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Buckypapers (BPs) were generally laid up interleaved with polyethylene (PE) films to form BPs/PE composites after hot press. However, the mechanical properties of BPs/PE composites as-prepared were not good enough owing to poor impregnation and weak interfacial interactions between the matrix and carbon nanotube (CNT). In this paper, controlled microwave radiation treatment was applied on the BPs/PE composites. It is found that the microwave irradiation can effectively improve the tensile strength and stiffness of BPs/PE composites. Specifically, the tensile strength of BPs/PE composites increases from 20.9 MPa upto 34.1 MPa, 2.8 times that of pure PE, while the modulus increases from 880 MPa to 1778 MPa, 3.0 times that of pure PE. In addition, the structures (including fractured morphology, the interfacial composition between CNT and PE, structure of CNT and PE matrix, and crystallization) of BPs/PE nanocomposites with and without microwave irradiation were observed by SEM, FTIR, Raman, X-ray, and DSC, and then a mechanism of microwave irradiation to enhance the mechanical properties of BPs/PE composites was also proposed. [ABSTRACT FROM AUTHOR]

Abstract: A novel kind of modified bismaleimide/cyanate ester (BCE) resins by copolymerizing with hyperbranched polysiloxane including high content of phenyl (HBPSi) was first reported. The effect of HBPSi on the curing mechanism, and that on the dielectric properties and flame retardancy of cured networks were systemically investigated. Results show that compared with BCE resin, HBPSi/BCE resin has obviously different cross-linked structure, and thus leading to simultaneously improved dielectric properties and flame retardancy. The reactions between HBPSi and the decomposition structure of BCE resin change the thermo-oxidative degradation mechanism of the first step in the thermo-oxidative degradation; in addition, the presence of HBPSi in BCE resin also significantly reduces the mass loss rate (MLR) and increases char yield at 800 °C under an air atmosphere. Therefore, the positive effect of HBPSi on improving the flame retardancy is attributed to the condensed phase mechanism. On the other hand, HBPSi/BCE resins exhibit improved dielectric properties (including decreased dielectric constant and loss) with increasing the content of HBPSi. More importantly, this investigation demonstrates that designing new polysiloxane with suitable chemical structure is important to develop high performance resins with attractive flame retardancy and dielectric properties. [Copyright &y& Elsevier]

[Display omitted] • A low-viscosity photosensitive resin system containing PU segments and PDMS segments was prepared. • The photosensitive resin systems had good 3D printing accuracy and the resultant cured photosensitive resin possess excellent flexibility and elasticity. • The flexible sensors prepared with photosensitive resin exhibit high signal sensitivity and stability. Flexible sensors show the wide range of applications in electronic products. However, challenges remain in developing sensors with internal complex construction, excellent flexibility, elasticity and strength. In this paper, a prepolymer (PU-PDMS-OH-HEMA) contain polyurethane (PU) segments and polysiloxane (PDMS) segments was synthesized, and the photosensitive resins with low viscosity for 3D printing were prepared by mixing prepolymers with diluents and photoinitiators. The resultant cured photosensitive resins showed the improved mechanical properties. The PDMS-OH-30 sample exhibit the excellent mechanical properties, with tensile strength and elongation at break of 10.03 MPa and 1046.15 %, respectively, and the resin viscosity of 62 cP. Conductive ionic liquids were added to the above photosensitive resins to prepare flexible sensors, which show the electrical sensitivity and stability. The findings in the work propose a contribution to the development of highly flexible 3D printing resins for fabricating flexible sensors. [ABSTRACT FROM AUTHOR]

Highlights: [•] K2CuCl4·2H2O can be used as the mimic laccase to cure the dead lacquer. [•] Optimal cure conditions are 0.6% K2CuCl4·2H2O, stirring 90min, 75% relative humidity. [•] The dead lacquer film has good thermal stability and chemical resistance. [ABSTRACT FROM AUTHOR]

In this study, an experimental investigation on fabricating Ni-free CoCrW alloys by selective laser melting (SLM) for dental application was conducted in terms of microstructure, hardness, mechanical property, electrochemical behavior, and metal release; and line and island scanning strategy were applied to determine whether these strategies are able to obtain expected CoCrW parts. The XRD revealed that the γ-phase and ε-phase coexisted in the as-SLM CoCrW alloys; The OM and SEM images showed that the microstructure of CoCrW alloys appeared square-like pattern with the fine cellular dendrites at the borders; tensile test suggested that the difference of mechanical properties of line- and island-formed specimens was very small; whilst the outcomes from the electrochemical and metal release tests indicated that the island-formed alloys showed slightly better corrosion resistance than line-formed ones in PBS and Hanks solutions. Considering that the mechanical properties and corrosion resistance of line-formed and island-formed specimens meet the standards of ISO 22674:2006 and EN ISO 10271, CoCrW dental alloys can be successfully fabricated by line and island scanning strategies in the SLM process. [ABSTRACT FROM AUTHOR]

Abstract: A novel modified bismaleimide resin system (BDP) with significantly improved flame retardancy and decreased dielectric loss was successfully prepared by copolymerizing 4,4′-bismaleimidodiphenyl methane (BDM) with 2,2′-diallyl bisphenol A (DBA) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Compared with BDM/DBA resin, BDP resin has obviously different crosslinked structure, and thus simultaneously improved dielectric properties and flame retardancy. Most attractively, with a very low content of phosphorus element, the BDP resins show significantly improved flame retardancy. For example, when the content of phosphorus is as low as 0.5 wt%, the flame retardancy of BDP resin is evaluated to be UL94 V-0 level, while that of BD resin is classified as UL94 V-1 level; in addition, the total heat release (THR) of BDP resin reduces to about 61% of that of BD resin, and similar phenomenon is also observed on the weight ratio of CO/CO2. This outstanding flame retardancy of BDP resins is attributed to the attractive phosphorus-nitrogen synergistic effect. The main flame retardancy mechanism of BDP resins is evaluated to be condensed phase mechanisms. On the other hand, BDP resins exhibit improved dielectric properties; specifically, the dielectric constant and loss at 1 GHz of BDP resin with 19.7 wt% of phosphorus are 2.90 and 0.0058, only about 92% and 51% of that of neat BD resin, respectively. These interesting results demonstrate that the co-reaction of DOPO with BD resin is important, and the method proposed herein is a new approach to develop high performance resins with attractive flame retardancy and dielectric properties. [Copyright &y& Elsevier]

To improve the interlaminar properties of carbon fiber reinforced polymer composites (CFRPs), a hybrid fiber mat (i-MBP-PCF) was prepared by in situ deposition of a multiwalled carbon nanotube buckypaper (i-MBP) on the surface of functionalized CF fabric (PCF). The effect of the hybrid fiber mat on the interlaminar and electrical properties was systematically investigated. The results showed that the i-MBP-PCF hybrid fiber mat showed excellent interlaminar and electrical property enhancement functions. The interlaminar shear strength (ILSS), Mode-II interlaminar fracture toughness (G IIC), and electrical conductivity in the out-of-plane direction of i-MBP-PCF/EP increased 68.6%, 44.4%, and 6080%, respectively, compared to those of the CF/EP composite. [Display omitted] • A novel hybrid fiber mat was prepared by in situ depositings of a carbon nanotubes buckypaper on a modified carbon fabric. • The hybrid fiber mat showed excellent interlaminar shear and electrical properties enhancement effects. • Composites' interlaminar shear strength (59MPa) and mode-II toughness (650J/m2) increased by 68.6% and 44.4% respectively. • The electrical conductivity in the out-of-plane and the in-plane direction increased by 6080% and 7 folds respectively. • The hybrid fiber mat has huge application potential in aerospace, conducting elements, and structural materials. [ABSTRACT FROM AUTHOR]

In order to improve the wear resistance and service life of the epoxy resin (EP)-bonded diamond abrasive tools, graphene oxide (GO) was incorporated through a green method without any organic solvents. A curing accelerator, 3-methyl-N,N-diethylbenzenamine (3-MBDEA) acts as a phase transfer agent which rapidly catches GO from water phase to epoxy phase, and the diamond/GO/EP abrasive tools were fabricated via in situ polymerization. The effect of GO on the structure of EP was characterized, and the grinding performances of as-prepared diamond/GO/EP abrasive tools were evaluated in the grinding of concrete. Results show that the service life of the diamond/GO/EP abrasive tools are significantly improved by the incorporation of GO. In the case of the diamond with the size of 50 μm (D50)/GO0.5/EP abrasive tool only with 0.5 wt% GO, its service life increases by 75% compares to that of the D50/EP abrasive tool. The excellent performance of diamond/GO/EP abrasive tools is attributed to the improvement of the wear resistance of EP and the enhancement of the interfacial adhesion between EP and diamond with the addition of GO. This work may provide a potential industrial application for graphene-related materials. Image 1 [ABSTRACT FROM AUTHOR]