HDPE/LLDPE reactor blends with bimodal microstructures—Part II: rheological properties

Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and vice versa HMW homopolymer to LMW copolymer. The shear flow characteristics of these polymers in the typical processing range mostly depend on the molecular weight and MWD of the polymer and are independent of the short chain branch content. From oscillatory shear measurements, it was observed that the viscosity of HMW polymers was reduced with the addition of LMW material. For the polymers produced with this two-step polymerization process, the LMW homopolymer and HMW copolymer blends and HMW homopolymer and LMW copolymer blends were melt miscible, despite the large viscosity differences of the pure components.     

超细粉在内循环流化床中的流态化特性

在内径120 mm的半圆柱形内循环流化床中,以平均粒径387 nm的Ti O2为原料,考察了单独通入流化气、射流气和同时通入流化气和射流气三种流化方式下超细粉的流化特性以及射流气速对超细粉聚团尺寸的影响。结果表明:同时通入流化气和射流气时,流化气能促进粉体循环,消除环隙死区;高速射流能有效破碎聚团,显著减小聚团尺寸,从而使超细粉在环隙区与导流管之间形成稳定循环,小聚团在环隙区实现平稳流态化。随着射流气速的增大,聚团尺寸减小,粒度分布变窄,在射流气速分别为60,90,120,150 m/s的条件下,聚团平均直径分别为194,158,147,135μm。     

The studies of physical properties of dimeric fatty acid-modified thiodiphenyl epoxy resins

A thermally stable thiodiphenyl epoxy resin was modified with a dimeric fatty acid at an epoxy resin:fatty acid molar ratio of 4:1. The thermal and mechanical properties of the modified epoxy resin were studied by preparing an epoxy composition with an amine curing agent and a catalyst, followed by curing at 170 °C to produce a neat plastic epoxy resin. The tensile and impact strengths of the resin indicated improved flexibility and toughness compared to other epoxy resins. Enhanced toughness was confirmed by the increased lap shear strength in single lap joints prepared with steel substrates attached by the resin.     

Problems in the Extraction of Polycyclic Aromatic Hydrocarbons from Diesel Particulate Matter

In this work, a comparison between Soxhlet, ultrasonic, and microwave-assisted extraction (MAE) (using hexane:acetone 1:1) of polycyclic aromatic hydrocarbons (PAHs) from SRM 1650 diesel particulate matter was made. As good recoveries were not obtained for the higher molecular weight compounds, MAE with toluene and dichloromethane was also tested. Achieved recoveries were compared with the results obtained in the same assays made with SRM 1648 urban particulate matter and real atmospheric particulate samples. In order to explain the difficulty of the extraction of PAHs from SRM 1650 in comparison to SRM 1648 and real atmospheric particulate samples, elemental analysis, X-ray diffraction, and particle analysis using scanning electron microscopy coupled to an automatic computer imaging system were also made. It is important to notice that SRM 1650 shows a high percentage of carbon and differences in the morphology of the particles between SRM 1650 and SRM 1648 were observed.     

Thermal degradation characteristic of Tetra Pak panel boards under inert atmosphere

hermal degradation characteristics of Tetra Pak panel boards (TPPB) can be useful to improve usage of such panels as an alternative to wood-based products such as plywood, fiberboard, and particleboard. In the study, samples from the TPBBs manufactured from waste Tetra Pak packages (WTPP) were heated in a nitrogen atmosphere at different heating rates (10, 15 and 20 °C/min) using a thermal analysis system. The Coats-Redfern kinetic model was applied to calculate kinetic parameters. The degradation rate equations were then established. In addition, the kinetic compensation effect (KCE) was used to correlate the pre-exponential factor (k _o ) with activation energy (E _a ) and the existence of the KCE was accepted. TG-FT/IR analyses were applied to the TPPB degradation and then the FT-IR stack plot was used to analyze gas products (CO₂, CH₄, HCOOH, and CH₃OH). Infrared vibrational frequencies and the micro, crystal structure of the TPPBs were investigated by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) and X-Ray diffraction analysis (XRD), respectively.     

阿戈美拉汀的合成新工艺

介绍了以7－甲基四氢萘－1－酮和氰乙酸为原料,合成（7－甲氧基－3,4－二氢－1－萘基）乙腈,再芳构化生成（7－甲氧基－1－萘基）乙腈,再还原乙酰化“一锅”反应得到阿戈美拉汀的全过程。全程反应条件温和,总收率约77％。     

Increases in nitrogen use efficiency decrease nitrous oxide emissions but can penalize yield in sugarcane

Nutrient Cycling in Agroecosystems - Nitrogen (N) fertilization strategies focused on increasing nitrogen use efficiency (NUE) and decreasing nitrous oxide (N2O) emissions are important for...     

稀土在涂料中的应用研究

稀土元素具有特殊的电子结构,在制备功能涂层领域有重要的应用.阐述了目前稀土在制备功能有机涂料、耐腐蚀涂层、耐高温涂层及其他领域中的一些应用,初步探讨了稀土在功能涂料和涂层中的作用机理.     

马来酸单酯稀土包覆硅灰石改性PA6的研究

采用马来酸单酯稀土(RETM)对硅灰石表面进行包覆后用于尼龙6(PA6)的改性,研究了RETM对改性PA6的拉伸强度、缺口冲击强度、耐磨损性能、吸水性及成型收缩率等的影响。结果表明,与硅烷偶联剂包覆处理的硅灰石相比,采用RETM包覆处理的硅灰石改性PA6时硅灰石的分散均匀性较好,改性PA6的拉伸强度、缺口冲击强度、耐磨损性能都得到了提高,吸水率及成型收缩率显著降低。     

Preparation and the light transmittance of TiO2 deposited fabrics

Nanoscale titanium dioxide (TiO₂) films were deposited on the surface of polyester nonwovens by using direct current reactive magnetron sputtering. The effect of oxygen flow on the surface structures and properties of the fabrics was investigated in this article. The surface morphology, microstructure, and the chemical composition of TiO₂-coated fibers were characterized by atomic force microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The effect of oxygen flow on deposition rate, white degree, and light transmission properties of the fabrics with nanoscale TiO₂ films were examined. The test results proved that the oxygen flow was a key factor in sputter processing. The deposition speed decreased and the white degree of the fabric increased with increasing oxygen flow. The ultra-violet absorption by the polyester nonwoven fabric with TiO₂ coatings was also enhanced as the oxygen flow increased in a proper range.