Research on properties of hollow glass microspheres/epoxy resin composites applied in deep rock in-situ temperature-preserved coring

Deep petroleum resources are in a high-temperature environment.However,the traditional deep rock coring method has no temperature preserved measures and ignores the effect of temperature on rock porosity and permeability,which will lead to the distortion of the petroleum resources reserves assessment.Therefore,the hollow glass microspheres/epoxy resin(HGM/EP)composites were innovatively proposed as temperature preserved materials for in-situ temperature-preserved coring(ITP-Coring),and the physical,mechanical,and temperature preserved properties were evaluated.The results indicated that:As the HGM content increased,the density and mechanical properties of the composites gradually decreased,while the water absorption was deficient without hydrostatic pressure.For composites with 50 vol%HGM,when the hydrostatic pressure reached 60 MPa,the water absorption was above 30.19%,and the physical and mechanical properties of composites were weakened.When the hydrostatic pressure was lower than 40 MPa,the mechanical properties and thermal conductivity of composites were almost unchanged.Therefore,the composites with 50 vol%HGM can be used for ITPCoring operations in deep environments with the highest hydrostatic pressure of 40 MPa.Finally,to further understand the temperature preserved performance of composites in practical applications,the temperature preserved properties were measured.An unsteady-state heat transfer model was established based on the test results,then the theoretical change of the core temperature during the coring process was obtained.The above tests results can provide a research basis for deep rock in-situ temperature preserved corer and support accurate assessment of deep petroleum reserves.

Preparation and Composition Distribution in Hollow Tubular TiB-Ti Composites during Centrifugal Spraying Process

The hollow cylinders of TiB-Ti composites with a gradient distribution of Ti phase were synthesized by the combination of traditional slurry spray with centrifugal forming process.The influences of the concentration of sodium hexametaphosphate(SHMP),the concentration of polyvinyl alcohol(PVA)and solid content(20 vol%-35 vol%)on the rheological properties of the TiB_(2)-Ti composite slurries were investigated.Slurries with low viscosity,weak thixotropy and shear-thinning behaviour were obtained for facilitating the slurry spraying process.The effects of different centrifugal conditions on the migration of components during the forming process were studied.The phase composition and the elements distribution of the prepared samples were characterized by the energy-dispersive X-ray spectrometer.The observations revealed that the samples fabricated at 1500 r/min for 3 min had a significant composition variation.For two-phase systems with small density differences and large particle size variation,centrifugal time was more important than centrifugal speed in forming a continuous gradient structure.

STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

Composite polyurethane(PU)-SiO_2 hollow fiber membranes were successfully prepared via optimizing thetechnique of dry-jet wet spinning,and their pressure-responsibilities were confirmed by the relationships of pure water flux-transmembrane pressure(PWF-TP)for the first time.The origin for this phenomenon was analyzed on the basis of membranestructure and material characteristics.The effects of SiO_2 content on the structure and properties of membrane wereinvestigated.The experimental results indicated that SiO_2 in membrane created a great many interfacial micro-voids andplayed an important role in pressure-responsibility,PWF and rejection of membrane:with the increase of SiO_2 content,theability of membrane recovery weakened,PWF increased,and rejection decreased slightly.

CO2/CH4 separation using inside coated thin film composite hollow fiber membranes prepared by interfacial polymerization

Carbon dioxide(CO_2) is greenhouse gas which originates primarily as a main combustion product of biogas and landfill gas. To separate this gas, an inside coated thin film composite(TFC) hollow fiber membrane was developed by interfacial polymerization between 1,3–cyclohexanebis–methylamine(CHMA) and trimesoyl chloride(TMC). ATR-FTIR, SEM and AFM were used to characterize the active thin layer formed inside the PSf hollow fiber. The separation behavior of the CHMA-TMC/PSf membrane was scrutinized by studying various effects like feed gas pressure and temperature. Furthermore, the influence of CHMA concentration and TMC concentration on membrane morphology and performance were investigated. As a result, it was found that mutually the CHMA concentration and TMC concentration play key roles in determining membrane morphology and performance. Moreover, the CHMA-TMC/PSf composite membrane showed good CO_2/CH_4 separation performance. For CO_2/CH_4 mixture gas(30/70 by volume) test, the membrane(PD1 prepared by CHMA 1.0% and TMC 0.5%) showed a CO_2 permeance of 25 GPU and the best CO_2/CH_4 selectivity of 28 at stage cut of 0.1. The high CO_2/CH_4 separation performance of CHMA-TMC/PSf thin film composite membrane was mostly accredited to the thin film thickness and the properties of binary amino groups.

PREPARATION OF POLYVINYLIDENE FLUORIDE/POLYVINYL DIMETHYLSILOXANE COMPOSITE HOLLOW FIBER MEMBRANES AND THEIR SEPARATION PROPERTIES

Microporous polyvinylidene fluoride(PVDF)hollow fibre membranes were spun using the dry-wet phaseinversion method.By means of dip-coating technique,a uniform coating with thickness of around 5-12 μm of polyvinyldimethylsiloxane(PVDMS)was formed on the surface of porous PVDF hollow fibers.The structural parameters of PVDFsubstrate membrane were estimated by gas permeation test.Using N_2/O_2 as the medium,the separation properties ofPVDMS-PVDF composite hollow fiber membranes were also evaluated experimentally.The experimental data of bothpermeability and selectivity are in good agreement with the theoretical results predicted by the presented pore-distributionmodel.In order to obtain the compact composite membrane free of defects by the dip-coating technique,the thickness ofPVDMS skin must be higher than 5 μm.

Sodium alginate-polyvinyl alcohol/polysulfone (SA-PVA/PSF) hollow fiber composite pervaporation membrane for dehydration of ethanol-water solution

Using polysulfone （PSF） hollow fiber ultrafiltration membranes as the substrate, sodium alginate （SA） and polyvinyl alcohol （PVA） blend solutions as the coating solution, and maleic anhydride （MAC） as the cross-linked agent, SAPVA/PSF hollow fiber composite membranes were prepared for the dehydration of ethanol-water. The effects of different sodium alginate concentration in the coating solutions and different operating temperatures on pervaporation performance were investigated. The experimental results showed that pervaporation performance of the SA-PVA/PSF composite membranes for ethanol-water solution exhibited a high separation factor although they had a relatively low permeation flux. As SA concentration in SA-PVA coating solution was 66.7% and the operating temperature was 40 ℃, SA-PVA/PSF hollow fiber composite membrane （PS4） had a separation factor of 886 and flux of 12.6 g/（m^2·h）. Besides, SA-PVA/PSF hollow fiber composite membranes （PS3 and PS4） were used for the investigation of the effect of ethanol concentration in the feed solution on pervaporation performance.

Eigen value analysis of composite hollow shafts using modified EMBT formulation considering the shear deformation along the thickness direction

Composite hollow shafts are used in power transmission applications due to their high specific stiffness and high specific strength.The dynamic characteristics of these shafts are important for transmission applications.Dynamic modelling of these shafts is generally carried out using Equivalent Modulus Beam Theory(EMBT)and Layerwise Beam Theory(LBT)formulations.The EMBT formulation is modified by considering stacking sequence,shear normal coupling,bending twisting coupling and bending stretching coupling.It is observed that modified EMBT formulation is underestimating the shafts stiffness at lower length/mean diameter(l/dm)ratios.In the present work,a new formulation is developed by adding shear deformation along the thickness direction to the existing modified EMBT formulation.The variation of shear deformation along the thickness direction is found using different shear deformation theories,i.e.,first-order shear deformation theory(FSDBT),parabolic shear deformation theory(PSDBT),trigonometric shear deformation theory(TSDBT),and hyperbolic shear deformation theory(HSDBT).The analysis is performed at l/d_(m) ratios of 5,10,15,20,25,30,35,and 40 for carbon/epoxy composites,E-glass/epoxy composites,and boron/epoxy composite shafts.The results show that new formulation has improved the bending natural frequency of the composite shafts for l/d_(m)<15 in comparison with modified EMBT.The effect of new formulation is more significant for the second and third bending modes of natural frequencies.

Embedding ZnSe nanodots in nitrogen-doped hollow carbon architectures for superior lithium storage

Transition metal chalcogenides represent a class of the most promising alternative electrode materials for high-performance lithium-ion batteries （LIBs） owing to their high theoretical capacities. However, they suffer from large volume expansion, particle agglomeration, and low conductivity during charge/discharge processes, leading to unsatisfactory energy storage performance. In order to address these issues, we rationally designed three-dimensional （3D） hybrid composites consisting of ZnSe nanodots uniformly confined within a N-doped porous carbon network （ZnSe ND@N-PC） obtained via a convenient pyrolysis process. When used as anodes for LIBs, the composites exhibited outstanding electrochemical performance, with a high reversible capacity （1,134 mA.h.g-1 at a current density of 600 mA.g-1 after 500 cycles） and excellent rate capability （696 and 474 mA.h.g-1 at current densities of 6.4 and 12.8 A.g-1, respectively）. The significantly improved lithium storage performance can be attributed to the 3D architecture of the hybrid composites, which not only mitigated the internal mechanical stress induced by the volume change and formed a 3D conductive network during cycling, but also provided a large reactive area and reduced the lithium diffusion distance. The strategy reported here may open a new avenue for the design of other multi functional composites towards high-performance energy storage devices.

Fabrication of polymeric-Laponite composite hollow microspheres via LBL assembly

Hollow structure microspheres with composite polymeric-Laponite shells were prepared by electrostatic self-assembly of Laponite on the polymeric hollow microspheres in this work.The multilayer hydrophilic core/hydrophobic shell polymer latex particles containing carboxyl groups inside were first synthesized via seeded emulsion polymerization,followed by alkali treatment,generating polymeric hollow microspheres.Then,polyethyleneimine（PEI） and Laponite were alternately electrostatic adsorbed on the prepared polymeric hollow microspheres to form polymeric-Laponite composite hollow microspheres.It was indicated that the morphology of alkali-treated microspheres could be tuned through simply altering the dosage of alkali used in the post-treatment process.Along with the increasing of the coating layers,the zeta potential of microspheres absorbed PEI or Laponite approximately tended to be constant respectively,and the thickness of Laponite layer around the hollow microspheres increased clearly,getting more uniform and homogenous.Furthermore,the corresponding polymeric-Laponite hollow microspheres showed high pressure resistance ability compared to the polymeric hollow microspheres.

Influence of morphology of hollow silica-alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane

Hollow silica-alumina composite spheres were prepared by a polystyrene(PS)template method using various amounts of PS suspension.Homogeneous hollow spheres prepared using 40 g were found to be with a diameter of about 300 nm in scanning electron microscopy,and transmission electron microscopy demonstrated their hollow sphere morphology.From the nitrogen adsorption isotherm results,the homogeneous hollow spheres prepared using 40 g of the PS suspension were found to be an ordered pore structure.The activities of the hollow spheres prepared using various amounts of the PS suspension for hydrolytic dehydrogenation of ammonia borane were compared.The results showed that 10,7,and 6 mL of hydrogen were evolved from the aqueous ammonia borane solution in about 40 min in the presence of the hollow spheres prepared using 40,80,and 120 g of PS suspension,respectively.The homogeneous hollow spheres with an ordered pore structure showed the highest activity among all the hollow spheres.The amount of acid sites and the coordination number of aluminum active species were characterized using neutralization titration and solid-state ^(27)Al magic angle spinning nuclear magnetic resonance spectroscopy.The homogeneous hollow spheres with an ordered pore structure had high amount of acid sites and 4-coordinated aluminum species.The relative proportion of 4-coordinated aluminum species was related to the dispersion of aluminum species.These results indicate that the homogeneous hollow spheres with an ordered pore structure showed the high activity because of high amount of acid sites induced by the highly dispersed aluminum species.