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.     

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.     

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。     

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.     

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 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.     

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.     

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.     

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.     

Characterization and Properties of Poly(methyl methacrylate)/Graphene,Poly(methyl methacrylate)/Graphene Oxide and Poly(methyl methacrylate)/p-Phenylenediamine-Graphene Oxide Nanocomposites

In this study, poly(methyl methacrylate)/p-phenylenediamine-graphene oxide, poly(methyl methacrylate)/graphene, and poly(methyl methacrylate)/graphene oxide nanocomposite series were prepared using simple solution blending technique. In poly(methyl methacrylate)/p-phenylenediamine-graphene oxide series, graphene oxide modified with p-phenylenediamine was used to improve its dispersion and interfacial strength with matrix. Morphology study of poly(methyl methacrylate)/p-phenylenediamine-graphene oxide nanocomposite revealed better dispersion of p-phenylenediamine-graphene oxide flakes and gyroid patterning of poly(methyl methacrylate) over the filler surface. Due to nonconducting nature of graphene oxide, there was no significant variation in the thermal or electrical conductivity of these nanocomposites. Thermal conductivity of poly(methyl methacrylate)/p-phenylenediamine-graphene oxide 1.5 was 1.16 W/mK, while the electrical conductivity was found to be 2.3 × 10^?3 S/cm.     

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.     

石墨烯/聚乙烯高性能复合材料的制备与性能表征

采用液相超声分散热压制备了氧化石墨烯/聚乙烯(GO/PE)复合材料,研究了GO的微观结构,及GO/PE复合材料的热稳定性、力学性能、显微硬度及耐摩擦性能。对比纯PE与GO/PE复合材料可以发现,添加GO,复合材料的热稳定性、力学性能、显微硬度和耐磨性能有了明显提高,显微硬度的增加减少了PE及其复合材料与金属表面的有效接触面积,提高了材料的摩擦性能。     

Surface Modification of Graphene Oxide and Investigation of Its Effects on Surface Properties of Aramid Membranes

To manufacture aramid thin-film-composite membrane for desalination application (reverse osmosis) via in situ interfacial polymerization, the different weight percents of modified graphene oxide were applied into the aramid layer during interfacial polymerization. The dispersion of the modified graphene oxide was investigated by X-ray Diffraction (XRD) and Transition Electron Microscopy (TEM) methods. Also, the effect of the modified graphene oxide on the surface chemical composition and surface morphology of aramid membrane was investigated by Attenuated Total Reflectance-Infrared Spectroscopy (ATR-IR), scanning electron microscopy, and atomic force microscopy, respectively. The results showed that in the presence of the modified graphene oxide, the interfacial polymerization reaction is transferred between the nanoparticles so the depth of surface porosity is increased strongly. In addition, the hydrophilic value of aramid layer in the presence of the modified graphene oxide firstly increased up to 0.15 wt% but with an increase in the modified graphene oxide percent at 0.2 wt%, the surface hydrophilicity decreased gradually. As a result, the optimum hydrophilic and morphological properties were observed in samples containing 0.15 wt% of modified graphene oxide.     

Tailoring the properties of spark plasma sintered SiAlON containing graphene nanoplatelets by using different exfoliation and size reduction techniques: Anisotropic mechanical and thermal properties

SiAlON ceramics are intensively used in different areas but still there is a need to improve the mechanical and thermal properties as well as ease of machinability and reduce the weight. In this study, the effect of graphene nanoplatelets (GNPs) exfoliation and dispersion techniques on the microstructure and properties of SiAlON ceramics were investigated. For this purpose, 2, 4 and 8 wt% GNPs were dispersed by using traditional sonication and newly proposed microfluidization techniques. Then, composites were densified in spark plasma sintering (SPS) furnace. Scanning electron microscope (SEM), x-ray diffraction analyses (XRD) and property measurements were performed in through-plane and in-plane directions. The microfluidization technique found to be more effective than sonication for the exfoliation, size reduction and homogenization of GNPs. Addition of GNPs prepared by both techniques increased the fracture toughness and in-plane direction thermal conductivity whereas decreased the hardness and through-plane direction thermal conductivity of the SiAlON.     

氧化石墨烯与聚羧酸减水剂单体共聚物的制备与性能

通过氧化石墨烯(GO)与聚羧酸系减水剂单体甲基丙烯酸聚乙二醇单甲醚(MAAPEGME)、甲基丙烯酸(MAA)及甲基丙烯磺酸盐(SMAS)进行自由基共聚反应制备了氧化石墨烯与聚丙烯酸系减水剂(PCs)单体的共聚物(GO-PCs),旨在解决GO掺入水泥基材料时存在的分散不均匀及流动性降低的问题,制备GO-PCs时各组分的质量比为m(MAAPEGME)∶m(MAA)∶m(SMAS)∶m(GO)=17∶2∶1∶0.2。检测结果表明GO与单体之间发生了共聚反应,GO纳米片层均匀地分布在PCs中,达到了GO在水泥材料中分布均匀、不影响水泥流动性及增强增韧的目的,SEM形貌说明GO-PCs对水泥浆体的微观结构有较好的调控作用,研究结果对于制备高性能长寿命混凝土具有积极的意义。     

Study on the structure and properties of Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide nanocomposites

In this paper Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide (PMMA/PPy-GO) nanocomposites were prepared using in-situ chemical polymerization method and its structure and properties were studied. Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis confirmed that PPy nanopraticles covered the GO nanosheets surface and PMMA/PPy-GO nanocomposite were prepared successfully. The mechanical, electrical and thermal stability of the PMMA nanocomposites were also investigated using Tensile, Impact, Thermogravimetric analysis (TGA) and four-point probe methods. Correlation between direct morphological observation and final properties demonstrated that network structure formed by PPy-GOs in PMMA matrix. Tensile analysis showed that the addition of 0.4 wt % PPy-GO hybrids lead to 24.4 % enhancement in the Young’s modulus of PMMA compared to 5.0 % improvement that achieved at the same loading level of GO. Electrical conductivity measurement showed that dispersion of PPy-GO in PMMA matrix increased AC conductivity in the range of 8 orders of magnitude compared to PMMA. TGA analysis showed that the thermal stability of the PMMA nanocomposites improved over 20 ?C.     

A comparison of the temperature dependence of the modulus, yield stress and ductility of nanocomposites based on high and low MW PA6 and PA66

Nanocomposites with both organically modified and unmodified silicate have been prepared by an extrusion process using low and high molecular weight grades of PA6 and a low MW grade of PA66. Mechanical properties have been tested at temperatures ranging from 20 to 120 °C. The modulus increase in all nanocomposites with organically modified nanocomposites is similar: at room temperature an increase in the modulus of approximately 10% for each wt% of silicate is found. PA66 nanocomposites display an identical normalized modulus increase as PA6 nanocomposites, while unmodified silicate nanocomposites show a smaller increase in the modulus. The yield stress also increases with the addition of layered silicate. Low MW PA6 and PA66 nanocomposites show brittle fracture behaviour at room temperature, while high MW PA6 nanocomposites are ductile. With increasing temperature all nanocomposites become ductile at a certain temperature.