Zhuo Ru Yang

Preparation and Performance of RTV Coating for Anti-Pollution Flashover with Superhydrophobicity by Filling CaCO3/SiO2 Composite Particles into Silicone Rubber

Room temperature vulcanizing (RTV) silicone rubber coating with superhydrophobicity for anti-pollution flashover is prepared by filling silica-encapsulated calcium carbonate particles (CaCO3/SiO2 composite particles) into polydimethylsiloxane (PDMS) rubber. Two-step spraying technology is applied for fabricating the superhydrophobic RTV coating film on outdoor insulators. The primary spray coating provides basically the strong adhesion and certain hydrophobicity, and the second one produces the appropriate roughness structure and further enhances the superhydrophobicity. The water contact angle on the prepared RTV coating film is 165°and the sliding (rolling) angle of water droplet is about 5°, allowing water droplets to move easily on the coating surface and give self-cleaning function of the RTV coated insulator surface. The flashover voltage of insulators with superhydrophobic RTV coating is 29.95 kV, quite higher than that of insulators with common RTV coating (23.29) and that without RTV coating (11.34 kV).

Mechanical Properties of Oil Filter Paper Impregnated by a Novel Waterborne Novolac Epoxy Emulsion

A novel cationic waterborne epoxy emulsion for oil filter paper was synthesized. Hydrophilic groups were introduced into a multifunctional bisphenol-A novolac epoxy resin (NEP) by chemical modification, while maintaining the epoxy groups as many as possible, which were neutralized to form the equably water dispersed epoxy resin. The structure of modified NEP in different rate of ring-opening was characterized by Fourier Transform Infrared Spectroscopy (FTIR). The emulsion particle dispersion and micromorphology of waterborne bisphenol-A novolac epoxy resin (WNEP) was detected by granularity measured instrument and TEM. Mechanical properties and microstructure of oil filter papers impregnated by five different waterborne epoxy emulsions were tested and observed by SEM. From the results it can be shown that oil filter paper impregnated by WNEP emulsion has comprehensive properties better than other four commercialized products, exhibiting the best air permeability and improved bursting strength15% higher than that impregnated by poly-styrene-acrylate (PSA) latex.

Processing Science of Isotactic Polypropylene Fiber Reinforced with Halloysite Nanotubes Based on Masterbatch Dilution Technique

The properties of nanocomposites can be improved significantly by the addition of nanoparticles into polymer. Nanocomposites of isotactic polypropylene (iPP) and Halloysite Nanotubes (HNT) at 100/0 and 99.2/0.8 weight ratios were prepared in a co-rotating twin screw extruder using masterbatch dilution technique. IPP/HNT fibers were obtained in a single-screw extruder with extrusion temperature of 231°C, screw speed of 1.38 rpm and 0.6mm diameter die L/D of 6. The effect of processing variables, such as pick-up speed (0.05m/s, 0.15m/s and 0.45m/s), horizontal distance (0, 0.5m and 1m),and annealing (120°C), were investigated. The air cooling time was crucial for fiber processing and exhibited a linkage with crystal morphology, degree of crystallinity as well as the mechanical performance of the fiber. More importantly, the incorporation of HNT into isotactic polypropylene reduced the deficiencies of the annealing process on the toughness and elongation at break of the pure polypropylene fibers, and significantly enhanced the tensile strength of the fiber.

Preparation of Raspberry-Like Polymer/Silica Composite Particles through Cationic Soap-Free Emulsion Polymerization

In this paper raspberry-like composite particles were prepared via cationic soap-free emulsion polymerization with silica sol as stabilizer and 2-(methacryloyl) ethyltrimethylammonium chloride (MTC) as cationic auxiliary monomer. According to the TGA and TEM results we could find that the electrostatic attraction supplied by MTC played a vital role in the adsorption of silica particles as well as the generation of raspberry-like morphology. The silica content and appearance of composite particles were found to be improved with the increasing amount of silica sol and MTC while varied little with changes of AIBA amount.

An Experimental Study on Relationship between (Meth)Acrylate Polymers Structure and its Film Surface Wettability

The relationships between (meth)acrylate polymers structure and its film surface wettability were analyzed. A series of random (meth)acrylate polymers were prepared by the free radical solution polymerization and their coating film wettability was analyzed by measuring water contact angles(CAs). There are three kinds of functional groups on the surface, including methyl, ethyl and ester group, and the surface energy of ester group is greater than the others. The more ester group on the surface will result in the better surface hydrophilicity. Polymer structure parameters as the side chain length(m) and glass temperature(Tg) are taken into account in discussing the migration of functional group to the outermost surface. It was found that the less m and lower Tg will promote the motion of the side chain and hence cause the surface exhibiting more hydrophilicity.

Fabrication and Performances of Titanium-Grafted Microencapsulated Phase Change Materials

Nanocomposite microspheres were successfully prepared by grafting TiO2 particles to microPCMs by chemical reaction method. The effects of modification of nano TiO2 particles, adding time of TiO2 dispersion and the amount of TiO2 on the surface morphology were investigated. The results indicated that the optional method is adding the TiO2 dispersion as soon as all the prepolymer was added to the reaction system, and the optional mass ratio of TiO2 to microPCMS is 10wt%.

Comparison and Thermodynamic Analysis of Crystallinity of Noncrosslinking and Crosslinking Fluorinated Acrylate Copolymers Films

In this manuscript two different fluorinated acrylate copolymers films, one was non-crosslinking Stearyl acrylate/2-(perfluorooctyl) ethyl methacrylate (SA/FOEMA) and another was cross-linked SA/2-hydroxyethyl methacrylate(HEMA)/FOEMA/hexamethylene diisocyanate trimers (N3300), were prepared and their crystallinities were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It can be shown from the XRD results that the value of crystallinities of SA/FOEMA and SA/HEMA/FOEMA/N3300 copolymer were 80.95% and 84.02%, respectively. Based on DSC curves and theoretical thermodynamic analysis , it is indicated that crosslinking can improve crystallinity of copolymer composed of SA and FOEMA.

Research of Aluminum Sheet Encapsulated by Organic Silane Acrylate Resin and Tetraethyl Orthosilicate

Aluminum sheet was encapsulated by inorganic-organic hybrid film through a base catalyzed sol-gel method using organic acrylate silane resin PMBV and TEOS as precursors. FTIR and AFM characterizations prove that PMBV and TEOS have hydrolyzed and co-condensed with each other in the sol-gel process to form an uniform film on the surface of aluminum sheet. XPS result shows hydroxyl groups on aluminum surface have taken part in the co-condensation reaction.

Novel Thermally Stable Epoxy-polyurethane Composites: Preparation, Characterization

A novel series of hydroxyl terminated bisphenol-A type novolac epoxy resins modified with propionic acid (MEP) were prepared by one-step ring-opening reaction process in the presence of tetramethylammonium bromide catalyst. The obtained MEP was characterized using FTIR, 1HNMR analyses. In addition, Intercross-linked epoxy-polyurethane composites networks were also obtained by curing reaction among MEP, cross linker polyisocyanate IL1351 and phthalic anhydride. The thermal characteristics of the epoxy-polyurethane composites were determined by thermogravimetric analysis (TGA). The thermal stability of the cured MEP with different ring-opening rate and cured alkyd polyol A450 were compared. The results showed that the obtained epoxy-polyurethane composites had much better thermal stability than the conventional polyurethane system A450/IL1351, and the thermal stability of them was correlated to the content of MEP.

Liquid Flow in Rectangular Microchannels with Gradient Wettability Inner Surface Driven by Capillary Force and Gravity

A mathematical model for predicting liquid flow velocity in a rectangular microchannel driven by capillary force and gravity is derived. The model takes into account the additional driving force arising from the wettability gradient on inner surface of a microchannel. The results of model prediction show that the velocity of liquid flow decreases with the length of microchannel and the wettability gradient on channel surface will accelerate the motion of the liquid when the flow-front approaches to the end of the microchannel. The analysis of driving force along the moving path matches well with the flow velocity predicted by the model.