Cellulose nanocrystal-mediated assembly of graphene oxide in natural rubber nanocomposites with high electrical conductivity

This study reports a green and powerful strategy for preparing cellulose nanocrystal (CNC)/graphene oxide (GO)/natural rubber (NR) nanocomposites hosting a 3D hierarchical conductive network. Due to good dispersibility and amphiphilic nature of CNC, well dispersed CNC/GO nanohybrids were prepared. Hydrogen bonding interactions between CNC and GO greatly enhanced the stability of the CNC/GO nanohybrids. CNC/GO nanohybrids were introduced into NR latex under sonication and the mixture was cast. Self-assembled CNC/GO nanohybrids preferentially dispersed in the interstice between latex microspheres allowing the construction of a 3D hierarchical conductive network. By combining strong hydrogen bonds and 3D conductive network, both electrical conductivity and mechanical properties (tensile strength and modulus) have been significantly improved. The electrical conductivity of the nanocomposite with 4 wt% GO and 5 wt% CNC exhibited an increase of nine orders of magnitude compared to the nanocomposite with only 4 wt% GO; meanwhile, the electrical percolation threshold was 3-fold lower than for NR/GO composites.     

Probing the reinforcing mechanism of graphene and graphene oxide in natural rubber

Natural rubber (NR) containing graphene (GE) and graphene oxide (GO) were prepared by latex mixing. The in situ chemically reduction process in the latex was used to realize the conversion of GO to GE. A noticeable enhancement in tensile strength was achieved for both GO and GE filled NR systems, but GE has a better reinforcing effect than GO. The strain‐induced crystallization was evaluated by synchrotron wide‐angle X‐ray diffraction. Increased crystallinity and special strain amplification effects were observed with the addition of GE. The incorporation of GE produces a faster strain‐induced crystallization rate and a higher crystallinity compared to GO. The entanglement‐bound tube model was used to characterize the chain network structure of composites. It was found that the contribution of entanglement to the conformational constraint increases and the network molecular parameters changes with the addition of GE and GO, while GE has a more evident effect than GO. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An environmentally friendly and efficient route for the reduction of graphene oxide by aluminum powder

We have demonstrated an environmentally friendly and efficient route for the reduction of graphene oxide by aluminum powder in only 30 min. The highly reduced graphene oxide had been confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis. Furthermore, the bulk conductivity of the prepared graphene sheets is 2.1 × 10³ S/m, which is only one order of magnitude lower than that of pristine graphite (∼3.2 × 10⁴ S/m).     

环保型丁苯橡胶与传统丁苯橡胶性能对比

对比考察了环保型丁苯橡胶与传统丁苯橡胶的相对分子质量及其分布、微观结构、混炼胶的硫化特性、硫化胶的物理机械性能及加工性能,结果表明,环保型丁苯橡胶SBR 1500 E与SBR 1500、环保型丁苯橡胶SBR 1502 E与SBR 1502及环保型丁苯橡胶SBR 1712 E与SBR 1712的相对分子质量及其分布、分子...     

氧化石墨烯/天然橡胶复合材料的制备与性能

采用己内酰胺（CPL）改性氧化石墨烯（GO）（CPL-GO）,与天然橡胶（NR）复合后通过熔融共混法制备了CPL-GO/NR复合材料。考察了CPL-GO用量对CPL-GO/NR复合材料物理机械性能、界面相互作用和气体阻隔性能的影响。结果表明,CPL改性GO后,X射线衍射层间距增加,片层堆砌更为松散,CPL-GO与水接触角增至91.2°。当CPL-GO的质量分数为2.0%时,CPL-GO/NR复合材料的拉伸强度为26.1 MPa,较纯NR提高了50.9%。随着CPL-GO用量的增加,复合材料的储能模量增加,损耗因子的峰值减小,表明GO经CPL表面改性后与NR复合,增强了两相界面间的相互作用,从而提高了复合材料抵抗变形的能力。在40 ℃下,当CPL-GO的质量分数为3.0%时,CPL-GO/NR复合材料的气体渗透系数较纯NR下降了57.1%。     

氧化石墨烯与白炭黑并用填充丁苯橡胶纳米复合材料的性能

采用乳液共混与机械剪切法制备氧化石墨烯/白炭黑/丁苯橡胶纳米复合材料,并对其综合性能进行研究。结果表明:两种并用填料在橡胶基体中均能达到纳米级分散,且白炭黑粒子填补了氧化石墨烯片层间的空隙。氧化石墨烯的加入延长了复合材料的正硫化时间,改变了其交联密度。氧化石墨烯等量替代白炭黑,可以提高橡胶基体中填料的有效体积分数,改善复合材料的物理性能和动态力学性能。氧化石墨烯的加入使复合材料的耐磨性能显著提高。与白炭黑填充相比,氧化石墨烯/白炭黑填充复合材料的60℃时损耗因子有所降低,能进一步降低滚动阻力,但其0℃的损耗因子也呈现降低趋势,对复合材料抗湿滑性能不利。     

Enhanced mechanical properties of graphene/natural rubber nanocomposites at low content

Graphene/natural rubber (GE/NR) nanocomposites were prepared by a modified latex mixing method combined with in situ chemical reduction. It was found that the GE nanosheets are well dispersed and have strong interfacial interaction with NR. Thus, adding a low content of GE can remarkably increase the tensile strength and the initial tensile modulus of NR. With incorporation of as low as 0.5 phr of GE, a 48% increase in the tensile strength and an 80% increase in the initial tensile modulus are achieved without sacrificing the ultimate strain. But further increasing the GE loading degrades the tensile strength and the ultimate strain. Dynamic mechanical measurement indicates that the storage modulus of the nanocomposites is greatly enhanced with addition of GE, while the loss tangent peak is depressed due to the reduced mobility of the rubber molecules. The reinforcement effect of GE on NR is interpreted as a change in the strain induced crystallization and network structure of the nanocomposites, based on the analysis of Mooney ? Rivlin plots and the tube model.© 2013 Society of Chemical Industry     

Multifunctional ZnO/Fe-O and graphene oxide nanocomposites: Enhancement of optical and magnetic properties

ZnO is a semiconductor with a great interest, but it has several deficiencies which limit its use in technologic applications. One important limitation is having the band gap in the UV which reduces its use in optical devices. To solve this problem, in this work, composites based in ZnO with goethite and graphene oxide (GO) by sol-gel are prepared. The obtained samples (powders and thin films) were characterized microstructurally (DTA, XRD, micro-Raman, FE-SEM), optically (transmittance and photoluminescence) and magnetically (SQUID). The ZnO band gap of multifunctional composites shows a red-shift towards visible range (E_g ∼3.01 eV) with high transmittance ∼85% (thickness of 362 nm) over the visible wavelength range. A long-range magnetic order at room temperature appears in these nanocomposites (Ms = 1.60·10⁻² emu/g). The combination of both dopants allows modifying the functional properties of ZnO, opening a great field of applications in ZnO composites, such as spintronic and optoelectronic devices.     

A review of environmentally friendly rubber production using different vegetable oils

Vegetable oils were investigated as plasticizers to improve the sustainability of rubber compounding. The potential use of different vegetable oils as an alternative to petroleum-based rubber process oils was reviewed. This article presents a literature review on the current understanding of the influence of vegetable oil properties on natural rubber (NR) compounding. Hansen solubility parameters of the vegetable oils were determined to assist with the selection of vegetable oil for NR. We believe that the use of Hansen parameters could make the use of vegetable oils in rubber more convenient and cost-effective.     

Preparation of graphene oxide/natural rubber composites by latex cocoagulation: Relationship between microstructure and reinforcement

Graphene oxide(GO) has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials. In this research, GO was incorporated in natural rubber(NR) composites through latex co-coagulation technique. The microstructures of GO/NR composites were characterized through a combination of transmission electron microscope, scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and Differential scanning calorimeter. The results showed that highly exfoliated GO sheets were finely dispersed into NR rubber matrix with strong interface interaction between GO and NR. The mechanical properties of the GO/NR composites were further evaluated. The results showed that the tensile strength, tear strength and modulus can be significantly improved at a content of less than 2 phr. Especially,GO exhibited specific reinforce mechanism in NR due to the stress-induced crystallization effects of NR. The stress transfer from the NR to the GO sheets and the hindrance of GO sheets to the stress-induced crystallization of NR were further displayed in stress–strain behavior of GO/NR composites. These enhanced properties were attributed to the high surface area of GO sheets and highly exfoliated microstructures of GO sheets in NR.     

Ionic liquid assisted polyetheretherketone-multiwalled carbon nanotubes nanocomposites: An environmentally friendly approach

Reinforcement of PEEK by nanoparticles such as multiwalled carbon nanotubes (MWCNTs), is a promising technique to prepare PEEK nanocomposites with improved properties for promising biomedical applications. However, proper dispersion of MWCNTs in the polymer matrices is a primary processing challenge. The present study reports a novel and environmentally beneficial approach for homogeneous dispersion of MWCNT in PEEK by using ionic liquid (IL) 1-ethyl-3-methylimidazolium hydrogen sulfate ([EMIM][HSO₄]). Neat PEEK, PEEK-MWCNTs (using conventional organic solvent dimethylformamide), and PEEK-MWCNTs-IL (using [EMIM][HSO₄]) nanocomposites were fabricated via melt-compounding and compression molding techniques. The fabricated composites were characterized for morphological, thermal, and mechanical properties and compared to those of neat PEEK and PEEK-MWCNTs. Ionic liquid provoked proficient dispersion of the MWCNTs in PEEK, as confirmed by FESEM and optical micrographs. The thermal stability of PEEK-MWCNTs-IL composite was significantly superior to that of the neat PEEK and PEEK-MWCNTs. Analysis of tensile strength and nanoindentation depicted that the modulus of elasticity of PEEK-MWNCTs-IL was significantly increased by 76% as compared to that of neat PEEK. We believe that the present work could provide a new and green platform for the manufacturing of PEEK nanocomposites with enhanced dispersion of nanofillers for biomedical applications.     

Effects of substitution for carbon black with graphene oxide or graphene on the morphology and performance of natural rubber/carbon black composites

In this study, nanosheets including graphene oxide (GO) and reduced graphene oxide (rGO), were incorporated into natural rubber (NR), to study the effects of substituting GO or rGO for carbon black (CB) on the structure and performance of NR/CB composites. The morphological observations revealed the dispersion of CB was improved by partially substituting nanosheets for CB. The improvements in static and dynamic mechanical properties were achieved at small substitution content of GO or rGO nanosheets. With substitution of rGO nanosheets, significant improvement in flex cracking resistance was achieved. NR/CB/rGO (NRG) composites has a much lower heat build‐up value compared with NR/CB/GO (NG) composites at a high load of nanosheets. However, both GO and rGO tended to aggregate at a high concentration, which led to the poor efficiency on enhancing the dynamic properties, or even deteriorate the performance of rubber composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41832.     

Influence of environmentally friendly curing system on properties of railway rubber pad

Improving the aging resistance and elasticity of rubber materials can increase the service life of rubber pads and reduce railway operation costs. The purpose of this work was to improve aging resistance, decrease compression set and ratio of dynamic stiffness to static stiffness (R_d/s) of railway rubber pads by using environmentally friendly accelerators N-t-butyl-2-benzothiazole sulfenimide (TBSI) and tetrabenzylthiuram disulfide (TB_zTD). The influence of the curing system on the properties of rubber pads was assessed using multiple techniques. Compared to sulfur/tetramethylthiuram disulfide (TMTD) /N-cyclohexyl-2-benzothiazole sulfenamide (CZ), compression set of S/TBSI/TB_ZTD decreased to 29.5% from 35.7%, retention of elongation at break after hot air aging increased to 77.7% from 66.1%, and R_d/s decreased to 1.82 from 1.85. Thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis indicated that maximum thermal decomposition temperature of TBSI/TB_ZTD was higher, which was the reason for the good aging resistance and low compression set results. Rubber processing analysis (RPA) demonstrated that the loss factor of TBSI/TB_ZTD was smaller. The rubber cured by TBSI/TB_ZTD had a higher crosslinking density and smaller loss factor, which decreased the R_d/s. This study provides a reference for preparing of environmentally friendly rubber pads with a low R_d/s and long service life.     

用协同还原一步法制备氢化丁腈橡胶/还原氧化石墨烯纳米复合材料（英文）

选择具有还原特性的物质,如维生素C、对苯二酚或茶多酚作为协同还原剂,协同水合肼对丁腈橡胶/氧化石墨烯(GO)纳米复合胶乳中的碳碳双键及GO片层同时进行加氢和还原,制备了氢化丁腈橡胶(HNBR)/还原GO纳米复合材料,并利用衰减全反射傅里叶变换红外光谱仪、拉曼光谱仪和热重分析仪等仪器对所制备的纳米复合材料进行了表征。结果表明,GO的引入进一步改善了HNBR的性能;同时协同还原剂可与水合肼共同参与还原反应,提高了碳碳双键的加氢度和GO片层的还原程度,使得复合材料的热稳定性得到改善。     

Influence of graphene functionalized with zinc dimethacrylate on the mechanical and thermal properties of natural rubber nanocomposites

An effective approach is developed to synthesize zinc dimethacrylate functionalized graphene (ZDMA‐GE) as reinforcing nanofiller for natural rubber (NR). The morphology and structure of ZDMA‐GE were characterized to confirm the exfoliation and functionalization of GE. The as‐prepared nanocomposites were investigated by transmission electron microscopy, mechanical analysis, crosslinked network analysis, and the analysis of thermal conductivity. The results demonstrated that there is strong interfacial interaction between GE and rubber matrix due to good dispersion and special two‐dimensional structure of GE. The crosslink density of the nanocomposites is greatly improved with the introduction of ZDMA‐GE because of the homopolymerization and graft polymerization of ZDMA. It is also noticed that the tensile strength, tear strength, and modulus at 300% elongation of NR nanocomposites with 15 phr ZDMA‐GE have been improved by 133, 42, and 174%, respectively. The thermal conductivity of nanocomposites with 40 phr ZDMA‐GE is enhanced 1.3 times as that of the pure NR. This remarkable improvement is attributed to the formation of covalent crosslinked network and ionic crosslinked network, good dispersion of GE, and efficient interfacial interaction between GE and NR matrix. This method provides the potential applications of functionalized GE in the polymer composites. POLYM. COMPOS., 36:1775–1785, 2015. © 2014 Society of Plastics Engineers     

Physical properties of natural rubber/organoclay nanocomposites compatibilized with epoxidized natural rubber

Onium ion‐modified montmorillonite (organoclay) was melt compounded with natural rubber (NR) in an internal mixer and cured by using a conventional sulfuric system. Epoxidized natural rubber with 50 mol % epoxidation (ENR 50) was used in 10 parts per hundred rubber (phr) as a compatibilizer. The effect of organoclay with different filler loading up to 10 phr was studied. Cure characteristics were determined by a Monsanto MDR2000 rheometer, whereas the tensile, compression, and tear properties of the nanocomposites were measured according to the related ASTM standards. While the torque maximum and torque minimum increased slightly, both scorch time and cure time reduced with the incorporation of organoclay. The tensile strength, elongation at break, and tear properties went through a maximum (at about 2 phr) as a function of the organoclay content. As expected, the hardness, moduli at 100% (M100) and 300% elongations (M300) increased continuously with increasing organoclay loading. The compression set decreased with incorporation of organoclay. The dispersion of the organoclay in the NR stocks was investigated by X‐ray diffraction and transmission electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1083–1092, 2006     

氧化石墨烯在橡胶中的应用研究进展

介绍了氧化石墨烯的结构与制备工艺,总结了氧化石墨烯/橡胶复合材料的制备方法,评价了氧化石墨烯对硫化橡胶力学性能、阻隔性能、导热性能、热稳定性及其他性能的影响。     

Comparative study on the natural rubber nanocomposites reinforced with carbon black nanoparticles and graphite oxide nanosheets

To achieve dramatic improvements in the performance of natural rubber (NR), the graphite oxide nanosheets (GON)‐reinforced NR nanocomposites have been prepared through solution mixing on the basis of pretreatment of graphite. The mechanical and thermal properties of GON/NR nanocomposites were characterized in contrast to the carbon black (CB)/NR nanocomposite. The mechanical properties of the GON‐reinforced NR showed a considerable increase compared to the neat NR and traditional CB/NR nanocomposite. The initial modulus of pure NR was increased for up to 53.6% when 7 wt% GON is incorporated. The modulus and strength of NR with GON appear to be superior to those of CB with the same filler content. The dispersion state of the nanofillers into NR was investigated by scanning electron microscopy and X‐ray diffraction, and the results indicated that nanofillers have been dispersed homogeneously in the NR matrix. Fourier transform infrared spectra showed possible interfacial interactions between fillers and NR matrix. Differential scanning calorimetry and thermogravimetric analysis showed that the T _g and thermal decomposition temperature of NR slightly increased with the addition of the fillers, especially for that of GON/NR nanocomposites. According to this study, application of the physical and mechanical properties of GON to NR can result in rubber products which have improved mechanical, physical, and thermal properties, compared with existing NR products reinforced with CB. POLYM. COMPOS., 38:1427–1437, 2017. © 2015 Society of Plastics Engineers