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Gao, Tianming,Na, Bokgyun,Choi, Hyoungjin,Chung, Kyungho North-Holland 2018 Materials letters Vol.214 No.-
<P><B>Abstract</B></P> <P>The metal-ligand complex (sacrificial bonds) that exist in the mussels, bone and silk can dissipate energy and reinforce mechanical strength. Inspired by the high performance of metal-ligand complex, we introduced a kind of metal-ligand crosslink into the rubber network. In this work, ethylene acrylic elastomer (AEM) was filled with ZnO, and was cured by the amine cure system. The metal-ligand crosslink structure was verified by FTIR and XPS, and the tensile strength and dynamic properties were examined with a universal testing machine and rubber process analyzer (RPA). The results showed that coordination crosslink formed in the AEM matrix and exhibited outstanding tensile strength and unexpected dynamic properties due to the coordination bonds between Zn<SUP>2+</SUP> and amine group.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zinc oxide (ZnO) filled AEM and reacted with the amine group to achieve the coordinated bonds. </LI> <LI> The coordinated bonds had been verified by FTIR and XPS. </LI> <LI> The coordinated bonds can dissipate energy and preserve the structure integrity of elastomer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The zinc oxide (ZnO) filled AEM and reacted with the amine group to achieve the coordinated bonds. The dynamic properties of AEM exhibit that the coordinated bonds can dissipate energy and preserve the structure integrity of elastomer.</P> <P>[DISPLAY OMISSION]</P>
Characterization of the Dynamic Properties of Natural Rubbers Coagulated Using Different Methods
Tianming Gao,Ruihong Xie,Linghong Zhang,Puwang Li,Hongxing Gui,Maofang Huang,Kyungho Chung(정경호) 한국고분자학회 2016 폴리머 Vol.40 No.3
천연고무 라텍스를 아세트산을 사용한 응고(A-NR), 자연 응고(N-NR) 및 미생물을 사용한 응고(M-NR) 등 다른 방법들로 응고하였고, 이들의 가교도, 가교특성, 동적특성 및 열축적 특성 등을 조사하였다. 결과에 따르면 MNR의 경우 가장 높은 가교도와 가장 빠른 경화속도를 나타냈으며, A-NR은 정 반대인 가장 낮은 가교도와 가장 느린 경화속도를 나타내었다. 이들 고무의 동적특성은 rubber process analyzer(RPA), dynamic mechanical analyzer(DMA) 및 압축 열축적 분석방법 등을 이용하여 측정하였다. 동적특성은 고무의 가교도와 매우 밀접한 관계가 있었음을 알 수 있었고, 손실계수는 M-NR이 가장 낮았으며 A-NR의 경우는 가장 높은 값을 나타내었다. Natural rubber (NR) was coagulated using different methods, i.e., acid coagulation with acetic acid (A-NR), natural coagulation (N-NR), and microorganism coagulation (M-NR). The crosslink density, vulcanization properties, dynamic properties, and heat build-up were investigated. The results showed that M-NR had the highest crosslink density and fastest cure rate, and A-NR had the lowest crosslink density and slowest cure rate. The dynamic properties were measured using a rubber process analyzer, dynamic thermomechanical analysis and compression heat build-up tester; the results showed that the dynamic properties had a close relationship with the crosslink density. The loss factor was lowest for M-NR and highest for A-NR.
Tianming Gao(고천명),Bokgyun Na(나복균),Namyun Kim(김남윤),Kyungho Chung(정경호) 한국고분자학회 2018 폴리머 Vol.42 No.4
엘라스토머 가공에서 가황반응은 매우 중요한 공정이다. 천연고무(NR)를 사용한 자기유변탄성체(MRE)에 관한 연구들은 많이 수행되어 왔지만 엘라스토머 경화 시스템이 천연고무계 MRE의 계면접착 및 기계적 특성에 미치는 영향에 대해서는 연구가 거의 이루어지지 않았다. 본 연구에서는 경화제로 황과 디큐밀퍼옥사이드(DCP)를 사용하여 이들이 NR계 MRE의 특성에 미치는 영향을 조사하였다. MRE 매트릭스에 분산된 카보닐 철 입자(CIP)와 매트릭스의 계면 접착력은 주사전자현미경을 사용하여 분석하였다. 결과에 따르면 경화제로 황을 사용할 경우보다 DCP를 사용할 경우 MRE의 가교도가 높았다. 또한 CIP가 30 vol% 배합되었을 때 DCP 경화 시스템의 경우는 인장강도가 증가하였지만, 황 경화 시스템의 경우는 감소하였다. 개선된 DMA 장치를 사용하여 자기장이 인가된 상태에서 MRE의 자기유변 특성이 조사되었다. Vulcanization is an important procedure for elastomers processing. The effects of vulcanization system on the interfacial interaction and mechanical properties of magneto-rheological elastomers (MREs) based on natural rubber (NR) have not been researched, even though, there were many researches focusing on the natural rubber based MREs. In this work, sulfur and dicumyl peroxide (DCP) acted as curing agents preparing MREs based on NR. Scanning electron microscopy was used to characterize the interfacial adhesion of carbonyl iron particles (CIPs) in the matrix. Crosslink density provided evidence that the MREs with DCP system had higher crosslink density than that of MREs with sulfur system. The tensile strength of MREs with DCP system increased, while that of MREs with sulfur system decreased, when 30 vol% of CIPs filled into NR. Finally, the magneto-induced dynamic mechanical properties were tested using a modified dynamic thermo-mechanical analysis under magnetic fields.