Publications

Carbon nanodots as an eco-friendly activator of sulphur vulcanization in diene-rubber composites

It is widely accepted that zinc oxide (ZnO) is the best activator for sulphur vulcanization of rubber composites. However, ZnO is recognized as a toxic substance for both human and aquatic organisms. Therefore, it is of great importance, but still challengeable to exploit eco-friendly alternatives to reduce ZnO, without comprising the performance of rubber composites. Herein, we describe a novel strategy to achieve substantial reduction of ZnO in diene-rubber composites, by utilizing carbon nanodots (CDs) as an efficient activator for sulphur vulcanization. With the substitution of CDs for ZnO, the cross-linking rate of the rubber composites remarkably accelerated, mainly due to the fact that the N-related moieties of CDs can facilitate the formation of sulphur-based networks via significantly reducing the activation energy of the cross-linking reactions. Moreover, the activation efficiency of the synthesized CDs was also confirmed in the rubber formulations filled with conventional fillers. We envisage that this strategy can provide a green and practical avenue towards the substantial pollution abatement from ZnO in rubber composites.

Strikingly improved toughness of nonpolar rubber by incorporating sacrificial network at small fraction

It poses a huge challenge to create nonpolar rubber with high fracture toughness. In the present letter, inspired by the concept of sacrificial bonding associated with many biological materials, we propose that a small fraction of additional sacrificial network can strikingly improve the fracture toughness of nonpolar rubbers. As a proof of concept, we created the additional “fragile” epoxidized natural rubber (ENR) network in commercially available SBR rubber in a facile process. With addition of only 10 phr ENR, the SBR/ENR double network (DN) exhibits a fracture energy nearly fourfold higher than that for the neat SBR. The formation of DN formation and the correlation between the high toughness and presence of the second brittle network have been fully discussed. This is the first time sacrificial networks are created in diene‐based rubber towards high toughness elastomers in a facile and efficient way. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 781–786

Natural inorganic nanotubes reinforced epoxy resin nanocomposites

No abstract is provided for this article.

Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by sorbic acid

Sorbic acid (SA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed mechanisms for the largely improved performance were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), porosity analysis and crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through SA intermediated linkages. SA bonds SBR and HNTs through grafting copolymerization/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and SA was achieved. Formation of zinc disorbate (ZDS) was revealed during the vulcanization of the composites. However, in the present systems, the contribution of ZDS to the reinforcement was limited. Effects of SA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of SA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and SA and the largely improved dispersion of HNTs.

Dynamic crosslinked elastomers and rubbers

Mediating the carbon black–natural rubber interface with thioamide-functionalized polysulfide for energy-saving composites

Thioamide-functionalized polysulfide SCA is synthesized and utilized as an intelligent interfacial regulator for preparing rubber composites with low-hysteresis loss.

Superhydrophobic surfaces with nanofibers or nanorods based on thiophene derivatives

Fabricating superhydrophobic surfaces via self-assembly of organic conjugated small molecules is realized by spray-drying the thiophene derivates organic solutions. Formation of microsized pores and arrayed nanofibers or nanorods on the surfaces is responsible for the superhydrophobicity of the coatings. This technique can be applied for fabrication of large area superhydrophobic surfaces with conjugated molecules on different substrates.

Sodium Humate Functionalized Graphene and Its Unique Reinforcement Effects for Rubber

Sodium humate (SH), a cost-effective and environmentally friendly humic substance, was employed to noncovalently functionalize graphene. The functionalized graphene (SHG) could stably and individually be dispersed in water at very high concentration (up to 30 mg/mL). The stabilization mechanism of SHG colloid was revealed to be π–π interaction and hydrogen bonding between SH and graphene layer. SHG was incorporated into carboxylated nitrile rubber (XNBR) through latex co-coagulation to form XNBR/SHG composites. The composites were cured with sulfur and magnesium oxide (MgO). A unique reinforcement effect of SHG toward XNBR was found. For instance, with the incorporation of 1 phr SHG, the fracture energy of the composite was doubled and the extensibility was improved, while the modulus was practically unchanged. The unique combination of high fracture energy, high extensibility, and low modulus was correlated with the interactions between SHG and MgO which pronouncedly affected the cross-linking of the rubber.

Heterogeneous Network Design

This chapter focuses on heterogeneous network design in dynamic covalent polymer networks (especially rubbers). The design, performance, and mechanisms of heterogeneous networks from the perspectives of inhomogeneous crosslinking and hybrid multi-networks are briefly reviewed. The exchangeable functions of dynamic covalent bonds (DCBs) enable unique properties of the heterogeneous crosslinked polymer networks. Based on characteristics such as micro-phase separation, interlocking, or interconnection between the multiple sub-networks crosslinked by DCBs, the relative independence and synergistic effect between the heterogeneous networks are exploited to achieve the robustness, functionalization, and melt-processing ability of DCB crosslinked elastomers. This new approach is expected to open a new avenue for intelligent application and sustainable development of polymer networks.

Ni2P@MoS2/CC catalysts with heterogeneous structure are used for highly efficient electrolysis of water for hydrogen evolution

Efficient and inexpensive electrocatalysts play an important role in electrolysis of water and hydrogen evolution reaction. The catalytic activity of electrocatalyst can be improved by adjusting the electronic structure and increasing the active center. In this study, Ni2P nanosheets were grown on carbon cloth through straightforward solvothermal, and tiny MoS2 nanosheets were uniformly covered on Ni2P nanosheets by in-situ growth method to form heterogeneous electrocatalyst (Ni2P @ MoS2/CC). The results show that Ni2P @ MoS2/CC had more active sites than Ni2P/CC and MoS2/CC catalysts. In addition, the interface interaction based on heterogeneous structure promotes its charge transfer kinetics. In alkaline electrolyte, Ni2P @ MoS2/CC electrocatalyst had good HER performance. At a current density of 10 mA cm−2, the overpotential was 99 mV, and the Tafel slope was 97 mV dec−1. In addition, the catalyst showed excellent electrochemical stability, with no significant loss of activity after 2000 cyclic voltammetry tests and 50 h i-t tests.

Bioinspired Engineering of Sacrificial Metal–Ligand Bonds into Elastomers with Supramechanical Performance and Adaptive Recovery

Reinforcing rubbers and expanding their application galleries are two important issues in material science and engineering. In this work, we demonstrate a bioinspired design of high-performance and macroscopically responsive diene-rubber by engineering sacrificial metal–ligand motifs into a chemically cross-linked architecture network. The metal–ligand bonds are formed through the coordination reaction between the pyridine groups in butadiene–styrene–vinylpyridine rubber (VPR) and metal ions. Under external load, the metal–ligand bonds serve as sacrificial bonds that preferentially rupture prior to the covalent network, which dissipates energy and facilitates rubber chain orientation. Based on the function mechanisms, the modulus, tensile strength, and toughness of the samples are simultaneously improved without sacrificing the extensibility, and these properties can be conveniently tuned by varying the structure parameters of the covalently cross-linked network and metal–ligand bonds. Moreover, the dissociation/re-formation of metal–ligand bonds upon heating/cooling can endow VPR with thermally triggered adaptive recovery for shape memory application.

CHALLENGE OF RUBBER/GRAPHENE COMPOSITES AIMING AT REAL APPLICATIONS

Graphene has attracted a great deal of interest in recent years, illustrated by its potential in a variety of areas in physics, chemistry, and engineering. Specifically, graphene has opened up exciting possibilities for high-performance and functional rubber composites. Although copious literature deals with the fascinating properties related to graphene, its real (large scale) applications in rubber-based composites have not been approached. We discuss the state of the art in development in processing and the status in understanding of structure/performance relationships. Accordingly, the prospectives and challenges of some real applications of graphene-based rubber composites such as tires and sensors are surveyed and discussed.

Thermoplastic Elastomers Derived from Scrap Rubber Powder/LLDPE Blend with LLDPE‐<i>graft</i>‐(Epoxidized Natural Rubber) Dual Compatibilizer

Summary: Attempts were made to prepare thermoplastic elastomers (TPE) from scrap rubber powder (SRP) and linear low‐density polyethylene (LLDPE) as thermoplastic polymer matrix. The solid‐phase grafted copolymer of LLDPE (LLDPE‐g‐VM) and epoxidized natural rubber (ENR) were used as dual compatibilizers to improve the interfacial adhesion between SRP and LLDPE. The compatibilized SRP/LLDPE blends had obviously improved the interfacial properties between SRP particles and LLDPE. Using this method, thermoplastic elastomer was prepared successfully. The mechanical properties especially elongation at break was improved significantly. SEM and TEM studies showed that the ENR/LLDPE‐g‐VM dual compatibilizer improved the distribution state of SRP particles in LLDPE and the adhesion between SRP and LLDPE. DSC results showed a distinct glass transition at 74 °C of the interfacial region. The improvement in mechanical properties was attributed to the enhanced interfacial properties of the blend. Surface of SRP particles of the composites compatibilized by the dual compatibilizer. image Surface of SRP particles of the composites compatibilized by the dual compatibilizer.

Preparation and performance of bio-based carboxylic elastomer/halloysite nanotubes nanocomposites with strong interfacial interaction

Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid) (PDIM)/halloysite nanotubes (HNTs) nanocomposites with strong interfacial interaction were prepared by co-coagulation of PDIM latex and HNTs aqueous suspension, followed by mechanical kneading with rubber additives. The interfacial interaction, thermal properties, morphology, and mechanical properties of the nanocomposites were investigated. The hydrogen bonds were confirmed in the nanocomposites. Morphology investigation showed uniform and individual dispersion of HNTs in the PDIM matrix. With the incorporation of HNTs into the PDIM matrix, the tensile strength and the fracture energy were significantly improved without sacrificing the extensibility. The improved mechanical properties were correlated to the co-coagulation and the strong hydrogen bonds. Especially, the morphology investigation of tensile fracture surfaces revealed a mechanism for the improved mechanical performance, in which the stress was efficiently transferred from PDIM to HNTs via hydrogen bonds and then the dissociation of the hydrogen bonds dissipated energy to increase the fracture energy of the nanocomposites.

Significantly improved rubber-silica interface via subtly controlling surface chemistry of silica

It has been commonly acknowledged that particle dispersion and interfacial interactions are vital in determining the ultimate performance of polymer composites. However, the interplay between dispersibility and interfacial interaction in polymer composites has not been explicitly unraveled. In this contribution, a series of silica with controlled surface chemistry are prepared to reveal the effects of subtle change in surface property of filler on the structures and mechanical performance of the rubber composites. On the basis of thermodynamic theory, the dispersibility of modified silica in rubber is quantitatively evaluated by using surface energy. The modified silica was introduced into styrene-butadiene rubber (SBR) to investigate the effects of surface modification on the dispersion of silica and interfacial interaction of the rubber composites. It has been demonstrated that subtle change in surface chemistry of silica drastically improves its dispersibility in rubber matrix, leading to much improved accessible surfaces and hence much complete interfacial reaction. At very low grafting content (0.2 molecule/nm2), improved modulus (44%) and wet-traction (54%), together with reduced rolling-resistance (11%), are concurrently observed.

Vapor grown carbon nanofiber reinforced bio-based polyester for electroactive shape memory performance

Bio-based polyester (BE) was synthesized through polycondensation using the plant-derived resources as the starting materials. Vapor grown carbon nanofiber (VGCF) was then incorporated into BE to prepare BE/VGCF composites by simple melting blending. The uniform dispersion of VGCF and fairly strong interfacial adhesion between BE and VGCF led to a significant improvement in the mechanical properties of the composites. Besides, the incorporation of VGCF successfully converted the insulating BE into electrically conductive composites with a percolation threshold of 2.5vol.%. The composites showed excellent electroactive shape memory properties, which reached a shape recovery ratio of 97% within 90s with a direct current voltage of 20V. The combination of the significantly improved mechanical properties and excellent electroactive shape memory performance of BE/VGCF composites opens up the new opportunity for the electroactive actuator materials in a sustainable manner.

Styrene-butadiene rubber/halloysite nanotubes composites modified by epoxidized natural rubber

The reinforcement effects of halloysite nanotubes (HNTs) on styrene-butadiene rubber (SBR) and the modification effect of epoxidized natural rubber (ENR) on SBR/HNTs composites were studied. The structure, morphology and properties of SBR/HNTs composites before and after the incorporation of ENR were investigated. The results indicated that ENR can promote the dispersion and orientation of HNTs in SBR matrix at nanoscale and strengthen interfacial combination between HNTs and SBR by the formation of covalent bonds and hydrogen bonds between ENR and HNTs. Consequently ENR can improve the mechanical properties of the vulcanizates of SBR/HNTs composites. Besides ENR can decrease the rolling resistance of the vulcanizates and increase the wet grip property of the vulcanizates.

High perfermance light-colored rubber nanocomposites

High performance light-colored rubber-inorganics nanocomposites were fabricated by the direct incorporation of sorbic acid (SA) in the filled rubber compounds. The mechanisms of largely improved performance were studied in details. The strong interfacial bonding between rubber matrix and the filler and significantly improved dispersion of the filler were resulted through SA intermediated linkages. Effect of SA on the vulcanization behavior, morphology and mechanical properties were studied. Formation of zinc disorbate (ZDS) and its reinforcing effect on rubber was investigated. High content of ZDS leaded to high ionic crosslink density and had a more significantly effect on enhancing the performance of rubber. The composites with high nanotubular clay content were found to be highly ionic crosslinked, optical transparent and exhibited high mechanical strength and heat resistance. The properties of the composites were ascribed to the strong interfacial interactions and the excellent dispersion of nanotubular clay.