Application of Polyimide-based Microfluidic Devices on Acid-catalyzed Hydrolysis of Dimethoxypropane

Microfluidic devices intensify transport phenomena and can improve chemical processes. New manufacturing processes and materials are perpetually developed due to constantly growing interest in process intensification. In this contribution, the authors present the design and application of polyimide-foil-based microfluidic mixing devices manufactured by reactive ion etching. As appropriate model reaction system, acid-catalyzed 2,2-dimethoxypropane (DMP) hydrolysis was chosen and investigated in three different mixing structure with varying flow rate. Energy dissipation rates were calculated to estimate mixing performances. The results show good mixing quality for Reynolds numbers between 10 and 100 and similar mixing times scales for all investigated microstructured mixers.     

Effects of the joining process on the microstructure and properties of liquid-phase-sintered SiC-SiC joints formed with Ti foil

The joining of liquid-phase sintered SiC (LPS-SiC) ceramics was conducted using spark plasma sintering (SPS), through solid state diffusion bonding, with Ti-metal foil as a joining interlayer. Samples were joined at 1400 °C, under applied pressures of either 10 or 30 MPa, and with different atmospheres (argon, Ar, vs. vacuum). It was demonstrated that the shear strength of the joints increased with an increase in the applied joining pressure. The joining atmosphere also affected on both the microstructure and shear strength of the SiC joints. The composition and microstructure of the interlayer were examined to understand the mechanism. As a result, a SiC-SiC joining with a good mechanical performance could be achieved under an Ar environment, which in turn could provide a cost-effective approach and greatly widen the applications of SiC ceramic components with complex shape.     

The effects of hydrogen-induced lattice distortion and Nb-D formation on its permeation through niobium

Abnormal permeation behavior of hydrogen through niobium has been investigated in this paper, i.e. the permeation flux saturated with long-term decrease after reaching a maximum. The diffusivity and permeability have been deduced from the decay edge of permeation transient. Three kinds of polycrystalline niobium foils with different annealing temperature have been compared, to verify the effect of defects and grain properties on the permeability and diffusivity. In the temperature range of (773–1023) K, the heat treatment along with the permeation cycles could either reduce or increase the permeability and diffusivity depending sensitively on temperature and showing a temperature threshold around 950 K. The permeation flux is proportional to square root of pressure, revealing that the abnormal permeation was still bulk diffusion-limited. The diffusivity gradually decreased with permeation cycles, and became more and more sensitive to pressure. The niobium foil expanded macroscopically along the gradient of hydrogen concentration, which reveals the strong and unrecoverable lattice distortion in this temperature and pressure range. The X-ray diffraction studies showed that splitting of all the Nb peaks and shifting of Nb-D peaks along with hydrogen loadings. The phase transition was expected to eliminate the lattice strain during hydrogen loading and which in turn acted as a diffusion barrier.     

Exploring the photocatalytic hydrogen production potential of titania doped with alumina derived from foil waste

The multifunctional potential of a catalyst previously synthesised for thermal processes is explored by investigating its activity for photocatalytic production of H₂ from glycerol, a by-product from the manufacture of bio-diesel. The studied catalyst contains TiO₂ doped with Al₂O₃ that was derived from aluminum foil waste. This catalyst showed higher photocatalytic activity than the analogous catalyst prepared with a commercial Al₂O₃. Pt and Pd act as electron traps while the Al₂O₃ demonstrated a promotional effect, partially through proton donation. Under optimum conditions, a steady-state of 4.2 mmol H₂ gTiO₂⁻¹ hr⁻¹ was produced, which is comparable to the 4.7 mmol H₂ gTiO₂⁻¹ hr⁻¹ obtained with Pt–TiO₂, which is a standard photocatalytic material. It should be noted that the reported Pt/Pd/TiO₂-ANFL catalyst has not yet been optimised and so this result is encouraging. It is hoped that these findings can inspire more sustainable and less expensive hydrogen production, including from biomass feedstocks such as glycerol.     

超深溜井爆破一次成井技术实践

为解决溜井掘进效率低、安全性差等问题，以柿竹园多金属矿掘进出矿溜井为例，提出了爆破一次成井技术，根据矿山具体爆破条件，设计了布孔参数、装药结构和起爆顺序等。实践表明，爆破一次成井技术施工天井效果良好，溜井贯穿上下2个分段，与设计相符，相较于普通法施工天井，节约成本30.7%，节约时间58.3%，经济效益显著，施工周期短，且安全性好，值得在其他类似矿山推广应用。     

SG-5型PVC软树脂的研发与规模化生产

介绍了SG-5型PVC软树脂在调试过程中存在的问题和解决方法,试验过程中通过调整聚合温度、分散剂用量及比例、引发剂比例、搅拌转速等,制得既满足管材型材的使用要求、又尽可能倾向于软制品加工要求的SG-5型软树脂。     

浅谈压延铜箔光面色差的成因

针对压延铜箔在表面处理过程中光面易出现色差的问题,从设备、工艺、人员操作等方面进行成因探讨,并给出了应对措施。     

Effect of different initiators on temperature-sensitive monolithic columns and application in online enrichment of β-sitosterol

Three temperature-sensitive monolithic columns were prepared by atom transfer radical polymerization and oxidation–reduction method using the initiator systems of CCl₄/FeCl₂, BPO/DMA, and APS/TEMED, respectively. The three monoliths were characterized by scanning electron microscopy, nitrogen adsorption, and thermogravimetric analysis. The obtained monolithic columns were used as on-line solid phase extraction sorbent coupled with high-performance liquid chromatography for the enrichment of β-sitosterol. By comparing some influencing factors on the adsorption, the optimum temperature-sensitive monolithic column which was initiated by CCl₄/FeCl₂ was selected for enrichment of β-sitosterol from plant oil. The maximum adsorption capacity of the monolith for β-sitosterol was 10.0031 mg/g. The limit of detection and limit of quantitation were 0.039 and 0.13 mg/mL, respectively. The recovery was in the range of 90.21–98.26%. The results showed that the monolith had better selectivity for β-sitosterol and could be used for enrichment of β-sitosterol in food samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47683.     

Grain size effect on cyclic deformation behavior and springback prediction of Ni-based superalloy foil

In order to clarify the influence of grain size on cyclic deformation response of superalloy sheets and springback behavior, cyclic loading–unloading and shearing tests were performed on the superalloy foils with 0.2 mm in thickness and diverse grain sizes. The results show that, the decline ratio of elastic modulus is weakened with increasing grain size, and the Bauschinger effect becomes evident with decreasing grain size. Meanwhile, U-bending test results determine that the springback is diminished with increasing grain size. The Chaboche, Anisotropic Nonlinear Kinematic (ANK) and Yoshida-Uemori (Y-U) models were utilized to fit the shear stress–strain curves of specimens. It is found that Y-U model is sufficient of predicting the springback. However, the prediction accuracy is degraded with increasing grain size.     

Linear amphiphilic diblock copolymers of lactide and 2-dimethylaminoethyl methacrylate using bifunctional-initiator and one-pot approaches

Linear amphiphilic diblock copolymers of polylactide (PLA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP) of DMAEMA followed by ring-opening polymerization (ROP) of LLA using the bifunctional initiator, 2′-hydroxyethyl 2-bromoisobutyrate. NMR showed that the resulting PLA block was racemic and a quaternization/precipitation technique showed that there were significant amounts of racemic PLA homopolymer. In addition, simultaneous ATRP of DMAEMA and ROP of l-lactide by tin octoate were conducted at varied temperatures, indicating 90 °C as a suitable compromise temperature; this one-pot process also led to racemization and P(L)LA homopolymer. The racemization was attributed to reversible deprotonation of LLA by the N(CH₃)₂ moiety of (P)DMAEMA and the PLA homopolymer impurity was related to in situ formation of lactoyl lactate (LA–LA) due to nucleophilic ring opening of lactide by the amino moieties of (P)DMAEMA. The methods presented can be useful for the preparation of PDMAEMA–b–PLA/PLA composites in a two-step process or in a single step, one-pot process.