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Dielectric elastomer generators (DEGs) based on silicone rubber composites have received considerable attention in recent years. However, the addition of traditional rigid dielectric fillers not only increases the modulus of composites but also leads to interface debonding between the filler and elastomer matrix under high stretching conditions, thereby limiting the energy harvesting performance. Here, gel-like ester group grafted butadiene rubber (GEBR) with a relatively low modulus was synthesized and used as a "soft filler" to enhance energy harvesting performance of PMVS-based DE composites. The GEBR filler with a high concentration of polar groups could lead to an increase in the dielectric constant of GEBR/PMVS composites by the introduction of interfacial polarizability and the improvement of dipole polarizability. Most notably, compared with TiO2 as the rigid filler, the combination of GEBR's deformability under stretching and strong interfacial interaction between the GEBR filler and PMVS matrix could effectively prevent weak interface formation under high strain conditions, and thus hinder the propagation of electrical treeing. As a result, benefiting from the GEBR filler with a low modulus, 5 vol% GEBR/PMVS DEG exhibits an excellent maximal energy density (65.4 mJ g−1) and outstanding power conversion efficiency (38.4%), achieving a high energy density at relatively low input mechanical force. This study presents a pioneering methodology to fabricate high-performance all-organic DE composites for DEGs through designing a soft dielectric filler with exceptional deformability under stretching. [ABSTRACT FROM AUTHOR]

Metal materials play an important role in electromagnetic interference (EMI) shielding due to their ultra‐high electrical conductivity, but they are rigid and inflexible, as well as of high density, which limits their application in some areas. In this study, a novel and simple method to fabricate the composites of metal foil and polymer is reported. A copper foil (Cuf) with micropores on the surface is used as a shielding matrix, then interpenetrating and interlocking nanostructure as well as reactive groups are introduced on its surface, and then silicone rubber (SiR) is coated on both surfaces to form a sandwich structure, and the obtained Cuf/SiR composites possesses high EMI shielding efficiency (SE), strong interface adhesion, and low density. The average EMI shielding efficiency of the obtained Cuf/SiR composites in the range of 1.13–18 GHz is 111.5 dB, with a high interface adhesion strength of 5.2 N cm−1 and low density of 1.3 g cm−3, and it also possesses bending and splicing properties, which exhibits broad potential application in the field of EMI shielding tents and shielding rooms. This preparation method of the composites is simple and efficient, and provides a guideline for the design and fabrication of metal foil/polymer composites in molding method. [ABSTRACT FROM AUTHOR]

In this study, erucamide as a non‐toxic and tasteless lubricant was melt blended with thermoplastic polyurethane (TPU) to reduce the coefficient of friction (COF) of TPU and thus to improve the wearing comfort of intelligent wearable devices. The results show that when the content of erucamide reaches percolation, erucamide can migrate to the TPU surface, forming a layer of lubrication film, and thus significantly reduces the COF of TPU. In addition, erucamide with amide groups can form hydrogen bonds with carbamate groups from TPU chains and thus can disrupt the hydrogen bonds between two amide groups of TPU chains. With the introduction of erucamide, the chain mobility of TPU increases, the partial phase mixing of soft phase and hard phase of TPU occurs, and the interchain interaction between TPU chains decreases. Under the appropriate content of erucamide (0.5 wt%), both the elasticity and processability of TPU are also significantly improved, whereas the high tensile strength, tear strength and elongation at break of the TPU blend is still obtained, facilitating its practical application in intelligent wearable devices. © 2022 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Intelligent fluorescent coatings have received widespread attention in the encryption technique field such as anti‐counterfeit, while the traditional fluorescent coatings are easy to be damaged by external force. In this study, the fluorescent and self‐healing anti‐counterfeit coatings are prepared after rational molecular design. Two polymers containing fluorescent groups, including polyurethane containing the anthracene (AN) side group and polyimide containing the naphthalenediimide (NDI) structure are synthesized to realize multiple color changes with fluorescence through simply blending. Due to the overlapping fluorescence spectra of the groups, enabling the fluorescence resonance energy transfer effect (FRET), the coating with different group ratios exhibits tunable fluorescence under the same excitation light, providing diverse patterns. Moreover, due to the reversible photo‐crosslinking and thermal de‐dimerization properties of anthracene, the recording, erasure, and rewriting of the surface pattern can be realized, and the fluorescent anti‐counterfeit coatings exhibit excellent self‐healing properties after cross‐linking due to the FRET effect, which solves the problem of poor healing and ensures the stability and integrity. The fluorescent coating with cross‐linked structure and self‐healing behavior based on the FRET effect greatly expands the functional applications of traditional polyurethane materials. [ABSTRACT FROM AUTHOR]

To achieve dielectric elastomer generators (DEGs) with excellent energy harvesting performance and long life, electrode materials with high compliance, high electrical conductivity (EC), high stability of EC under high strain, and high durability are key. Nevertheless, the compliance of previously reported electrodes for DEGs still needs to be improved, and they cannot be repaired at room temperature after being damaged, inducing the trouble of disassembling the DEG device. In this study, a highly conductive supermolecule-based electrode material for DEGs was designed and prepared by synthesizing a polyborosiloxane supermolecule network (PBS-SN) matrix with multiple dynamic bonds followed by introduction of highly conductive carbon black (CB) and carbon grease (CG) into the PBS-SN matrix. Benefiting from the multiple dynamic bonds of the PBS-SN matrix and the introduction of appropriate content of a silicone oligomer (SO) with high chain mobility and plasticizing effect, the as-prepared CB/CG/PBS-SN electrode exhibits a high elongation at break (>1000%), high compliance, high self-healing efficiency of EC at room temperature (93% for 3 h), good recyclability (at least five times without performance reduction) and high durability (up to 10 000 cycles). Compared with a DEG using the commonly used CG electrode, the DEG using the CB/CG/PBS-SN electrode exhibits higher energy density, which is 60.9% higher than that of the former, and much higher than that reported in many previous studies. The excellent room temperature self-healing ability of the electrode can help the in situ repair of the DEG device, reducing the trouble of disassembling the device and improving the convenience of usage. [ABSTRACT FROM AUTHOR]

The interfacial interactions between ultra‐high molecular weight polyethylene (UHMWPE) fiber and polymer determine the overall performance and service life of the fiber reinforced composite materials. In this article, polyaniline (PANI) layer is uniformly deposited on the surface of the UHMWPE fiber after plasma treatment to enhance the interfacial adhesion between UHMWPE fiber and rubber. At the same time, the PANI layer can also form a conductive path at the interface to monitor the damage of the composites in real time. Compared with the untreated UHMWPE fiber, the H pull‐out force of the PANI‐deposited UHMWPE fiber with rubber is increased by 67.9%, which is due to good mechanical interlocking and chemical bond between the fiber and the matrix. Moreover, the electrical resistance change during the fiber pull‐out process has a good correlation with the pull‐out force curve, which provides a new idea for in‐situ monitoring of the damage of composites. [ABSTRACT FROM AUTHOR]

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, a simple and facile method of aramid nanofiber (ANF) coating is demonstrated in this article. Tannic acid (TA) and polyethyleneimine (PEI) are polymerized in an alkaline solution to form a thin TA/PEI (TP) layer that is deposited on the surface of AF to introduce functional groups such as hydroxyl and amino groups. Then, the ANF coating is utilized to construct nanostructures on the surface of AF to improve the interfacial adhesion between the fiber and the rubber. Through hydrogen bonding and/or π‐π stacking between the TP layer and the ANF, the ANF coating is firmly attached to the surface of AF. Compared with the untreated fiber, the interfacial adhesion of AF coated with ANF after 1, 3, 5, 7, 9 deposition cycles is increased by 27.8%, 29.1%, 31.5%, 43.1%, and 30.3%, and the mechanical properties of the fibers remain almost unchanged. This method shows its advantages of simple, facile, and time‐effective, which is of great significance for industrial applications. [ABSTRACT FROM AUTHOR]

Dielectric elastomer (DE) materials suffer from high driving voltages and cracks or breaks during repetitive actuation cycles. New DE materials with a simultaneous high dielectric constant (ε′) and fast and efficient self-healing ability are in urgent need. Herein, we report a self-healable silicone DE by constructing a supramolecular network assembled by coordination bonds between carboxylated polymethylvinylsiloxane (PMVS-COOH) and FeCl3 as well as hydrogen bonds between carboxyl groups through introducing FeCl3 into PMVS-COOH. Both experimental results and density functional theory indicate that the Fe3+/COO− complex is formed and can further aggregate into clusters, which can simultaneously realize the crosslinking of PMVS-COOH and introduce interfacial polarization. Interestingly, the interfacial polarization largely increases with increasing FeCl3 content and FeCl3 can promote dipole polarization by disrupting some of the hydrogen bonds and releasing carboxyl groups when the FeCl3 content is higher than 5%, leading to a significant enhancement in ε′. The as-prepared PMVS-COOH/FeCl3 (SiR-Fe) DE with 8% FeCl3 shows comparatively high ε′ (12.3 at 104 Hz), much higher than that of the commercial silicone DE (∼2.7) or PMVS-COOH (6.1). Meanwhile, a self-healing efficiency of 99% in tensile strength and 100% in tensile toughness are achieved for SiR-Fe with 8% FeCl3 after being treated for 1 h at room temperature. This is ascribed to the high chain mobility of SiR-Fe and the robust supramolecular dynamic network resulting from the combination of coordination bonds and hydrogen bonds. It is demonstrated that SiR-Fe can be effectively used as a dielectric elastomer sensor. And it is promising that this highly efficient self-healable SiR-Fe DE with high ε′ finds applications especially in biological and medical fields. [ABSTRACT FROM AUTHOR]

It is a significant but challenging task to simultaneously reinforce and functionalize diene rubbers. Inspired by 'sacrificial bonds', the authors engineer sacrificial hydrogen bonds formed by pendent urazole groups in crosslinked solution-polymerized styrene butadiene rubber (SSBR) via triazolinedione click chemistry. This post-crosslinking modification reveals the effects of the sacrificial bonds based on a consistent covalent network. The 'cage effect' of the pre-crosslinked network facilitates the heterogeneous distribution of urazole groups, leading to the formation of hydrogen-bonded multiplets. These multiplets further aggregate into clusters with vicinal trapped polymer segments that form microphase separation from the SSBR matrix with a low content of urazole groups. The clusters based on hydrogen bonds, serving as sacrificial bonds, promote energy dissipation, significantly improving the mechanical properties of the modified SSBR, and enable an additional wide transition temperature region above room temperature, which endows the modified SSBR with promising triple-shape memory behavior. [ABSTRACT FROM AUTHOR]

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]

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]

Herein, graphene oxide (GO)-encapsulated silica (SiO2) hybrids (GO@SiO2) were prepared via electrostatic self-assembly of the 3-aminopropyltriethoxysilane (APS)-modified SiO2and GO. The as-prepared GO@SiO2was introduced into polydimethylsiloxane (PDMS) elastomer to simultaneously increase the dielectric constant (k) and mechanical properties of PDMS. Then, the in situ thermal reduction of GO@SiO2/PDMS composites was conducted at 180°C for 2 h to increase the interfacial polarizability of GO@SiO2. As a result, the values ofkat 1000 Hz are largely improved from 3.2 for PDMS to 13.3 for the reduced GO@SiO2(RGO@SiO2)/PDMS elastomer. Meanwhile, the dielectric loss of the composites remains low (<0.2 at 1000 Hz). More importantly, the actuated strain at low electric field (5 kV/mm) obviously increases from 0.3% for pure PDMS to 2.59% for the composites with 60 phr of RGO@SiO2, an eightfold increase in the actuated strain. In addition, both the tensile strength and elastic modulus are obviously improved by adding 60 phr of RGO@SiO2, indicating a good reinforcing effect of RGO@SiO2on PDMS. Our goal is to develop a simple and effective way to improve the actuated performance and mechanical strength of the PDMS dielectric elastomer for its wider application. [ABSTRACT FROM AUTHOR]

Dielectric elastomers are referred to as artificial muscles because of their excellent properties. However, the need for high operating voltage limits their practical application. A reduction of the operating voltage can be achieved with novel elastomers offering intrinsically high electromechanical sensitivity. In this work, slide-ring materials with a necklace-like molecular structure are prepared as dielectric elastomer materials. These slide-ring materials are found to exhibit high dielectric constants, low elastic moduli, and high electromechanical sensitivity due to their special structural characteristics. Barium titanate particles modified by γ-methacryloxypropyl trimethoxy silane (KH570) are incorporated into the slide-ring materials to further improve the actuated performance of the slide-ring materials. A high actuated strain (26%) at a relatively low electric field (12 kV mm−1) is obtained on the circular membrane actuator without any pre-strains, much more excellent than those of other dielectric elastomers reported in the literature. In addition, an obviously larger displacement is achieved by the slide-ring composite than that of commercial dielectric elastomer VHB 4910 on a cone-type actuator at the same electric field. These results demonstrate that our research might help to establish a new synthetic route to high performance dielectric elastomers. [ABSTRACT FROM AUTHOR]

We report the design and preparation of a separated-structured all-organic dielectric elastomer (DE) with large actuation strain under ultra-low voltage and high mechanical strength. Based on the protonic-conductivity mechanism of gelatin, a novel organic conductive filler with high dielectric constant and low elastic modulus was prepared by mixing gelatin and glycerol (GG). The separated structured DE was prepared by spraying a solution of GG into the multiple layers of thermoplastic polyurethane elastomer (TPU) nonwoven fabric by electrospinning, followed by hot pressing under vacuum. The densely packed TPU nonwoven fabric not only ensures the good mechanical strength of GG/TPU DE, but also separates GG filler and stops the formation of the GG continuous phase, preventing the formation of a conducting path under an exerted electric field. The novel GG filler considerably increases the dielectric constant and decreases the elastic modulus of the GG/TPU DE. As a result, the as-prepared DE exhibits good mechanical strength and 5.2% actuation strain at a very low electric field (0.5 kV mm−1). To the best of our knowledge, the required electric field for the same actuation strain is the lowest compared to other DE reported in the literature. Because all components in this composite are organic and biocompatible, this study offers a new method for preparing a DE with large actuation strain at low electric fields for its application in biological and medical fields, in which a low electric field is required. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) can lead to surprisingly large deformations by applying an electric field. The biggest challenge for DEAs is to get a large actuated strain at a low electric field. Herein, a novel approach was used to largely improve the actuated strain at a low electric field of a thermoplastic polyurethane (TPU) dielectric elastomer (DE) by introducing polyethylene glycol (PEG) oligomer into the matrix. The dielectric constant (εr) of TPU was obviously increased by adding PEG due to the combined effect of the increase in the interfacial polarization ability of TPU/PEG blends by the ionic conductivity of PEG and the increase in dipole polarization ability of TPU chain segments by the disruption of hydrogen bonds of TPU chains. Meanwhile, the elastic modulus (Y) of TPU was obviously decreased due to the plasticizing effect of PEG on TPU. The simultaneous increase in εr and decrease in Y resulted in a 7500% increase in actuated strain at a low electric field (3 V μm−1) by adding PEG. The actuated strain (5.22% at 3 V μm−1) is considerably higher than that of other DEs at the same electric field reported in the literatures. Our work provides a simple and effective method to largely improve the actuated strain at a low electric field of a DE, facilitating the application of DE in biological and medical fields. [ABSTRACT FROM AUTHOR]

ABSTRACT Dynamic vulcanization to prepare blended thermoplastic vulcanizates (TPV) is a kind of complicated blending technology, where the breakup of the rubber phase happens accompanying with the crosslinking of rubber. In this study, we aim to investigate the effect of crosslinking on the breakup of chlorobutyl rubber (CIIR) phase in thermoplastic polyamide 12 (PA 12) matrix by purposely using pre-crosslinked CIIR with different crosslink degrees and plasticizer contents. Besides, the effect of blending conditions on the breakup of crosslinked CIIR phase was studied. The results show that a low crosslink degree, a high content of plasticizer, a low blending temperature and a morderate rotor speed of 70 rpm facilitate the breakup of pre-crosslinked CIIR in PA 12 matrix. This is ascribed to the decrease in the modulus of pre-crosslinked CIIR phase because of either a low crosslink degree or a high content of plasticizer, the increase in the molten viscosity of thermoplastic matrix because of a low blending temperature and a moderate rotor speed. It is indicated that the breakup of pre-crosslinked rubber is mainly dominated by the modulus of crosslinked rubber phase as well as the molten viscosity of thermoplastic matrix and shear stress. This study will provide guidance for the preparation of CIIR/PA TPV. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40765. [ABSTRACT FROM AUTHOR]

A novel dielectric composite with high dielectric constant (k), low dielectric loss, low elastic modulus and large actuated strain at a low electric field was prepared by a simple, low-cost and efficient method. The graphene oxide nanosheet (GO)-encapsulated carbon nanosphere (GO@CNS) hybrids were fabricated for the first time via π-π interaction and hydrogen bonding interaction by simply mixing the CNS and GO suspension. The assembly of GO@CNS hybrids around rubber latex particles was realized by hydrogen bonding interaction between carboxylated nitrile rubber (XNBR) and GO@CNS hybrids during latex compounding. The thermally reduced GO (RGO)@CNS/XNBR composites were then obtained from GO@CNS/XNBR by vulcanization and in situ thermal reduction, resulting in the formation of a segregated filler network. The results showed that k at 103 Hz obviously increased from 28 for pure XNBR to 400 for the composite with 0.75 vol% of the hybrids because of the formation of a segregated filler network and the increased interfacial polarization ability of the hybrids after in situ partial thermal reduction. Meanwhile, the composite with 0.75 vol% of the hybrids retained low conductivity (10-7 S m-1), resulting in low dielectric loss (<0.65 at 103 Hz). In addition, the elastic modulus only mildly increased with the addition of 0.75 vol% of the hybrids, retaining the good flexibility of the composites. More interestingly, the actuated strain at 7 kV mm-1 obviously increased from 2.69% for pure XNBR to 5.68% for the composite with 0.5 vol% of RGO@CNS, and the actuated strain at a lower electric field (2 kV mm-1) largely increased from 0.23% for pure XNBR to 3.06% for the composite with 0.75 vol% of RGO@CNS, which is much higher than that of other dielectric elastomers reported in previous studies, facilitating the application of the dielectric elastomer in biological and medical fields, where a low electric field is required. [ABSTRACT FROM AUTHOR]

In this work, an elastomeric FeO nano-particles (NPs)/polybutadiene rubber (BR) composite membrane was prepared by using the combined technique of electrospinning and in-situ crosslinking. The results showed that the saturation magnetization (M) and the coercive force (H) of the electrospun composite membrane with 5 wt.% FeO NPs was increased by 21 % and 69 %, respectively, comparing with the membrane prepared by solution casting. This was ascribed to the fine nano-dispersion of FeO NPs in BR matrix by using the electrospinning and in-situ crosslinking technique because the re-aggregation of FeO NPs was largely restrained by the fast evaporation of solvent, the confined space of nano/micro-sized fibers and the rapid crosslinking during electrospinning. Our work demonstrated that electrospinning and in-situ crosslinking is a simple and efficient method to improve the dispersion of nanoparticles in an elastomer matrix, and thus prepare high performance elastomeric nanocomposite. [ABSTRACT FROM AUTHOR]

In this study, the early stage of interfacial crystallisation behaviour of low molecular weight polyethylene (PE) and isotactic polypropylene (iPP) oligomer on the surface of carbon nanotubes (CNTs) with different diameters, chiralities and topography structures was studied using MD simulations. We started to simulate the effect of CNTs chirality and diameter on PE molecular chain orientation, and then the effect of CNTs topography structure on PE and iPP molecular chain orientation was investigated. Finally, some experiments were carried out to prove the simulated results. Our study shows that for CNTs with a diameter comparable with the radius of gyration (Rg) of a polymer chain, an easy orientation of PE chains along CNTs axis is observed for all the systems of the CNTs with different chiralities due to a geometric confinement effect. For CNTs with a much larger diameter, multiple orientation of PE chains is induced on its surface due to the lattice matching between graphite lattice and PE molecular chains. In this case, the chirality of CNTs dominates the orientation of graphite lattice, which determines the orientation of PE chains arrangement on CNTs surface. More importantly, it was found that the groove structure formed by CNT bundles is very useful for the stabilisation of polymer chain, and thus facilitates the orientation of molecular chain along the long axis of CNTs. As a result, a novel nanohybrid shish–kebab (NHSK) structure with CNTs acting as central shish while polymer lamellae as kebab can be successfully obtained for both PE with zigzag conformation and iPP with helical conformation. This simulation result was well supported by the experimental observation. Our study could provide not only a deep understanding of the origin of the polymer chain orientation on CNTs surface but also the guidance for the preparation of polymer/CNTs nanocomposites with novel NHSK structure. [ABSTRACT FROM PUBLISHER]

Ethylene-Propylene-Diene Monomer/Polypropylene thermoplastic vulcanizates (EPDM/PP TPVs) have been widely used as a kind of typical 'green' elastomer because of their excellent mechanical properties and recyclability. The industrial TPVs always contain various types of additives, which influence the viscosity ratio of EPDM and PP and the morphology of TPVs. This work studied the morphology evolution of EPDM/PP TPVs with various amounts of curing agents, fillers, and plasticizer during dynamic vulcanization in a twin-screw extruder, which provides much more complicated dynamic vulcanization process than haaker rheometer. The results show that the increased curing agents content leads to the faster morphology evolution of TPV because it enhances the cross-linking speed and the viscosity of EPDM. The increased fillers content leads to the later breakup of EPDM and the bigger size of the rubber aggregation because it enhanced the modulus of EPDM and weakens the interfacial interaction between EPDM and PP. In addition, the increase in the plasticizer content leads to the earlier breakup of EPDM and the larger size of the rubber phase in TPV. Our work firstly demonstrates the morphology evolution of industrial EPDM/PP TPV, and thus can provide a guidence for the industrial production of high-performance EPDM/PP TPVs. [ABSTRACT FROM AUTHOR]

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]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique "groove structure" formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM AUTHOR]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique “groove structure” formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM PUBLISHER]

In our previous work, the formation of a nanohybrid shish kebab (NHSK) structure was successfully achieved in helical polymer systems promoted by using single-walled carbon nanotube (CNT) bundles with a unique 'groove structure', which is of great crystallographic interest. To further investigate the effect of surface groove structure of CNT bundles on the formation of NHSK structure in helical polymer systems, in the work reported here double-walled carbon nanotube (DWNT) fibers with bundle structure were used as nucleating agents and orientation templates for poly( L-lactide) (PLLA) crystallization. A fine NHSK structure with controlled lateral size and period of kebabs was successfully obtained under various experimental conditions by using DWNT bundles. This could be due to the geometric confinement effect of the surface groove structure of the DWNT bundles, which could facilitate the orientation of PLLA chains along the DWNT axis and the lateral formation of a stable nucleus. Our work suggests an efficient method for the functionalization of CNTs with biocompatible PLLA, which may have some potential applications in biomedical areas. In addition, it is demonstrated that the formation of NHSK structure can effectively improve the physical bonding between PLLA and nanotubes, thus significantly improving the mechanical properties of PLLA/CNT nanocomposite fibers. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is derived from oxidization of natural graphite and contains many active groups. These active groups make GO a potential compatibilizer for polymer blends or coupling agent for polymer composites. In this work, a novel core-shell structured hybrid submicroparticles of graphene oxide-encapsulated silica (GO-SiO2) were fabricated using GO sheets via an electrostatic assembly between ultrathin negatively charged graphene oxide sheets and positively charged amino-modified silica. The possible application of this new hybrid filler was explored in preparation of maleated polypropylene (PP- g-MA)/GO-SiO2 composites. The microstructure and interface enhancement of the prepared composites were analyzed by SEM, TEM, OM, TGA, FTIR, and DMA measurements. A uniform dispersion of GO-SiO2 hybrids, enhanced interfacial adhesion and improved mechanical property were evidenced. The reason might be that graphene oxide can be covalently assembled onto the amino-modified silica surface, and simultaneously it provides strong interaction with the PP- g-MA due to similar polarity or possible hydrogen bonding. This work suggests a potential application of graphene oxide-encapsulated particle in preparation of high performance polymer composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Interfacial interaction plays a key role in the preparation of high performance polymer composites. In this work, in order to explore the possibility to enhance the interfacial interaction via interfacial crystallization of polymer matrix onto the filler surface, interfacial crystallization structure and mechanical properties of linear low density polyethylene (LLDPE)/whisker composites were investigated. The composites were firstly prepared by melt compounding, followed by processing in both traditional and dynamic injection molding. DSC, WAXD, SEM were used to characterize the interfacial crystallization structure. And the mechanical properties were measured by tensile testing. An imperfect shish-calabash structure, with whisker served as shish, and irregular LLDPE spherulite as imperfect calabash, was formed during common injection molding processing. Such a structure was considered as the main reason for the strong interfacial adhesion and the obviously improved tensile strength and modulus. Furthermore, introducing shear could cause the formation of relatively perfect shish-calabash structure, leading to the stronger interfacial adhesion. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

As part of a continuous effort to develop high performance isotactic polypropylene (iPP) based on β-form crystalline and morphological change induced by rare earth nucleator (WBG), various WBG contents (from 0.025 to 1.0 wt%) were adopted to prepare β-nucleated iPP at a fixed final molten temperature (240°C) in this study. The crystallinity, polymorphic composition, and crystalline morphology were inspected in detail by a series of crystallographic characterizations, including calorimeter, X-ray diffraction, polarized light microscopy (PLM), and electron microscopy. Furthermore, the self-organization and re-crystallization behavior of β-nucleating agent occurred during cooling was characterized by rheometry. Finally, the dependence of mechanical properties, including tensile strength, elongation at break, and impact strength, on WBG content was discussed based on the variations in β-form content and crystalline morphology. Interestingly, it is found that while the WBG content is below 0.1 wt%, the toughness of β-nucleated iPP increases with increase in WBG content due to additional β-form content; as the WBG content is in range of 0.1-0.5 wt%, the toughness increases at a lower rate with increase in WBG content due to β-crystalline morphological change. However, a decrease in toughness is observed while nucleator content is above 0.5 wt% as WBG remains undissolved in iPP upon the adopted processing conditions. The result of this study provides valuable information for potential industrial applications. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The dielectric elastomer (DE) generator (DEG), which can convert mechanical energy to electrical energy, has attracted considerable attention in the last decade. Currently, the energy-harvesting performances of the DEG still require improvement. One major reason is that the mechanical and electrical properties of DE materials are not well coordinated. To provide guidance for producing high-performance DE materials for the DEG, the relationship between the intrinsic properties of DE materials and the energy-harvesting performances of the DEG must be revealed. In this study, a simplified but validated electromechanical model based on an actual circuit is developed to study the relationship between the intrinsic properties of DE materials and the energy-harvesting performance. Experimental verification of the model is performed, and the results indicate the validity of the proposed model, which can well predict the energy-harvesting performances. The influences of six intrinsic properties of DE materials on energy-harvesting performances is systematically studied. The results indicate that a high breakdown field strength, low conductivity and high elasticity of DE materials are the prerequisites for obtaining high energy density and conversion efficiency. DE materials with high elongation at break, high permittivity and moderate modulus can further improve the energy density and conversion efficiency of the DEG. The ratio of permittivity and the modulus of the DE should be tailored to be moderate to optimize conversion efficiency (η) of the DEG because using DE with high permittivity but extremely low modulus may lead to a reduction in η due to the occurrence of premature "loss of tension". [ABSTRACT FROM AUTHOR]

In this work, the conductive network, probability, and percolation threshold of nanorod/polymer composites under tensile strain are investigated using the molecular dynamics simulation. The internal interactions, including polymer-polymer, polymer-nanorod, and nanorod-nanorod interactions, are taken into account in simulations. In particular, the influence of polymer induced depletion force on the orientation of nanorods is analyzed. Under a constant strain, the conductive stability firstly declines and then rises with the increasing concentration of fillers, and the minimum corresponds to the percolation threshold. As strain increases, the result exhibits a strong anisotropy in the stability of conductive property. [ABSTRACT FROM AUTHOR]