• 한국염색가공학회지
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• 제2권3호
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• pp.51-58
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• 1990

Cotton fabrics were mercerized in ammonia water, sodium hydroxide and mixture of ammonia/sodium hydroxide, slack and under tension. X-ray and infrared spectra analyses were used to measure crystallinity of treated cottons. Changes due to swelling, which took place in the accessible regions were determined by moisture regain and dye adsorption. In addition to that crease recovery was compared mutually, and breaking strength-elongation compared, too. Both ammonia water and caustic treatments produced changes in morphology (swollen fibers, decrease in convolutions) and in fine structure of the cellulose (increase accessibility as measured by increased moisture regain, dye adsorption). X-ray diffraction showed partial recrystallization into cellulose III lattic after tension treatment with ammonia water. Both reagents produced increased cotton elongation-at-break with slack mercerization, increased cotton breaking strength with tension mercerization, and increased moisture regain or dye adsorption with slack mercerization.

• Elastomers and Composites
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• 제50권1호
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• pp.24-29
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• 2015

In this study, we investigated the effects of a crosslinking agent and a compatibilizer on the mechanical and rheological properties of waste PP and waste ground rubber tire (WGRT) composites. In order to simulate a commercial TPV, the component of waste PP and WGRT was fixed at 30 and 70 wt%, respectively. With the simple addition of SEBS-g-MA into the waste PP/WGRT composites, the tensile strength of the composite was decreased, whereas both the elongation at break and impact strength were significantly increased because of rubbery characteristics of SEBS-g-MA. In order to further improve the properties of the composites, the waste PP/WGRT/SEBS-g-MA composites was revulcanized with dicumyl peroxide (DCP). As expected, mechanical properties of the revulcanized composites was generally improved. Especially, with 15 and 1 phr of SEBS-g-MA and DCP, elongation at break was highest value of about 183% because of the recross-linking of WGRT without chain scission of the main chain. It was found that complex viscosity of the revulcanized composite increased which might verify further vulcanization of the WGRT.

• 한국안전학회지
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• 제23권4호
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• pp.99-104
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• 2008

본 연구에서는 저밀도 폴리에틸렌과 에털렌 비닐 아세테이트 블렌드(LDPF/EVA)의 난연성을 향상시키기 위해 난연제인 수산화 마그네슘과 난연상승보조제인 zinc borate를 첨가한 후, 난연성과 체적저항률, 유전정접, 교류 절연파괴강도 등의 전기적 특성, 인장강도 및 연신율 등의 가계적 특성을 비교 분석하여 가장 우수한 LDPF/EVA 블렌드의 혼합비 및 적절한 $Mg(OH)_2$의 zinc borate의 첨가량을 선정하고자 하였다. 혼합비 70/30phr의 LDPF/EVA 블렌드에 10phr의 $Mg(OH)_2$와 6phr 정도의 zinc borate를 첨가한 시편에서 가장 우수한 난연성 및 전기/기계적 특성을 나타내었다.

• 한국주조공학회지
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• 제18권6호
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• pp.570-577
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• 1998

An investigation has been conducted to describe solidification characteristics in Sn-Zn binary system and Sn-Zn-Ag ternary system added by Ag produced by the continuous casting process using heated mold as a basic study for developing Pb-free solder materials. To obtain the continuous casting rods with mirror surface and near net shape at higher casting speed, water flow rates must be increased and mold temperature must be lowered. However, surface tearing in the casting rods occured at lower continuous casting speed while break out occured at higher continuous casting speed even if optimum conditions such as water flow rate and heated mold temperature are determined. Primary ${\alpha}Sn$ and eutectic structure in unidirectioally solidified Sn-Zn alloys were finer with increased casting speed. But, directionality may not be expected for primary Zn in hypereutectic Sn-Zn alloy. It was found that the addition of $0.2{\sim}0.8%$ Ag promoted the growth of primary ${\alpha}Sn$ dendrites. The changes of tensile strength and elongation in Sn-Zn binary alloys were not observed while the increase of tensile strength and the decrease of elongation in Sn-Zn-Ag ternary alloys were observed with increased casting speed.

• 폴리머
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• 제39권2호
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• pp.200-209
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• 2015

In this study, the influence of dilauroyl peroxide on mechanical and thermal properties of different polypropylene (PP) matrices was investigated. Polypropylene matrices, different molecular weight isotactic PP containing 0.01, 0.02, 0.04, 0.06, 0.08, and 0.1 wt% of dilauroyl peroxide (DLP) were prepared by using a single-screw extruder. The effect of the visbreaking agent (DLP) on mechanical, physical, thermal and morphological properties of different molecular weight PP had been studied. Mechanical properties (tensile strength at break point, at yield and elongation at break point), melt flow index (MFI), scanning electron microscope (SEM) and differential scanning calorimetric (DSC) analyses of these matrices were examined. Melting ($T_m$) and crystallization ($T_c$) temperatures, crystallinity ratio (%) and enthalpies were determined. The microstructure of isotactic polypropylene matrix was investigated by scanning electron microscopy (SEM). From SEM analysis, it was observed that the surface disorder increased by the increasing amount of DLP. As a result of DSC analyses, the crystallinity ratio of the PP matrices has varied between 1.64-7.27%. Mechanical properties of the matrices have been improved. Particularly, the mechanical tests of PP have given interesting results when compounded with 0.06-0.08 wt% dilauroyl peroxide (DLP). Mechanical properties and thermal decomposition processes were all changed by increasing the amount of DLP in the matrix structure.

• 한국재료학회지
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• 제17권11호
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• pp.601-605
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• 2007

The tribological properties of acrylonitrile-butadiene rubber (NBR) filled with two kinds of carbon black filler were examined. Different types of Semi-Reinforcing Furnace (SRF), and High Abrasion Furnace (HAF) blacks were used as filler material to test the influence of carbon black particle size on the friction and wear of NBR. Results from tribological tests using a ball on disk method showed that the smaller HAF particles were more effective for reducing the wear of NBR during frictional sliding. The hardness, elastic modulus at 100% elongation, and elongation at break were measured to examine the correlation between the effects of carbon black on the mechanical and tribological properties of the NBR specimens. The wear tracks of the NBR specimens were observed with scanning electron microscopy (SEM). The wear tracks for NBR with different ratios of SRF and HAF showed clearly different abrasion patterns. Mechanisms for the friction and wear behavior of NBR with different sizes of carbon black filler were proposed using evidence from wear track observation, as well as the mechanical and tribological test results.

• Elastomers and Composites
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• 제44권3호
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• pp.308-314
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• 2009

n-Butyl acrylate, n-butyl methacrylate, acrylonitrile, glycidylmethacrylate, and allyl methacrylate를 사용하여 유화중합에 의해서 아크릴 고무를 합성하였다. 가교단량체의 첨가량을 일정하게 고정시킨 후 주단량체 중 acrylonitrile을 변량시켰을 때 중합체의 Tg가 acrylonitrile의 증가에 따라 증가하면서 무니 점도, 경도(Shore A), 인장강도가 증가하였다. 신장률은 acrylonitrile의 증가에 따라 체인의 유동성이 감소하면서 감소하였다. 가교 단량체인 glycidylmethacrylate의 순수한 중합체의 Tg는 약 $56^{\circ}C$로 중합 시 첨가량이 증가하면 중합물의 Tg는 증가하고, 무니 점도, 경도, 인장강도도 증가하며 신장율은 감소하였다. 이는 rheometer의 측정 결과 glycidylmethacrylate의 증가에 의한 가교밀도의 증가에 기인하는 것으로 판단되었다.

• 한국잠사곤충학회지
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• 제14권1호
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• pp.43-47
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• 1972

견층부위별견사의 기계적특성을 파악하고저 Deniroscope와on을 이용하여 실험한바 다음과 같은 결과를 얻었다. 1) 견층별견사의 건조 및 습윤절단강도는 견사섬도감소율에 비례하여 저하한다. 2) 내층견사의 습윤항장력은 외층견사에 대하여 37%로 나타났다. 3) 습윤처리에 의한 전견층의 절단강도(g/d) 31%, 감소하였다. 4) 대섬도당 견사의 건조 및 습윤절단강도는 내층견사가 제일 높았다. 5) Apparent young's modulus는 내층견사에서 증가하였다. 6) 습윤견사의 절단신도는 건조견사에 비해 15% 증가하였다.

• Composites Research
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• 제28권3호
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• pp.112-117
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• 2015

Mechanical properties of nonwoven alfa fiber based reinforced biocomposite were evaluated to assess the possibility of using it as a new material in engineering applications such as orthopedic application. Samples were fabricated by needle punching, thermal bonding and Hydroentanglement, by blending alfa fibers with wool fibers or Polypropylene fibers. The mechanical properties were tested and showed that the nonwoven NW3 (alfa fiber/PP/PLA, with hydroentanglement) is the best. It has a value of stress at break of 1.94 MPa, a strain of 54.2% and a young's module of 7.95 MPa, in a production normal direction. A biocomposite has been made with NW3 mixed with PMMA matrix. The use of nonwoven based alfa fiber in reinforcing the composite material increases its rigidity and the tensile strength; the elongation was found to be 1.53%, the Young's Module of 1.79 GPa and the tensile at break of 15.06 MPa. Results indicated that alfa fibres are of interest for low-cost engineering applications and can compete with glass fibres in orthopedic application.

• 한국의류산업학회지
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• 제21권2호
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• pp.203-208
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• 2019

This paper considers the moisture permeability and fashion in the upper fabrics of cotton fabric shoes woven into various tissues and properties measured to examine the use as upper fabrics. We measured the tissues of the manufactured upper fabric are 1/3 twill, $4{\times}4$ weft rib, Maya, Triple, Deformed twill design (DTD), Diamond tissues and tear strength, tensile strength, breaking elongation, stretching under load at 100N, stitch tear resistance, and fastness. In the case of $4{\times}4$ weft rib, the tear strength and tensile strength were excellent; however, the elongation and stitch tear resistance at 100N load were less than the standard value. DTD fabrics are characterized by physical properties in the warp direction that are superior to those in the weft direction; however, the tear strength and tensile strength in the weft direction are less than the standard value. The 1/3 twill fabrics showed high tensile strength value and stitch tear resistance value in the warp direction; however, toughness, the main property of the shoe upper, was below the standard value. Triple and diamond fabrics, which have a significant effect on the performance of the shoe upper fabric, also had less than the standard value of tear strength. Maya upper fabric for shoes has better properties than other upper fabrics except for the elongation at break, and the stitch tear resistance has a value of 178% in the warp direction and 214% in the weft direction compared to the standard value. Therefore, the Maya fabric showed the possibility of being used as an upper textile for shoes.