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With the development of power industry, the recycling of waste insulator silicone rubber (WSR) remains a significant challenge. Herein, an efficient alcoholysis strategy for the surface modification of WSR was explored by using nerol as alcoholysis reagent, and then the nerol modified WSR (Nerol-WSR) was utilized in polypropylene toughening. FTIR spectra indicate that nerol can served as nucleophilic reagent to cleave the Si–O bonds in WSR, resulting in an efficient surface grafting of nerol moieties on WSR. The grafting content of nerol moieties gradually increases with alcoholysis times. Morphology investigation demonstrates that with the increase of alcoholysis time, the dispersion state of Nerol-WSR particles in PP matrix is significantly improved, along with a much smaller particle size. Accordingly, with the addition of 10 wt.% of Nerol-WSR, the resulting PP composites can achieve a remarkable increase of approximately 200% in impact strength. This should be due to the grafted nerol moieties can substantially improve the interfacial adhesion of the composites and hence facilitate the dispersion of WSR particles in PP matrix. Therefore, the stress concentration of PP can also be effectively delivered to the adjacent Nerol-WSR and thus retard the propagation of cracks. In addition, the addition of Nerol-WSR can also increase the loss tangent values of the composites, which indicates its potential application in polymer damping. [ABSTRACT FROM AUTHOR]

Low dielectric loss (tanδ < 0.05) within a frequency range of 20 Hz–2 MHz and a temperature range of 25–350 K was obtained through an optimized annealing process in colossal permittivity (CP) (εʹ > 104) (La0.5Nb0.5)0.005Ti0.995O2 ceramics. The effects of annealing on two important dielectric relaxations, electron-pinned defect-dipole (EPDD), and Maxwell–Wagner polarization were explored. An enhancement of activation energy (Ea) value and a large distribution of relaxation time τ were detected in EPDD relaxation for the ceramics annealed at 1123 K. The EPDD polarization was destroyed, accompanied by the disappearance of CP in the high annealing temperature range (> 1273 K). Impedance spectroscopy analysis suggested that grain boundary impedance could greatly enhanced as the ceramics were annealed at 1123 K. Strong electrode-material-dependent dielectric properties were detected, and a high tanδ was observed after the insulating surface layer was removed. The CP and low tanδ were ascribed to the maintenance of EPDD polarization, the enhancement of grain boundaries resistance, and the formation of an insulating surface layer through appropriate annealing. [ABSTRACT FROM AUTHOR]

The pure phase Li4Mg3Ti2O9 with nanopowders of 37 nm was prepared by a sol-gel method and calcinated at 600, 450 °C lower than that by a conventional solid-stated method. The sintering temperature of Li4Mg3Ti2O9 with addition of LiF (≥ 2 wt%) was reduced from 1275 to 800 °C with enhancement of density and microwave dielectric properties, related to the substitution of F− ion for O2− ion in Li4Mg3Ti2O9 compound at low temperature. Addition of LiF broadened the sintering window (800-1000 °C). The Li4Mg3Ti2O9-4 wt% LiF ceramic sintered at 850 °C exhibited good microwave dielectric properties of εr = 17.5, Q × f = 89,320 GHz (at 9.1 GHz), and τf = − 37.4 ppm/°C. Such samples were compatible with Ag electrodes, promising to be a candidate material for low-temperature co-fired ceramics technology application. [ABSTRACT FROM AUTHOR]

The MgNbO co-doped with 20 wt% TiO (MNT) and x wt% LiF (1 ≤ x ≤ 8) composite ceramics were prepared by a solid-state reaction method for developing ultralow-fired (≤800 °C) microwave dielectric ceramics. The sintering temperatures of MNT ceramics were successfully lowered to 750 °C due to the formation of liquid phase (LiF). A secondary phase of MgTiO was observed at above 700 °C for MNT-8 wt% LiF ceramics. All the composite ceramics have the optimal bulk densities at 800 °C, which corresponds to the maximum Q × f value of 32,000 GHz and ɛ value of 15.7. The well microwave dielectric properties of ɛ = 15.6, Q × f = 25,000 GHz, and τ = −56 ppm /°C were obtained at 750 °C for 5 h for MNT-8 wt% LiF ceramics. This material is compatible with Ag electrodes, suitable for low-temperature co-fired ceramics applications. [ABSTRACT FROM AUTHOR]

Natural occurred nanotubes, halloysite nanotubes, were modified by silane and incorporated into epoxy resin to form nanocomposites. The morphology of the nanocomposites was characterized by transmission electron microscopy (TEM). Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed on the nanocomposites. Flexural property and coefficient of thermal expansion (CTE) of the nanocomposites were also determined. Comparing with the neat resin, about 40% increase in storage modulus at glassy state and 133% at rubbery state were achieved by incorporating 12 wt% modified HNTs into the epoxy matrix. In addition, the nanocomposites exhibited improved flexural strength, char yield and dimensional stability. TEM examination revealed a uniform dispersion of the nanotubes in the epoxy resin. The remarkably positive effects of the HNTs on the performance of the epoxy resin were correlated with the unique characteristics of the HNTs, the uniform dispersion and the possible interfacial reactions between the modified HNTs and the matrix. [ABSTRACT FROM AUTHOR]

The article reports a research study of the construction of a filler network to reinforce crystalline plastics, through the use of a self-assembly process using hydrogen bonding. Naturally-occurring halyosite nanotubes and silica are used as inorganic hydrogen-bonding couplers (IHC), because they offer specific sites for unpaired electron exchange. Organic species used as organic hydrogen-bonding couplers (OHC) include melamine, melamine cyanurate, and diphenyl guanidine. Paired IHC and OHC form a strong inorganic network using hydrogen bonds.