A novel method based on ultrastable foam and improved gelcasting for fabricating porous mullite ceramics with thermal insulation–mechanical property trade-off

Foam instability and long drying cycle limits the widespread use of foaming method. In this paper, a kind of porous mullite ceramic with thermal insulation–mechanical property trade-off were fabricated via novel ultrastable foam and improved gelcasting procedure. The solidification process and stability of foam slurry, as well as the thermal, mechanical property and pore structure of the porous mullite ceramics were investigated. The results showed that porous mullite ceramics with different bulk densities could be prepared via varying volume of foam which was stable enough to be maintained in slurry for a long time. The accelerated gelation rate as well as the gelation degree resulted in the improved gelcasting method led to a shortened period of drying and demould. The obtained pores, which were small, smooth, and unimodal distributed in size in porous mullite ceramics, contributed to achieving the trade-off between thermal insulation and mechanical property.     

Preparation of dendritic–linear polyether-modified silica sol and its application in coatings

Dendritic–linear polyether-modified silica sol (DLPS) was synthesized using diethylenetriamine, methyl acrylate, epoxy-terminated polyether, triethoxysilane, and silica sol in five steps. The prepared sol was stable and transparent. DLPS was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and particle size distribution analysis. Subsequently, DLPS was examined as a stain-resistant additive in (paint) coatings. The surface of the sample coatings with and without DLPS additive was examined by scanning electron microscopy, energy-dispersive spectrometry analysis, and contact angle analysis. The results showed that the stain-resistant additive appeared on the surface of the coating, which made the surface more compact and hydrophilic. The performance of the stain-resistant additive was examined in commercial outdoor emulsion coatings (WB200). The result showed that the presence of the stain-resistant additive could enhance the stain resistance performance of paint. Furthermore, the stain resistance performance improved with increasing amounts of additive. Specifically, the stain resistance performance of paint improved by 40.63% in the presence of 6 wt% DLPS. Therefore, the current findings demonstrate the importance of DLPS in advancing progress and application in the paint coating industry.     

Method to remove wafer surface particles

A big yield drop has been observed during the automatic inspection (AOI) after the saw stage. A step by step AOI inspection check and defect review is made to see which step made a big yield drop and which kind of defect contributed most to the yield drop. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis showed the shape and chemical element of the particle. From the EDS result, particles can be separated into two categories. One was the inorganic related materials, mainly including silicon (Si) element, which came from the saw stage. A design of experiment (DOE) is used to find some reasonable saw relative parameter and optimize it in order to remove the particle from the saw stage. But the quantity of this kind of particle was small. Yield was only improved by less than 5%. Our main effort was to remove another kind of particle which was organic related materials, mainly including carbon (C) and oxygen (O) element. This kind of particle was from tape residue. In order to remove the tape residual, one step was added before the saw stage. Almost all of the tape residual was removed. Finally, the final yield was improved by more than 15%.     

Molecular‐Level Design of Hierarchically Porous Carbons Codoped with Nitrogen and Phosphorus Capable of In Situ Self‐Activation for Sustainable Energy Systems

Hierarchically porous carbons are attracting tremendous attention in sustainable energy systems, such as lithium ion battery (LIB) and fuel cell, due to their excellent transport properties that arise from the high surface area and rich porosity. The state‐of‐the‐art approaches for synthesizing hierarchically porous carbons normally require chemical‐ and/or template‐assisted activation techniques, which is complicate, time consuming, and not feasible for large scale production. Here, a molecular‐level design principle toward large‐scale synthesis of nitrogen and phosphorus codoped hierarchically porous carbon (NPHPC) through an in situ self‐activation process is proposed. The material is fabricated based on the direct pyrolysis of a well‐designed polymer, melamine polyphosphate, which is capable of in situ self‐activation to generate large specific surface area (1479 m² g^?1) and hierarchical pores in the final NPHPC. As an anode material for LIB, NPHPC delivers a high reversible capacity of 1073 mAh g^?1 and an excellent cyclic stability for 300 cycles with negligible capacity decay. The peculiar structural properties and synergistic effect of N and P codopants also enable NPHPC a promising electrocatalyst for oxygen reduction reaction, a key cathodic reaction process of many energy conversion devices (for example, fuel cells and metal air batteries). Electrochemical measurements show NPHPC a comparable electrocatalytic performance to commercial Pt/C catalyst (onset potential of 0.88 V vs reversible hydrogen electrode in alkaline medium) with excellent stability (89.8% retention after 20 000 s continuous operation) and superior methanol tolerance.     

Synthesis and characterization of a novel fluorene‐alt‐carbazole polymer to host green,blue, and red phosphorescence

A novel fluorene‐alt‐carbazole polymer host Poly(9,9‐dioctyl‐9H‐fluorene‐2,7‐diyl‐alt‐N‐tetrahydropyran‐3,6‐carbazole) (PFCz), composed of N‐tetrahydropyran‐3,6‐carbazole and 9,9‐dioctyl‐2,7‐fluorene in the polymer backbone, was synthesized by Suzuki coupling. The PFCz possesses good thermal stability and proper lowest unoccupied molecular orbital (LUMO)/highest occupied molecular orbital (HOMO) energy levels to facilitate the injection and transport of electrons and holes. Upon doping with blue, green, and red phosphors, red ‐ green ‐ blue (R‐G‐B) phosphorescent devices hosted by PFCz have been fabricated and investigated. In contrast to those of blue and green devices, the red devices give better performances with a maximum luminous efficiency of 4.88 cd/A and a maximum power efficiency of 1.85% at 149.84 cd/m², due to favorable triplet energy level (E_T) of PFCz for red phosphor, bis(2‐methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(III) [Ir(MDQ)₂(acac)]. Additionally, with different doped concentrations of Ir(MDQ)₂(acac), the PFCz‐related red devices emit nearly pure red light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.57, 0.38), (0.60, 0.38), (0.61, 0.38), and (0.62, 0.38), which were very close to the standard red (0.66, 0.34) by the National Television System Committee. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43234.     

Influence of 1,2‐polybutadiene on properties of dicumyl peroxide cured brominated butyl rubber

Peroxide curing of brominated butyl rubber (BIIR) is an attractive topic, but the degradation of BIIR during the curing is a drawback needed to be overcome. Coagent assisted peroxide curing system is an attractive and effective choice in order to increase the crosslink density of rubbers. 1,2‐polybutadiene (1,2‐PB) is used as a crosslinking coagent for the curing of BIIR by dicumyl peroxide (DCP), and the effect of 1,2‐PB on the curing characteristics, crosslink density, and mechanical properties is investigated. The addition of 1,2‐PB affects the curing characteristics of BIIR compound and significantly increases the crosslink density of BIIR vulcanizates. With increasing 1,2‐PB content, the tensile strength and stresses at a given extension of BIIR vulcanizates increase, but the elongation at break decreases. A stress‐softening effect of the carbon black filled BIIR vulcanizates is observed and becomes more pronounced with increasing 1,2‐PB content. The addition of 1,2‐PB increases the stress relaxation index of BIIR. GPC and ¹³C‐NMR results indicate 1,2‐PB participates in the crosslinking reaction, and the existence of 1,2‐PB component in the insoluble fraction of BIIR/1,2‐PB vulcanizates is confirmed by solid‐state ¹³C‐NMR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43280.     

Stepwise cure and properties of silicone resin for high‐ultraviolet‐transmission optical elements

A new high‐ultraviolet (UV)‐transmission silicone‐resin polymeric material was prepared via curing during hydrosilylation of tetramethyltetravinylcyclotetrasiloxane with tetramethylcyclotetrasiloxane by a liquid‐surface supernatant method, using a stepwise heating program to avoid spontaneous combustion of the reaction mixture. The relationships were investigated in detail between reactive groups, cross‐linking density, mechanical and UV‐transmission properties. For this purpose, UV transmittance and dynamic mechanical properties, respectively, of the silicone resin were measured with UV–visible spectrophotometry and dynamic mechanical thermal analysis. In addition, surface roughness was evaluated with an atomic force microscope as well as an interferometer. The curing process was monitored by Fourier transform infrared spectroscopy and rotational rheometry. The cyclic silicone oils were compared with linear ones in structure and product properties. The results indicated that stepwise temperature control during curing process was particularly indispensible due to the presence of active Si?H bonds, and that the silicone resin of high modulus, high UV transmittance (92.7%) and low surface‐roughness was largely homogeneous in cross‐linking points distribution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43308.     

Combined Urea Complexation and Argentated Silica Gel Column Chromatography for Concentration and Separation of PUFAs from Tuna Oil: Based on Improved DPA Level

Eicosapentaenoic acid (EPA, 20:5n‐3), docosapentaenoic acid (DPA) isomers (22:5n‐6 and 22:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3) derived from tuna oil were concentrated by three stages of urea fractionation at various crystallization temperatures and different fatty acid/urea ratios. Thereafter, polyunsaturated fatty acids concentrate containing comparatively enriched DPA levels was purified by argentated silica gel column chromatography. A product containing 22.2 ± 0.6 % EPA, 4.6 ± 0.0 % DPAn‐6, 5.9 ± 0.1 % DPAn‐3 and 42.3 ± 1.2 % DHA was obtained at 1:1.6 fatty acid/urea ratio (w/w) by crystallization at ?8 °C for 16 h, ?20 °C for 8 h, and ?8 °C for 16 h. A DPA isomer concentrate containing 26.1 ± 0.5 % DPAn‐6 and 22.3 ± 0.4 % DPAn‐3 was achieved by argentated silica gel chromatography in the 6 % acetone/n‐hexane solvent fraction (v/v), and the recovery of both fatty acids was 66.1 ± 3.2 and 70.7 ± 2.2 %, respectively. Furthermore, 91.9 ± 2.5 % EPA and 99.5 ± 2.1 % DHA with recoveries of 47.8 ± 2.0 and 56.7 ± 3.3 %, respectively, were obtained in various fractions.