SPECIAL EFFECT OF ULTRA-FINE RUBBER PARTICLES ON PLASTIC TOUGHENING

According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (UFPR) were introduced,which were prepared through irradiating common rubber lattices and spray drying them. Epoxies toughened with UFPRshowed a much better toughening effect than those with CTBN, and the heat resistance of epoxy was unexpectedly elevated.For polypropylene toughening, UFPR can improve the toughness, stiffness and heat resistance of PP simultaneously. Thesespecial toughening effects overcome the deficiencies in rubber toughening technology and are worth further investigating.

Enhanced Electrical Properties of Styrene-grafted Polypropylene Insulation for Bulk Power Transmission HVDC Cables

Polypropylene(PP)is considered to be a rather promising material for HVDC cable insulation.Grafting modification has proved to be an effective method on the electrical property improvements of PP.This paper reports on the highlyenhanced electrical properties of styrene-grafted polypropylene(PP-g-St)and their related mechanism.The influence of grafting styrene on crystallization structures,thermal properties and electrical properties of PP-g-St are characterized and analyzed.These results show that PP-g-St exhibits remarkably enhanced DC volume resistivity,suppressed space charge accumulation and improved DC breakdown strengths as compared to PP.Crystallization observation shows PP-g-St has small,imperfect spherulites with indistinct boundaries,which is strongly correlated to enhanced electrical properties.This study provides an effective grafting strategy to design high-performance HVDC cable insulation materials for bulk power transmission systems.

Free radical reaction model for n-pentane pyrolysis

A mathematical mechanism of the n-pentane pyrolysis process based on free radical reaction model was presented.The kinetic parameters of n-pentane pyrolysis are obtained by quantum chemistry and the reaction network is established. The solution of the stiff ordinary differential equations in the n-pentane pyrolysis model is completed by semi implicit Eular algorithm. Then the pyrolysis mechanism based on free radical reaction model is built,and the computational efficiency increases 10 times by algorithm optimization. The validity of this model and its solution method is confirmed by the experimental results of n-pentane pyrolysis.

Highly Selective Diphoshinoamine/Cr(III) Catalysts for Ethylene Tetramerization

Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activity up to 2.5×10^6 g/mol Cr.h and high selectivity to produce 1-octene （Cs in products is being 89.80 wt%）.

Fast growth of large single-crystalline WS_(2) monolayers via chemical vapor deposition

Two-dimensional(2D)tungsten disulfide(WS2)has emerged as a promising ultrathin semiconductor for building high-performance nanoelectronic devices.The controllable synthesis of WS2 monolayers(1L)with both large size and high quality remains as a challenge.Here,we developed a new approach for the chemical vapor deposition(CVD)growth of WS2 monolayers by using K2WS4 as the growth precursor.The simple chemistry involved in our approach allowed for improved controllability and a fast growth rate of~30μm·min−1.We achieved the reliable growth of 1L WS2 flakes with side lengths of up to~500μm and the obtained WS2 flakes were 2D single crystals with low density of defects over a large area as evidenced by various spectroscopic and microscopic characterizations.In addition,the large 1L WS2 single crystals we obtained showed higher electrical performance than their counterparts grown with previous approaches,demonstrating the potential of our approach in producing high quality and large 2D semiconductors for future nanoelectronics.

PREPARATIOPREPARATION OF 1-OCTENE BY ETHYLENE TETRAMERIZATION WITH HIGH SELECTIVITY

Two novel PNP ligands have been synthesized and characterized by 1H-NMR, elemen- tal analysis, and mass spectra. In combination with Cr(Ⅲ ) and cocatalyst MAO, they generate active catalytic systems that tetramerize ethylene with both high catalytic activity and high selectivity to produce 1-octene. The results show that these catalyst sys- tems are able to catalyze ethylene tetramerization, with high catalytic activity up to 0.89×106 g/mol Cr.h, and the selectivity of C8 in products is 72.52%, and the percentage of 1-olefins in the C8 cut is 97.87%.

Good dispersion of hydrophilic nanoscale silica in rubber matrix and the effects on rubber nanocomposites

Using the industrial technologies of rubber latex irradiation,preparation of nanoscale silica(SiO2) slurry,mixing irradiated rubber latex with SiO2 slurry,and the spray drying,we have prepared the ultrafine fully-vulcanized powder carboxyl styrene-butadiene rubber(UFPCSBR)/SiO2 nanocompound powder,in which the SiO2 particles and UFPCSBR particles are isolated and stuck each other.When the UFPCSBR/SiO2 nanocompound powder is mixed with crude rubber,the UFPCSBR particles are dispersed well in rubber matrix because of their good compatibility,then the SiO2 particles are also dispersed well in rubber matrix because of the carrier nature of the UFPCSBR particles during the mixing procedure,and the novel rubber/UFPCSBR/SiO2 nanocomposites are fabricated.Compared with the rubber composites prepared by mixing the crude rubber with the UFPCSBR powder and SiO2 powder one after the other,the novel UFPCSBR/SiO2 nanocompound modified rubber/UFPCSBR/SiO2 nanocomposites have better abrasion resistance,higher tensile strength and tear strength,and lower heat build-up data.Noteworthily,the tanδ-temperature curve of the novel rubber/UFPCSBR/SiO2 nanocomposites has the second tanδ peak due to the newly generated boundary layer surrounding the SiO2 particles,increasing the tanδ values in the temperature range of 0-20℃,which is very important to the research of green tyre tread.

PdAg bimetallic electrocatalyst for highly selective reduction of CO2 with low COOH^* formation energy and facile CO desorption

For electrocatalytic reduction of CO2 to CO,the stabilization of intermediate COOH^* and the desorption of CO^* are two key steps.Pd can easily stabilize COOH^*,whereas the strong CO^* binding to Pd surface results in severe poisoning,thus lowering catalytic activity and stability for CO2 reduction.On Ag surface,CO^* desorbs readily,while COOH^* requires a relatively high formation energy,leading to a high overpotential.In light of the above issues,we successfully designed the PdAg bimetallic catalyst to circumvent the drawbacks of sole Pd and Ag.The PdAg catalyst with Ag-terminated surface not only shows a much lower overpotential(-0.55 V with CO current density of 1 mA/cm^2)than Ag(−0.76 V),but also delivers a CO/H2 ratio 18 times as high as that for Pd at the potential of-0.75 V vs.RHE.The issue of CO poisoning is significantly alleviated on Ag-terminated PdAg surface,with the stability well retained after 4h electrolysis at-0.75 V vs.RHE.Density functional theory(DFT)calculations reveal that the Ag-terminated PdAg surface features a lowered formation energy for COOH^* and weakened adsorption for CO^*,which both contribute to the enhanced performance for CO2 reduction.

Different influences of nucleating agents on crystallization behavior of polyethylene and polypropylene

The crystallization behavior of polyethylene (PE) and polypropylene (PP), including the neat ones and the ones nucleated with the same nucleating agent (NA), was studied by DSC. It was found that the nucleating agent decelerated the PE nonisothermal crystallization process. NA did enhance the nucleating rates for both PE and PP, but the linear growth rate dominated the volumetric growth rate for PE, and the volumetric growth rate dominated the overall crystallization rate. That is why PE nucleated with NA had a slower overall crystallization rate than the neat one.

The abnormal behavior of polymers glass transition temperature increase and its mechanism

In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original values. According to the classical theory, the Tg of plastic component shall remain unchanged or move toward the lower Tg of rubber component in a rubber/plastic blend. However, ultra-fine full-vulcanized powdered rubber (UFPR) with a diameter of ca. 100 nm can simultaneously increase the toughness and the Tg of plastics, which is abnormal and is difficult to explain by classical theory. In this feature article, the abnormal behavior and its mechanism are discussed in detail.

Parallelized microfluidic droplet generators with improved ladder-tree distributors for production of monodisperseγ-Al_(2)O_(3)microspheres

In this paper,we present a parallelized microfluidic device with improved ladder-tree distributors for the scaled-up production of monodisperse microspheres.Owing to the improved distribution form comprising a ladder distributor in the center and tree distributors around the circumference,the uniformity of the generated droplets for our device was improved by 32.9%and 86.1%compared to those achieved in devices with conventional tree and ladder distributors,respectively,in the final production stage with 32 droplet generators,indicating the potential of our device for further scale-up while maintaining the monodispersity of the generated droplets.The effect of the 2D scale-up of our device was investigated by varying the continuous-phase flow rate and viscosity.Using our device,γ-Al_(2)O_(3)microspheres with a diameter of 598.1μm and a CV of 2.58%,as catalyst support for microreactors,were continuously synthesized at high production rate.The nickel-based catalyst prepared fromγ-Al_(2)O_(3)microspheres with large specific surface area and pore volume had an average NiO size of 14 nm,which was 60.9%of that supported on industrial support.The CO methanation conversion of the Ni@Al_(2)O_(3)microspheres was 1.7 times larger than Ni@Al_(2)O_(3)industrial support at 140℃.

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.

Anion engineering of hierarchical Co-A(A=O,Se,P) hexagrams for efficient electrocatalytic oxygen evolution reaction

Water electrolysis is considered to be an effective and promising technology to make high-purity H_(2),however,the relationship between anion species and catalytic performance of electrocatalysts is still not completely clear.Herein,we report an anion engineering strategy to tune electrocatalytic water oxidation activity for Co-based materials.Novel hierarchical Co-based oxide/selenide/phosphide(Co-A,A = O,Se,P)hexagrams have been chosen as model materials.Electrochemical results and theoretical calculations reveal that the electron configuration,the electrical conductivity,and the oxidation potential of Co element in Co-A hexagrams could be moderated by the substitution of P atoms,which leads to the superior OER performance.Particularly,Co-P hexagram displays a low overpotential(η = 269 mV) at j = 10 mA/cm^(2) for the oxygen evolution reaction(OER) compared to Co-O hexagram(η = 399 m V) and Co-Se hexagram(η = 347 mV).This work is of great importance in understanding coordination atoms(O,Se and P)induced electrocatalytic properties of hierarchical Co-based materials.

Effect of polyamide on selectivity of its supported Raney Ni catalyst

A newly-developed polyamide supported Raney Ni catalyst, which is suitable for use in fix-bed reactions with high selectivity, was studied in this paper. Selective hydrogenation of acetone to isopropanol was chosen as a probe reaction. It has been found that clean preparation of isopropanol could be achieved, that is to say, the two main byproducts(isopropyl ether and methyl-iso-butyl carbinol) could be eliminated with the newly-developed polyamide supported Raney Ni catalyst. The elimination of these side reactions was attributed to the adsorption effect of polyamide support and a model was proposed. The proposed model was further proved by hydroamination reaction of acetone. According to this model, catalyst support can play an important role in chemical reactions. Different products could be produced when different catalyst support is used, the main reaction and side reactions can even be reversed sometimes when the chemicals, active component of catalyst and reaction condition are the same. This model could help to improve catalytic selectivity of many Raney metal catalysts used routinely in chemical and oil refining industry, and is also useful for hydrogenation reactions in pharmaceutical and food industry.

Getting to the Bottom Morphology of Block Copolymer Thin Films

We demonstrate a general approach for attaining the bottom morphology of block copolymer（BCP） thin films. In our former measurements on PS-b-PMMA films, surface morphology maps of the BCP films revealed distinct ordering regimes where the cylinders orient predominantly perpendicular or parallel to the interface and an ‘intermediate＇ regime where these morphologies coexist. However, this earlier work did not explore the bottom morphology of BCP thin films. In this study, we investigated the block copolymer morphology near the solid substrate in the cast block copolymer film having a perpendicular cylinder morphology on the surface.

Numerical simulation of single bubble boiling behavior

The phenomena of a single bubble boiling process are studied with numerical modeling.The mass,momentum,energy and level set equations are solved using COMSOL and temperature field in time are analyzed,and reasonable results are obtained.The numeral model is validated by the empirical equation of Fritz and could be used for various applications.

Visible-Light-Mediated Photocatalyst-Free Hydroacylation of Azodicarboxylic Acid Derivatives with 4-Acyl-1,4-dihydropyridines

A visible-light-enabled,photocatalyst-free hydroacylation reaction of azodicarboxylic acid derivatives was described.This radical conjugate addition(RCA)protocol relied on the dual role of 4-acyl-1,4-dihydropyridine(acyl-DHP)reagents that besides being as radical reservoirs,they also enabled the conversion of radical adducts to anion intermediates via reduction.Under“catalyst-oxidant-additive free”conditions,a wide range of structurally different acyl hydrazide products were readily obtained in 56%—99%yields.The utility of this transformation was further demonstrated by the scale-up synthesis and downstream derivatization.

具有疏离子特性的碳电极用于高性能有机电解液双电层电容器

活性碳材料应用于有机电解液双电层电容器中存在比电容低的问题,但目前的研究主要围绕改善活性碳的比表面积和孔结构来提高双电层电容器的性能,而活性碳纳米孔与有机电解液形成的界面微环境往往被忽略.本工作通过一个简单而有效的方法形成具有疏离子表面的活性碳以解决双电层过程低效率的问题.在活性碳上形成极性的C-F键,并用近边X射线吸收精细结构光谱和X射线光电子能谱对其进行了表征.通过接触角和小角X射线散射研究发现YP-F60s在有机电解液中具有疏离子特性.采用YP-F60s制备的双电层电容器在有机电解液中展现出高比电容,较低的内阻和优良的循环稳定性.本论文证明了活性碳与电解液形成的界面微环境对双电层电容器电化学性能的重要性,也为CF;等离子体技术构建低成本、优质的碳材料用于双电层电容器提供了新的思路.

Bicontinuous porous membranes with micro-nano composite structure using a facile atomization-assisted nonsolvent induced phase separation method

The micro-nano composite structure can endow separation membranes with special surface properties,but it often has the problems of inefficient preparation process and poor structural stability.In this work,a novel atomization-assisted nonsolvent induced phase separation method,which is also highly efficient and very simple,has been developed.By using this method,a bicontinuous porous microfiltration membrane with robust micro-nano composite structure was obtained via commercially available polymers of polyacrylonitrile and polyvinylpyrrolidone.The formation mechanism of the micro-nano composite structure was proposed.The microphase separation of polyacrylonitrile and polyvinylpyrrolidone components during the atomization pretreatment process and the hydrogen bonding between polyacrylonitrile and polyvinylpyrrolidone molecules should have resulted in the nano-protrusions on the membrane skeleton.The membrane exhibits superhydrophilicity in air and superoleophobicity underwater.The membrane can separate both surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency and permeation flux.With excellent antifouling property and robust microstructure,the membrane can easily be recycled for long-term separation.Furthermore,the scale-up verification from laboratory preparation to continuous production has been achieved.The simple,efficient,cost-effective preparation method and excellent membrane properties indicate the great potential of the developed membranes in practical applications.

ONE-STEP PROCESS TO MAKE ELECTRICALLY CONDUCTIVE THERMOPLASTIC VULCANIZATES FILLED WITH MWCNTs

Electrically conductive thermoplastic vulcanizates（TPVs） filled by multi-walled carbon nanotubes（MWCNTs） are prepared by a simple one-step melt mixing process,based on linear low density polyethylene（LLDPE） and ultrafme full-vulcanized rubber particles（UFRP）.An ideal morphology with controlled localization of MWCNTs in continuous LLDPE matrix and appropriate size of finely-dispersed UFRP can be achieved at the same time.The controlled localization of MWCNTs in the continuous phase facilitates the formation of conductive pathway,and thus the volume resistivity of the as-prepared LLDPE/UFRP/MWCNTs thermoplastic vulcanizates is significantly decreased.The results show that both the blend ratio of LLDPE/UFRP and the loading of MWCNTs have remarkable effect on the volume resistivity.Significantly, the electrically conductive TPVs exhibit good mechanical properties duo to the fine dispersion of UFRP in LLDPE.The added MWCNTs are capable of imparting reinforcement effects to thermoplastic vulcanizates with just a slight loss of stretchability and elasticity.