Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces

Temperature-programmed desorption (TPD) and Density Functional Theory (DFT) were used to investigate the reactions of oxametallacycles derived from ethylene oxide on clean and oxygen-covered Ag(110) surfaces. Ethylene oxide ring-opens following adsorption at 250 K on both clean and O-covered Ag(110) to form a stable oxametallacycle. On the clean Ag(110) surface, the oxametallacycle reacts to reform the parent epoxide at 280 K during TPD, while the aldehyde isomer, acetaldehyde, is observed at higher oxametallacycle coverages. In the presence of coadsorbed oxygen atoms, a portion of the oxametallacycles dissociate to release ethylene. However, of those that react to form oxygen-containing products, the fraction forming ethylene oxide is similar to that on the clean surface. The acetaldehyde product of oxametallacycle reactions combusts via formation of acetate species; the acetates react to form CO₂ at temperatures as low as 360 K on the O-covered surface. No evidence was observed for other combustion channels. This work provides experimental evidence for the connection of oxametallacycles to combustion via acetaldehyde formation as well as to ring-closure to form ethylene oxide.     

乙烯-醋酸乙烯(EVA)树脂生产及市场分析

综述了国内乙烯-醋酸乙烯(EVA)的生产及市场情况,对发展趋势进行了分析及预测,并对国内EVA行业发展提出了几点建议.     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

改性乙烯-醋酸乙烯共聚物(EVA)彩色防水涂料及施工

介绍了EVA防水涂料的生产工艺、配比及施工方法。此种防水涂料无污染，防水效果好，并可配成各色涂料。     

Blends of Ethylene Vinyl Acetate (EVA) and Chlorosulphonated Polyethylene (CSM) with Reference to their Shrinkability

Abstract

The blends of ethylene vinyl acetate (EVA) and chlorosulphonated polyethylene (CSM) were investigated wity respect to their shrinkability and micro-structure of the blends.     

酰胺化纳米晶纤维素提高乙烯-醋酸乙烯酯共聚物薄膜阻透性的研究

合成了三种酰胺化纳米晶纤维素,并采用溶液共混成膜法制备了酰胺化纳米晶纤维素（CNC）/乙烯醋酸乙烯醋共聚物(EVA)复合膜材料。通过紫外-可见分光光度计、电子万能试验机和透湿仪研究了酰胺化CNC/ EVA复合膜的光学性能、力学性能以及水蒸气阻隔性,并通过原子力显微镜研究热压处理的EVA复合膜的表面形貌。结果表明,添加三种不同碳链的酰胺化CNC都使 EVA膜的透光率有所降低,当添加量为5 %时,EVA膜透光率仍高达90%。一定程度的热压能够让酰胺化纳米晶纤维素在EVA基体中分散更均匀,使EVA复合膜的透光率提高了2%～3%;随着纳米晶纤维素含量的逐渐增加,三种酰胺化CNC/EVA膜的拉伸强度均逐渐增强,透湿率（WVTR值）均减小;酰胺化CNC含量相同时, 十六胺改性的纳米晶纤维素(CNC-N16)/EVA复合膜的力学性能和水蒸气阻隔效果优于相应的十二胺和正辛胺。     

Long Term Effects of Air Dielectric Barrier Discharge Treatment on the Surface Properties of Ethylene Vinyl Acetate (EVA)

This paper discusses the long term effects of dielectric barrier discharge (DBD) treatment on the surface properties of ethylene vinyl acetate (EVA) film. The EVA surface was characterised using contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and 180° peel tests. EVA subjected to two different treatment times was compared to as-received and solvent cleaned film. The long term stability of the surface modification induced by the DBD treatment was studied over a period of 466 days. On initial application of DBD treatment to the EVA surface an increased wettability was observed, evident from a decreased water contact angle, improved peel strength when bonded, and an increased level of carbon–oxygen moieties measured using XPS. However, over the storage period of 466 days the material reverted to almost its original state with the contact angle being only ～3° lower than that of as-received EVA compared to a difference ～25° directly after treatment. AFM measurements showed that the treatment had a slight smoothing effect on the surface topography.     

聚乳酸/乙烯-醋酸乙烯酯共聚物/碳酸钙复合材料的性能研究

采用熔融共混法制备了聚乳酸/乙烯-醋酸乙烯酯共聚物/碳酸钙（PLA/EVA/CaCO3）复合材料,利用差示扫描量热仪、X射线衍射仪、偏光显微镜、扫描电子显微镜、力学性能测试和热变形温度测试等手段,研究了EVA和CaCO3对复合材料的结晶性能、断面形貌、力学性能和耐热性能的影响。结果表明,EVA 具有增韧作用,但降低了复合材料的强度和耐热性;而CaCO3可以提高复合材料的强度、韧性、结晶性能和耐热性能;CaCO3与EVA的加入对PLA有协同增韧作用,且不改变PLA的晶型;当PLA/EVA=90/10,加入10 %（质量分数,下同）的CaCO3时,复合材料有最佳的综合性能。     

On the Melt Rheological Behavior and Microstructure of Nanoclay-Filled Polyethylene/Ethylene Vinyl Acetate (PE/EVA) Blend

Correlation of rheological response with microstructure and also the tensile mechanical properties of nanoclay-filled polyethylene/ethylene vinyl acetate blends were studied. From transmission electron microscopy observations, the same clay localization within polyethylene- and ethylene vinyl acetate-rich blends was revealed. However, a better clay dispersion in the ethylene vinyl acetate-rich blend was found by analyzing the changes in the linear viscoelastic rheological properties discussed by the fractional Zener model and the power law expression. The clay influences on the tensile properties of polyethylene- and ethylene vinyl acetate-rich blends were in good agreement with its microstructure, implied by the rheological studies.     

研究乙二醇与乙酸酯反应的双反应段反应精馏塔设计

乙二醇与乙酸酯的反应是现代人们研究的一项重点内容,两者在反应过程中会消耗大量的能量,在具体分析过程中,需要对反应段反应精馏塔结构进行适当的优化对比,从而使两者在具体反应过程中的分离效果和反应效果都能够得到进一步提升。     

Polyethylene/Ethylene Vinyl Acetate and Ethylene Octene Copolymer/Clay Nanocomposite Films: Different Processing Conditions and Their Effect on Properties

Polymer nanocomposites based on a layered clay used as nanofiller and copolymers ethylene and vinyl acetate matrix (EVA, the content of vinyl acetate (VA) component 19 wt% and 5 wt%) and ethylene octene copolymer (EOC, 17% and 45% of octene) were prepared. KO Buss kneader and double screw extruder were used. The MMT Na+ and four types of commercial products such as Nanofil N5 and N3000, Cloisite 93A and 30B were used as nanofillers—5 wt% in relation to the content of montmorillonite. The aim was to evaluate the influence of copolymer composition and processing on prepared nanocomposite properties. The morphology of samples was examined by means of X‐ray diffraction (XRD) and transmission electronic microscopy TEM. Furthermore, mechanical and especially barrier properties were observed. Despite the fact that the XRD and microscopy results have revealed that complete exfoliation did not take place in any case, mechanical properties as well as the permeability showed that used 5 wt% of clay was enough to achieve the improvement of properties. Cloisite 30B might be the most suitable for the polyethylene/EVA matrix. In case of EOC copolymer the nanofiller Nanofil N3000 and mainly Cloisite 93A seems to be more suitable. The better properties were achieved for the version of EVA with lower VA content and also for EOC 17, but not for each evaluated property. POLYM. ENG. SCI., 59:2514–2521, 2019. © 2019 Society of Plastics Engineers     

Effect of Mixing Conditions on the Tensile Properties of Ethylene Vinyl Acetate/Waste Tire Dust (EVA/WTD) Blend

Blends of Ethylene Vinyl Acetate/Waste Tire Dust (EVA/WTD) were prepared by using a Haake Rheomix at 100/0, 90/10, 80/20, 70/30, and 60/40 blend ratios. The effect of mixing temperature, blend ratio and blending time on the tensile properties of EVA/WTD blends were investigated. The mixing time was varied from 5 to 30 minutes, while the mixing temperature was varied from 120 to 160°C. The tensile properties of the blends found to show a gradual decrease with the addition of WTD. EVA/WTD blends prepared at 140°C mixing temperature and 10 min mixing time found to be suitable mixing parameters to obtain optimum blend properties. In general, declines in the EVA/WTD blends properties were also observed with increase in mixing time and temperature.     

影响白乳胶稳定性的因素

以醋酸乙烯酯为主单体,聚乙烯醇为保护胶体,两者按照35：1的质量比合成了稳定性好、粘接力强的白乳胶。讨论了引发剂、乳化剂、反应温度、搅拌方式等因素对白乳胶稳定性的影响,确定了引发剂最佳用量为单体用量的0．6％-0．8％;选用的复合乳化剂为OP-10和K-12,它们和醋酸乙烯酯的最佳质量比为1：2：92。     

甲醛在Pd(111)与Pd(100)晶面上氧化的计算化学研究

使用密度泛函理论对甲醛分子在Pd(111)晶面与Pd(100)晶面的氧化反应机理进行研究,结果表明,Pd(100)晶面相比于Pd(111)晶面更有利于甲醛分子的氧化,为进一步合理设计甲醛氧化贵金属催化剂提供了理论依据。     

Chloroform Hydrodechlorination on Palladium Surfaces: A Comparative DFT Study on Pd(111), Pd(100), and Pd(211)

Topics in Catalysis - Palladium has been shown to be an effective catalyst for chloroform hydrodechlorination, which serves as a promising treatment method for industrial chloroform waste. To...     

Effects of Multi-Walled Carbon Nanotube (MWCNT) Content on Physical Properties and Cell Structure in Ethylene Vinyl Acetate Copolymer (EVA)/MWCNT Nanocomposite Foams

Melt compounding is used to mix ethylene-vinyl acetate copolymer (EVA) and multi-walled carbon nanotube (MWCNT). Then the obtained EVA/MWCNT mixtures were foamed using a chemical blowing agent. Without any modification of MWCNT, a significant improvement of the tensile properties was observed for the EVA/MWCNT foams. With increasing the MWCNT content to 10 phr, the average cell size decreases to 36 µm due to the higher melt viscosity and the average cell density increases to 10.5 × 10⁶ cell/cm³ due the heterogeneous nucleation. To investigate the possible applications for static dissipative purpose, the surface resistivity of EVA/MWCNT foams was also investigated.