http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Gopi Sathi, Shibulal (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
-
Yoonjae Seong,Shibulal Gopi Sathi,Jongho Park,In-Seok Park,나창운 한국섬유공학회 2020 Fibers and polymers Vol.21 No.1
Composites based on ethylene-acrylic rubber and 1 mm short aramid fibers (AF) were developed by varying thefiber content from 3 to 40 phr. At 10 phr short fiber loading, the tensile modulus (10 % modulus) of the neat matrix wasaround 11 times increased. However, its breaking elongation was decreased from 408 to 58 %. This drastic reduction in thebreaking elongation even at a 10 phr fiber loading leads to a brittle failure with inferior toughness. The tensile-fracturedsurface of the fiber-filled composite showed an intact matrix with no plastic deformation during fiber pulled-out. To solve thisproblem, carbon black (CB) was used as a toughening agent. Surprisingly, the addition of 20 phr CB onto a 10 phr AF-filledcomposite enhanced its 10 % modulus in the longitudinal direction by 70 % and also enhanced its breaking elongation from58 to 351 %. From the morphological analysis, it has been presumed that the addition of CB enhanced the friction betweenthe fiber and the matrix at a very low strain and also facilitate the matrix for a plastic deformation at a higher strain. Thisenhanced friction between the fiber and the matrix is considered as the improved low strain modulus and the subsequentplastic deformation at a higher strain is responsible for the improved toughness.
-
Lifetime Prediction of Flame Retardant-Filled Ethylene-Propylene-Diene-Termonomer Rubber Compounds
Jaeho Oh(오재호),Gopi Sathi Shibulal(고피사티 쉬부랄),Bismark Mensah(비스마르크 맨사),Dae-Up Ahn(안대업),Seong-Jin Kim(김성진),Kwang-Un Jeong(정광운),Changwoon Nah(나창운) 한국고분자학회 2015 폴리머 Vol.39 No.5
여러 가지 난연제(Sb₂O₃, 브롬 및 염소계 난연제)를 함유하는 에틸렌-프로필렌-디엔-터모노머(EPDM) 고무컴파운드의 수명을 예측하였다. 각 고무 컴파운드에 대해 120, 135, 150, 165℃온도조건에서 열노화를 진행하고 노화전후의 인장특성을 조사하였다. 본 연구에서는 노화전 파단신장률이 50%로 감소되는 시간을 수명이라 정의하고 Dakin-Arrhenius 방정식을 이용하여 수명을 예측하였다. 미충전 EPDM과 Sb₂O₃,을 함유한 EPDM의 경우 상온에서 100년에 가까운 수명이 예측되었다. 그러나 브롬계 난연제를 단독 혹은 Sb2O3와 혼용한 EPDM의 경우 미충전EPDM 수명의 절반으로 감소하였다. 염소계 난연제를 단독 혹은 Sb₂O₃,와 혼용한 EPDM의 경우 각각 90년과 82년으로 예측되었다. The lifetime of ethylene-propylene-diene-termonomer (EPDM) based rubber compounds with various flame retardants (FRs) including antimony trioxide (Sb₂O₃), halogenated (Br, Cl) materials and their combinations with Sb₂O₃ have been explored in this study. The tensile properties of the compounds have been evaluated before and after the thermal ageing over a range of temperatures, 120, 135, 150 and 165℃ for different span of time. A 50% reduction in elongation at break (EB) due to thermal ageing is fixed as a failure criterion to predict the lifetime with the help of Dakin- Arrhenius equations. The predicted lifetime of the base EPDM and its Sb₂O₃-filled compounds shows almost 100 years at ambient temperature. However, the bromine containing flame retardant-filled EPDM as well as its combination with Sb₂O₃-filled EPDM compounds have reduced their lifetime to almost half of the lifetime of base EPDM. The predicted lifetime of EPDM compounds with chlorine containing FR and its combination with Sb₂O₃ shows around 90 years and 82 years, respectively.
-
Development and Characterization of Asymmetric Swelling-Induced Wrinkles on Natural Rubber Surface
( Gi-bbeum Lee ),( Shibulal Gopi Sathi ),( Min Jung Kim ),( Changsin Park ),( Yang Il Huh ),( Changwoon Nah ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.4
Characteristics of the swelling-induced wrinkles on the surfaces of natural rubber (NR) film were investigated. The wrinkle structure was generated by swelling of NR film pre-stretched and firmly bonded onto an aluminum substrate in hexane. A novel experimental method was adopted to replicate the swelling-induced wrinkles on the NR film using an epoxy-hardener system. To get insight into the wrinkle parameters; the wrinkle length (L), wrinkle distance (D), wrinkle height (H) and the angle between two consecutive wrinkles (θ), the cross-sections of the replicas obtained from saturated swollen NR film were examined using an optical microscopy (OM). From the OM images, the wrinkling parameters were measured as a function of the thickness of NR film from 0.42 to 1.76 mm. Also, it was evaluated that the effects of swelling time on the wrinkling parameters. The length (L), distance (D) and height (H) of wrinkles increased as the thickness of the NR film and the swelling time increased. However, the angle between the wrinkles (θ) showed a sharp decrease up to a swelling time of 200 minutes and slightly decreased afterwards.
-
Nah, Changwoon,Kim, Seung Gyeom,Shibulal, Gopi Sathi,Yoo, Yong Hwan,Mensah, Bismark,Jeong, Byeong-Heon,Hong, Bo Ki,Ahn, Jou-Hyeon Elsevier 2015 International journal of hydrogen energy Vol.40 No.33
<P><B>Abstract</B></P> <P>Ethylene-propylene-diene-termonomer (EPDM) rubber based fuel cell gasket compounds have been designed and explored the effects of various vulcanization systems on different properties. Three types of sulphur-accelerated vulcanization systems such as conventional vulcanization (con), semi-efficient vulcanization (sev) and efficient vulcanization (ev) and also a peroxide vulcanization system were employed in this study. The curing characteristics, tensile, hardness and compression set properties of the cured compounds were evaluated. The crosslink density was assessed by equilibrium swelling method in dodecane. The chemical stability of the cured EPDM compounds was also evaluated through an accelerated durability test (ADT) using a solution (1 M H<SUB>2</SUB>SO<SUB>4</SUB> + 10 ppm HF) very close to the fuel cell atmosphere. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were employed to investigate the chemical and physical changes of the cured EPDM compounds before and after exposure to the ADT solution over time. The results indicate that the EPDM compounds cured with peroxide exhibit the highest crosslink density with lowest compression set value at both room temperature and at elevated temperature. The FTIR and the corresponding SEM results show no significant chemical degradation of the peroxide cured EPDM compounds due to ADT ageing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We examine the long-term ageing resistance of rubber vulcanizates in a simulated fuel cell environment. </LI> <LI> We monitor the chemical and physical change during ageing. </LI> <LI> The peroxide cure system shows much enhanced resistance to ageing than sulphur cure system. </LI> <LI> The cure additive such as ZnO in the sulphur cure system can negatively affect the performance of fuel cell. </LI> </UL> </P>
DBpia연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
