A new approach for the characterization of the pore structure of dual porosity rocks

For the realistic representation of the pore space of dual porosity rocks, a new method of pore structure characterization is developed by combining experimental Hg intrusion/retraction curves with back-scattered scanning electron microscope (BSEM) images and inverse modeling algorithms. The pore space autocorrelation function measured by processing the digitized BSEM images is combined with the surface fractal dimension estimated from the high pressure Hg intrusion (MIP) data to derive a synthetic small-angle neutron scattering (SANS) intensity function, the inversion of which provides a volume-based pore body radius distribution (PBRD). The volume-based PBRD is fitted with a multimodal number-based PBRD consisting of two component distributions: one representing the macroporosity and another one representing the microporosity. Based on arguments of percolation theory, analytical mathematical models are developed to describe the Hg intrusion in and retraction from dual pore networks in terms of the complete PBRD, pore throat radius distribution (PTRD) of macroporosity, drainage accessibility functions (DAFs) of both porosities, and imbibition accessibility functions (IAFs) of both porosities. Inverse modeling of the Hg intrusion data set enables us to estimate the PTRD and DAFs. Inverse modeling of the Hg retraction datasets enables us to estimate a set of primary and secondary IAFs. The method is demonstrated by the pore structure characterization of four outcrop samples of carbonate and sandstone rocks. Analytic approximate equations developed from the critical path analysis (CPA) of percolation theory enable us to calculate explicitly the absolute permeability and the formation factor of the porous rocks using the estimated parameters (PBRD, PTRD, DAF) of the macroporosity. The measured permeability of cores is predicted satisfactorily and observed discrepancies may be attributed to large length-scale macro-heterogeneities which are not evident in BSEM images and Hg porosimetry data.     

Elongational creep experiments - A new method for investigations of morphology development in polymer blends

This work is focused on the changes of phase structure in polystyrene/polyethylene blends with up to 15 wt.% of dispersed phase during elongational experiments in creep. In the first part, features of the experiments at constant stress with a special attention to morphology development in polymer blends are discussed. In the second part of the paper the deformation behavior of the dispersed droplets in dependence on applied stress and total strain is studied. It was found that with increasing the initial particle size the formation of homogeneously deformed long fibrils is preferred during the elongation. A maximum deformability of the droplets was observed, which cannot be increased by applying higher stresses, although the affine deformation of the droplets was not reached.     

A new approach to characterize the nanostructure of activated carbons from mathematical morphology applied to high resolution transmission electron microscopy images

A new characterization method of the nanoporous structure of activated carbons (ACs) is proposed, based on mathematical morphology analysis of high resolution transmission electron microscopy (TEM) images. It produces refined statistics describing the shape, size and orientation of the defective graphene sheets seen edge on as individual fringes on TEM images. It also provides some quantitative information regarding their spatial arrangement. Especially, assemblages composed of 2–4 nearly parallel fringe fragments could be detected, which were relevant of some partial stacking of the defective graphene sheets. Such assemblages were possibly locally oriented along a common direction to form large continuous domains. To prove the ability of the image analysis tool to reveal distinctive features and degrees of disorder of the AC structures, a set of various commercial carbon adsorbents was characterized. The measured effective spaces separating the individual fringes, the stacks and the continuous domains were examined and compared with the porosity data derived from 77 K–N₂ adsorption isotherms. Consistency between the two sets of data was assessed and interpreted by considering the N₂ diffusional limitations resulting from the micropore network connectivity.     

A density based segmentation method to determine the coordination number of a particulate system

The coordination number is an important parameter for understanding the particulate systems, especially when agglomerated particles are present. However, experimental determination of the coordination number is not trivial. In this study, we describe a 3D classification method, which is based on the revised DBSCAN (Density-Based Spatial Clustering of Applications with Noise) and its application to X-ray micro-tomographic (XMT) images to determine the coordination number distribution. Pellets of micro-crystalline cellulose were used as model particles. The validity of the segmentation was checked by comparing the particle size distribution (PSD) obtained by XMT-DBSCAN with PSD obtained by optical microscopy. The results were found to be in good agreement, demonstrating the suitability of the DBSCAN method. The means and standard deviations of coordination numbers were (8.2±1.7, n=994 particles), (8.1±1.5, n=904) and (6.2±1.2, n=159) for pellets with length based mean sizes of 157, 307 and 437 μm, respectively. The coordination number distribution was in line with previous finding in mono-sized acrylic beads.     

A novel way to fabricate tubular porous mullite membrane supports by TBA-based freezing casting method

Porous tubular mullite supports with gradient unidirectional aligned pores were successfully fabricated by TBA-based freezing casting method. The effects of freezing temperature, solids loading and particle size distribution of mullite powders on the microstructure and properties of the supports were investigated extensively. The results show that the pore size, porosity and compressive strength of the supports can be effectively adjusted by controlling the parameters. Both the results of microstructure observations and properties testing indicate that the pore channel size increases along the freezing direction, accompanied by the changes of pore structure from homogeneous near the freezing medium to unidirectional away from the freezing medium. The pore channel size decreases significantly with increasing solids loading, decreasing freezing temperature and reducing the particle size. The porosity also decreases with increases of solids loading and freezing temperature, as well as reduces of the particle size, while the compressive strength increases.     

Freeze-dried solid foams prepared from carbon nanotube aqueous suspension: Application to gas diffusion layers of a proton exchange membrane fuel cell

Freeze-dried macroporous solid foams were prepared from the multi-walled carbon nanotube (MWCNT) aqueous suspensions dispersed by chitosan. Thin film shaped CNT solid foams were prepared, and applied to the gas diffusion layers (GDLs) of a laboratory scale proton exchange membrane fuel cell (PEMFC). It was demonstrated that the prepared carbon foams in this study were useful to a fuel cell GDL material. The prepared cell performances were fairly comparable to the cell prepared with conventional carbon paper for GDL material. The microstructures of the prepared carbon foams were found to affect on the PEMFC performances. It was suggested that the interconnected carbon networks formed during the freezing step closely link to the cell performances. Hence, the defection of the interconnected microstructure lead degradation of the GDL quality. The impedance measurement made clear that the prepared foam materials were also advantageous for reducing the ohmic resistance in PEMFC assembly. The kinetic resistance values and the thermal conductive characteristics suggested that the freezing process would also control the degree of overlaps among single CNTs in a freeze-dried bulk that influenced on the electrochemical properties.     

A 2-dimensional small-angle X-ray scattering study of the microphase-separated morphology exhibited by thermoplastic polyurethanes and its response to deformation

The morphological behaviour of poly(ether-urethane)s undergoing deformation was studied using two-dimensional small-angle X-ray scattering (2D-SAXS). The data was analysed using the Zernike-Prins and Percus-Yevick models, which fitted the data well and indicated morphologies composed of discrete, elongated hard segment (HS) microdomains. Although the formulations contained relatively large HS weight fractions, relatively low volume fractions of scattering bodies were indicated, which implied limited segmental de-mixing. Possible explanations for this were discussed.Curve-fitting the 2D-SAXS data for deformation experiments using the Zernike-Prins model, indicated that HS microdomains initially became aligned with the applied strain and subsequently fragmented. This suggested a morphological basis for the observed mechanical properties of these materials, which will be explored in more detail, in subsequent publications.     

Enzyme‐labeled phages detected by amperometry: A new method to study inline virus retention in membrane processes

A new method is presented to characterize the retention dynamics of membrane processes with a new virus surrogate used as a tracer and developed in our laboratory. This virus surrogate is an enzyme‐labeled MS2 bacteriophage whose activity can be directly and rapidly detected and quantified by amperometry, which is a sensitive electrochemical technique. In the first step, the amperometric measurement was developed and validated. Microfiltration and ultrafiltration experiments consisting of injecting tracers into the feed and monitoring the tracer presence in permeate (or in retentate) by amperometry, and then validating the use of the tracer and its detection technique in the field of membrane filtration. In particular, global retention experiments demonstrated the ability of this method to differentiate among membrane behaviors and dynamic experiments showed the ability of the method to characterize dynamics of retention in a reproducible way. © 2012 American Institute of Chemical Engineers AIChE J, 59: 68–78, 2013     

N-甲氧基偕溴代亚胺的光解成腈反应的研究

N-甲氧基偕溴代亚胺能以高产率光解转化为相应的腈产物,而且对常见的脱水剂和卤化剂敏感的官能团不影响。     

A new method to extract elastic modulus of brittle materials from Berkovich indentation

This work describes a method to reliably measure the elastic modulus of brittle materials from Berkovich indents under the continuous stiffness mode. It involves depositing a metallic film at the surface of the tested material to absorb the inelastic damage caused by the penetrating indenter. The Zhou-Prorok model was employed and rearranged to decouple the film and substrate contributions. This converted it into a hyperbolic form that approached an asymptote as the indenter approaches the film/substrate interface. This asymptote was described by a simple linear approximation whose slope directly revealed the substrate’s elastic modulus. The method enabled the elastic behavior of the brittle ceramic to be assessed without the indenter penetrating it. In fact, this method can assess properties of an unknown film/substrate composite as long as one has an estimate of the film thickness and the film can appreciably plastically deform.     

不同云芝菌株腐朽杨木过程的扫描电镜研究

本文应用扫描电镜观察研究了白腐菌云艺（Coriolusvericolor）三个菌株腐朽杨木的过程，对试材的显微形态变化以及各菌株的降解特性进行了详细描述和探讨．实验结果表明，三个菌株降解木材的性能和方式存在着差异。NFU008对木质素和纤维素均具有很强的降解能力，它在腐朽早期优先降解胞间层中的木质素并能使纤维解离，在腐朽后期，它对纤维素产生强烈降解。NFU006对木质素和纤维素的降解是同时进行的，但对纤维次生壁中木质素的降解率明显高于对纤维素的降解率。NFU019降解木质素的能力相对较弱，但对纤维素的降解能力却很强，早期它以降解出生壁的木质素为主，而在腐朽后期它对纤维素产生剧烈降解。三个菌株最终均造成纤维细胞壁不同程度的减薄和破坏。     

A method to calculate the multiphase flow properties of heterogeneous porous media by using network simulations

A method is suggested to compute the capillary pressure and relative permeability curves of heterogeneous porous media. The broad pore radius distribution (PRD) and throat radius distribution (TRD) are decomposed into relatively narrow component distribution functions which are used for the computer‐aided construction of pore‐and‐throat networks. The quasi‐static motion of menisci in pores and throats is tracked by accounting for capillary forces. The presence of fractal roughness along pore walls ensures the coexistence of both phases in pores. The calculation of the hydraulic conductance of each phase is based on the concept of constricted unit cell. Simulations in component pore networks constructed from narrow PRD and TRD produce a set of capillary pressure and relative permeability functions, the arithmetic averaging of which yields the corresponding functions for a heterogeneous synthetic pore network. This information is used by a dynamic simulator of drainage in permeability networks to predict experimental results of soil columns. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

电石法氯乙烯高沸残液综合利用的新方法

提出了从电石法氯乙烯高沸残液中回收45-65℃的馏分,再经羰基化反应生产二氯丙醇以及光氯化反应生产三氯乙烷等产品的综合利用方案,并进行了经济效益评价。结果表明,该方案具有很好的经济效益、社会效益和环境效益。     

废紫铜催化制备氯化亚铜新工艺

介绍以废紫铜为原料，在催化剂作用下，铜直接同盐酸，空气中氧发生反应制备氯化亚铜的新工艺，试验确定了最佳反应条件，产品质量达到了GB1619－79的标准要求，该工艺具有原料消耗少，反应速度快，流程短，操作简单，生成成本低等特点。     

Comparison of parameters calculated from the BET and Freundlich isotherms obtained by nitrogen adsorption on activated carbons: A new method for calculating the specific surface area

The empirical linear relationship between the BET surface area S_BET and the Freundlich constant K_F, calculated from nitrogen adsorption isotherms of activated carbons, S_BET = a₀K_F is mathematically demonstrated. This correlation exists in the relative pressure domain in which the BET equation is valid, whatever the value of c for the BET equation and for values of the Freundlich exponent, , between 0 and 0.2. This study allows to determine the correlation factor a₀ = 1/a with . From this result, a new expression, depending of and K_F, can be deduced for calculating the specific surface area.     

A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation

Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.     

A new approach to quantify the microporosity of activated carbons by analysing the N2/77 K and CO2/273 K adsorption data by the simplex flexible method

A mathematical model has been applied to N₂/77 K and CO₂/273 K adsorption isotherms for a series of activated carbons prepared by carbonising olive stones in N₂ and then activating them in CO₂ to six different levels of burn-off in the range 8–80%. Narrow and wide micropore volumes of activated carbons were calculated from the Dubinin-Radushkevich and Dubinin-Astakhov equations considering one, two and three micropore size distributions in each sample, and allowing a variation of the micropore volume and characteristic energy of each distribution with the burn-off. The flexible simplex method was applied to obtain the parameters of each distribution in the mathematical model. Generally, it was found that increasing the number of micropore size distributions above two did not significantly improve fits. Each isotherm was fitted using six parameters at most. However, various constraints were imposed, and the parameters were estimated from each isotherm using non-linear, least-squares regression analysis. The results obtained confirm the valuable use of CO₂/273 K adsorption to quantify the narrow microporosity of activated carbons. Differences between N₂/77 K and CO₂/273 K adsorption in microporous activated carbons were due to the wide microporosity. An agreement between micropore volumes obtained from CO₂/273 K adsorption and that corresponding to one of the two distributions of micropores obtained from N₂/77 K adsorption was obtained. The Dubinin-Radushkevich equation was more successful than the Dubinin-Astakhov equation in the quantification of the microporosity with N₂/77 K and CO₂/273 K. On the other hand, the exponent n of the Dubinin-Astakhov equation was better correlated with the burn-off of the carbons than with the parameter B.     

A new method to synthesize high solid content waterborne polyurethanes by strict control of bimodal particle size distribution

A new method named two-step emulsification process was developed to synthesize high solid content waterborne polyurethanes by strict control of the bimodal particle size distribution. In the first step, a series of 40% solid content polyester-based (WPU-1) with low content of hydrophilic group and large particle size were firstly synthesized. In the second step, polyether-based prepolymers (WPU-2 prepolymers) with high content of hydrophilic group were firstly prepared and WPU-1 emulsions were used to emulsify WPU-2 prepolymers to obtain the final emulsions with high solid content (WPU-3). The particle size of WPU-3 present bimodal distribution and the diameter ratio and volume percentage of large particles to small particles in WPU-3 were able to be strictly controlled by this method. The viscosity of WPU-3 with 55% solid content was only 489.1 mPa s⁻¹ when the diameter ratio of large particles to small particles was 9.2 and the volume percentage of large particles was 74%.     

A new method to determine monomer concentration in the polymer particles of emulsion polymerization systems by dynamic light scattering

Emulsifier‐free emulsion polymerization of styrene was performed in the presence of small amount of methacrylic and itaconic acids as carboxylic acid monomers and potassium persulfate as an initiator at 70°C to prepare monodisperse polymer particles. Diameter of monomer swollen polymer particles (d_pswol) was measured by dynamic light scattering for samples taken from the reaction mixture during the Intervals II and III of the emulsion polymerization. Graphically treatment of d_pswol versus conversion data allowed us for the first time to directly determine the critical monomer conversion (x_c), from which constant monomer concentration in the polymer particles (C_MP) during the Interval II was then calculated. x_c and C_MP were obtained to be 0.379 and 5.68, respectively. C_MP value is in good agreement with that obtained by centrifugation method and those reported in the literature for the similar system. Attempts were also made to evaluate the average number of growing chain per particle ( ) during the Interval II of emulsion polymerization of styrene. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009