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An improved method is developed to synthesize octavinylsilsesquioxanes (VPOSS) with shorter time and higher yield, and then VPOSS is used to prepare new hybrids based on bismaleimide-triazine (BD/CE) resin, coded as VPOSS/BD/CE. The effect of the content of VPOSS on the key properties including curing behavior, thermal, mechanical, and dielectric properties as well as water resistance of VPOSS/BD/CE hybrids were systematically discussed. Compared with BD/CE resin, hybrids show similar curing behavior but different chemical structures and thus macro-performance. These key properties of hybrids are dependent on the content of VPOSS, all hybrids show significantly improved dielectric properties, water resistance, and dimensional stability; moreover, the hybrids with suitable content of VPOSS have bigger impact strengths. Specifically, with the addition of 7 wt% VPOSS to BD/CE resin, the dielectric constant decreases from 3.7 to 3.2, the dielectric loss decreases 55%, and the coefficient of thermal expansion reduces 23%; moreover, the glass transition temperature and initial decomposition temperature increase about 15°C. The attractive integrated properties suggest that VPOSS/BD/CE hybrids have great potential to be used as structural and functional materials for many cutting-edge fields. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The correlation between microstructure and dielectric properties of cyanate ester (CE)/hollow silicate tube (HST) hybrids was investigated by positron annihilation lifetime spectroscopy, coincidence Doppler-broadening spectroscopy, Fourier transform infrared spectra, and dynamic mechanical analyses. The addition of HST to CE resin brings a multi-aspect influence (cross-linked structure and density, free volume, and interfacial action) on the structure of the cross-linked network and thus results in significantly varied dielectric properties. There is an optimum content of HST in hybrids to get the lowest dielectric constant and loss. When the content of HST is smaller than the percolation threshold, the hybrid has decreased dielectric constant and loss; this mainly results in the reduced size of free volume and orthopositronium intensity ( I3), although when the content of HST is larger than the threshold, the increased I3 and the size of free volume as well as the interfacial polarization are responsible for the significantly enlarged dielectric constant and loss. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel method is proposed to synthesize new mesoporous silica containing amine groups (MPSA), and it was further employed to modify bismaleimide-dialllyl bisphenol (BD)/cyanate ester (CE) resin to form novel MPSA/BD/CE hybrids; in addition, the typical properties of MPSA/BD/CE were systematically investigated. Results show that these hybrids have very low dielectric constant and loss as well as good thermal properties. Compared with BD/CE resin, all hybrids have not only decreased dielectric constant and loss but also similar dependence of dielectric properties on frequency over the whole frequency from 10 to 106 Hz. Specifically, with the addition of MPSA to BD/CE resin, the dielectric constant reduces from 3.5 to 3.0, and the dielectric loss is only 85% of that of BD/CE resin. Note that all hybrids show better thermal resistance (reflected by higher glass transition temperature, decreased maximum degradation rate, and higher char yield at 800°C) than BD/CE resin. All these differences in macro-properties are attributed to the different structure between MPSA/BD/CE hybrids and BD/CE resin. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

New high performance insulating composites based on hollow silica tubes (mHST) and bismaleimide/diallylbisphenol A (BDM/DBA) resin, which exhibit improved toughness, dielectric properties, and flame retardancy, were successfully developed. The effect of the amount of mHST on the properties of composites was systematically studied. Results show that the impact strength of the composite with 0.5 wt% mHST is about 2.2 times that of BDM/DBA resin. In addition, compared with BDM/DBA resin, the composites show lower and stable dielectric constant, better frequency stability of dielectric loss, significantly improved flame retardancy, and similarly outstanding thermal resistance. The reasons behind these attractive integrated properties are discussed from the view of structure-property relationship. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel kind of solventless silicone hybrids (SSiH) containing branched poly(methylphenylvinylsiloxane) (PMPVSi), end-capped hydrogen-functionalized hyperbranched polysiloxane (EHFHPSi), and octavinyl-polyhedral oligomeric silsesquioxane (OVPOS) was developed through a hydrosilylation reaction. Each of the three basic components was synthesized by harmless and recyclable methods. The new hybrids are considerably suitable for vacuum pressure impregnation process, and can serve as an excellent class C insulating material. The effect of differing stoichiometries of OVPOS and EHFHPSi on the performance of cured hybrids is discussed. Results show that SSiH hybrids possess excellent dielectric and thermal properties as well as low viscosity. The reduction in the dielectric constant and the improvement of thermal property of SSiH hybrids can be explained by the unique structure and morphology of hybrids resulting from the presence of OVPOS and EHFHPSi. The novel silicone hybrids exhibit great potential to be used for many cutting-edge industries, especially the microelectronic and insulation fields. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Using conventional mixing techniques, the mechanical properties of prepared carbon nanotube (CNT)/polymer composites are not impressive enough, because of their aggregation problem at a high loading of CNTs. In this article, high mechanical performance ultrahigh molecular weight polyethylene (UHMWPE) nanocomposites with high loading of multiwalled CNTs were successfully fabricated by a new manufacturing technique. Specifically, the tensile strength and storage modulus at 25 °C of UHMWPE nanocomposites with 32 wt % of nanotubes prepared by the novel technique reaches 107.6 MPa and 6.0 GPa, respectively, about 4.7 times and 5.0 times of that of pure UHMWPE resin, which are also very high experimental results compared with polyethylene nanocomposite prepared by traditional hot‐compression techniques. These attractive results suggest that the high‐loading CNTs without sacrificing their dispersion and the impregnation quality of polymer‐impregnated buckypapers are essential for fabricating CNTs/polymer composites with superior mechanical properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48667. [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]

The large-scale synthesis of high-purity SiC nanowires is a challenge. In this context, sponge-like graphene oxide (GO) was used as a carbon source as well as a reaction template for directly synthesizing SiC nanowires. GO was completely reacted with SiO to prepare high-purity 3C-SiC nanowires by thermal evaporation and carbothermal reduction without the use of any catalyst, rather than by epitaxy. Characterization was conducted using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and selected-area electron diffraction. The SiC nanowires had lengths of several tens of micrometers and a perfect single-crystalline structure with a bamboo-like morphology., Competing Interests: The authors declare no competing financial interest.