonate Having a Small Particle Size on the Print Quality of an Inkjet-Grade Paper (초미립자탄산칼슘이 잉크제트 인쇄품질에 미치는 영향)

  • Lee Yong-Kyu;Lee Hee-Myung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제37권2호
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    • pp.38-46
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    • 2005
  • Experimental work was carried out in order to produce a novel grade of ink-jet paper that has both high print-out quality and price competitiveness. Usually, silica and PVOH has been used for ink-jet paper to design the coating layer that has a hydrophilic and micro-porous structure. However, poor rheological characteristics and low productivity of the silica-PVOH system make the price of the ink-jet paper high. The main focus of this study was replacing the conventional silica (coating pigment) PVOH (binder) coating system with the new PCC (coating pigment) cationic starch (binder) coating system, and optimizing thecoating technology associated with PPC-cationic starch system. In this study, ink-jet print quality of PCC-coated papers was compared with that of silica-coated paper. Two types of PCC were used: conventional type and colloid type. It turned out that PCC C, a conventional coating pigment, has not given a desirable result: it showed high dot reproduction, but it gave low optical density. In spite of low dot reproduction, the qualities of PCC A were comparable or superior to those of silica in optical density, color reproduction, and the uniformity of printing surface. It was also shown that the problems that are happened when the dosage level of cationic starch was too low were varied with ink-type used in each printer. However, in the case of low binder level, the produced image was widely spread resulting fromtoo low optical density of images, or from the lack of bonding ability to set ink into coating surface.

A Study of the Printability Coefficients on the Newspaper(III) - A study of the printability coefficients on the color newspaper printing - (신문용지의 인쇄적성 계수에 관한 연구(제3보) - 칼라 신문인쇄의 인쇄적성 계수 -)

  • Ha, Young-Baeck;Kim, Chang-Keun;Oh, Sung-Sang;Lee, Yong-Kyu;Koo, Chul-Whoi;Youn, Jong-Tae
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제38권3호
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    • pp.1-6
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    • 2006
  • The increasing use of newsprints in the media and an advertisement have brought the needs to improve the printing quality of the advance full-color newspaper. The printability coefficients used in this research such as Ymax for the density and Tollenaar's density smoothness constant value $\ulcorner$m$\lrcorner$ were introduced early in Europe and have been in use to control printing quality. In order to improve printing quality of domestic full-color newsprints, those printability coefficients could be used to control printing quality. This study was carried out to measure the printability coefficients of domestic full-color newspapers. Four kinds of domestic newspapers and two kinds of newspaper printing inks were tested by IGT printability tester. The printed density smoothness coefficient $\ulcorner$m$\lrcorner$ value showed good results when the samples have low porosity and roughness. The printability coefficients obtained are expected to be useful to the korean newspaper printing industry.

The Application of Rule of Mixtures to Fiber-Reinforced Composites(1) - Mechanical Properties of Fiber-Reinforced, Sulfur-Based Composites - (목재 섬유 복합재(複合材)에 혼합이론(混合理論)의 적용에 관(關)한 연구(硏究) (1) - 유황(硫黃) 화합물(化合物)을 사용한 목재(木材) 섬유(纖維) 복합재(複合材)의 기계적 성질(性質) -)

  • Lee, Byung-G.
    • Journal of the Korean Wood Science and Technology
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    • 제11권3호
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    • pp.3-13
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    • 1983
  • Fiber mats were made at five density levels, using fibers from kraft pulp screening rejects, rice straw and a 50/50 mixture of the two. They were soaked in the sulfur compounds. Specimens cut from the composite panels were tested in flexure at time intervals for one year to study the effect of aging. Modulus of elasticity (MOE) and modulus of rupture (MOR) were determined. Under optimum conditions of fiber mat preparation and saturation with molten sulfur and modified sulfur, composites were produced which exhibited mechanical properties comparable to conventional fiberglass in some properties and superior to conventional wood-based composition boards, For example. the moduli of elasticity of the reinforced composites made from pulp screening rejects, with a density of 0.35 gm/$cm^3$, were greater than 1,000,000 psi as compared 800.000 psi for high-density hardboard (1.28 gm/$cm^3$). Modulus of rupture of the best reinforced composites was about 7,000 psi, comparable to 6,000 psi of high-density hardboard.

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Studies on the Printability of Hanji by Sizing and Calendering

  • Kang Jin-Ha;Seo Seung-Man;Park Seong-Cheol
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제37권5호통권113호
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    • pp.70-77
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    • 2005
  • The development of printable Hanji is regarded as an important work to create a new demand of Hanji in information-oriented era. Hanji has rougher surface, huger absorption of ink and lower optical properties and printabilities than common printing papers. Improving those shortcomings of Hanji is required to be printable Hanji. Sizing and calendering have known as a way to make properties of paper good. Accordingly, this research was performed to find out useful sizing agents for reforming its drawbacks. Four sizing agents (CMC, com starch, PVA, AKD) were used in this research. The optical properties and the printabilities of sized Hanji were tested. The obtained results were as follows. Based on concentration, each sizing agent was prepared. These were CMC(0.5, 1, $1.5\%$), corn starch(1, 2, $3\%$), PVA(1, 5, $10\%$), AKD(0.5, 0.1, $0.15\%$) respectively. After sizing, we performed calendering treatment with pressure of 0.5, $1\;kgf/cm^2$. All the sizing agents and calendering treatment improved the properties of Hanji to some extent. Particularly, com starch was good for gloss. In case of printability, $1\%$ AKD with $1\;kgf/cm^2$ was recommendable for typography ink density, $3\%$ com starch with $0.5\;kgf/cm^2$, inkjet ink density, $2\%$ com starch with $0.5\;kgf/cm^2$, inkjet ink girth. PVA and AKD without calendering were counter-effective agents for inkjet ink density. Printable Hanji is required to have not only better surface strength enough to appear non-picking, higher ink density and lower show-through than base paper but also the lowest ink girth in comparison with base paper. When referring to them, efficient sizing agents were regarded as $0.1\%$ AKD with $1\;kgf/cm^2$, calender pressure, for typography printing and $2\%$ com starch with $0.5\;kgf/cm^2$, calender pressure, for inkjet printing.

Effect of Dampening Component on Printed Quality of Textbook in lithography printing (평판인쇄의 축임물 조성이 교과서 인쇄품질에 미치는 영향)

  • Koo, Chul-Whoi;Sim, Woo-Seok;Ha, Young Baeck
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제48권1호
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    • pp.134-141
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    • 2016
  • Dampening in printing is not only used with plain water but also used with various substances like dampening additive, in order to improve the wetting property by lowering the surface tension and to control material for modifing the ink transfer characteristic with proper emulsification. We have studied the printing quality according to these, looking into interrelationship among the dampening solution's pH, electrical conductivity and IPA content, prescribing the proper usage and minimum usage of fountain solution and dampening additive. In this study, it shows good result when mixing at the 7 wt% dampening with additive solution, which is result from the color density of printed sheets in accordance with the change of dampening solution condition. And the printed density value calculated 1 hour after printing, it shows relatively safe value at the etch liquid 4 wt% and IPA addition 2 wt%. The dry down at this test showed similar results regardless of various dampening conditions on coated paper, but in case of uncoated paper, the dry down showed a quite gap of different due to the fast penetration to the paper.

Study on CMS Application in Hybrid UV Waterless Off-Set Printing (H-UV 무습수 오프셋 인쇄에서 CMS 적용에 관한 연구)

  • Koo, Chul-Whoi;Cho, Ga-Ram
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제45권5호
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    • pp.1-13
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    • 2013
  • This study found fit optimum C, M, Y, K solid density and $CIEL^*a^*b^*$ value to paper & ink as well as check about printing machine state for color management in H-UV waterless off-set printing first. These values applied to GRACoL G7 calibration method. This method is one of color standard management method of printing. GRACoL G7 calibration method is possible stable tone reappearance by controlling gray balance by NPDC(Natural Printing Density Curve). Also, this study used values to make device profile as result that is gotten by application of GRACoL G7 calibration method. This profile was applied to CMS(Color Management System) of H-UV waterless off-set printing, and the result was possible by color management that correspond in printing quality standard of ISO 12647-2 and GRACol 2006 specifications.

Preparation of Cu-Ag Powder having Core-Shell Structure by Electroless Plating Method (무전해 도금법을 이용한 코어 셸 구조의 Cu-Ag분말 제조)

  • Kim, Jong-Wan;Lee, Huk-Hee;Won, Chang-Whan
    • Journal of the Korean institute of surface engineering
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    • 제42권1호
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    • pp.47-52
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    • 2009
  • Cu-Ag powder having Core-Shell structure was prepared from by electroless plating method using agents such as $AgNO_3$, $NH_{4}OH$, Hydroquinone. Ag coated copper powders were analyzed using scanning electron microscopy(SEM) and energy dispersive X-ray spectrometer(EDX). The silver coating layer of copper powder was affected from various reaction conditions such as molar ratio of $NH_{4}OH$, $AgNO_3$, and pulp density. Free silver was generated below 0.1M or 0.3M and above of $NH_{4}OH$ mole ratio. Silver coating layer thickened as addition of $AgNO_3$. When the pulp density reached 12% with 0.2M $NH_{4}OH$, and 0.15M $AgNO_3$ at $4^{\circ}C$, silver was homogeneously distributed around the copper particles and free silver particles were not generated.

Improvement of Ink Jet Printing Paper Quality with Oxidized Starch Ester and Additives (산화에스테르전분과 첨가제를 활용한 잉크젯용지의 품질개선)

  • Jung, Kwang Ho;Jeong, Young Bin;Lee, Hak Lae
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • 제45권4호
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    • pp.21-26
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    • 2013
  • The effect of esterified starch as surface sizing agent for inkjet printing paper has been evaluated and compared with oxidized starch. Also the influence of various additives including cationic poly-DADMAC, stearic acrylic copolymer, calcium chloride, and GCC was examined. Results showed that starch ester gave higher ink density than oxidized starch. Addition of poly-DADMAC improved water fastness. In general, low molecular weight poly-DADMAC performed better than high molecular weight one, and it was attributed to the fact that it gave more uniform film forming characteristics in surface sizing. Use of styrene acrylic acid copolymer increased hydrophobicity of the paper surface, but it did not increase the ink density. Use of GCC and calcium chloride had only marginal effect on printing quality.