Interfacial Actions Research Articles

A facile and green strategy to achieve metallized woven carbon fiber through the triple roles of dopamine in in-situ thermal reduction of Ag

Metallized carbon fiber (CF) has received lots of attention due to its improved electrical conductivity and electromagnetic interference (EMI) shielding performance. Herein, we propose a facile and environmental strategy to achieve uniform and dense silver (Ag) deposition on polydopamine (PDA) modified woven CF by a simple in-situ thermal reduction approach. PDA plays three important roles for anchoring and formatting Ag layer by accommodating the CF surface with improved interfacial actions, capturing the silver ions (Ag+) and then reducing the Ag+ during the hot-pressing process. The CF as intrinsic conductive substrate simultaneously promoted the reduction capability of PDA through electrons transfer during the reduction process. As a result, the single-layered Ag coated CF fabric can be easily formed and exhibits excellent EMI shielding effectiveness (73.08 dB) and reliable shielding performance. This strategy saves tedious fabrication process and avoids the use of toxic and harmful substances, which is highly promising in fabricating large scale metallized fiber cloths.

Water Droplets Tailored as Wax Crystal Carriers to Mitigate Wax Deposition of Emulsion.

This study explores how the micro-distribution change of wax crystals from the continuous oil phase to the oil-water interface mitigates the macro wax deposition of an emulsion. Two types of interfacial actions between wax crystals and water droplets, interfacial adsorption and interfacial crystallization, which were induced by two different emulsifiers, sorbitan monooleate (Span 80) and sorbitan monostearate (Span 60), respectively, were detected by differential scanning calorimetry and microscopy observation. The wax interfacial crystallization promoted by Span 60 resulted in the wax being nucleated directly at the oil-water interface prior to the continuous oil phase, conferring the nascent wax crystals and water droplets to be combined as coupled particles. The utilization of the wax interfacial crystallization behavior to hinder wax deposition of an emulsion was further explored. When the coupled wax crystal-water droplet particles were formed during the wax deposition process, water droplets acted as wax crystal carriers, entraining these nascent wax crystals to disperse in the emulsion, which significantly reduced the amount of wax crystals available to form the network of the deposit. In addition, this change also led to the basic structural units in the wax deposit evolving from wax crystal clusters/networks to water droplet flocs. The study elucidates that through adjusting the dispersion of wax crystals from the oil phase to the oil-water interface, water droplets could act as a functional component to tailor the properties of the emulsion or resolve related flow and deposition problems in pipeline transportation.

Micro-seepage directed evaporation and salt nucleation of a brine droplet on oil-impregnated steel surfaces

The lubricant/oil-impregnated surface was intensively investigated due to its versatile functionality in service environments. However, its environmentally sensitive failure caused by water droplets is still unclear. In this paper, we speculated that the evaporation/crystallization of a droplet depends on the microscopic interactions at the droplet/oil/substrate interface, which determines the failure of an oil-impregnated surface on reactive substrates. Experiments were conducted by placing a brine droplet on the oil-impregnated steel surface (OISS) and the oil-coated steel surface (OCSS) directly prepared on carbon steel. The evaporation and crystallization processes were systematically investigated by microscopic and spectroscopic methods. A dynamic polar coordinate was developed to qualitatively determine the location of the salt nucleus during evaporation. Our findings address the crucial role of the micro-scale interfacial actions affecting the macro-droplet behavior. The asymmetric edge pegging leads to a displacement of the center mass of a droplet, which alters the evaporation modes and rates. The micro-seepage of water causes the local rupture of oil layers and the droplet nailing, resulting in corrosion of the substrate structures, which constrains the nucleation of salt grains on OISS. The similar mechanism was verified by the droplet behavior on OCSS. Our findings are of great significance for deciphering the droplet behavior on engineering materials surfaces.

Sustainable green composites from biodegradable plastics blend and natural fibre with balanced performance: Synergy of nano-structured blend and reactive extrusion

We herein report a unique scientific strategy in engineering green composites with excellent balanced performance of stiffness, toughness and heat deflection temperature (HDT). To achieve such target, a high melt strength bioplastic blend of poly (butylene succinate), PBS and poly (butylene-adipate-co-terephthalate), PBAT with super toughness could take-up stiff natural fibres like inexpensive purpose grown Miscanthus fibre and Oat hull (a co-product from food industry) in the green composite structure through reactive extrusion. The novelty of this work is to allow the free radical reaction to occur within polymer matrix and between the blend and natural fibres by introducing biomass from a side feeder, aiming to achieve matrix toughening and polymer/fibre interface enhancement simultaneously. Tensile modulus of the bio-blends was improved by maximum 650% with the reinforcement of 40 wt% agricultural by-products. For equal amounts of 40% biomass fibres, the Miscanthus fibre is more suitable to strengthen the biopolymers, in terms of higher modulus (3.0 GPa), higher HDT (110 °C) and lower water absorption (3.4%); however, the oat hull composites show much higher impact strength of 83 J/m. A systematical structure-properties relationship study indicates that higher aspect ratio, higher cellulose contents and stronger interfacial actions account for the higher stiffness and HDT of the Miscanthus fibre composites compared to the oat hull-filled counterparts. This abundant biomass has potential to fabricate sustainable composites to substitute certain fossil fuel-based plastics in terms of mechanical and thermal properties, as well as cost and energy-saving via using the industrial friendly technology as proposed here.

Wettability and imbibition mechanism of continental and marine shales by aqueous phase

With regards to the present situations in the exploration of the continental shale of Yanchang formation in Ordos Basin and the marine shale of Longmaxi formation in Sichuan Basin, the characteristics of the interfacial actions between aqueous phase and shale at different positions under different sedimentary environments are studied. The mineral composition analysis, natural porosity observations and rock mechanics tests were conducted. The water phase contacting angle on the shale surface and the spontaneous imbibition of the matrix were explored. The results show that the continental shale has a higher clay mineral content, so it tends to be water-sensitive and consequent damages to the reservoir may be caused. In Fuling area, the matrix of the marine shale gas reservoir is relatively tight, the fracture morphology is simple, the amount of filling material is less, and the micro-fractures and micro-pores are more fully developed than the continental Yanchang formation. Due to the high content of brittle minerals, the Young’s modulus and Poisson’s modulus of the shale in Fuling area are relatively high, which is beneficial to the SRV and the fracture complexity. The surface of shale represents strong hydrophilicity. Differences exist in the wettability effects of water phase on shales at different positions, The effects of different types of surfactants on the wettability of shale are different.

Preparation of Chitin-PLA laminated composite for implantable application

The present study explores the possibilities of using locally available inexpensive waste prawn shell derived chitin reinforced and bioabsorbable polylactic acid (PLA) laminated composites to develop new materials with excellent mechanical and thermal properties for implantable application such as in bone or dental implant. Chitin at different concentration (1–20% of PLA) reinforced PLA films (CTP) were fabricated by solvent casting process and laminated chitin-PLA composites (LCTP) were prepared by laminating PLA film (obtained by hot press method) with CTP also by hot press method at 160 °C. The effect of variation of chitin concentration on the resulting laminated composite's behavior was investigated. The detailed physico-mechanical, surface morphology and thermal were assessed with different characterization technique such as FT-IR, XRD, SEM and TGA. The FTIR spectra showed the characteristic peaks for chitin and PLA in the composites. SEM images showed an excellent dispersion of chitin in the films and composites. Thermogravimetric analysis (TGA) showed that the complete degradation of chitin, PLA film, 5% chitin reinforced PLA film (CTP2) and LCTP are 98%, 95%, 87% and 98% respectively at temperature of 500 °C. The tensile strength of the LCTP was found 25.09 MPa which is significantly higher than pure PLA film (18.55 MPa) and CTP2 film (8.83 MPa). After lamination of pure PLA and CTP2 film, the composite (LCTP) yielded 0.265–1.061% water absorption from 30 min to 24 h immerse in water that is much lower than PLA and CTP. The increased mechanical properties of the laminated films with the increase of chitin content indicated good dispersion of chitin into PLA and strong interfacial actions between the polymer and chitin. The improvement of mechanical properties and the results of antimicrobial and cytotoxicity of the composites also evaluated and revealed the composite would be a suitable candidate for implant application in biomedical sector.

Discrete approaches for the nonlinear analysis of in plane loaded masonry walls: Molecular dynamic and static algorithm solutions

Abstract The aim of the paper is to present and validate a non commercial discrete element model (DEM) code for the nonlinear analysis of in plane loaded masonry panels, with dry or mortar joints. Such model is based on the hypothesis of rigid blocks and joints modeled as interfaces, that turn out to be both suitable for representing the behavior of ancient masonry, characterized by joint size negligible with respect to block size and block stiffness larger than joint stiffness. Hence, the elastic and inelastic behavior of a masonry assemblage is concentrated at joints by defining their stiffness and adopting a Mohr-Coulomb law as a restraint for interfacial actions. The proposed strategy is based on two approaches: a static solution method and a molecular dynamics algorithm. The static solution method allows to determine the stiffness matrix of a masonry panel and to update such matrix accounting for actual joint stiffness and blocks arrangement. Such method turns out to be computationally faster and equally effective with respect to the molecular dynamics one for performing incremental analysis of in plane loaded masonry panels. On the other hand, the molecular dynamics method is computationally less onerous than the static solution method, since it does not require to define and update panel stiffness matrix and to invert it for determining displacements. Both approaches are used and critically compared for solving several case studies of masonry panels modeled by DEM. In addition, it must be pointed out that results in terms of ultimate loads and collapse mechanisms are in good agreement with existing experimental data and numerical solutions.

Interfacial Actions and Adherence of an Interpenetrating Polymer Network Thin Film on Aluminum Substrate

The interpenetrating polymer networks (IPN) thin film with the –C=O group in one network and the terminal –N=C=O group in another network on an aluminum substrate to reinforce the adherence between IPN and aluminum through interfacial reactions, were obtained by dip-pulling the pretreated aluminum substrate into the viscous-controlled IPN precursors and by the following thinning treatment to the IPN film to a suitable thickness. The interfacial actions and the adhesion strengths of the IPN on the pretreated aluminum substrate were investigated by the X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and strain-stress(?-?) measurements. The XPS and FTIR detection results indicated that the elements’ contents of N, O, and Al varied from the depths of IPN. The in-terfacial reaction occurred between the –N=C=O group of IPN and the AlO(OH) of pretreated aluminum. The in-creased force constant for –C=O double bond and the lower frequency shift of –C=O stretching vibration absorption peak both verified the formation of hydrogen bond between the –OH group in AlO(OH) and the –C=O group in IPN. The adherence detections indicated that the larger amount of –N=C=O group in the IPN, the higher shear strengths between the IPN thin film and the aluminum substrate.

Integration of movable structures in PDMS microfluidic channels

In this paper, we analyzed the behavior of moving structures in a check valve micropumping system and proposed a method to improve the freedom of motion of such structures. A model ball valve in a microchannel system was designed for this study. The behavior of the glass sphere, which acted as an independent flow check valve in the PDMS microfluidic channel, was analyzed. We found that the motion of the ball valve in the microchannel was sensitive to the properties of the interface between the ball, channel, and liquid. The glass ball valve moved freely when methanol or ethanol was introduced into the PDMS channel. However, the ball valve adhered to the PDMS channel when deionized (DI) water or cell culture media was introduced. Such behavior inhibits the applicability of this micropump to biological systems. The adhesion properties were modeled using the theory of interfacial actions between heterogeneous materials. The theoretical model successfully predicted the interaction properties that governed ball valve motion in the PDMS microchannels. To ameliorate the excessive adhesion in DI water or cell culture media, a hybrid inorganic/organic polymer (HR4) was used to coat the PDMS channel. In the HR4-coated ball valve micropump, the glass ball moved freely in DI water and cell culture media. Finally, the biocompatibility of the HR4 coating was evaluated by pumping human mesenchymal stem cells (hMSCs) suspended in media, and the pumped cells were cultured and evaluated for viability. A good viability demonstrated that the HR4 pump was biocompatible.

Study of Chemical Interactions at the Stainless Steel / Polymer Interface by Infrared Spectroscopy

AbstractThe interfacial interaction of a thermoplastic copolymer ethylene-maleic anhydride with stainless steel has been studied by infrared spectroscopie techniques (FTIR) in order to improve the durability of steel/polymer association, by modifying formulation of polymer or surface treatment of stainless steel.In order to be successful, an analytical methodology has been established. Interfacial chemical actions of maleic anhydride with stainless steel are simulated through thin layer of succinic anhydride on polished metal surface. FTIR spectroscopie (grazing angle) permit a direct access ot interphase for identifying new bounds between organic and metallic compounds.Interaction of succinic anhydride with the polar OH groups of the oxidized metal surface follawed a reactional mechanism which can be described by two steps:- opening of the anhydrid ring for reacting with adsorbed water and formation of acid group (-COOH),- reaction of acid group with hydroxylic fraction of metal surface and formation of carboxylate anion (-COO-) groups.

懸濁粒子の圧縮率について

In this paper, a new relationship between compressibility of suspension and those of its components were led considering the effect of the interfacial actions at the surface of suspended particle.The approximations, showing us the possibility that the compressibility of suspended particles could be determined graphically, were obtained by using some assumptions and were verified experimentally by measurements of sound velocity in suspension and its density.The value for the compressibility of the particle in question derived from these approximations with the suitable quantity of the constant “p” was in good agreement with the values obtained by another investigators.