• Elastomers and Composites
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• v.36 no.3
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• pp.162-168
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• 2001

Low molecular weight polybutadiene (liquid BR) improves the filler dispersion in a silica-filled styrene-butadiene rubber (SBR) compound. In the present work, influence of molecular weight or the liquid BR on properties of a silica-filled SBR compound was studied. Minimum and maximum torques in the rheocurve for the compound containing the liquid BR with higher molecular weight (HLBR) are lower than those for the compound containing the liquid BR with lower one (LLBR) while the delta torques are nearly the same. Mooney scorch time of the compound containing HLBR is faster than that of the compound containing LLBR. Modulus or the compound containing HLBR is lower than that of the compound containing LLBR while tensile strength of the former is higher than that of the latter. The elongation at break of the former is also longer than that of the latter. Stability for the thermal aging at $90^{\circ}C$ for 3 days is less favorable for the former than for the latter.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.712-718
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• 2016

In this study, we investigate the effect of the$Li_3BO_3$ additive on the densification and ionic conductivity of garnet-type $Li_7La_3Zr_2O_{12}$ solid electrolytes for all-solid-state lithium batteries. We analyze their densification behavior with the addition of $Li_3BO_3$ in the range of 2-10 wt.% by dilatometer measurements and isothermal sintering. Dilatometry analysis reveals that the sintering of $Li_7La_3Zr_2O_{12}-Li_3BO_3$ composites is characterized by two stages, resulting in two peaks, which show a significant dependence on the $Li_3BO_3$ additive content, in the shrinkage rate curves. Sintered density and total ion conductivity of the system increases with increasing $Li_3BO_3$ content. After sintering at $1100^{\circ}C$ for 8 h, the $Li_7La_3Zr_2O_{12}-8$ wt.% $Li_3BO_3$ composite shows a total ionic conductivity of $1.61{\times}10^{-5}Scm^{-1}$, while that of the pure $Li_7La_3Zr_2O_{12}$ is only $5.98{\times}10^{-6}Scm^{-1}$.

• Elastomers and Composites
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• v.12 no.2
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• pp.157-164
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• 1977

(1) 탄성체(彈性體) MBMA를 가황제(加黃劑)로 사용한 가황체(加黃體)는 MOCA를 가황제(加黃劑)로 한 것 보다 Pot life가 긴 것이 특징(特徵)이다. 물리적(物理的) 특성(特性)에 있어서는 2가지 공(共)히 비승하였으나, 내열성(耐熱性)은 MOCA의 경우가 더 우수(優秀)하였다. 인장강도(引張强度), 신장률(伸張率), 반발탄성(反潑彈性)에 있어서는 MBMA를 사용(使用)한 가황(加黃體)와 MOCA를 사용(使用)한 가황체(加黃體)가 동일(同一)하였으나 압축(壓縮)줄음율은 전자(前者)가 높았다. 인열강도(引裂强度)에 있어서는 10부(部)의 MBMA를 가(加)했을 때 후자(後者)와 동일(同一)하였다. 또 MBIA 가황제(加黃劑)를 사용하였을 경우 인장강도(引張强度), 신장률(伸張率) 그리고 반발탄성등(反潑彈性等)이 MBMA 또는 MOCA의 경우와 거의 동일(同一)하였으나 고무가 부드러운 것이 특징이었다. 다만 100% 모듈러스의 경우 전자(前者)가 후자(後者)들보다 낮은 값이었다. NCO와 OH의 비(比)가 2 : 1인 Prepolymer를 사용한 MBIA가황체(加黃體)(MBIA를 가황제(加黃劑)로 한 가황체(加黃體))는 MBMA 가황체(加黃體) 또는 MOCA 가황체(加黃體)에 비(比)해 인열강도(引裂强度)는 낮았다. 그러므로 인열강도(引裂强度)를 향상(向上)시키기 위하여 NCO와 OH의 비(比)를 2 : 1보다 높은 비율(比率)로 취(取)하면 된다. 내열성(耐熱性)에 있어서 MBIA가황체(加黃體)가 MOCA가황체(加黃體)보다 우수(優秀)하였 고 또 배합작업(配合作業)에 있어서도 MOCA나 MBMA 가황체(加黃體)보다 작업성(作業性)이 용역(容易)하였는 바 이같은 이유(理由)는 전자(前者)의 녹는 점(點)$(70^{\circ}C)$이 후자(後者)들보다 낮기 때문이다. MBIA의 기타(其他) 특성(特性)으로서는 Pot life가 MOCA가황체(加黃體)보다 2.5배(倍) 길었다. 끝으로 MBEHA와 MBCHA가황체(加黃體)의 특징(特徵)은 가황속도(加黃速度)가 MBIA가황체(加黃體)보다 느림과 동시(同時)에 고무자체(自體)가 부드러웠을 뿐만 아니라 물리적(物理的) 특성(特性)도 좋지 않았다. (2) 미세구조용(微細構造用) 포옴라버 미세구조용((微細構造用) 포옴라버를 제조(製造)할 경우 이때까지 사용(使用)해온 MOCA가황제(加黃劑) 대신(代身) MBMA를 가황제(加黃劑)로 대체사용(代替使用)이 가능(可能)한 바, 이를 사용(使用)하였을 때의 물리적(物理的) 특성(特性)은 MOCA를 사용(使用)하였을 때 보다 인열강도(引裂强度), 신장률(伸張率) 그리고 열안정성등(熱安定性等)은 월등(越等)히 우수(優秀)하였다.

• Elastomers and Composites
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• v.39 no.1
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• pp.61-70
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• 2004

This work is about the development or asphalt sealant using the waste edible oil. Asphalt sealant has been used for crack filler and bridge deck joint sealer Several plasticizers such as aromatic or paraffin process oils, DOP, Bunker C fuel oil, and waste edible oil were compounded with the basic components such as asphalt(AP-5), a thermoplastic elastomer(SBS triblock copolymer), a tackifying agent(petroleum resin), and stabilizers. Penetration, softening point, ductility, and elongation by tensile adhesion of those asphalt sealant compounds were measured. Their properties were changed largely depending on both the type and content of plasticizers. Waste edible oil and DOP were the best plasticizers for the low temperature tensile adhesion characteristics. Penetration and elongation by tensile adhesion of asphalt sealant compounds increased with the increase of waste edible oil content and decreased with the increase of talc content. The manufacture of asphalt sealant with low penetration and excellent low temperature tensile adhesion was possible by the recipe optimization.

• Elastomers and Composites
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• v.6 no.1
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• pp.71-81
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• 1971

The intention of this study is to investigate the properties of polymer blend, NBR/PVC vulcanizates and blending procedures such as roll-mixing temperatures and sequences for polymer blending of NBR and PVC(resin type). The results obtained are as follows: 1. The roll temperature applied for polymer blending is around $150^{\circ}C$. At this temperature region, the degradation of rubber stock, which may be caused by heat, can be minimized and mill processing in practical application in industries can also be facilitated. 2. It is obviously necessary that a small amount of plasticizers should be added to the stock for improving processibility of roll mixing and physical properties. 3. On roll-mixing sequence, it is more effective that PVC compounded with plasticizer is added to NBR milled on hot roll. 4. The vulcanizates of the blends with different degree of polymerization of PVC ale similar to one another in properties. 5. NBR/PVC(70/30) blends shows the better physical characters than eve,-made foreign latex blend except abrasion-resistance. 6. As PVC addition ratio is increased, the physical properties such as resistance to ozone, tear, heat and oil and tensile strength, modulus, hardness have also improved, on the other hand, tension set and rebound character decreased. 7. The curve of ultimate elongation have point of inflection at the ratio of $30\sim40$ part of PVC. 8. While CR is blended, the physical properties such as brittle point, rebound and resistance to oil in high temperature have improved. 9. Polymer blend of NBR and domestic PVC is applied for the industrial utility such as rubber sole and heel, electric wire cover and oil-resistant packing, coating and gasket, printing roll, film for food packing etc.

• Elastomers and Composites
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• v.44 no.1
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• pp.47-54
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• 2009

EPDM(Ethylene-propylene-diene-terpolymer) compound reinforced with carbon black having four different particle size, acetylene black(thermal conductivity carbon black), and silica were manufactured by internal mix and open mill. To investigate the effect of particle size of filler and filler type on far-infrared vulcanization, intermal temperature of compound, degree of curing, infrared spectroscopy, and thermal analysis were measured. The thermal conductivity of far-infrared vulcanized EPDM compound increased with increasing particle size of carbon filler, but hot air vulcanized EPDM compound is not affected by particle size. The thermal conductivity was increased in the order of carbon black < silica < acetylene black(thermal conductivity carbon black).

• Elastomers and Composites
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• v.48 no.1
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• pp.18-23
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• 2013

Nylon 12 elastomer was slightly crosslinked in molten state by the addition of small amount of dicumyl peroxide (DCP) as a crosslink agent and triallycyanuate (TAC) as a co-agent during melt compounding at $160^{\circ}C$ in an internal mixer. The effect of the peroxide crosslinking on mechanical, dynamic mechanical and rheological properties of the nylon 12 elastomer was investigated by means of tensile testing, dynamic mechanical analysis (DMA) and small amplitude oscillating rheometer, respectively. With modification, there is an improvement in tensile modulus and Young's modulus with decease in elongation at break. DMA results for peroxide modified nylon 12 elastomers demonstrated that the glass transiaiton temperature of PTMG segment shifted to higher temperature and the storage modulus remained constant above the melting temperature of nylon 12 segments. Melt rheological studies revealed that the peroxide modified nylon 12 elastomer exhibited a more solid like behavior and stronger shear thinning behavior compared to neat nylon 12 elastomer, which was more prominent at higher TAC content in the polymer matrix. The peroxide modified nylon 12 elastomer exhibited good elastic recoverability and improved mechanical properties without sacrificing melt processibilty, and especially the service temperature range increased as compared to neat nylon 12 elastomer.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.56.1-56.1
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• 2009

The intermediate operating temperature of solid oxide fuel cells (IT-SOFCs) have achieved considerable importance in the area of power fabrication. This is because to improve materials compatibility, their long-term stability and cost saving potential. However, to conserve rational cell performance at reduced-temperature regime, cathode performance should be obtained without negotiating the internal resistance and the electrode kinetics of the cell. Recently, double perovskite structure cathodes have been studied with great attention as a potential material for IT-SOFCs. In this study, double-perovskite structured cathodes of $GdBaCoCuO_{5+\delta}$, $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ compositions and $(1-x)GdBaCo_2O_{5+\delta}+xCe_{0.9}Gd_{0.1}O_{1.95}$ (x = 10, 20, 30 and 40 wt.%) composites were evaluated as the cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). Electrical conductivity of the cathodes were measured by DC 4-probe method, and the thermal expansion coefficient of each sample was measured up to $900^{\circ}C$ by a dilatometer study. Area specific resistances(ASR) of the $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ cathode and 70 wt.% $GdBaCo_2O5+\delta$ + 30wt.% Ce0.9Gd0.1O1.95 composite cathode on CGO electrolyte substrate were analyzed using AC 3-probe impedance study. The obtained results demonstrate that double perovskite-based compositions are promising cathode materials for IT-SOFCs.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.581-585
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• 2012

Machinability is important in engineering applications, especially in the current micro-electronics industry. Most ceramic components have complex shapes and hence require machining generally with diamond tools, which incurs a high production cost. Recently, h-BN-containing machinable ceramics have been developed, but these materials are very expensive due to the high raw materials and production costs. Therefore, the development of low-cost machinable ceramics is necessary. In this study, inexpensive $Al_2TiO_5$ was studied as a replacement for h-BN. $Al_2O_3$, $TiO_2$ and partially stabilized $ZrO_2$(PSZ) powders were mixed with various mole ratios and were sintered at $1500^{\circ}C$ for 1 h. The density, hardness and strength were then measured. The phase analysis and microstructures were observed by XRD and SEM, respectively. The machinability of each specimen was tested by micro-hole machining. The results of this research showed that the produced composites could be used as low-cost machinable ceramics.

• Current Photovoltaic Research
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• v.3 no.1
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• pp.5-9
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• 2015

Absorption and luminescence characteristics of disperse red-19 (DR-19) and $TiO_2$ composite have been investigated with various poling electric field strengths. Two step synthetic processes were employed to employ the DR-19 to the $TiO_2$ sol-gel. Firstly, urethane bond formation between DR-19 (-OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, -N=C=O) performed (ICPDR) prior incorporation to the $TiO_2$ sol-gel. Secondary, the hydrolysis of the ethoxy group from the ICPTES and condensation reaction between silanol groups from ICPTES and $TiO_2$ sol-gel were performed. The ICPDR and $TiO_2$ sol-gel ($DRTiO_2$) were mixed and stirred for several days. The composite was coated to the ITO coated glass substrate. Corona poling were performed before drying the composite with various electric field strengths. The absorption intensity decreased with the increase of the poling field strength, which resulted in the increase of poling efficiency. The photoluminescence also decreased as the poling field strength increased. There is long luminescence tail for the poled $DRTiO_2$ film compared with unpoled $DRTiO_2$ film. The luminescence long tail indicates that the self-trapped excitons and polarons were generated when the $DRTiO_2$ film was poled with electric field.