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173. Directly and quantitatively studying the interfacial interaction between SiO2and elastomer by using peak force AFM

Author

Li, Xiangyan, Feng, Yuxing, Chu, Guangyu, Ning, Nanying, Tian, Ming, and Zhang, Liqun

Abstract

The interfacial interaction between nanofillers and elastomer plays an important role in properties of elastomer nanocomposites. Up to now, most methods focus on studying the interphase of elastomer nanocomposites. The filler-elastomer interaction forces have not been directly and quantitatively characterized yet. In this study, the interaction forces at nano-Newton scale between elastomer matrix and silica (SiO2) were directly and quantitatively characterized by using peak force quantitative nanomechanical mapping (PF-QNM) mode of atomic force microscopy (AFM). Three kinds of nitrile butadiene rubber (NBR) molecules with different molecular polarity were first grafted on the AFM tip by using click chemistry. The SiO2(or modified SiO2) were pressed into flat films and worked as substrate. The interaction forces between these NBR layer grafted on AFM tip and SiO2(or modified SiO2) substrate were directly and quantitatively obtained. The results show that as the acrylonitrile content of NBR increasing from 26wt% to 41wt%, the average interaction force of NBR/SiO2increases from 4.5 ± 1.0nN to 7.7 ± 1.1nN and that of NBR/m-SiO2increases from 6.2 ± 1.2nN to 12.9 ± 1.0nN. This study provides guidance in direct and quantitative characterization of filler-elastomer interactions at nano-Newton resolution.

Published
2018
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179. Tailoring dielectric properties of polymer composites by controlling alignment of carbon nanotubes.

Author

Liu, Suting, Tian, Ming, Zhang, Liqun, Lu, Yonglai, Chan, Tung, and Ning, Nanying

Subjects
POLYMERIC composites, ELECTRIC properties of materials, CARBON nanotubes, ORIENTATION (Chemistry), MECHANICAL behavior of materials
Abstract

We prepared hydrogenated butadiene-acrylonitrile (HNBR) elastomer composites with random orientations of carbon nanotubes (CNTs) and aligned CNTs, denoted by random composites and aligned composites, respectively, by means of a simple mechanical blending method. The CNTs were dispersed uniformly in the HNBR matrix in both types of composites. Interestingly, at CNT contents of 1-2.5 vol%, the dielectric loss (tan δ) of the aligned composites increases slightly, and the dielectric constant ( ε′) of aligned composites increases largely with the increasing content of CNTs, whereas both the tan δ and the ε′ of the random composites increase largely with the increasing content of CNTs. As a result, a high ε′ (5000 at 1000 Hz) and a low tan δ (0.42 at 1000 Hz) were obtained in the aligned composite with a CNT content of 2.5 vol%, whereas a high ε′ and a high tan δ were obtained in the random composites. The relationship between the microstructure and dielectric properties was qualitatively analyzed by means of the percolation theory and intercluster polarization model. The mechanism for the achievement of high ε′ and low tan δ for dielectric composites was discussed. This study provides a guide to design microstructure that yields composites with improved dielectric properties. [ABSTRACT FROM AUTHOR]

Published
2016
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180. Study on the microstructure and properties of bromobutyl rubber (BIIR)/polyamide-12 (PA12) thermoplastic vulcanizates (TPVs).

Author

Ning, Nanying, Hu, Linjia, Yao, Pengjun, Wu, Hanguang, Han, Jibin, Zhang, Liqun, Tian, Hongchi, and Tian, Ming

Subjects
THERMOPLASTIC composites, BUTYL rubber, POLYAMIDES, MICROSTRUCTURE, VULCANIZATION, MECHANICAL behavior of materials, POLYPROPYLENE
Abstract

In this study, polyamide-12 (PA12)/brominated isobutylene-isoprene (BIIR) TPVs with good mechanical properties and low gas permeability were prepared by dynamic vulcanization in a twin-screw extruder. The effects of three kinds of compatibilizers on the microstructure and properties of BIIR/PA12 TPV were studied. The compatibility between BIIR and PA12 was improved when maleated hydrocarbon polymeric compatibilizer is added. The reaction between maleic anhydride and amine in polyamide leads to the in situ formation of hydrocarbon polymer grafted polyamide which subsequently can be used to lower the interfacial tension between BIIR and polyamide. The compatibilizing effect of maleic anhydride modified polypropylene (PP-g-MAH) on BIIR/PA12 blends is the best among these compatibilizers because the surface energy of PP-g-MAH is very close to that of BIIR. The dispersed rubber phase of the blend compatibilized by PP-g-MAH shows the smallest size and more uniform size distribution, and the resulting TPVs show the best mechanical properties. The effects of fillers on the properties of BIIR/PA12 TPV were also investigated. The size of the BIIR phase increases with the increase in the content of CaCO3. The modulus and tensile strength of TPVs increased with the increase in the content of CaCO3 because of the reinforcing effect of CaCO3 on TPVs. [ABSTRACT FROM AUTHOR]

Published
2016
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182. High elasticity and conductivity of elastomer composites with arrayed carbon nanotubes as nanosprings.

Author

Ning, Nanying, Ji, Lianjie, Zhang, Liqun, Liu, Jun, Lu, Yonglai, Wu, Shemao, Zou, Hua, Tian, Ming, and Chan, Tung W.

Subjects
*ELASTOMERS, *SILICONES, *CARBON nanotubes, *COMPOSITE materials, *THERMAL conductivity, *VISCOELASTICITY, *MOLECULAR dynamics
Abstract

Previous studies using molecular simulation indicated that carbon nanotubes (CNTs) can act as nanosprings to adjust the viscoelasticity of elastomer composites. In this study, we prepared elastomer composites with both high elasticity and conductivity for the first time using carbon nanotubes array (CNTA) as nanosprings. A special CNTA bundle prepared by electrostatic self-assembly was directly blended with the polymethylvinylsiloxane (PMVS) matrix. The results indicated that these CNTAs were well dissociated into many single CNTs with almost no change in length in the PMVS matrix with low viscosity during mechanical shearing, and exhibited a nanospring effect. The CNTA composites exhibited not only higher conductivity and electromagnetic shielding effectiveness but also higher elasticity than the commonly used conductive carbon black composites at the same filler content. This study indicated that high performance conductive elastomer composites can be obtained by using special CNTAs as nanosprings. [ABSTRACT FROM AUTHOR]

Published
2015
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189. Superstretchable Liquid-Metal Electrodes for Dielectric Elastomer Transducers and Flexible Circuits

Author

Zang, Wenpeng, Wang, Yuhao, Wu, Wenju, Yao, Jiashuai, Hao, Xuesong, Yu, Bing, Wu, Daming, Cao, Peng-Fei, Jiang, Yingjie, Ning, Nanying, Tian, Ming, and Zhang, Liqun

Abstract

Dielectric elastomer transducers (DETs), with a dielectric elastomer (DE) film sandwiched between two compliant electrodes, are highly sought after in the fields of soft robotics, energy harvesting, and human–machine interaction. To achieve a high-performance DET, it is essential to develop electrodes with high conductivity, strain-insensitive resistance, and adaptability. Herein, we design an electrode (Supra-LMNs) based on multiple dynamic bond cross-linked supramolecular networks (Ns) and liquid metal (LM), which realizes high conductivity (up to 16,000 S cm–1), negligible resistance changes at high strain (1.3-fold increase at 1000% strain), instantaneous self-healability at ambient temperature, and rapid recycling. The conductive pathway can be activated through simple friction by transmitting stress through the silver nanowires (AgNWs) and cross-linking sites of LM particles. This method is especially attractive for printing circuits on flexible substrates, especially DE films. Utilized as dielectric elastomer generator (DEG) electrodes, it reduces the charge loss by 3 orders of magnitude and achieves high generating energy density and energy conversion efficiency on a low-resistance load. Additionally, serving as sensor (DES) and actuator (DEA) electrodes, it enables a highly sensitive sensing capability and complex interaction.

Published
2023
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190. Reactive Janus Particle Compatibilizer with Adjustable Structure and Optimal Interface Location for Compatibilization of Highly Immiscible Polymer Blends

Author

Hu, Jing, Hao, Xinyue, Ning, Nanying, Yu, Bing, and Tian, Ming

Abstract

Highly immiscible blend materials with distinctive and excellent properties play a key role in meeting the application needs, especially in extreme environments, and reactive nanoparticles are used to increase the interface adhesion and optimize the morphology of highly immiscible blending. However, these reactive nanoparticles tend to aggregate and even agglomerate during reactive blending, which significantly deteriorates their compatibilization efficiency. Herein, reactive Janus particles with the epoxy group and various siloxane molecular long chain grafting ratios (E-JP-PDMS) were synthesized using SiO2@PDVB Janus particles (JP) and used as compatibilizers for polyamide and methyl vinyl silicone elastomer (PA/MVQ) blends, which were highly immiscible. The effects of the structure of E-JP-PDMS Janus nanoparticles on their location at the interfaces between the PA and MVQ as well as their compatibilization efficiency for the PA/MVQ blends were investigated. The location and dispersion of E-JP-PDMS at the interfaces were improved by increasing the PDMS content in E-JP-PDMS. The average diameter of the MVQ domains of the PA/MVQ (70/30, w/w) was 79.5 μm and was reduced to 5.3 μm in the presence of 3.0 wt % of the E-JP-PDMS with 65 wt % PDMS. As a comparison, it was 45.1 μm in the presence of 3.0 wt % of a commercial compatibilizer (ethylene-butylacylate-maleic anhydride copolymer, denoted as EBAMAH), which provides a guideline for the design and preparation of efficient compatibilizers for highly immiscible polymer blends.

Published
2023
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197. Extremely high energy density and long fatigue life of nano-silica/polymethylvinylsiloxane dielectric elastomer generator by interfacial design

Author

Li, Weibo, Liu, Xueying, Jiang, Yingjie, Wu, Wenju, Yu, Bing, Ning, Nanying, Tian, Ming, and Zhang, Liqun

Abstract

Dielectric elastomer generator (DEG) can harvest electrical energy from various movement in nature such as human walking and ocean waves. To achieve high energy harvesting performance of DEG, dielectric elastomer (DE) composite with strong interfacial interaction, and thus high electrical breakdown strength (Eb) and long fatigue life (NFL) at high strain is a key. In this study, nano-silica (SiO2)/polymethylvinylsiloxane (PMVS) DE composite with strong interfacial interaction for DEG with extremely high energy density (w), high power conversion efficiency (PCE) and long NFLwas prepared by designing and synthesizing a new polar macromolecule coupling agent (MCA), ester group grafted liquid butadiene rubber using a photoinitiated thiol-ene click reaction. Compared with the common small molecule coupling agent (SCA) modified SiO2(SCA@SiO2)/PMVS composite, the new MCA modified SiO2(MCA@SiO2)/PMVS composite shows much stronger interfacial interaction owing to the largely increased co-crosslinking junction and chain entanglement, resulting in the significantly improved elongation at break and Ebat high strain (400%). As a result, MCA@SiO2/PMVS DEG exhibits an up-to-date highest w(92.2 mJ/cm3) and PCE(35.8%) among the previously reported DEG using unprestretched DE film, and its NFLreaches 141000 times, 3.9 times that of SCA@SiO2/PMVS DEG (36000 times). Thus, MCA@SiO2/PMVS DEG shows the highest full-life generating energy density (9710 J/cm3), 4.8 times and 2427 times that of SCA@SiO2/PMVS DEG and commercial VHB DEG, respectively.

Published
2022
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198. Towards optimization of electrical network and mechanical property of polymer nanocomposites with grafted nanoparticles.

Author

Feng, Yancong, Ning, Nanying, Wei, Zhaoyang, Zhang, Liqun, Tian, Ming, Zou, Hua, and Mi, Jianguo

Subjects
*ELECTRIC properties of polymers, *POLYMER networks, *MECHANICAL properties of polymers, *POLYMERIC nanocomposites, *GRAFT copolymers, *DISPERSION (Chemistry)
Abstract

Abstract: We demonstrate that comprehensive electrical network and mechanical property of polymer nanocomposite (PNC) are coherently related to the specific dispersion of nanoparticles, which can be controlled by grafting like and unlike polymer chains. For PNC where the graft chain has the same chemistry as matrix, if the graft chains are relatively short, the grafted nanoparticle containing 0.4 chains in unit area can result in a loose and continuous percolating cluster, at which the optimized electrical and mechanical utilities can be achieved. At low grafting density (0.08 chains in unit area), the optimized characteristics can be fulfilled through extending the graft chain length to the ratio of 0.4 (graft chain length to matrix chain length). If the graft chain has different chemical structure, the optimum performance of PNC emerges at the low grafting density, where the matrix–graft interaction is 1.5 times the matrix–matrix interaction, and the ratio is 0.5. [Copyright &y& Elsevier]

Published
2014
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199. Stretching induced interfacial crystallization and property enhancement of poly(l-lactide)/single-walled carbon nanotubes fibers.

Author

Zhang, Wei, Ning, Nanying, Gao, Yao, Xu, Fan, and Fu, Qiang

Subjects
*CRYSTALLIZATION, *LACTIDES, *SINGLE walled carbon nanotubes, *FIBROUS composites, *STRUCTURAL analysis (Engineering), *TENSILE strength
Abstract

Abstract: In this work, poly(l-lactide) (PLLA)/single-walled carbon nanotubes (SWNTs) fibers were first prepared at high drown ratio and low drown ratio, respectively. Then they subjected to tensile testing. It was found that the composite fibers obtained at low drown ratio showed no obvious enhancement of tensile strength and elongation at break, compared with the pure PLLA fibers obtained at the same low drown ratio. However, a significant property enhancement was observed for the composites fibers obtained at high drown ratio. Structure analysis of the as spun fibers before and after tensile testing suggests a possible stretching induced formation of brush-like hybrid structure in which the PLLA lamellae growing perpendicular to the SWNTs axis for fibers obtained at high drown ratio. This unique brush-like hybrid structure could largely enhance the interfacial interaction between PLLA and SWNTs, thus results in greatly improved tensile strength and elongation at break. [Copyright &y& Elsevier]

Published
2013
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200. Combined effect of β-nucleating agent and processing melt temperature on the toughness of impact polypropylene copolymer.

Author

Luo, Feng, Xu, Chenlong, Ning, Nanying, Wang, Ke, Deng, Hua, Chen, Feng, and Fu, Qiang

Subjects
COPOLYMERS, POLYPROPYLENE, NUCLEATION, TEMPERATURE, MICROSTRUCTURE, STRENGTH of materials
Abstract

The phase morphology and toughening behavior of impact polypropylene copolymer (IPC) with and without nucleating agent (NA), prepared at different processing melt temperatures ( Tp), were investigated. Interestingly, three different structures can be formed in the IPC samples by adding NA or tuning Tp. A well-defined core-shell structure is obtained in samples with α-NA or without NA prepared at all Tp. A developing multilayered structure is mainly formed at high Tp with added β-NA, while an incomplete phase separation structure with interpenetrating chains is the dominant structure for IPC samples prepared at low Tp with added β-NA. In this case, because of the synergistic effect between phase morphology and relatively high β-form crystal content, the chain interaction among the components and chain mobility of the amorphous portion of IPC are distinctly improved, resulting in a largely improved toughness under 0 °C. This improvement in toughness is very important for applications. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Published
2013
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