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SBR 컴파운드의 가황 및 기계적 성질에 미치는 카본블랙 표면의 화학적 개질의 영향
나창운(Chang Woon Nah),이종문(John M . Rhee),김완두(Wan Doo Kim),강신영(Shin Young Kaang),장영욱(Young Wook Chang),박수진(Soo Jin Park) 한국고무학회 2001 엘라스토머 및 콤포지트 Vol.36 No.1
To see the effect of chemical surface modification, the carbon black surfaces were treated with three types of chemicals (KOH, H₃PO₄, and benzene). Vulcanization and mechanical properties of a styrene-butadiene rubber (SBR) were investigated depending on the chemical treatments. The surface free energy increased considerably with the treatments by both the acid (HCB) and base (KCB), but only a slight increase was observed for benzene treatment(BCB). The BCB showed the highest level of the London dispersive component. The vulcanization reaction was found to be faster in the order of KCB-SBR$gt;BCB-SBR$gt;VCB-SBR(virgin)$gt;HCB-SBR. The difference in minimum and maximum torque of rheocurve, representing the degree of crosslinking, was found to be higher for the BCB-SBR compared to those of VCB-SBR, KCB-SBR, and HCB-SBR. The BCB-SBR and KCB-SBR showed the improved tensile and dynamic mechanical properties. A linear relationship was found to exist between the London dispersive component of surface free energy and mechanical properties.
나창운(Chang Woon Nah),김대훈(Dai Hoon Kim),김동진(Dong Jin Kim),김완두(Wan Doo Kim),장영욱(Young Wook Chang) 한국공업화학회 2002 공업화학 Vol.13 No.4
염소화 처리에 따른 천연고무 쉬트(sheet)의 마찰특성을 새로운 형태의 마찰시험기를 이용하여 조사하였다. 아울러 염소화에 따른 표면의 분자구조, 표면 모폴로지 및 경도의 변화를 조사하였다. 천연고무 쉬트의 표면은 염소화 반응으로 분자구조의 변화가 확인되었고, 장시간 처리조건에서는 고리화 반응도 관찰되었다. 염소화 처리시간에 따라 마찰계수는 큰 폭으로 감소하였고, 염소화 초기단계에서 보다 급격한 감소를 보였다. 염소화에 따른 마찰계수 감소의 주요 원인은 경도와 표면 거칠기로 설명되었다. 경도의 증가는 접촉면적과 고무의 변형을 감소시킴으로써 각각 접착마찰과 히스테리시스 마찰을 감소시키고, 거칠기의 증가는 접촉면적을 감소시켜 접착마찰을 감소시킨 것으로 설명되었다. Using a new friction tester, the frictional property of chlorinated-natural rubber sheet was investigated as a function of the chlorination time. The changes in molecular structure, morphology, and hardness on the surface of the rubber sheet were also investigated with the chlorination time. It was confirmed that the molecular structure on the surface of natural rubber sheet has changed due to the chlorination reaction, and with a longer chlorination treatments a cyclization reaction was observed. The frictional coefficient decreased significantly with increasing the chlorination time, and the decrease rate was the highest at the initial stage of the chlorination reaction. Such rapid drop in the frictional coefficient--upon chlorination--can explained by two main parameters: surface roughness and hardness. The increase in the hardness caused a reduction in both the contact area and deformation of rubber, thereby decreasing the adhesive and hysteresis frictions. The increase in the surface roughness reduced the contact area, which in turn decreased the adhesive friction.
Natural Rubber / Acrylonitrile - Butadiene Rubber 블랜드의 기계적 물성과 강선과의 접착거동
나창운(Chang Woon Nah),손봉영(Bong Young Sohn) 한국고무학회 2001 엘라스토머 및 콤포지트 Vol.36 No.2
N/A Mechanical properties and their adhesion behavior with zinc- and brass-plated steel cords of natural rubber/acrylonitrile-butadiene blend compounds were investigated as a function of blend ratio. The Mooney viscosity and stress relaxation time were found to be lowered with increasing NBR content. Tensile modulus generally increased with increasing NBR content. Tensile stress at break stayed constant up to about 40 phr and showed minimum at 50∼60 phr, and thereafter increased with increasing NBR content. Strain at break decreased linearly below 50 phr, and above the level it showed nearly constant value. Based on the abrupt drops in elastic modules and tan8 peak, the glass transition temperature of NR and NBR were found to be -55 and -10℃ respectively. In the case of NR/NBR blend compounds, two distinct transition points were observed and each transition position was not affected by NBR level indicating an incompatible nature of NR/NBR blend system. The pullout foroe and rubber coverage decreased to the level of about 40% to that of pure NR compound, when the 50 phr of NR was replaced by NBR. However, the pure NBR compound showed the comparable adhesion performance with NR(∼90%). The sulfur concentration was found to become lower with the increased NBR content at the adhesion interface based on the Auger spectrometer results, representing a lack of adhesion layer formation, and this was explained for a possible cause of low adhesion performance with adding NBR.
나창운(Chang Woon Nah),김현재(Hyeon Jae Kim),강신영(Shin Young Kaang) 한국고무학회 1998 엘라스토머 및 콤포지트 Vol.33 No.4
N/A Tensile properties including Young`s modulus and tear strength were measured for four different rubber compounds; natural rubber(NR), styrene-butadiene copolymer(SBR), ethylene-propylene dime monomer(EPDM), and brominated isobutylene-p-methyl-styrene copolymer(BIMS) as a function of temperature and degree of cure. To see the effect of over cure, a measurement was made of the tensile strength and swelling behavior of the over-cured rubber compounds. Young`s modulus, E, was found to have linear dependency on the degree of cure for all rubber compounds. EPDM and BIMS showed the highest and lowest slopes, respectively. The slope of NR and SBR lay between EPDM and BIMS. Tear strength, Gc, decreased in the order of NR$gt;BIMS$gt;SBR$gt;EPDM. As the cure time was extended the degree of cure of NR and SBR decreased, while that of BIMS increased. EPDM showed little change in the degree of cure.
고무층간 가교정도가 접착강도 및 파괴형태에 미치는 영향
나창운(Chang Woon Nah),김현재(Hyeon Jae Kim),강신영(Shin Young Kaang) 한국고무학회 1999 엘라스토머 및 콤포지트 Vol.34 No.1
N/A Interfacial adhesive strength between the fully-crosslinked and partially-crosslinked rubber layers were investigated at the temperature range of 30∼120℃ for four different rubbers(NR, SBR, EPDM, BIMS). The surfaces of interfacial failure were also investigated using a scanning electron microscopy(SEM). The physical interlinking played a major role in the adhesive strength between the fully-crosslinked rubber layers. When a partially-crosslinked rubber layer was bonded to the fully-crosslinked one, the chemical as well as the physical interlinking affected the adhesive strength. NR showed a $quot;interfacial knotty tearing$quot; pattern, while EPDM showed a typical $quot;cross-hatched$quot; one when the adhesive strength approached to the cohesive tear strength of each material.