hui Pi

Inspired by Stenocara Beetles: From Water Collection to High-Efficiency Water-in-Oil Emulsion Separation

Inspired by the water-collecting mechanism of the Stenocara beetles back structure, we prepared a superhydrophilic bumps-superhydrophobic/superoleophilic stainless steel mesh (SBS-SSM) filter via a facile and environmentally friendly method. Specifically, hydrophilic silica microparticles are assembled on the as-cleaned stainless steel mesh surface, followed by further spin-coating with a fluoropolymer/SiO2 nanoparticle solution. On the special surface of SBS-SSM, attributed to the steep surface energy gradient, the superhydrophilic bumps (hydrophilic silica microparticles) are able to capture emulsified water droplets and collect water from the emulsion even when their size is smaller than the pore size of the stainless steel mesh. The oil portion of the water-in-oil emulsion therefore permeates through pores of the superhydrophobic/superoleophilic mesh coating freely and gets purified. We demonstrated an oil recovery purity up to 99.95 wt % for surfactant-stabilized water-in-oil emulsions on the biomimetic SBS-SSM filter, which is superior to that of the traditional superhydrophobic/superoleophilic stainless steel mesh (S-SSM) filter lacking the superhydrophilic bump structure. Together with a facile and environmentally friendly coating strategy, this tool shows great application potential for water-in-oil emulsion separation and oil purification.

Droplet Motion on a Shape Gradient Surface

We demonstrate a facile method to induce water droplet motion on an wedge-shaped superhydrophobic copper surface combining with a poly(dimethylsiloxane) (PDMS) oil layer on it. The unbalanced interfacial tension from the shape gradient offers the actuating force. The superhydrophobicity critically eliminates the droplet contact line pinning and the slippery PDMS oil layer lubricates the droplet motion, which makes the droplet move easily. The maximum velocity and furthest position of droplet motion were recorded and found to be influenced by the gradient angle. The mechanism of droplet motion on the shape gradient surface is systematically discussed, and the theoretical model analysis is well matched with the experimental results.

Cure kinetics and chemorheological behavior of a wind epoxy resin system and its viscoelastic properties reinforced by glass fiber matt with process of vacuum assisted resin transfer molding

In order to investigate the processability of a wind epoxy resin for the vacuum-assisted resin transfer molding (VARTM) process, a differential scanning calorimeter and rheometry instrument were applied to characterize the curing properties and study the chemorheological behavior to obtain a better understanding of the resin system in order to define the implementation of the process. The curing temperature parameters were established along with a cure kinetic model to predict the cure behavior. In addition, the influence of the gelation and vitrification was also examined by rheological methods. No obvious vitrification appeared in the epoxy system and the apparent active energy of the cure reaction calculated by gel time was almost the same as the differential scanning calorimetry result. What is more, the viscoelastic properties of the composite reinforced by glass fiber matt was characterized through dynamic mechanical analysis, and it proved that post-cure was necessary to ensure complete cure and that the stiffness increased several magnitudes after glass fiber reinforcement.

Thermal Properties and Crystallite Morphology of Nylon 66 Modified with a Novel Biphenyl Aromatic Liquid Crystalline Epoxy Resin

In order to improve the thermal properties of important engineering plastics, a novel kind of liquid crystalline epoxy resin (LCER), 3,3′,5,5′-Tetramethylbiphenyl-4,4′-diyl bis(4-(oxiran-2-ylmethoxy)benzoate) (M1) was introduced to blend with nylon 66 (M2) at high temperature. The effects of M1 on chemical modification and crystallite morphology of M2 were investigated by rheometry, thermo gravimetric analysis (TGA), dynamic differential scanning calorimetry (DSC) and polarized optical microscopy (POM). TGA results showed that the initial decomposition temperature of M2 increased by about 8 °C by adding 7% wt M1, indicating the improvement of thermal stability. DSC results illustrated that the melting point of composites decreased by 12 °C compared to M2 as the content of M1 increased, showing the improvement of processing property. POM measurements confirmed that dimension of nylon-66 spherulites and crystallization region decreased because of the addition of liquid crystalline epoxy M1.

Mechano-Chemical Preparation and Application of Mulberry-Like CaCo3/SiO2 Composite Particles in Superhydrophobic Films

This study focuses on preparation of mulberry-like CaCO3/SiO2 composite particles with a mechanochemical method and their application in superhydrophobic films. Silicon dioxide nanoparticles were adhered to calcium carbonate microparticles to form mulberry-like composite particles through vigorous stirring, which prevented agglomeration of silicon dioxide nanoparticles and maintained their nanocharacteristics. Then, hexamethyldisilazane was employed for hydrophobic modification of the mulberry-like CaCO3/SiO2 composite particles. The effect of CaCO3/SiO2 mass ratios, stirring speed, reaction temperature, and amount of modifying reagent on morphology and lipophilicity of composite particles was studied. Moreover, the superhydrophobic films with excellent film properties were obtained by through combination of mulberry-like CaCO3/SiO2 hydrophobic composite particles and RTV silicon rubber. The water contact angle and sliding angle of the superhydrophobic surface were measured to be 170 ± 2.5° and 4°, respectively. This approach proves to be ideal for substantial improvement of the self-cleaning property of RTV silicon rubber anti-pollution flashover coating.

Preparation and Characterization of Soap-free Cationic Fluorinated Poly-styrene-acrylate Latex with Core-shell Structure

Soap-free cationic fluorinated Poly-styrene-acrylate latex particles with core-shell structure were synthesized by seeded semi-continues emulsion polymerization in the presence of water soluble cationic monomer Methacryloxyethyltrimethyl ammonium chloride (MADAC) and using ethanol as co-solvent. The effects of MADAC dosage and ethanol content on the stability of polymerization process and the properties of the latex particles were studied. The chemical component of the polymer was analyzed by Fourier transform infrared (FTIR). The surface element composition of the prepared copolymer film was analyzed by X-ray photoelectron spectroscopy (XPS), the micro-structure of the prepared latex particles were observed by transmission electron microscopy (TEM). The result shows that cationic soap-free fluorinated poly-styrene-acrylate emulsion with a core-shell structure can be prepared when monomer DAMAC is 6.0 wt% and ethanol is 7.5 wt%.

Preparation, characterization, and properties of novel bisphenol-A type novolac epoxy-polyurethane polymer with high thermal stability

In this study a series of modified bisphenol-A type novolac epoxy resins (MNEPs) were synthesized from bisphenol-A type novolac epoxy resin (NEP) and propionic acid (PA) by a one-step ring-opening reaction process in the presence of tetramethylammonium bromide as catalyst. Fourier transform infrared and 1 H-NMR were employed to confirm the chemical structures of the MNEPs. The spectra results indicated that MNEPs with different hydroxyl contents were obtained successfully by different ring-opening rates of NEP. In addition, Intercross-linked epoxy-polyurethane composites (MNEP-PUs) were also obtained by curing reaction among MNEP, cross linker polyisocyanate IL1351 and phthalic anhydride(PHA). The thermal stability of MNEP-PUs and the conventional polyol PU A450/IL1351 were determined and compared. The thermal analysis demonstrated that the obtained MNEP-PUs exhibited much better thermal stability than the conventional polyurethane system A450/IL1351, and the thermal stability of MNEP-PUs was correlated to the content of MNEP. Moreover, physico-chemical properties of MNEP-PUs such as pencil hardness, adhesive attraction, solvent resistance were reported. It demonstrated that incorporating MNEP into MNEP-PUs as inherent hardness of MNEP-PUs could greatly improve pencil hardness, adhesive attraction, water, acid and alkali resistance of MNEP-PUs.

Surface modification of light hollow polymer microspheres and its application in external wall thermal insulation coatings

Purpose – The purpose of this paper is to modify light hollow polymer microsphere (LHPM) with titanium dioxide nanoparticles (nano-TiO2) to improve its compatibility with latex and apply the obtained nano-TiO2/LHPM composite particles in external wall thermal insulation coatings. Design/methodology/approach – The nano-TiO2/LHPM composite particles were prepared via vigorous stirring. The morphology and chemical composition of the produced nano-TiO2/LHPM composite particles were characterized using scanning electron microscopy, energy dispersion spectrum, thermo-gravimetric analyzer and Fourier transform infrared. The performance of this new composite coating was evaluated by checking its stability, density, radiation reflectivity, thermal conductivity and the resulting insulation temperature difference when forming coating film. Findings – It was found that a 9:1 mass ratio of nano-TiO2/LHPM with total 10 weight per cent composite particles in the thermal insulation paint showed low density, good stabilit...

Preparation and characterisation of aluminium pigments encapsulated by composite layer containing organic silane acrylate resin and SiO2

Purpose – The purpose of this paper is to enhance the anticorrosion property of aluminium pigments and to improve their compatibility with polymers in coating.Design/methodology/approach – Aluminium pigments encapsulated by organic‐inorganic layer were prepared by hydrolysis and condensation of organic silane acrylate resin and tetraethoxy silane (TEOS) on the surface of pigments via sol‐gel method. TEOS and poly (methyl methacryalte‐n‐butyl acrylate‐vinyl triethoxysilane) (PMBV) formed in advance by co‐polymerisation of methyl methacrylate (MMA), n‐butyl acrylate (BA) and vinyl triethoxysilane (VTES) were used as precursors. The adhesion property of the aluminium pigments was measured by peel test, and the loss of silvery appearance after encapsulation and acid soaking were both evaluated by colour lightness difference (ΔL) measurement. The encapsulated aluminium pigments were further characterised by means of FTIR, SEM, TG and XPS.Findings – It was found that PMBV‐SiO2 thin films could be formed on the ...

Preparation and Characterization of Superhydrophobic/Superoleophilic SiO2 Film

Superhydrophobic/superoleophilic SiO2 surface was fabricated through a simple sol-gel process and post-treatment by DTMS. The chemical components and morphology of SiO2 particles, surface morphology and wetting behavior of SiO2 film were characterized by FTIR, TEM, SEM, and water/oil contact angle. The results show that the first prepared highly dispersed SiO2 particles by sol-gel method turn into nano-micro-binary structure SiO2 particles duo to gel effect during aging process, the morphology of SiO2 particles could keep stable by modifying the nano-micro-binary structure SiO2 with DTMS. Superhydrophobic/superoleophilic property of SiO2 film is duo to the nano-micro-binary structure SiO2 particles and hydrophobic/oleophilic nature of ‒CH3 groups.