Model for non-instantaneous LNG and gasoline spills

Predictions are made of the development and decay of the dimensions of liquid fuel spills on water resulting from collisional rupture of a single fuel tank on large tankers of LNG and of gasoline for the case in which ignition of the spills occurs immediately on rupture. Two sizes of rupture holes are considered, and the shape and duration of the LNG spills are compared with those of an ‘instantaneous’ spill. In contrast to the predicted circular shape of an instantaneous spill, the predicted shapes of the hole spills are long and narrow with aspect ratio, at maximum area, of about 10 to 1 for LNG and 5 to 1 for gasoline. The maximum spill area from a 9.3 m² (100 ft²) hole in an LNG tank is predicted to be attained in half the time predicted for an instantaneous spill of the same fuel volume and is one-third the maximum area of the latter.     

The reinforcing mechanism study of carbon nanotube in the NR matrix

The reinforcement mechanism of CNT in rubber matrix is an important and interesting subject. In this paper, carboxyled multi-walled carbon nanotubes (CNT) were used to prepare natural rubber (NR) nanocomposites (CNT/NR). CNT/NR composites were formed by mechanical blending method and the properties such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied. The results of Mechanical property show that the physical property of NR filled with 9 phr CNT (CNT/NR-9) is similar to that with 30 phr carbon black (CB) (CB/NR-30). In addition, the dispersion and interaction between CNT and NR were also studied by scanning electron microscope, transmission electron microscope, dynamic mechanical testing system and bound-rubber analysis. According to the results, CNT is considered to exhibit random orientations and form “string bag” structure in rubber matrix and the reinforcement mechanism of CNT is different to that of CB.     

A method for joining individual graphene sheets

A graphene-based device requires the graphene to have an ideal shape, structure, and orientation, and be large enough, to allow them to be formed into a new device. Here the joining of individual single-layer and multi-layer graphene is performed in a transmission electron microscope-scanning tunneling microscope (TEM–STM) holder inside a 200 kV field emission TEM. Attempts have been made to join individual graphene sheets (GSs) with the so-called “top-to-top” and “layer-to-layer” geometries by applying a voltage. In the two geometries, the “top-to-top” form has resulted in a seamless joining for both single-layer and multi-layer GSs. The as-joined GSs show the same excellent electrical and mechanical properties as those of the original GSs. Large Joule heating originating from the field emission current will cause atom diffusion and self-assembly and then rearrangement of carbon networks at the GS edge front. In this way individual GSs could be extended and mended with the so-called “top-to-top” geometries by applying a constant voltage, to meet the required and desired shape, size, configuration, and functions for a variety of the special micro/nano scaled devices.     

平板障碍物通道形状对油气爆炸传播特性影响

为研究平板障碍物通道形状对油气爆炸特性的影响，进行了1.3%（低）、1.7%（中）、2.1%（高）三种初始油气浓度工况下对比实验。研究表明：障碍物通道形状对油气爆炸超压随时间变化规律的影响较小；障碍物通道形状对最大爆炸超压峰值、最大升压速率、平均升压速率的影响程度分别按照通道形状为“梯形—圆形—三角形—正方形—矩形”、“梯形—圆形—三角形—正方形—矩形”、“梯形—圆形—正方形—三角形—矩形”的顺序递增；障碍物通道形状对障碍物上游火焰形态基本没影响，但矩形通道障碍物对障碍物下游火焰的湍流特性影响最显著，其次为正方形、梯形、三角形和圆形；初始油气浓度接近当量比时（约为1.7%），障碍物通道形状对最大火焰传播距离和平均火焰传播速度的影响要小于低浓度(1.3%)和高浓度(2.1%)工况，且圆形通道平板障碍物的影响程度最小，矩形和正方形通道的影响程度相对较大。     

Polyvinylpyrrolidone modified barium zirconate titanate /polyvinylidene fluoride nanocomposites as self-powered sensor

Highly flexible biocompatible nanocomposites comprising of Polyvinylpyrrolidone (PVP) modified Barium Calcium Zirconate Titanate (BCT-BZT) /Polyvinylidene fluoride (PVDF) were fabricated. The crystalline BCT-BZT powders were synthesized by a simple sol-gel method. Rietveld refinement analysis confirmed the coexistence of orthorhombic and tetragonal phase in the synthesized powders. The structural, dielectric and ferroelectric properties of the composites were analysed. Addition of PVP modified BCT-BZT powders was observed to enhance the polar phase in PVDF matrix. The piezoelectric output response as a function of different weight percentage of ceramic powders in the PVDF matrix was investigated. The optimal device with 60?wt% PVP modified BCT-BZT powders exhibited maximum peak to peak voltage of 23?V when tested for harnessing waste biomechanical energy (human hand palm force). The nanogenerator was easily scaled up to 4?×?4?cm and the stored power was utilized for powering fifty five LEDs. The fabricated device is flexible, light- weight and eco-friendly. Therefore, it can be explored as a potential candidate for application as self powered sensor.     

Influence of rubber content on mechanical,thermal, and morphological behavior of natural rubber toughened poly(lactic acid)–multiwalled carbon nanotube nanocomposites

The effects of natural rubber (NR) on the mechanical, thermal, and morphological properties of multiwalled carbon nanotube (CNT) reinforced poly(lactic acid) (PLA) nanocomposites prepared by melt blending were investigated. A PLA/NR blend and PLA/CNT nanocomposites were also produced for comparison. The tensile strength and Young's modulus of PLA/CNT nanocomposites improved significantly, whereas the impact strength decreased compared to neat PLA. The incorporation of NR into PLA/CNT significantly improved the impact strength and elongation at break of the nanocomposites, which showed approximately 200% and 850% increases at 20 wt % NR, respectively. However, the tensile strength and Young's modulus of PLA/NR/CNT nanocomposites decreased compared to PLA/CNT nanocomposites. The morphology analysis showed the homogeneous dispersion of NR particles in PLA/NR/CNT nanocomposites, while CNTs preferentially reside in the NR phase rather than the PLA matrix. In addition, the incorporation of NR into PLA/CNT lowered the thermal stability and glass‐transition temperature of the nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44344.     

Characterization of polyisoprene-clay nanocomposites prepared by solution blending

The effects of clay dispersion and the interactions between clays and polymer chains on the viscoelastic properties of polymer/clay nanocomposites are investigated using oscillatory shear rheology, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Four different montmorillonite silicates of natural clays, plasma-treated clays, and organically modified clays (OCs) have been used in this study. For the polyisoprene (PI)/clay nanocomposites, the exfoliation of the OC dispersed in the PI matrix is confirmed with XRD and SAXS although TEM images show both exfoliated and non-exfoliated nanoclay sheets. In contrast aggregation or intercalation is obtained for the other PI/clay composites studied here. Additionally, the effective maximum volume packing fraction of OC for the exfoliated nanocomposites is determined from the overlapping of dynamic viscosity at low frequency regime, in which the effective maximum volume packing fraction is larger than the percolation threshold determined from the storage modulus of the nanocomposites.     

Fabrication of thermo-sensitive optical switches based on lanthanide-polyoxometalates and their “on-off” luminescence controlled by temperature

The temperature-responsive luminescent nanocomposites were prepared by the combination of poly (N-isopropylacrylamide) (PNIPAM) with lanthanide-polyoxometalates/SiO₂ spheres, exhibiting controlled reversible luminescent behavior with change in temperature. The structures and properties of nanocomposites were characterized by transmission electron microscopy, scanning electron microscope, FT-IR, UV-vis, dynamic light scattering and luminescence spectra. The research shows that the nanocomposites in aqueous solution display “on–off” luminescence by simple temperature stimuli. For example, the hybrid nanocomposites of PNIPAM/Eu-polyoxometalate/SiO₂ in aqueous solution show bright red luminescence under UV light, which could be observed by the naked eye when the temperature is below the lower critical solution temperature (LCST), showing the “on” state. However, the red luminescence of nanocomposites in aqueous solution is significantly decreased when temperature is above LCST, showing the “off” state.     

Effect of shell phase composition on the dielectric property and energy density of core-shell structured BaTiO3 particles modified poly(vinylidene fluoride) nanocomposites

Dielectric nanocomposites have attracted much attention due to their wide applications in electronics and electrical industry. Recently, incorporating core-shell nanoparticles into polymer matrix to improve the dielectric properties of nanocomposites has been widely reported. Tailoring the interfacial region between the polymer and the nanoparticles plays a crucial role in achieving the desired dielectric and energy storage properties of nanocomposites. However, the effect of shell structure in the interface region on the dielectric and energy storage properties is rarely studied. Based on this, core-shell BaTiO₃ nanoparticles with two different shell polymers, a “hard-soft” copolymer of methyl methacrylate and butyl acrylate (P[MMA-BA]) and a “hard” homopolymer of methyl methacrylate (PMMA), were prepared in this paper. The effect of core-shell BaTiO₃ nanoparticles with different shell structures on the dielectric and energy storage properties of poly(vinylidene fluoride) (PVDF) was investigated in depth. Due to the formation of a tight interfacial region between P(MMA-BA)@BT and PVDF matrix, P(MMA-BA)@BT/PVDF nanocomposites not only have low dielectric loss but also higher energy efficiency than PMMA@BT/PVDF nanocomposites. This study suggests a potential strategy that fabricating a “hard-soft” copolymer shell on BaTiO₃ surface can obtain desirable energy storage efficiency than the single “hard” shell structure in dielectric nanocomposites.     

In situ measurement of combustion wave propagation during combustion synthesis of α-Si3N4 powder

α-Si₃N₄ powder was prepared by combustion synthesis method. The propagation characteristics of combustion wave were investigated by thermocouple temperature measurement and “resistance—combustion wave displacement response device.” The results show that the combustion reaction takes place in a narrow area, and there is a maximum temperature gradient of 180°C/mm in the combustion front. The “resistance—combustion wave displacement response device” was innovatively used to realize the in situ measurement of combustion wave propagation process. The test results showed the pulse combustion mode in which the combustion front took 10 s as a cycle, and the quantitative data of Si–N₂ discrete combustion characteristics were obtained for the first time.     

Preparation and characterization of organoclay‐rubber nanocomposites via a new route with skim natural rubber latex

Skim natural rubber latex (SNRL) is a protein rich by‐product obtained during the centrifugal concentration of natural rubber (NR) latex. A new method to recover rubber hydrocarbon and to obtain nanocomposites with organoclay (OC) was investigated. The approach involved treatment of SNRL with alkali and surfactant, leading to creaming of skim latex and removal of clear aqueous phase before addition of OC dispersion. Clay mixed latex was then coagulated to a consolidated mass by formic acid, followed by drying and vulcanization like a conventional rubber vulcanizate. X‐ray diffraction (XRD) studies revealed that NR nanocomposites exhibited a highly intercalated structure up to a loading of 15 phr (parts per hundred rubber) of OC. Transmission electron microscopy studies showed a highly exfoliated and intercalated structure for the NR nanocomposites at loadings of 3–5 phr organically modified montmorillonite (OMMT). The presence of clay resulted in a faster onset of cure and higher rheometric torque. The rubber recovered from skim latex had a high gum strength, and a low amount of OC (5 phr) improved the modulus and tensile strength of NR. The high tensile strength was supported by the tensile fractography from scanning electron microscopy. Thermal ageing at 70°C for 6 days resulted in an improvement in the modulus of the samples; the effect was greater for unfilled NR vulcanizate. The maximum degradation temperature was found to be independent of the presence and concentration of OC. The increased restriction to swelling with the loading of OC suggested a higher level of crosslinking and reinforcement in its presence. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3277–3285, 2006     

胶乳-悬浮液共沉法天然橡胶/埃洛石纳米管复合材料的结构与性能

利用天然橡胶(NR)胶乳和埃洛石纳米管(HNTs)悬浮液的负电稳定性,采用胶乳-悬浮液共沉法制备了NR/HNTs复合材料,并对其硫化特性、微观结构、力学性能以及动态力学性能进行了研究.结果表明,HNTs的引入可促进NR的硫化反应,随HNTs用量的增加,焦烧期和正硫化时间缩短;HNTs在复合材料中的分散性极佳;随着HNTs用量的增加,纳米复合材料的定伸应力和邵尔A硬度明显增大,扯断伸长率有所下降,综合力学性能在20份时最好;随着HNTs用量的增加,纳米复合材料的玻璃化转变温度略有升高,转变区的损耗因子明显下降.     

Enhanced piezo-phototronic effect of ZnO nanorod arrays for harvesting low mechanical energy

In this paper, ZnO photocatalytic activity was enhanced by a built-in piezoelectric field due to the piezoelectric effect of ZnO nanorods (NRs). A simple, practical, and self-powered device was designed to simulate and harvest the very low energy of ocean waves. By testing the degradation efficiency of ZnO for different polar dyes (methyl orange, natural red and rhodamine B), the role of the dynamic built-in electric field in the photocatalytic process was illustrated. The changing piezoelectric field acts as a “photo-induced carrier storage” in that the photo-induced carriers would be separated, stored, and released on the ZnO NR surfaces incessantly, improving the separation efficiency of photo-induced carriers in the ZnO NR array. The intensity and frequency of the built-in oscillating piezoelectric field are proportional to the ZnO NR array photocatalytic efficiency. The sustainable piezo-photocatalytic performance of the ZnO NR arrays should promote further applications of ZnO photocatalyst in pollution degradation.     

Poly(N‐isopropylacrylamide) microgel‐based etalons for determining the concentration of ethanol in gasoline

A device composed of a poly (N‐isopropylacrylamide)‐based microgel layer sandwiched between two thin gold layers was used as a platform for determining the amount of ethanol in gasoline (octane number of 87). This device, also known as an etalon, has unique optical properties, which depend on the diameter of the microgels that make up the device. We show that the optical properties of the device depend on the concentration of the ethanol in gasoline samples. Specifically, as the reflectance peaks shift to higher wavelength, the visual color of the device changes from green to red up to 12% (v/v) ethanol. We show that the response was consistent from sample to sample and that the devices are reusable at least three times. We went on to show that the response did not depend on the source of the gasoline, and that the etalon's response is specific to ethanol compared to other common solvents found in gasoline. The performance of these devices make them potentially useful for detecting ethanol in gasoline at the time of gasoline purchase, to determine if the gas being purchased has been adulterated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42106.     

Organoclay Filled Natural Rubber Nanocomposites: The Effects of Filler Loading

Organoclay filled natural rubber (NR) nanocomposites were prepared using a laboratory two-roll mill. The effect of organoclay loading up to 10 phr was studied. The vulcanized nanocomposites were subjected to mechanical, thermal, and swelling tests. The results indicated that the tensile strength and elongation at break reached optimum at 4 phr of organoclay loading, and the incorporation of organoclay increased the tensile modulus and hardness of NR nanocomposites. The thermal degradation was shifted to a higher temperature and the weight loss decreased with incorporation of organoclay. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to characterize the microstructure of NR nanocomposites. Results from TEM and XRD show the formation of intercalated and exfoliated individual silicate layers of organoclay filled NR nanocomposites particularly at low filler loading (< 4 phr).     

Modification of natural rubber tubes for biomaterials I. Radiation-induced grafting of N,N-dimethyl acrylamide onto natural rubber tubes

Radiation-induced simultaneous grafting of N,N-dimethyl-acrylamide (DMAA) onto natural rubber (NR) tubes has been studied to improve blood compatibility of the NR tubes. Concerning grafting of DMAA onto NR tubes, it was found that the grafting proceeds effectively in the presence of carbon tetrachloride (CCl₄) as a solvent. The degree of grafting was found to be saturated at about 26 wt%, but a higher degree of grafting can be obtained by either “so called two-step grafting” or “putting a standing time for a while before irradiation.” The initial grafting rate was proportional to 0.85 power of dose rate. The apparent activation energy of the graft-copolymerization was 7.42 kcal/mol. Evaluation of blood compatibility of DMAA-grafted NR tubes has been carried out by ex vivo test. According to the results, significant improvement of blood compatibility was obtained for the samples in which degree of grafting is higher than 30 wt%.     

Phenolic resin‐crosslinked natural rubber/clay nanocomposites: Influence of clay loading and interfacial adhesion on strain‐induced crystallization behavior

Nanocomposites of natural rubber (NR) and pristine clay (clay) were prepared by latex mixing, then crosslinked with phenolic resin (PhOH). For comparative study, the PhOH‐crosslinked neat NR was also prepared. Influence of clay loading (i.e., 1, 3, 5, and 10 phr) on mechanical properties and structural change of PhOH‐crosslinked NR/clay nanocomposites was studied through X‐ray diffraction (XRD), transmission electron microscopic (TEM), wide‐angle X‐ray diffraction (WAXD), tensile property measurement, and Fourier transform infrared spectroscopy (FTIR). XRD and TEM showed that the clay was partly intercalated and aggregated, and that the dispersion state of clay was non‐uniform at higher clay loading (>5 phr). From tensile test measurement, it was found that the pronounced upturn of tensile stress was observed when the clay loading was increased and a maximum tensile strength of the PhOH‐crosslinked NR/clay nanocomposites was obtained at 5 phr clay. WAXD observations showed that an increased addition of clay induced more orientation and alignment of NR chains, thereby lowering onset strain of strain‐induced crystallization and promoting crystallinity of the NR matrix during tensile deformation. FTIR investigation indicated a strong interfacial adhesion between NR matrix and clay filler through a phenolic resin bridge. This suggested that the PhOH did not only act as curative agent for crosslinking of NR, but it also worked as coupling agent for promoting interfacial reaction between NR and clay. The presence of strong interfacial adhesion was found to play an important role in the crystallization process, leading to promotion of mechanical properties of the PhOH‐crosslinked NR/clay nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43214.     

考虑碳排放因素的汽油调合在线优化

针对国家“双碳”战略目标要求,以炼化企业汽油调合在线优化为研究对象,分析了国Ⅵ汽油新标准下被控属性更多、更严、调合效率要求更高等特点,以及由此带来的调合组分油调整导致调合成品汽油携带碳排放量的变化情况。考虑到传统的汽油调合在线优化一般只考虑调合成本、质量卡边等目标,首先建立了非线性的汽油调合辛烷值、蒸气压和馏程等软测量模型,然后构建了基于调合效应的汽油调合优化模型,优化目标中引入调合成品油二氧化碳排放最低化目标,开发了一种融合携带碳排放特征的汽油调合优化模型。为满足在线调合优化需求,优化模型中考虑了实际累积调合过程,将调合工艺过程中储罐汽油属性合格转化成调合头属性区间合格,利用调合头处优化的属性补偿已调合体积和罐底油的属性偏差。仿真结果表明,设计的考虑碳排放因素汽油累积调合优化技术能很好地满足汽油调合在线优化需求,为国Ⅵ标准和碳交易背景下汽油调合工艺设计及在线优化控制提供了技术支撑。     

Curing Characteristics,Mechanical, Thermal,and Morphological Properties of Halloysite Nanotubes (HNTs)-Filled Natural Rubber Nanocomposites

Halloysite nanotubes (HNTs)-filled natural rubber (NR) nanocomposites with various filler loading were prepared by using a two-roll mill. The addition of HNTs increased the scorch time, cure time and maximum torque but reduced curing rate index. The tensile strength increased up to 20 phr of HNTs and then decreased. When HNTs loading increased, the elongations of break, swelling percentage and fatigue life were decreased while modulus at 100% and 300% elongation and thermal properties showed inversely. The dispersion of HNTs inside the NR matrix is shown from SEM images.     

两种橡胶/有机累托石纳米复合材料的结构与性能

比较了用熔体法制备的有机累托石(OR)/丁苯橡胶(SBR)以及有机累托石(OR)/天然橡胶(NR)2种纳米复合材料的结构与性能.TEM和XRD对材料的分析显示,由于橡胶基体的性质差异,OR/SBR为典型的插层型结构,而OR/NR为插层型和部分剥离型混合结构.应力应变行为的研究表明,随着OR用量的增加,OR/SBR的拉伸强度和拉断伸长率均增大,这主要是分子链滑移和填料的取向造成的.对于拉伸结晶型橡胶NR,由于部分剥离型填料的增强作用,NR的定伸应力随填料用量的增加而逐渐提高.由于对结晶的阻碍作用,当OR用量为20份时,OR/NR的拉伸强度有所降低.纳米累托石的加入可以显著提高SBR和NR的硬度和撕裂强度.热失重分析表明,OR/橡胶纳米复合材料与相应的纯橡胶相比,热稳定性提高,在NR体系中更为显著.