乙丙橡胶生产工艺与技术

乙丙橡胶以其独特的性能,在汽车工业、建筑行业、油品添加剂、塑胶跑道等领域有广泛的应用。本文主要介绍了乙丙橡胶生产技术、乙丙橡胶产品牌号、性能以及应用领域,结合现有的乙丙橡胶科研情况,阐述了乙丙橡胶催化剂的研发、核壳型球状乙丙橡胶、原位聚合法合成长链支化乙丙橡胶、乙烯、丙烯与其他二烯烃的共聚物研究进展;详细研究了乙丙橡胶溶液聚合工艺技术中的聚合技术、单体回收技术、失活洗涤技术、闪蒸提浓技术以及国外公司在中国建设装置的生产技术情况。提出了乙丙橡胶的关键生产技术是乙丙橡胶聚合所采用的催化剂体系,通过催化体系的更新换代,开发不同用途的乙丙橡胶,以满足开发高性能材料的要求。在此基础上,指出了今后乙丙橡胶新的催化体系开发将成为未来的研究重点。     

Nickel-based metal−organic framework-derived whisker-shaped nickel phyllosilicate toward efficiently enhanced mechanical,flammable and tribological properties of epoxy nanocomposites

Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials. In this work, the rod-like nickel-based metal−organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology. Then, the nickel phyllosilicate whiskers were evaluated to enhance the mechanical, thermal, flammable, and tribological properties of epoxy resin. The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix, improving the tensile strength and elastic modulus by 13.6% and 56.4%, respectively. Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings, it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities. Additionally, it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature. Moreover, the wear rate of epoxy resin nanocomposites was reduced significantly by 80% for pure epoxy resin by adding 1 phr whiskers. The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites.     

Slot die coating window for a uniform fuel cell ink dispersion

The continuous roll-to-roll slot die coating technique has shown great potential for fuel cell electrode fabrication. It is essential to determine the particulate coating window to obtain a defect-free film of uniform thickness and uniform particle dispersion. For this dual-purpose, an additional upper operating limit has been proposed via a “flow field analysis scheme” that combines analysis and simulation. In this analysis, the fundamentals of flow pattern transition (Poiseuille–Couette–bubbly flow) behind coating limits are clarified. The Couette flow is advantageous for uniform shear rate and dispersion. Furthermore, phase-field simulations systematically investigate the effect of fluid and geometrical parameters and quantitatively present the flow limit with explicit expression. Results reveal that the slope of the upper limit is inversely correlated with shear-thinning index n while proportional to the coating gap H. Combining the bubble entrainment boundary, lower n and H are favorable for a larger particulate coating window.     

Anisotropy of the elastic modulus for hybrid composites reinforced by short fibers and particles with respect to material porosity

Hybrid composites reinforced by short fibers and particles (HCRSFPs) have been widely used in many fields, and more and more scholars are paying attention to hybrid composites. In this study, the elastic moduli of HCRSFPs in arbitrarily chosen directions were investigated with respect to their porosities. A material model was built with the assumption of a compound of particles and polymer matrix containing voids as an effective matrix, and the HCRSFPs were treated as the compound of short fibers and the effective matrix. With consideration of the three‐dimensional spatial orientation distribution and the length distribution of the short fibers, the laminate analog approach and the Halpin–Tsai model were used to predict the elastic moduli of the HCRSFPs. Numerical examples and analyses showed that the fiber orientation distribution, reinforcement volume fraction, and porosity had great effects on the elastic moduli of the HCRSFPs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43708.     

The role of conductive pathways in the conductivity and rheological behavior of poly(methyl methacrylate)–graphite composites

Up to now, research on the dynamic process of conductive network formation has tended to focus on composite particles with one‐dimensional geometry, such as carbon black and carbon nanotubes. However, studies on this subject based on fillers with two‐dimensional structure, such as graphite, are rare in the literature. In this work, the dynamic percolation and rheological properties of poly(methyl methacrylate) (PMMA)–graphite composites under an electric field were investigated. The activation energies of conductive network formation and polymer matrix mobility were calculated from the temperature dependence of the percolation time and the zero‐shear viscosity. It was found that the activation energy calculated from the zero‐shear viscosity was not influenced by the electric field in the concentration range investigated, but the electric field had an effect on the activation energy calculated from the percolation time. This finding emphasizes that the electrical and rheological properties have different physical origins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43810.     

Influence of structure of amines on the properties of amines‐modified reduced graphene oxide/polyimide composites

Graphene oxide (GO), as an important precursor of graphene, was functionalized using alkyl‐amines with different structure and then reduced to prepare reduced amines grafted graphene oxide (RAGOs) by N₂H₄ · H₂O. The successful chemical amidation reaction between amine groups of alkyl‐amines and carboxyl groups of GO was confirmed by Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA). Then RAGOs/polyimide nanocomposites were prepared via in situ polymerization and thermal curing process with different loadings of RAGOs. The modification of amine chains lead to homogenous dispersion of RAGOs in the composites and it formed strong interfacial adhesion between RAGOs and the polymer matrix. The mechanical and electrical properties of polyimide (PI) were significantly improved by incorporation of a small amount of RAGOs, the influence of structure of amines grafted on RAGOs on the enhancement effects of composites was discussed. The research results indicated that the proper structure of amine could effectively enhance the properties of composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43820.     

Effect of attapulgite added in plating bath on the properties of Ni/TiC nano-composite coatings

Pure copper plates were coated by Ni-TiC dipulse current plating method. The effects of adding different concentration(ranging from 0.5 g/L to 3.0 g/L) of attapulgite nano particles to the plating bath on the surface morphology, wear resistance, and oxidation resistance of Ni/TiC/Attapulgite nano-composite coatings were investigated. The experimental results show that the composite coating is flat and compact with adding 3.0 g/L in the bath, and the coating preferred orientation is changed from the planes (111) to (200). The coefficient of the composite coatings decreases from 0.68 to 0.18 with increasing content of attapulgite in the bath, a mixed mode of adhesive-abrasive wear occurs for all coatings, and the wear mechanism shows a transition from adhesive-abrasive to predominantly abrasive wear mechanism when the concentration of attapulgite is beyond 1.5 g/L in electrolyte. The oxidation resistance of composite coatings is the best prepared when adding attapulgite particles at 0.5 g/L in the bath, the oxide mainly consists of a NiO phase by X-ray analysis.     

热塑性树脂基复合材料混合部件中的陶瓷衬里机筒研究

通过袂例阐述了热塑性树脂基复合材料对混合部件的磨损与磨损与腐蚀情况,概述了国内外提高耐磨和耐腐蚀部件的研究现状,报告了笔者对陶瓷衬里机筒的最新研究成果。     

Novel sol–gel‐derived Ag/SiO2–Al2O3 catalysts for highly selective oxidation of methanol to formaldehyde

Novel Ag/SiO₂–Al₂O₃ catalysts with low silver content prepared by the sol–gel method exhibit excellent catalytic properties in the catalytic oxidation of methanol to formaldehyde. The silver content was as low as 2% and the yield of formaldehyde was achieved as 90.3%, which is 16% higher than that of pumice‐supported silver and even 5–6% higher than that of a commercial electrolytic silver catalyst. XRD, XPS and SEM results reveal that all silver was present as Ag⁺ before catalytic reaction and was partially reduced to the metallic state after the reaction. It was also found that silver was aggregated on the surface after its reduction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Halogenated La1.6Sr.04CuO4 catalysts active for ethane selective oxidation to ethene

The catalytic performances and characterization of the catalysts La_1.6Sr_0.4CuO_3.852, La_1.6Sr_0.4CuO_3.857F_0.143, and La_1.6Sr_0.4 CuO_3.856Cl_0.126 have been investigated for the oxidative dehydrogenation of ethane (ODE) to ethene. X‐ray diffraction results indicated that the three catalysts have a single‐phase tetragonal K₂NiF₄-type structure. The incorporation of fluoride or chloride ions in the La_1.6Sr_0.4CuO_4-δ lattice can significantly enhance C₂H₆ conversion and C₂H₄ selectivity. We observed 83.2% C₂H₆ conversion, 76.7% C₂H₄ selectivity, and 63.8% C₂H₄ yield over La_1.6Sr_0.4CuO_3.857F_0.143> and 79.6% C₂H₆ conversion, 74.6% C₂H₄ selectivity, and 59.4% C₂H₄ yield over La_1.6Sr_0.4CuO_3.856Cl_0.126 under the reaction conditions of C₂H₆/O₂/N₂ molar ratio 2/1/3.7, temperature 660°C, and space velocity 6000 ml h^-1 g^-1. With the rise in space velocity, C₂H₆ conversion decreased, whereas C₂H₄ selectivity increased. Life studies showed that the two catalysts were durable within 60 h of on‐stream ODE reaction. Based on the results of X‐ray photoelectron spectroscopy, O₂ temperature-programmed desorption, and C₂H₆ and C₂H₆/O₂/N₂ (2/1/3.7 molar ratio) pulse studies, we conclude that (i) the inclusion of halide ions in the La_1.6Sr_0.4CuO_4δ lattice could promote lattice oxygen mobility, and (ii) the O^- species accommodated in oxygen vacancies and desorbed below 600°C favor ethane complete oxidation whereas the lattice oxygen species desorbed in the 600–700°C range are active for ethane selective oxidation to ethene. By regulating the oxygen vacancy density and Cu³/Cu ratio in the K₂NiF₄-type halo-oxide catalyst, one can generate a durable catalyst with good performance for the ODE reaction. This revised version was published online in July 2006 with corrections to the Cover Date.