Preparation of Poly(<Emphasis Type="Italic">o</Emphasis>-toluidine)/Nano Zirconium Dioxide (ZrO<Subscript>2</Subscript>)/Epoxy Composite Coating and Its Corrosion Resistance

Conducting polymers represent a promising application prospect in the field of metal corrosion control. In this investigation, poly(o-toluidine) (POT)/nano zirconium dioxide (ZrO₂) composite were prepared by in situ polymerization of o-toluidine monomer in the presence of nano ZrO₂ particles. Fourier transformation infrared spectroscopy, UV–visible spectroscopy, X-ray diffraction and Scanning electron microscopy were used to characterize the composition and the structure of the composite. POT/nano ZrO₂ composite was mixed with epoxy resin (EP) through a solution blending method and the three components POT/nano ZrO₂/epoxy composite coating was coated onto the surface of steel coupon, and its corrosion protective efficiency was studied by electrochemical measurements and immersion test in 3.5 % NaCl solution as corrosion environment and also compared with that of POT/epoxy composite coated steel, polyaniline (PANI)/epoxy composite coated steel and pure epoxy coated steel. According to the results, POT/nano ZrO₂/epoxy composite coated steel has got higher corrosion resistance than that of POT/epoxy composite coated steel and PANI/epoxy composite coated steel. It was found that POT powders dispersed in the epoxy and polyamide system improved the barrier and electrochemical protection properties of epoxy coating and the addition of nano ZrO₂ particles increased the tortuosity of the diffusion pathway of corrosion substances.     

Effect of nano‐SiO2 on granule characteristic and fusion process of Poly(vinyl chloride‐co‐vinyl acetate)/nano‐SiO2 composite resin

Poly(vinyl chloride‐co‐vinyl acetate) (PVVA)/nano‐SiO₂ composite resin was prepared by radical suspension polymerization of the monomers in the presence of fumed nano‐SiO₂ particles premodified with γ‐methylacryloxypropyl trimethoxysilane. The cool dioctyl phthalate absorption percentage, granule porosity, and specific surface area of the composite resin were enhanced through incorporation of nano‐SiO₂ into the PVVA. Scanning electron microscope pictures showed the resin had higher porosity. PVVA/nano‐SiO₂ composite resin was mixed with pure PVC resin to form a mixture sample (polymer‐composite blend [PCB]) and the mixture was fused in the torque rheometer. The rheological test results indicated that, at a certain nano‐SiO₂ content, the fusion speed of PCB was accelerated and the fusion temperature of PCB was decreased, owing to nano‐SiO₂ dispersed evenly in the polymer matrix. When excessive nano‐SiO₂ was loaded, the fusion torque, the fusion time, and the fusion temperature of PCB were all increased. These properties are correlative to the dispersive density of nano‐SiO₂ in the polymer matrix. This study also demonstrated that the introduction of small amounts of nano‐SiO₂ into the resin increased the impact strength and tensile strength of PCB simultaneously. J. VINYL ADDIT. TECHNOL., 20:230–236, 2014. © 2014 Society of Plastics Engineers     

Multilayered polypyrrole–SiO2 composite coatings for functionalization of stainless steel: Characterization and corrosion protection behavior

Two different multilayered composite polypyrrole/SiO₂ coatings were synthesized on 304 stainless steel. Electrochemical and electrophoretic depositions were used to grow polypyrrole and SiO₂ layers, respectively. Coatings were characterized by glow discharge optical emission spectroscopy to observe repartition of elements within different layers, by scanning electron microscopy to observe surface morphology and by electrochemistry to investigate corrosion protection behavior. The electrophoretic approach enables good incorporation of SiO₂ particles. This incorporation was more extensive and more homogeneous than for coatings obtained with the mixing method related in previous works. Moreover, incorporation and repartition of SiO₂ particles are greatly enhanced when the silica layer is grown directly on the steel surface. Corrosion protection of the stainless steel substrate was improved when multilayered composite polypyrrole/SiO₂ coatings were used.     

Nano‐SiO2/PMMA‐PU composite particles with core‐shell structure via emulsion polymerization and their application in epoxy resin

A novel method of nano‐SiO₂/poly(methyl methacrylate)(PMMA)‐polyurethane(PU) composite particles modifying epoxy resin is reported. The composite particles with the obvious core‐shell structure were prepared by emulsion polymerization of PMMA and PU prepolymer on the surface of nano‐SiO₂. The diameter of the composite particles was 50–100 nm with dark core SiO₂ (30–60 nm) and light shell polymer of PMMA and PU (20–30 nm); moreover, PU was well distributed in PMMA with about 10 nm diameter. After nano‐SiO₂ was encapsulated by PMMA and PU, the Si content on the surface decreased rapidly to 2.08% and the N content introduced by PU was about 1.27%. The ratio of polymer to original nano‐SiO₂ (f_p), the grafting ratio of polymer to original nano‐SiO₂ (f_r) and the efficiency grafting ratio of polymer (f_e) were, respectively, about 116.7%, 104.4%, and 89.5%. The as‐prepared composite particles were an effective toughness agent to modify epoxy resin, and the impact strength of the modified epoxy resin increased to 46.64 kJ m^?2 from 19.12 kJ m^?2 of the neat epoxy resin. This research may enrich the field of inorganic nanoparticles with important advances toward the modification for polymer composite materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41919.     

A novel method of hyperbranched poly(amide‐ester) modifying nano‐SiO2 and study of mechanical properties of PVC/nano‐SiO2 composites

A new method of surface chemical modification of nano‐SiO₂ was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano‐SiO₂ reacted with AB₂‐type monomer (N,N‐dihydroxyethyl‐3‐amino methyl propionate) by one‐step polycondensation. And the product's Fourier transform infrared graphs and transmission electron microscopy (TEM) images proved that hyperbranched poly(amine‐ester) (HPAE) was grafted from nano‐SiO₂ surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano‐SiO₂ composites were made by melt‐blending. The composites' structures and mechanical properties were characterized by TEM, scanning electron microscopy, and electronic universal testing machine. The results showed that nano‐SiO₂ grafted by HPAE increased obviously in dispersion in PVC matrix, and mechanical properties of PVC were effectively improved. Additionally, it was found that mechanical properties of PVC/nano‐SiO₂ composites reached the best when weight percent of nano‐SiO₂ in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano‐SiO₂/PVC composite increased by 24.68% and its break elongation, flexural strength, and impact strength increased by 15.73, 4.07, and 184.84%, respectively. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Effect of nano‐silica on the mechanical,thermal, and crystalline properties of poly(vinyl alcohol)/nano‐silica films

Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO₂) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO₂ films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO₂ were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO₂ and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO₂ decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO₂ content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO₂ loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Water‐dispersible conducting polyaniline/nano‐SiO2 composites without any stabilizer

A water‐dispersible conducting polyaniline/ nano‐SiO₂ composite, with a conductivity of 0.071 S cm^?1 at 25°C, was prepared by the oxidative polymerization of aniline in the presence of amorphous nano‐SiO₂ particles. And the structure, morphology, thermal stability, conductivity, and electroactivity of this composite were also investigated. This composite has been steadily dispersed in the aqueous solution for about 10–36 h without the need for any stabilizer. It would significantly impulse the commercial applications of conducting polyaniline/nano‐SiO₂ composite as fillers for antistatic and anticorrosion coatings. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Performance of EP/PpPDA and EP/PpPDA/SiO2 nanocomposite on corrosion inhibition of steel in hydrochloric acid solution

Epoxy-poly p-phenylendiamine (EP/PpPDA) and its nanocomposite with SiO₂ nanoparticles (EP/PpPDA/SiO₂) were synthesized and tested as potential corrosion inhibitors of steel in 1 M HCl solution. Performance of EP/PpPDA/SiO₂ and EP/PpPDA coatings on protection of steel against corrosion was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Atomic force microscopy (AFM) and at various temperatures between 298 and 328 K. Changes in the coating resistance and charge-transfer resistance with temperature were analyzed to determine the activation energies of the processes involved. The determined values of activation energy showed that the EP/PpPDA/SiO₂ coating has better anti-corrosion effect than EP/PpPDA. The thermodynamic functions of dissolution processes were also calculated and discussed. The results from AFM observations indicated that the presence of SiO₂ nanoparticles increased the roughness of Epoxy-poly p-phenylendiamine/SiO₂ nanocomposite (EP/PpPDA/SiO₂). It was finally concluded that the presence of silica nanoparticles enhance the protection properties of EP/PpPDA coating as a novel potential corrosion inhibitor for steel.     

Effects of nanosilica on retrogradation properties and structures of thermoplastic cassava starch

Composites of thermoplastic cassava starch (TPS) and nanosilica (SiO₂) were prepared by the melting method. The effect of nano‐SiO₂ on the retrogradation properties and structures of cassava starch was investigated. The retrogradation degree of TPS/nano‐SiO₂ composites increased with increasing retrogradation time. The retrogradation rate of TPS significantly increased after the addition of nano‐SiO₂, but excessive nano‐SiO₂ content leads to a decrease in the retrogradation rate of TPS. According to the Fourier transform infrared spectroscopy results, the retrogradation degree of TPS/nano‐SiO₂ composites increased with the increase of retrogradation time and addition of nano‐SiO₂. Scanning electron microscopy analysis indicated that nano‐SiO₂ particles were uniformly and finely dispersed in the starch materials, but the nano‐SiO₂ particles aggregated in the cassava starch with a further increase in nano‐SiO₂ content. X‐ray diffraction revealed that the crystalline structure of the starch was gradually altered from A‐type to V‐type with the increase of retrogradation time. TPS/SiO₂ composites indicated a mixture of A+V types, and the intensity of the V‐type strengthened with the increase of retrogradation time and SiO₂ content. Polarized light microscopy analysis revealed clear Maltese cross patterns, and the number of spherulites in TPS/nano‐SiO₂ composites increased with increasing retrogradation time and nano‐SiO₂ content, but the retrogradation of starch was inhibited with further increases of nano‐SiO₂ content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45687.     

Designing of corrosion resistant epoxy coatings embedded with polypyrrole/SiO2 composite

Polypyrrole/SiO₂ composite was synthesized by chemical oxidative polymerization of pyrrole using FeCl₃. The synthesized polymer composite was loaded in epoxy resin to develop coatings for mild steel substrates using powder coating technique. SEM and TEM images reveal homogenous dispersion of SiO₂ particles in polypyrrole matrix. TGA analysis confirms good thermal stability of the polymer composite. Tafel polarization and electrochemical impedance spectroscopy (EIS) results exhibit remarkably high corrosion protection efficiency of epoxy coatings with polymer composite in 3.5% NaCl solution. Corrosion studies of coatings with an artificial defect reveal the passivation of defect by the polymer composite present in the epoxy coatings. Salt spray test results revealed superior corrosion resistance offered by the polymer composite.     

Effect of nanosilica on the thermal,mechanical, and dielectric properties of polyarylene ether nitriles terminated with phthalonitrile

Nanosilica/polyarylene ether nitriles terminated with phthalonitrile (SiO₂/PEN‐t‐Ph) composites were prepared by hot‐press approach. To ensure the nano‐SiO₂ can disperse uniformly, the solution casting method combined with ultrasonic dispersion technology had been taken previously. The mass fraction of nano‐SiO₂ particles was varied to investigate their effect on the thermal, mechanical, and dielectric properties of the nanocomposites. From scanning electron microscope images, it was found that the nanoSiO₂ particles were dispersed uniformly in the PEN‐t‐Ph matrix when the addition of nano‐SiO₂ was less than 16.0 wt%. However, when the mass fraction of nano‐SiO₂ increased to 20.0 wt%, the nano‐SiO₂ particles tend to self‐aggregate and form microns sized particles. Thermal studies revealed that nano‐SiO₂ particles did not weaken the thermal stabilities of the PEN‐t‐Ph matrix. Mechanical investigation manifested that the SiO₂/PEN‐t‐Ph nanocomposites with 12.0 wt% nano‐SiO₂ loading showed the best mechanical performance with tensile strength of 108.2 MPa and tensile modulus of 2107.5 Mpa, increasing by 14% and 19%, respectively as compared with the pure PEN‐t‐Ph film. Dielectric measurement showed that the dielectric constant increased from 3.70 to 4.15 when the nano‐SiO₂ particles varied from 0.0 to 20.0 wt% at 1 kHz. Therefore, such composite was a good candidate for high performance materials at elevated temperature environment. POLYM. COMPOS., 35:344–350, 2014. © 2013 Society of Plastics Engineers     

Preparation and performance of nano‐SiO2 stabilized Pickering emulsion type sizing agent for glass fiber

The nano‐SiO₂ particles modified by silane coupling agent A‐1100 were used for preparing the vinyl ester resin (VE) Pickering emulsion. The stable emulsion could be served as the film former of sizing agent for glass fiber (GF). The influence of the wettability and the addition amount of nano‐SiO₂ on the stability of film former emulsion was explored. The effect of nano‐SiO₂ Pickering emulsion type sizing agent on the properties of GF was investigated. SEM images show that there existed a layer of sizing agent film with nano‐SiO₂ particles evenly on the GF surface. The abrasion resistance of the sized GF reached 3,579 times and the stiffness was 69 mm. The strand integrity also performed well. The fracture strength of GF bundles treated by Pickering emulsion type sizing agent increased by 28.6% to 0.504 N/Tex compared with that of the unsized GF bundles. The interlaminar shear strength (ILSS) of GF/VE composites sized by self‐made sizing agent which contained nano‐SiO₂ has improved, compared to the unsized GF reinforced VE composite. POLYM. COMPOS., 37:334–341, 2016. © 2014 Society of Plastics Engineers     

Preparation of a novel vitrified bond CBN grinding wheel and study on the grinding performance

The vitrified bond CBN grinding wheels are characterized by high efficiency, high precision, and low environmental pollution. In recent years, the vitrified bond CBN grinding wheel has been widely used in manufacturing industries such as aerospace, automotive, and machine tools. In this study, a novel vitrified bond formulation containing nano SiO₂ and nano CeO₂ is selected to prepare the grinding wheel. The grinding experiments on 45# steel and YG20 alloy indicate that the grinding performance of the nano vitrified bond grinding wheel is significantly better than that of the conventional vitrified bond grinding wheel. The introduction of nano SiO₂ and nano CeO₂ greatly improves the machining performance of the vitrified bond CBN grinding wheel.     

Preparation of styrene‐acrylic emulsion by using nano‐SiO2 as seeds

A styrene‐acrylic/SiO₂ nanoparticle composite emulsion was prepared by using SiO₂ nanoparticles as seeds. The effect of factors such as the level of nano‐SiO₂, reaction temperature and ultrasound treatment of nano‐SiO₂ on the stability of the polymerization reaction was investigated. Water‐resistance of the emulsion was measured. The level of nano‐SiO₂ in the emulsion was determined by inductively coupled plasma (ICP) spectrometry. The particle morphology of the emulsion with nano‐SiO₂ was observed with transmission electron microscopy (TEM). The kinetics of the polymerization was also studied at various temperatures and various levels of nano‐SiO₂. They showed that the level of nano‐SiO₂ and reaction temperature had a great influence on the monomer conversion, particle size, coagulum content and viscosity of the emulsion. Nano‐SiO₂ treated by ultrasonics can increase the coagulum content greatly, but it does not improve the water resistance of the emulsion. The level of nano‐SiO₂ in the emulsion was lower than the theoretical value. The reaction kinetics indicated that the level of nano‐SiO₂ had less influence on the reaction rate than the reaction temperature. Even a small amount of nano‐SiO₂ can decrease the reaction rate. Copyright © 2004 Society of Chemical Industry     

Boric acid incorporated on the surface of reactive nanosilica providing a nano‐crosslinker with potential in guar gum fracturing fluid

Small molecule borate crosslinker widely used in hydraulic fracturing treatment has a low crosslinking efficiency of less than 1%. Thus boric acid was introduced onto the surface of reactive nanosilica (denoted as nano‐SiO₂; size: about 20 nm) containing ? NH₂ group to obtain a nanosilica‐based crosslinker (denoted as nano‐crosslinker) with increased crosslinking efficiency, thereby broadening the application of nano‐SiO₂ in guar gum fracturing fluid. Moreover, the influence of the as‐prepared nano‐crosslinker on the rheological behavior of guar gum gel was investigated with borate crosslinker as a reference. Results show that boric acid chemically reacts with the amino group of the reactive nano‐SiO₂ to form N? B bond, which is beneficial to the formation of the network structure of guar gum gel. The guar gum gel crosslinked with the 57 ppm of borate based on the carrier of nano‐SiO₂ exhibits better temperature tolerance and shear resistance as well as breaking behavior than the counterpart crosslinked with 200 ppm of borate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45037.     

Effect of the mixing sequence on the morphology and properties of a polypropylene/polydimethylsiloxane/nano‐SiO2 ternary composite

Ternary composites of polypropylene (PP), polydimethylsiloxane (PDMS) elastomer, and nano‐SiO₂, prepared with three different mixing sequences, were studied for dispersion morphology and its effect on the crystallization of PP and the mechanical properties. The mixing sequence produced a significant effect on the dispersion morphology and, thereby, on the mechanical properties of the composites. A two‐step mixing sequence, in which nano‐SiO₂ was added in the second step to the PP/PDMS binary system, produced a significant encapsulation of nano‐SiO₂ by PDMS, and this, in turn, resulted in the poor modulus and impact strength of the composite. A one‐step mixing sequence of all three components produced a separated dispersion of PDMS and nano‐SiO₂ phases in the PP matrix with the occurrence of a fine band of nano‐SiO₂ particles at the boundaries of the PDMS domains and the presence of some nano‐SiO₂ filler particles inside the PDMS domains. This one‐step mixing sequence produced an improvement in the tensile modulus but a decrease in the impact strength with increasing nano‐SiO₂ content. In the third sequence of mixing, which involved a two‐step mixing sequence through the addition of PDMS in the second step to the previously prepared PP/nano‐SiO₂ binary system, the morphology of the dispersion showed separately dispersed PDMS and nano‐SiO₂ phases with a loose network of nano‐SiO₂ particles surrounding the PDMS domains. This latter series of ternary composites had the highest impact strength and exhibited high shear deformation under tensile and impact conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study of the effect of mechanically treated CeO2 and SiO2 pigments on the corrosion protection of painted galvanized steel

The effectiveness of mechanically treated CeO₂ particles and SiO₂ particles as active fillers into an organic coating was investigated. For this purpose, different combinations of CeO₂ and SiO₂ particles were added to an epoxy-polyester polymeric matrix: mechanically treated CeO₂ particles, mechanically treated CeO₂/SiO₂ particles and mechanically treated SiO₂ powders (used for comparison). The particles were dispersed into the polymeric matrix and HDG steel panels were coated with the different paints. A strontium chromates containing paint was used as a reference to compare the performances of the other samples. The salt spray results proved the good performance of coatings containing combinations of ceria and silica especially where these had been mechanically treated in a co-milling operation. The paint containing only the mechanically treated SiO₂ particles showed a fairly good resistance in the salt spray chamber considering the scratched samples. The EIS measurements evidenced the good corrosion protection properties of the paints containing the different combinations of mechanically treated CeO₂ and SiO₂ particles. After about 1000 h of immersion in 0.1 M NaCl solution, the samples containing the mix of mechanically treated CeO₂/SiO₂ particles showed impedance values which were comparable with the chromate control sample. The cathodic polarization tests evidenced the low extent of detachment of the coating containing the mix of mechanically treated CeO₂/SiO₂ particles. The electrochemical characterization and neutral salt spray test results proved the effectiveness of the mechanical treated cerium (IV) oxides treated together with SiO₂ as active pigments to improve the corrosion protection of the substrate. The reasons for the synergistic effect of the milled (together or separately) SiO₂ and CeO₂ particles was not clear at all, but a few hypothesis were discussed.     

Study of surface‐functionalized nano‐SiO2/polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO₂/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano‐SiO₂ particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO₂‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO₂‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO₂. At the same load of nano‐SiO₂, the nano‐SiO₂‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO₂/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO₂ content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO₂. The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

4D printing of polyurethane paint-based composites

ABSTRACT

In recent studies, polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing. In this study, we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose (CMC) and silicon oxide (SiO₂) nanoparticles to the paint. The first function of CMC and SiO₂ is to improve rheological properties of the polyurethane paint for making a printable precursor, which improves the printing resolution and enhances additive manufacturability. Second, the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties. Third, the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane. Finally, the 3D printed polyurethane-CMC and SiO₂ parts exhibit time-resolved shape transformation upon heat stimulation. To the best of our knowledge, this is the first study of using the polyurethane paint as the precursor for 4D printing, which would open new possibilities in future applications in biomedical engineering, soft robotics and so on.     

Influence of natural inhibitor,pigment and extender on corrosion of polymer coated steel

Lupine (Lupinous albus L.) seeds extract was incorporated into a vinyl chloride–vinyl acetate copolymer based paint formulation to control steel corrosion in 0.5 M NaCl. Evaluation of this system included the use of electrochemical impedance spectroscopy (EIS) and a salt spray cabinet for accelerated aging tests. The EIS data demonstrated that highest protection was attained at a lupine threshold concentration of 0.025 g/L. Two white color pigments (ZnO and TiO₂) and three extenders (CaCO₃, mica and talc) were tested as paint additives. The accelerated aging tests showed that the coated steel panels containing TiO₂ had a high degree of blistering while those containing ZnO exhibited reasonable hiding power and better protection efficiency. Field tests indicated that the presence of TiO₂ enhanced the growth of fouling organisms over the coated steel surface.