Preparation of Ethylene Vinyl Acetate Copolymer/Graphene Oxide Nanocomposite Films via Solution Casting Method and Determination of the Mechanical Properties

Ethylene vinyl acetate/graphene oxide (EVA/GO) nanocomposite films were prepared via solution casting method. The morphological studies investigated using SEM and XRD methods and the results confirmed the formation of likely exfoliation structures and good interaction between matrix and fillers. The results of permeability measurements showed that films have good resistance against oxygen. Mechanical measurements revealed that Young’s modulus and tensile strength of EVA have improved with introducing GO because of proper dispersion of GO into matrix and good interaction between them; however, elongation at break decreased due to formation of strong and rigid polymer/filler network preventing to elongate polymer chains.     

Preparation and Properties of Ethylene-vinyl Acetate/linear Low-density Polyethylene/Graphene Oxide Nanocomposite Films

Ethylene-vinyl acetate-based nanocomposites with 18 and 28 wt% vinyl acetate were prepared via solution casting method. To improve the mechanical and barrier properties of ethylene-vinyl acetate, linear low-density polyethylene, and graphene oxide were introduced to matrix. The morphological studies indicated that the graphene oxide diffraction peak disappeared in all prepared nanocomposites, probably due to its exfoliation; also proper dispersion and good interaction between nanofillers and polymer matrix were achieved. By introducing low amount of graphene oxide into the matrix, the mechanical and thermal properties and oxygen permeability were improved especially for those with 28 wt% vinyl acetate monomer.     

聚苯乙烯/氧化石墨烯复合建材的制备与保温性能研究

通过聚苯乙烯(PS)与氧化石墨烯(GO)共混,制备聚苯乙烯/氧化石墨烯(PS/GO)保温建筑材料,并对PS/GO阻燃性能以及保温性能进行研究。结果表明:GO含量为6%时,4号样品的综合性能最好。4号样品的LOI值为33.4%,阻燃等级达到V-1,热释放速率峰值(pHRR)为525.76 kW/m²,总产烟量(TSP)为629.37 m²。此外,4号样品具有较低的导热系数0.034 2 W/(m·K),并且吸水率以及水蒸气透过系数均满足标准值,说明其可以有效应用于建筑保温材料。     

还原氧化石墨烯增强水泥基复合材料微观结构及力学性能

采用水热还原法制备了不同还原程度的还原氧化石墨烯(RGO),并将其添加到水泥浆体中,制得石墨烯增强水泥基复合材料。采用傅里叶变换红外光谱(FT-IR)、力学性能测试仪、扫描电子显微镜(SEM)对氧化石墨烯(GO)还原程度及水泥基复合材料的力学性能和微观结构进行测试。结果表明,在120℃水热条件下,控制不同还原时间可以得到不同还原程度的RGO;随着GO还原程度的提高,复合材料力学强度不断增加;RGO可使水泥更加密实,降低了水泥浆体的孔隙率,对水泥基复合材料起到增强增韧的作用。     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.     

Facile Designing of Poly(vinyl alcohol-g-acrylonitrile)-Supported Flexible Graphene Films

Graphene has attracted considerable interest over recent years due to its good electrical and mechanical properties. In the present study, a safe and facile method has been adopted for the preparation of reduced graphene oxide solution and its subsequent homogeneous dispersion into the poly(vinyl alcohol-g-acrylonitrile) film prepared by in situ free radical polymerization method. The prepared polymer-supported graphene films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques.     

氮化铝/氧化石墨烯对环氧树脂胶黏剂导热性能的影响

使用硅烷偶联剂KH-560对氮化铝进行了表面改性,并以其为导热填料,环氧树脂为基体,制备了氮化铝/环氧树脂导热胶黏剂。采用FTIR、SEM、TG、热常数分析仪对导热胶黏剂进行了表征。结果表明:改性后硅烷偶联剂分子成功接枝在氮化铝表面。改性后,氮化铝与环氧树脂的界面粘结力增强,热稳定性和导热性均得到明显改善。当氮化铝质量为导热胶黏剂质量的70%时,改性氮化铝/环氧树脂热胶黏剂的导热系数为2.24W/(m·K),而未改性氮化铝/环氧树脂的导热系数仅为1.73W/(m·K)。为进一步提高其导热性能,制备了改性氮化铝/氧化石墨烯/环氧树脂导热胶黏剂,当改性氮化铝和氧化石墨烯的质量分数分别为50%和3%时,导热胶黏剂导热系数为3.05 W/(m·K)。     

氧化石墨烯/钒钛酸复合材料的制备及湿敏性能研究

通过Hummers法制备氧化石墨后进行超声分散,得到分散均匀的氧化石墨烯(GO)分散液,物理复合滴涂制备氧化石墨烯/钒钛酸薄膜并对其感湿性能进行了研究,并通过交流与直流方法对其感湿机理进行了深入探究。结果表明:氧化石墨烯/钒钛酸复合膜的湿敏性能优于氧化石墨烯和钒钛酸单层膜,该湿敏薄膜的湿滞为8.3%RH,灵敏度变化2个数量级,响应时间为8 s,还原时间为10 s,曲线线性度良好。材料在低湿阶段主要表现为电子导电,中高湿阶段为电子导电和离子导电同时存在,高湿阶段主要表现为离子导电。     

Preparation and Characterization of Insensitive HMX/Graphene Oxide Composites

To improve the safety of HMX, a two‐dimensional (2D) graphene oxide (GO) was introduced to HMX by the solvent nonsolvent method. The morphology, composition, thermal decomposition characteristic were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and differential scanning calorimetry (DSC). Compared to the previous reports, GO sheets exhibited better desensitizing effect than [60]Fullerene and CNTs. When 2.0 wt‐% GO sheets were added, the impact sensitivity of raw HMX decreased from 100 to 10 %, and the friction sensitivity reduced from 100 to 32 %. The DSC results proved that GO sheets were compatible with HMX. In addition, by determining the thermal decomposition kinetic parameters of the samples, it was found that the activation energy (E_a) of HMX with 2.0 wt‐% GO increased by 23.5 kJ mol⁻¹, suggesting that GO sheets could improve the thermal stability of HMX.     

Nano TiC-Graphene-Cu composites fabrication by a modified ball-milling method followed by reactive sintering: Effects of reinforcements content on microstructure,consolidation, and mechanical properties

A two-step mechanical milling followed by a reactive sintering process was used to synthesize Nano TiC-Graphene-Cu composites from a mixture of Cu, Ti, and Graphene (GN) powders in four different compositions, and effects of reinforcements content on the microstructure and mechanical properties were studied. The results showed that a part of GN reacted with Ti atoms in the matrix, leading to the successful formation of hybrid nanocomposites. Uniform distribution of in-situ TiC with nanometer size and unreacted GN in the nanostructured Cu (Ti) solid solution were obtained. Addition of high percentage of the reinforcements led to an increase in the porosity and microhardness, coarsening of TiC nanoparticles, and decreasing the grain size of the matrix after sintering. The simultaneous presence of GN and TiC nanoparticles in the Cu matrix improved the hardness and wear resistance and reduced the friction coefficient by self-lubricating behavior. The nanocomposite with the nominal composition of Ti-40 vol % TiC showed the highest wear resistance and the lowest friction coefficient.     

Preparation and Properties of Graphene Oxide-Modified Waterborne Polyurethane-Acrylate Hybrids

A series of graphene oxide-modified waterborne polyurethane-acrylate (GEO/WPUA) hybrids were prepared and characterized by FT-IR, SEM, TEM and XRD. The result shows that graphene oxide in the hybrid has good dispersion. The mechanical property, thermal stability and water resistance of hybrids with different content of GEO were investigated. The results indicate that GEO/WPUA films have bigger tensile strength and hardness than pure WPUA. When the content of GEO is 0.015%, the hybrid has the best water resistance. The obtained GEO/WPUA hybrids have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes.     

ATO/GO纳米复合材料的制备及抗静电防腐性能研究

以氧化石墨烯(GO)作为前体,通过氨丙基三乙氧基硅烷将氧化锡锑（ATO）锚定到氧化石墨烯片层上,制备得到氧化锡锑-氧化石墨烯纳米复合材料（ATO/GO）。通过XRD,XPS和SEM对其结构进行测试。并研究了ATO/GO含量对水性环氧涂料（AE）防腐及抗静电性能的影响。结果表明：随ATO/GO含量的增加,复合涂料表面电阻降低,ATO/GO含量大于3%时,表面电阻降低至108Ω以下,达到了抗静电的使用要求;当ATO/GO含量为3%时,漆膜水蒸气透过率降低至（62.13g/m2 h）,具有最低的腐蚀电流密度（Icorr=3.73E-9 A/cm2）和最高的腐蚀电压（Ecorr=-0.19926v）,防腐效率与空白样相比提高了99.95%。     

Graphene for tough and electroconductive alumina ceramics

A simple, fast and upscalable method is described to produce graphene/alumina (G/Al₂O₃) composites by spark plasma sintering (SPS) with a significant improvement on both mechanical and electrical properties of monolithic Al₂O₃. Graphene oxide (GO) was mixed with Al₂O₃ using a colloidal method obtaining an excellent dispersion of GO in the alumina matrix. The material was consolidated by SPS that allowed, in one-step, the in situ reduction of the GO during the sintering process. A detailed Raman analysis was found to be very useful to study the orientation of the graphene in the composite and to evaluate and optimise its thermal reduction. Graphene platelets acted as elastic bridges avoiding crack propagation and providing this material with a crack bridging reinforcement mechanism. A very low graphene loading (0.22 wt%) led to a 50% improvement on the mechanical properties of the alumina and to an increase of the electrical conductivity up to eight orders of magnitude.     

二氧化钛/天然橡胶纳米复合材料的制备及性能研究

采用乳液共混法将纳米二氧化钛(TiO_(2))与天然胶乳直接混合,制备TiO_(2)/天然橡胶(NR)纳米复合材料,研究自然凝固、乙酸凝固、氯化钙凝固3种凝固方式和TiO_(2)用量对TiO_(2)/NR纳米复合材料性能的影响。结果表明:乙酸凝固制得的NR及TiO_(2)/NR纳米复合材料的综合性能最优;TiO_(2)的加入可有效提高NR复合材料的物理性能和耐老化性能;随着TiO_(2)用量的增大,TiO_(2)/NR纳米复合材料的物理性能明显提高,耐老化性能有一定程度提升。     

Preparation and Characterization of a Graphene Oxide Film Modified by the Covalent Attachment of Polysiloxane

Hybrid materials consisting of polydimethylsiloxane (PDMS) and polycyclohexyl-methylsiloxane (PCHMS) grafted graphene oxide (GO) were obtained by condensation polymerization in toluene. Fourier transform infrared spectroscopy indicates that the composites were synthesized through the formation of Si-O bond. The X-ray diffraction, scanning electron microscopy and thermogravimetric indicate that the hydrolysis polycondensation can accelerate the graft reaction. The hybrid films were prepared by simple filtration of the dispersed system of PDMS/GO/water, PCHMS/GO and PCHMS/GO/water in dimethylformamide. Tensile tests indicate the mechanical properties of the films varied with their structure. The rigid PCHMS/GO/water films have a tensile strength of 17.83 MPa, and the pliant PDMS/GO/water films have an elongation at break of 3.14%. UV-Vis spectra of GO and the hybrids indicate that the addition of polysiloxane caused a red-shift (10–20 nm) of the absorption peak.     

Effect of Graphene Oxide on Structure and Properties of Impact-Modified Polyamide 6

Modification of polymer blends with nanofillers is an efficient way to improve material parameters. This work deals with application of neat and stearylamine-modified graphene oxide in the polyamide 6/elastomer system using different mixing protocols. Combination of ethene–propene elastomer and graphene oxide leads to a polyamide material with increased strength, stiffness, and toughness. The reason is synergistic effect of the core–shell structure (nanofiller localized at interface) on mechanical properties. The structure-directing effect of graphene oxide is comparable with that of nanoclay. The mechanism of affecting dynamic phase behavior is different as a consequence of graphene oxide nature and interactions with polymer components.     

Highly Efficient Method for Preparing Homogeneous and Stable Colloids Containing Graphene Oxide

Phase transfer method has been developed for preparing homogeneous and stable graphene oxide colloids. Graphene oxide nanosheets (GONs) were successfully transferred from water to n-octane after modification by oleylamine. Corrugation and scrolling exist dominantly in the modified GONs. GONs were single layered with the maximum solubility in n-octane up to 3.82 mg mL^-1. Oleylamine molecules chemically attach onto the GONs. Compared with traditional strategies, the phase transfer method has the features of simplicity and high efficiency.     

In Situ Synthesis of Reduced Graphene Oxide and Gold Nanocomposites for Nanoelectronics and Biosensing

In this study, an in situ chemical synthesis approach has been developed to prepare graphene–Au nanocomposites from chemically reduced graphene oxide (rGO) in aqueous media. UV–Vis absorption, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were used to demonstrate the successful attachment of Au nanoparticles to graphene sheets. Configured as field-effect transistors (FETs), the as-synthesized single-layered rGO-Au nanocomposites exhibit higher hole mobility and conductance when compared to the rGO sheets, promising its applications in nanoelectronics. Furthermore, we demonstrate that the rGO-Au FETs are able to label-freely detect DNA hybridization with high sensitivity, indicating its potentials in nanoelectronic biosensing.     

Morphology,thermal and mechanical properties of epoxy adhesives containing well-dispersed graphene oxide

Graphene oxide (GO) is prepared and introduced into epoxy resins through a wet-transfer migration technique using a three-roll mill. The results of TEM, XRD and digital microscope observation show that good dispersion of GO is achieved without using any additives. The mechanical and thermal properties of GO/epoxy (GO/EP) adhesives are enhanced with GO incorporated. A 10.2% increase in Young's modulus and a 56.3% increase in elevated-temperature (120 °C) lap shear strength (LSS) was observed on addition of 1.0 wt% GO, compared to the neat epoxy adhesive. Increased glass transition temperature and improved thermal stability of the GO/EP adhesives are also observed in the DMA and TG analysis. Moreover, the toughness of the GO/EP adhesives is improved and much rougher fracture surface can be observed compared with the neat epoxy adhesive. No GO agglomeration can be observed in the SEM images of GO/EP adhesive with 1.0 wt% loading.     

Effect of Type of Surfactants and Organoclay Loading on the Mechanical Properties of EVOH/Clay Nanocomposite Blown Films

EVOH/clay nanocomposite films were prepared by using four types of surfactants to treat surface of clay because the surfactants were expected to affect the degree of clay dispersion in the EVOH matrix, which would in turn affect the properties of film. The nanocomposite films that contained the single alkyl tail with two repeating units of oxyethylene surfactants or single alkyl tail surfactant showed higher tensile strength, tensile modulus and elongation at break than those with 15 repeating units of oxyethylene surfactants or those with double alkyl tail surfactant.