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.

Study of a Novel Fourth-generation Supported Ziegler-Natta Catalyst for Propylene Polymerization: Relationship between Catalyst Structure and Polymerization Properties

This article presents a detailed structural study of a new spherical Mg Cl2-supported Ti Cl4 Ziegler-Natta catalyst for isotactic propylene polymerization, and researches on the relationship between catalyst structure and polymer properties. The spherical support with the chemical composition of CH3CH2 OMg OCH(CH2Cl)2 has been synthesized from a new dispersion system and is used as the supporting material to prepare Ziegler-Natta catalyst. The XRD analysis indicates that the catalyst is fully activated with δ-Mg Cl2 in the active catalyst. The far-IR spectrometric results confirm again the presence of δ-Mg Cl2 in the active catalyst. Textural property of the active catalyst exhibits high surface area coupled with high porosity. The high activity in propylene polymerization is mainly ascribed to the full activation and the porous structure of the catalyst. Scanning electron microscopy/energy dispersive spectrometer mapping results indicate a uniform titanium distribution throughout the catalyst particles. Particle size analysis shows that the catalyst has a narrow particle size distribution. The perfect spherical shape, uniform titanium distribution and narrow particle size distribution of the catalyst confirm the advantage of polymer particles production with less fines. The solid state 13 C NMR and mid-IR spectroscopic analyses indicate that there exists strong complexation between diisobutyl phthalate and Mg Cl2, which leads to the high isotacticity of polypropylene.

Procurement Management of China Oil Majors in Global Market

(from No.3)What kind of procurement mode is applied by China oil majors?Three China oil majors all choose centralized procurement as their core strategies.It is helpful to achieve scale efficiency as well as to reduce procurement costs.It is also helpful to utilize resources more efficiently and enhance their market influence.In the summary

Procurement Management of China Oil Majors in Global Market

(from No.3)What kind of procurement mode is applied by China oil majors?Three China oil majors all choose centralized procurement as their core strategies.It is helpful to achieve scale efficiency as well as to reduce procurement costs.It is also helpful to utilize resources more efficiently and enhance their market influence.In the summary

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.

新型高性能Ziegler-Natta催化剂用于乙烯淤浆聚合(英文)

A novel high performance MgCl2/TiCl4 catalyst with tetrabutyloxsilicane as electron donor was pre-pared for ethylene slurry polymerization process. The properties of the catalyst such as particle size distribution, catalytic activity, hydrogen responsibility and copolymerization performance were investigated and compared with commercial catalyst (imported catalyst). Copolymerization of ethylene and 1-butylene using the catalyst was stud-ied in a pilot plant. The composition, structure and property of the copolymer were characterized by 13C nuclear magnetic resonance (13C NMR) and gel permeation chromatography-Infrared (GPC-IR), and compared with those of the copolymer obtained from a commercial catalyst. In comparison with the commercial catalyst, the novel cata-lyst had a higher activity (up to 34.6 kg·g-1) and a better particle size distribution (PSD), and produced polymers having higher bulk density (up to 0.37 g·cm-3) with less fine resin. Meanwhile, the novel catalyst showed a higher hydrogen responsibility and better copolymerization performance. The results indicated that the copolymer obtained from the novel catalyst has a higher branch in the high molecular weight fraction and lower branch in the low mo-lecular weight fraction.

α-氧化铝负载的粒径可控Pd纳米粒子在乙炔选择加氢中的应用(英文)

Size-controlled Pd nanoparticles(PdNPs) were synthesized in aqueous solution, using sodium carboxymethyl cellulose as the stabilizer. Size-controlled PdNPs were supported on α-Al2O3 by the incipient wetness impregnation method. The PdNPs on α-Al2O3 support were in a narrow particle size distribution in the range of 1-6 nm. A series of PdNPs/α-Al2O3 catalysts were used for the selective hydrogenation of acetylene in ethylene-rich stream. The results show that PdNPs/α-Al2O3 catalyst with 0.03%(by mass) Pd loading is a very effective and stable catalyst. With promoter Ag added, ethylene selectivity is increased from 41.0% to 63.8% at 100°C. Comparing with conventional Pd-Ag/α-Al2O3 catalyst, PdNPs-Ag/α-Al2O3 catalyst has better catalytic performance in acetylene hydrogenation and shows good prospects for industrial application.

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%）.

AN EVA/UNMODIFIED NANO-MAGNESIUM HYDROXIDE/SILICONE RUBBER NANOCOMPOSITE WITH SYNERGISTIC FLAME RETARDANCY

A novel EVA/unmodified nano-magnesium hydroxide （NMH）/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber （CFR）. The flammability of the ternary composite was studied by cone calorimeter test （CCT）. Synergistic effect on flame retardancy was found between silicone rubber and NMH. EVA/CFR ternary nanocomposite showed the lowest peak heat release rate （PHRR） and mass loss rate （MLR） among the samples of virgin EVA, EVA composites. The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.

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.

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.

琥珀酸酯为内给电子体的新型MgCl2载体催化剂用于丙烯聚合

A novel MgCl2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was prepared and propylene polymerizations with the combination of such catalyst and four external donors were investigated in detail. The catalyst was compared with a commercial one with phthalate as internal donor in terms of catalytic activity, hydrogen sensitivity and stereospecificity in propylene polymerization. The molecular weight,molecular weight distribution and microstructure of the produced polypropylenes were compared also. It was found that the novel catalyst containing succinate internal donor showed higher activity and higher stereospecificity than those with phthalate as internal donor. Consequently, polypropylenes obtained by the succinate-based catalyst showed high molecular weight, high melting temperature, high isotactic index and broad molecular weight distribution than those obtained with the commercial catalyst.

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.

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

稀土元素(Nd， Y， La， Dy ) 硬脂酸盐被综合了并且为第一次准备的 dimethyl terephthalate，己二酸酸和 1,4-butanediol 的 polycondensation 用作单个部件催化剂可被细菌破坏 poly (丁烯 adipate-co-terephthalate )(PBAT ) 与高分子的重量。PBAT 的微观结构被 1H NMR 系列描绘。PBAT 展出象高张力的力量那样的好机械性质(ca。20 MPa ) 并且长裂缝延伸(>700%) 。

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℃.

Effect of Nano-fillers on Conductivity of Polyethylene/Low Melting Point Metal Alloy Composites

A novel method for preparing conductive polyethylene （PE） composites has been developed. In the method, the powder of low melting point metal alloy （LMPA） is filled into the PE matrix by using twin screw extruder at a temperature below the melting point of the LMPA, and followed by a die drawing process at a temperature around the melting point of the metal alloy. It has been found that die drawing process, repeating the die drawing process and adding nano-fillers, such as montmorillonite （MMT） and multi-wall carbon nanotubes （MWCNTs）, all help reduce the metal particle size in the PE matrix, thus improve the conductivity of the composite. The conductivity improvement is attributed to an increased number of the smaller metal particles. Therefore, conductive composites of polymer/metal alloy/nano-filler with high conductivity are possible to be prepared by using the new method.