Effects of ethylene-octene copolymer (POE) on the brittle to ductile transition of high-density polyethylene/POE blends

Three kinds of ethylene-octene copolymers (POE) were melt-blended with high-density polyethylene (PE-HD) in different proportions. Detailed characterizations were conducted to analyze their structural differences of POE and its effects in toughening PE-HD. The higher molecular weight POE can improve the toughness of PE-HD. 60:40 PE-HD/POE is elongated to break up to 700% while impact strength is 84.7 kJ/m² at −30°C, which is 21-fold of PE-HD. In the brittle to ductile transition (BDT) during impact, the fracture mechanism changes from the crazing mode to the shear yield-plastic deformation mode. The BDT temperature decreases as the POE molecular weight and its content increase. The interface strength in tension is estimated to access their effects. The Boltzmann-type models were successfully extended to describe the typical S-shaped curves in BDT of notched impact strength vs POE content or temperature. The supplementary decay model is suggested for the attenuation in toughening. Transition map in impact is proposed to select the use range of composition (c ) and temperature (T ) for high toughness. The curves are converted into 3D graph of T -c -impact strength for illustrating their coupling-separate effects, and further into the contour map of impact strength in T -c space for finding their partial equivalence.     

Preparation of Aqueous Nanodispersions of Disperse Dye by High-Gravity Technology and Spray Drying

Disperse dyes are poorly water-soluble and difficult to stably disperse in an aqueous medium, which greatly limits their application in dyeing synthetic fibers. Micronization can solve this problem. Herein, a facile way to prepare stable aqueous nanodispersions of disperse dye (C.I. disperse yellow 54) is presented by combining high-gravity antisolvent precipitation in a rotating packed bed (RPB) with spray drying. The as-prepared product had an average particle size of 120 nm, which could be readily redispersed in water. Compared with raw dye, the wettability and dispersibility of disperse dye nanoparticles were remarkably improved. Furthermore, the dyeing properties of the nanodispersions were obviously better than those of the commercial dye, which was micronized by ball milling.     

Direct-Contact Heat Transfer during n-Pentane Vaporization in a Two-Dimensional Water Column

Direct-contact vaporization heat transfer is investigated by analyzing the heat transfer coefficient with the area of liquid-liquid direct-contact interface. The interface areas of liquid-liquid heat transfer are determined by stroboscopic images. At higher temperature, the heat transfer area per unit volume decreases. The water temperature has no significant influence on the heat transfer coefficient. The effects on droplet size distributions of operating variables including inlet water temperature, n-pentane flow rate, and test position with packing and without packing are compared.     

Microplastics in soils: a review of possible sources,analytical methods and ecological impacts

Microplastics are emerging persistent pollutants that have been extensively detected in aqueous environments. Yet, scientists have little knowledge of microplastic pollution in soils. This study reviewed over 60 articles, with the following objectives: (i) to discuss sources and the global distribution of microplastics in soils; (ii) to evaluate current extraction techniques and analytical methods for microplastics in soils; and (iii) to comprehensively assess their adverse impacts on soils and soil organisms. Moreover, this review highlights the lack of research into microplastic contamination in soils as a significant knowledge gap. Research into the fate, sources and analytical techniques of soil microplastics and the interactions between soil organisms, soils and microplastics is essential in order to underpin management decisions aimed at safeguarding the ecological integrity of our soils. © 2020 Society of Chemical Industry     

基于AMESim的液压马达加载系统研究

液压马达作为液压系统的执行元件在工程机械上广泛应用,针对液压马达加载工况下的输出特性,利用Simulink和AMESim软件对系统进行联合仿真建模,并对系统的运行状态、控制性能、回收性能进行研究,对液压马达加载系统的设计和改进具有重要的参考意义。     

山西某斑岩型金矿工艺矿物学特性

为高效充分利用山西某斑岩型金矿资源,采用矿物定量分析仪(MLA)、光学显微镜、电子显微镜(电镜)等测试手段进行工艺矿物学特性研究。主要开展原矿矿块和-0.074 mm含量占60%细度浮选给矿的详尽矿物学研究。结果表明,金矿物产出形式主要为含银自然金、银金矿、自然金,主要金属矿物为黄铁矿、闪锌矿、方铅矿和微量黄铜矿,金属矿物总量少,达不到可回收边界工业品位,脉石矿物主要为长石、石英、白云母等硅酸盐矿物。对金的化学物相、金在矿样中的嵌布特征和嵌布粒度的配分测试,并评价重选、浸出、浮选三种选冶方法的可回收性,确定采用浮选的工艺回收效果较佳,金浮选理论回收率约93.78%。     

Highly Stretchable and Sensitive SBS/Graphene Composite Fiber for Strain Sensors

Flexible strain sensors have attracted tremendous interests due to the emergence of intelligent wearable technology. Electrically conductive fibers are desirable candidates for flexible strain sensors, but up til now, there still exist enormous challenges to obtain conductive fibers exhibiting simultaneously high stretchability and high strain sensitivity. This paper introduces a poly (styrene‐butadiene‐styrene) (SBS)/graphene (Gr) composite fiber‐based flexible strain sensor fabricated by a facile and highly scalable wet spinning method. The results demonstrate that the graphene content has significant influence on the morphology, mechanical properties, and electromechanical properties of the composite fibers. The fibers with 5 wt% graphene have a wide response range of up to 100% strain, a high electrical sensitivity with the gauge factor of 10083.98 at 100% strain, and meanwhile, a high level of stability for 2100 stretching–releasing cycles under an applied strain of 20%. Furthermore, the SBS‐5%Gr composite fibers display excellent sensing performance in detecting human upper limb movements at different joints including hand joints, wrist joints, elbow joints, and shoulder joints.     

热处理工艺对30MnCrNiMo高强钢组织与性能的影响

借助全自动淬火膨胀仪测定钢的Ac₁、Ac₃相变点,通过对试验钢进行淬火+亚温淬火+回火热处理和淬火+回火热处理,研究了两种热处理工艺下30MnCrNiMo高强钢的组织与性能。结果表明:30MnCrNiMo高强钢的Ac₁、Ac₃相变点分别为653、807 ℃。采用淬火+亚温淬火+回火的热处理工艺所获得的马氏体和铁素体复相组织比直接淬火+回火得到的全马氏体组织更为细小、均匀,试验钢的屈服强度为1499 MPa,伸长率为14.0%,室温、-40 ℃冲击吸收能量分别为35.5和29.5 J,钢的塑性和冲击性能显著提升,有效改善了30MnCrNiMo高强钢的强韧性能。