Polyvinyl Butyral Coatings Research Articles

Corrosion resistance of polyvinyl butyral coatings enhanced by montmorillonite-chitosan composites

To improve the corrosion resistance of 304SS, a polyvinyl butyral/organic montmorillonite-chitosan (PVB/OMMT-Ch) composite coating was prepared by the spin coating method. The Montmorillonite was organically modified with Cetyltrimethylammonium Bromide and compounded with Chitosan to obtain OMMT-Ch. OMMT-Ch filler has been introduced into the polyvinyl butyral coating to improve the corrosion resistance of 304 stainless steel. Scanning electron microscope and transmission electron microscope observations showed that the introduction of chitosan made the montmorillonite layers rounded and loose, and the X-ray diffraction (XRD) results indicated that the interlayer spacing between the montmorillonite layers changed significantly, and the FT-IR results of the chitosan/montmorillonite insertion complexes were in good agreement with those of the XRD analyses, which showed that chitosan successfully inserted between the layers of montmorillonite. The corrosion resistance of the composite coatings in 3.5% NaCl solution was tested by Tafel polarization curves and electrochemical impedance spectroscopy. The results showed that the composite coatings doped with 0.5% OMMT-Ch had the best corrosion resistance with long-lasting protection of more than 160 days. This study suggests a novel approach for nanocomposites for dealing with the 304SS corrosion issue.

Efficiency of Anti-Corrosion Protective Coatings Based on Graphene Oxides Functionalised with Green Inhibitors

Mild steel (MS) is commonly used for infrastructure and machinery due to its various engineering properties and benefits, but they are highly prone to corrosion. For decades, organic polymeric coatings are widely applied to protect metallic systems against corrosion. Besides the physical barrier, the organic coatings have been manipulated by adding anti-corrosion pigments or corrosion inhibitors, such as red-lead or chromate to enhance protection. However, these conventional anticorrosive pigments have been substituted because of their toxicity and environmental problems. Recent studies have been consequently conducted to develop environmentally safe and green alternatives obtained from natural products.In the framework of this study, a novel green hybrid pigment nano-pigment based on graphene oxide (GO) and an organic natural inhibitor was prepared and included in a Polyvinyl Butyral (PVB) coating. The protective properties of PVB coatings without and with the addition of GO and f-GO on steel in 3.5wt% NaCl solution were studied by electrochemical methods.The new pigment functionalised GO (f-GO) is not only able to be an outstanding barrier, but it can also store a considerable amount of corrosion inhibitors and release them, when necessary, on the protective coating system. GO was functionalised with the green inhibitor in aqueous phase and the compound obtained was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA), ultraviolet-visible spectroscopy (UV-Vis) and atomic force microscopy (AFM).FT-IR and UV-Vis spectroscopy results indicated that the organic compound effectively reduced GO into f-GO and PVB/f-GO composite coatings showed 100 times higher anticorrosion resistance than PVB/GO and neat PVB. Figure 1

Effects of g-C3N4 on the corrosion protection performance of polyvinyl butyral coatings

Graphitic carbon nitride (g-C3N4) can function as nanofillers in anti-corrosion coatings due to its two-dimensional structure. Here, we investigate the corrosion protection performance of g-C3N4 for polyvinyl butyral (PVB) coatings. Transmission electron microscope (TEM) of the calcinated g-C3N4 displays a sheet-like nanostructure with a single or few layers. By subjecting PVB coatings containing g-C3N4 to electrochemical impedance spectroscopy (EIS) and salt spray tests, we were able to investigate their anti-corrosion performance thoroughly. Results of EIS shows that the values of coating resistance increased significantly for all PVB coatings enriched with g-C3N4 nanosheets. The PVB coating containing 10 wt% g-C3N4 nanosheets survived after a 300 h salt spray test. UV and Xenon lamp aging tests provide additional information and evidence to prove their potential in practical application.

Investigation of polyvinyl butyral coatings with carbon quantum dots on the characteristics of silicon solar cells

Investigation of polyvinyl butyral coatings with carbon quantum dots on the characteristics of silicon solar cells

A novel graphene/silica composite nanocontainer prepared by electrochemically assisted deposition

A novel electrochemically assisted deposition technique (EAT) was proposed to construct graphene-based nanocontainers that store corrosion inhibitors. EAT enables graphene (Gr, rather than graphene oxide, GO) to be used for the first time to fabricate composite nanocontainers. Silica films deposited on graphene nanosheets by EAT have high coverage, strong adherence and can be up to 60 nm thick. The resulting Gr/SiO2 nanocontainers were further modified by dodecyltrimethoxysilane (DTMS) to prepare superhydrophobic nanocontainers. The high-barrier graphene and hydrophobically modified SiO2 in Gr/SiO2/DTMS nanocontainers could synergistically resist corrosive mediums. The polyvinyl butyral coatings doped with Gr/SiO2/DTMS nanocontainers pre-loaded with inhibitors exhibited excellent protective properties.

Improvement of physical and thermal properties of polyvinyl butyral coating with nanosilica

In this paper, polyvinyl butyral (PVB) coatings with different nanosilica contents (0- 1.5 weight percent (wt%) were prepared for improving properties such as mechanical properties, corrosion protection, thermal oxidation stability of coating. Presence of nanosilica in coating was characterized by FT-IR. Corrosion resistance of PVB coatings containing nanosilica was investigated by salt mist testing. Effects of nanosilica on adhesion, flexural strength and relative hardness and thermal oxidation stability of PVB coatings were also examined. Nanosilica with content of 1.2 wt% significantly improved mechanical properties, corrosion resistance and thermal oxidation stability of PVB coatings.

Wrinkled p-phenylenediamine grafted graphene oxide as reinforcement for polyvinyl butyral anti-corrosive coating

Wrinkled p-phenylenediamine (PPD)-functionalized graphene oxide (PGO) is synthesized, characterized, and subsequently incorporated in a ethanol-based polyvinyl butyral (PVB) film (ca. 10 μm thick). The anti-corrosive properties of the pure PVB and nanocomposite (PVB-PGO and PVB-GO) films are tested on steel and compared. Electrochemical impedance spectra reveal that the PGO-reinforced PVB nanocomposite film exhibits the slowest corrosion rate (4 × 10−4 mm a−1 after a 20-day immersion) among the samples, and the results of 7-day saline spray bombardment tests show it is the most robust and durable. The PVB-PGO coating protects the steel substrate from visible corrosion. Incorporation of GO in the PVB matrix results in a reduction of the PVB film anti-corrosion properties. However, by functionalizing GO with PPD, highly dispersible wrinkled PGO flakes are obtained, thus leading to a uniform film that presents a highly tortuous path for impeding liquid and gas molecules. The PVB-PGO nanocomposite film exhibits high, stable capacitance without film delamination, cracking, or other visible damage. Readily accessible as a simple and environmentally friendly, this approach may present an advantageous strategy for creating protective coatings in marine and other applications. PGO with wrinkle structure, as nanometer reinforcing materials in PVB coatings, improved the corrosion resistance of the coatings by extending the permeation path of the corrosive medium.

Sandwich-like polyvinyl alcohol (PVA) grafted graphene: A solid-inhibitors container for long term self-healing coatings

Polyvinyl alcohol (PVA) grafted graphene was served as the container of solid inhibitors (cerium hydroxide). The graphene-PVA-Ce (rGPC) was embedded in polyvinyl butyral (PVB) coating and applied on mild steel. Artificial defects in the modified PVB coatings were produced. Electrochemical impedance spectroscopy (EIS) analysis was performed in 3.5 wt% NaCl solution at pH ~ 7 and pH ~ 4 respectively to study the corrosion-inhibition effect and long-term healing behavior of rGPC/PVB composite. From the results, the long-term healing properties of rGPC/PVB composite was confirmed. It is ascribed to the fact that the PVA-grafted graphene, with high encapsulating capacity and controllable release rate of inhibitors, provided a prolonged release of cerium inhibitor. The rGPC composite coating also has high impermeability and anti-corrosion performance. It is attributed to that rGPC has smaller size, better dispersion and stability than graphene-Ce when embedded in PVB coating.

A comparative study of nanoscale poly N-(vinyl) pyrrole in polyvinyl butyral coatings for the anti-corrosion property of zinc: Nanotubes vs nanoparticles

Poly N-(vinyl) pyrrole (PNVPY) nanotubes (NTs) and nanoparticles (NPs) were prepared via a UV-catalyzed green chemical oxidative method in the presence of cetyltrimethylammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP) as soft templates, respectively. The chemical structure of the PNVPY nanostructures was characterized by FTIR spectroscopy, UV–vis absorption spectra and 1H-NMR spectroscopy. The morphologies of PNVPY nanostructures were observed by the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was indicated that PNVPY NTs had an outer diameter less than 200 nm and a length in microscale. PNVPY NPs had an average diameter of 30 nm. Moreover, a series of anti-corrosion coatings on zinc were prepared by blending nanostructured PNVPY and carbon black with polyvinyl butyral (PVB) matrix to investigate the effect of the morphologies of PNVPY nanostructures on the corrosion protection ability. The surface and cross-sectional morphologies of the anti-corrosion coatings were observed by optical microscopy and SEM. Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed that PNVPY NPs with a larger surface area and a smaller scale yield a better anti-corrosion performance than PNVPY NTs in the coatings. The probable anti-corrosion mechanism of these anti-corrosion coatings was proposed.

Effect of Nano-SnS and Nano-MoS2 on the Corrosion Protection Performance of the Polyvinylbutyral and Zinc-Rich Polyvinylbutyral Coatings.

In this paper, four composite coatings of nano-SnS/polyvinylbutyral (PVB), nano-MoS2/PVB, nano-SnS-Zn/PVB, and nano-MoS2-Zn/PVB were prepared, and their anti-corrosion mechanism was analyzed by experimental and theoretical calculations. The results of the electrochemical experiments show that the effect of nano-MoS2 on the corrosion protection performance of PVB coating is better than that of nano-SnS in 3% NaCl solution, and that the addition of Zn further enhances this effect, which is consistent with the results of weight loss measurements. Furthermore, the observation of the corrosion matrix by the field emission scanning electron microscope (FESEM) further confirmed the above conclusion. At last, the molecular dynamics (MD) simulation were carried out to investigate the anti-corrosion mechanism of the nanofillers/PVB composites for the copper surface. The results show that both nano-SnS and nano-MoS2 are adsorbed strongly on the copper surface, and the binding energy of nano-MoS2 is larger than that of nano-SnS.

Influences of semiconductor oxide fillers on the corrosion behavior of metals under coatings

Semiconductor oxides are widely used as coating fillers, while few studies have focused on the interactions between semiconductor fillers and metal substrates. In this paper, common semiconductor fillers including TiO2, Fe2O3 and Cu2O were prepared and incorporated into polyvinyl butyral coatings. Localized EIS, EIS, SEM and electrochemical noise analysis were applied to study the corrosion behavior of semiconductor/metal contacts at coating defects. Results revealed that TiO2 and Fe2O3 accelerated the corrosion of metals, while Cu2O showed no promising effect. Meanwhile, a micro-galvanic corrosion mechanism based on work function difference and oxygen reduction reaction activity was proposed to explain the corrosion-promotion phenomenon.

Novel edible coatings to improve longevity of rodent baits

ABSTRACTRats and mice cause severe biodiversity impacts worldwide, including in New Zealand, where poisoning campaigns are undertaken on the mainland and offshore islands using cereal-based baits. However, bait stations are often irregularly serviced so wildlife managers require a bait that would remain palatable to rodents for at least 6 months in the field. One potential way to improve the field life of baits is by coating them in materials that reduce water uptake and subsequent mould growth. However, these coatings must be palatable to the rodents. This report investigates the palatability to captive Norway rats (Rattus norvegicus) and mice (Mus musculus) of both weathered and unweathered rodent food pellets coated with various polymer solutions. When compared with uncoated alternatives, fresh baits coated with shellac or polyvinyl butyral (PVB) in ethanol solvent were preferred by the rats. The use of acetone rather than ethanol solvent did not affect bait palatability. A combination of shellac and PVB reduced palatability compared with shellac alone. Weathered shellac-coated baits remained more palatable than uncoated fresh pellets to rats for up to 6 months and outperformed the PVB and combination coatings. Overall, the palatability of fresh-coated baits was lower for mice. The PVB-coated baits had lower mean palatability scores than the shellac-coated baits but none of the bait types was significantly less palatable than uncoated baits. The shellac-coated baits remained palatable to mice for up to 4 months. Shellac is recommended as a coating for multi-species rodent baits.

Synthesis of Silica/Polypyrrole Nanocomposites and Application in Corrosion Protection of Carbon Steel.

Silica/polypyrrole nanocomposites without dopant (SiO2/PPy) and with oxalate dopant (SiO2/PPyOx) were synthesized using polymerization of pyrrole in the presence of nano SiO2. Synthesized SiO2/PPy and SiO2/PPyOx were characterized by FTIR, SEM, TEM and EDX and their electrical conductivities were determined by CV method through the two-point-electrode without electrolyte. The corrosion protection performance of polyvinylbutyral (PVB) coatings containing SiO2/PPyOx was evaluated and compared with that of pure PVB coatings and of PVB coatings containing SiO2/PPy by electrochemical impedance spectroscopy and adhesion measurement. The results show that electrical conductivities of SiO2/PPy and SiO2/PPyOx were 0.181 and 0.109 S/cm, respectively. The ratio of PPy on SiO2 in SiO2/PPy and SiO2/PPyOx composites was 0.77/1 and the ratio of oxalate on PPy in SiO2/PPyOx composite was 1.24/1. SiO2/PPy and SiO2/PPyOx improved corrosion resistance and adhesion of PVB coatings. The presence of oxalate in SiO2/PPyOx significantly enhanced the effect of SiO2/PPy on the protection performance of PVB coatings.

Novel Corrosion Inhibitor Pigments Based on Benzotriazolium Cation Exchanged Resin

A novel corrosion-inhibitor pigment is described which is prepared by the reaction of benzotriazole (BTA) with a crosslinked polystyrene sulfonic acid resin (Amberlite 120H). This pigment is completely insoluble in water and may readily be ground to sub-micron particle size. The formation reaction relies on the resin sulfonic acid functions (pKa -2.8) being significantly more acidic than BTA (pKa 1.1) so that proton transfer produces the benzotriazolium cation ( BTAH+) in an exchangeable form. The kinetics of BTA uptake from aqueous solution at 60oC are followed spectrophotometrically. It is thus shown that uptake is rapid (complete in minutes) and results in a BTAH+ exchange capacity of 143 milli-equivalents per100g. The BTAH+ pigment is evaluated as a corrosion inhibitor by dispersion in an ethanolic solution of polyvinylbutyral (PVB) which is then coated onto the cleaned surface of zinc-coated (hot dip galvanized) steel to produce a dry film thickness of ca. 30 microns. The BTAH+ pigmented PVB coatings thus prepared had BTAH+ pigment volume fractions of between zero and 0.2. A corrosive electrolyte solution (5% w/w aqueous NaCl) was introduced into a penetrative defect in the organic coating and the subsequent process corrosion-driven cathodic coating disbondment was followed using a scanning Kelvin probe (SKP) instrument in a “Stratmann type”experiment at 96% R.H. The SKP data show that increasing BTAH+ pigment volume fraction produces two well defined effects. First the potential of the intact (undisbonded) coated surface becomes depressed by up to 0.3 V versus the unpigmented case. Second the kinetics of cathodic disbondment are profoundly inhibited, becoming immeasurably slow for pigment volume fractions greater than 0.1. These results are interpreted in terms of two phenomena. First the “etching” of the zinc surface by the acidic resin with a consequent release of Zn2+ cations and neutral BTA. Second the inhibition of underfilm cathodic O2 reduction(COR) by surface adsorbed BTA or BTA-zinc complex. The inhibition of COR by BTA in solution is systematically investigated using a zinc rotating disk electrode (RDE) in conjunction with potentiodynamic polarization. The polarization data show that, although BTA profoundly inhibits COR on zinc, BTA is actually a mixed inhibitor and inhibits both anodic zinc dissolution and the COR.

Self-healing Anticorrosion Coatings for Gas Pipelines and Storage Tanks

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica (<TEX>$SiO_2$</TEX>). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch_<TEX>$SiO_2$</TEX>_PVB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch_<TEX>$SiO_2$</TEX> coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB_Ch/Glu_PVB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

A Smart-Release Corrosion Inhibitor Pigment for Galvanised Steel Based on Salicylaldoxime-Loaded Hydrotalcite

Smart-release anticorrosion pigments are a promising alternative technology to traditional anticorrosive pigments such as sparingly soluble salts. Due to legislation prohibiting the use of chromium (VI) containing protective coatings, new environmentally friendly alternatives are required. Smart release pigments have numerous advantages over traditional pigment technologies. Sparingly soluble salts slowly leach out their constituent ions over time, which both reduces the lifetime of the coating and leads to environmental effects. In contrast, smart release pigments utilise ion-exchange properties to release inhibitor species on demand, whilst simultaneously sequestering corrosive species such as chloride ions. In this work intelligent release pigments based on anion-exchange hydrotalcite (HT) like materials were studied with respect to their efficiency in the inhibition of cathodic disbondment of a model coating. The ability of the various organic-anion loaded HT pigments to inhibit cathodic delamination of hot dip galvanised steel was evaluated using polyvinyl butyral (PVB) coatings containing a range of volume fractions of the inhibitive pigments. An in-situ Scanning Kelvin Probe (SKP) technique was used to measure the rate of delamination over time, by measuring time-dependent changes in free corrosion potential of the zinc surface under the organic coatings. Of the selection of organic anions evaluated, the most effective corrosion inhibitor was found to be salicylaldoxime, a well-known chelating reagent for various divalent metal cations. The slowing of cathodic delamination rates with increasing pigment volume fraction compared well with the performance of a hexavalent chromate-containing benchmark. To determine the importance of the release of salicylaldoxime from the coating into the electrolyte in contact with bare metal at a penetrative coating defect, experiments were also conducted using unpigmented PVB coatings in a situation where inhibitor additions were made to the initiating electrolyte. The conclusion of this investigation is that for the corrosion protection of galvanised steel surfaces, salicylaldoxime-loaded HT intelligent-release pigments represent effective, yet environmentally friendly alternatives to the current chromate containing coating technologies.

Anti-corrosion behavior of layer by layer coatings of cross-linked chitosan and poly(vinyl butyral) on carbon steel

Anti-corrosion coatings of chitosan were fabricated by layer-by-layer (lbl) addition of chitosan (Ch) and poly vinyl butyral (PVB) on mild carbon steel substrate. Corrosion inhibition of chitosan in lbl coatings was analyzed by electrochemical, spectroscopic and morphological measurements. Sandwiching of chitosan between two hydrophobic PVB layers enhanced its bonding strength and enabled the amine and hydroxyl groups of chitosan to chelate with iron ions that led to the formation of a chitosan stabilized iron oxide passive layer on the metal surface. Effect of chitosan crosslinking on the stabilization process of passive oxide layer as well as the coating stability was studied by incorporating glutaraldehyde in the chitosan layer. The results obtained from electrochemical impedance spectroscopy and Tafel plots clearly showed a superior corrosion protection of lbl coatings generated by 1 % glutaraldehyde incorporation in the middle chitosan layer. SEM and Raman spectra confirmed the formation of passive oxide layer on the metal surface stabilized by chitosan polymer backbone. Improvement in the anti-corrosion properties of PVB_Ch/1 %Glu_PVB coatings were not observed after the incorporation of fillers like graphene and vermiculite in the chitosan layer probably due to the imperfect adhesion of the fillers with the polymeric matrix.

Effects of different polypyrrole/TiO2 nanocomposite morphologies in polyvinyl butyral coatings for preventing the corrosion of mild steel

This study addresses the synthesis and comparison of the corrosion protective properties of two different polypyrrole/TiO2 nanocomposite (PPy/TiO2 NC) morphologies in a polyvinyl butyral coating on mild steel. The polymerization was performed via low-temperature in situ chemical oxidative polymerization in the presence of methyl orange (MO) and dodecyl benzene sulfonic acid (DBSA). The field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results show two different spherical and tube shapes in the core–shell structure of the PPy/TiO2 NCs synthesized in the presence DBSA and MO, respectively. The TEM results indicate that a thinner polypyrrole (PPy) shell is synthesized on the PPy/TiO2 NCs in the presence of MO than that synthesized in the presence of DBSA. Thermogravimetric analysis (TGA) results indicate that the mass percentages of the TiO2 NPs in the PPy/TiO2 NCs synthesized in the presence of MO and DBSA are 29.71 and 33.84%, respectively. The PPy/TiO2 NCs synthesized in the presence of MO were found to yield better anti-corrosion performance than those synthesized in the presence of DBSA. This result is due to the effect of the PPy surface area, which has more influence over corrosion control than the percentage of TiO2 nanoparticles in the nanocomposites.

S-SIMS and MetA-SIMS study of organic additives in thin polymer coatings

In the present study a methodology for TOF-S-SIMS measurements is developed to gain information on the distribution of molecules on and in polymer coatings (thickness ∼100 μm). Experiments were carried out on model systems consisting of one or more additive-containing polyvinylbutyral coatings. Several organic additives were selected: carbocyanine dyes, basonyl blue and the pharmaceutical risperidone. The additives have been measured as pure compounds on a Si substrate to obtain good reference spectra. After optimisation of the sample preparation method, the coatings were embedded in epoxy resin and stored in an oven (60 °C) for 24 h. Cross-sections were made by means of a microtome. S-SIMS spectra were taken on the prepared cross-sections before and after Au was deposited on the sample surface. Compared to the untreated samples, the Au covered samples give rise to more intense secondary ion signals. Generally, signals of the intact cations were more intense than those of the fragment ions. Apart from mass spectra, images of the additive distribution in the coatings could also be acquired by recording structural ion signals. It was possible to make secondary ion images of the additive molecule ions with a (sub)-micrometer lateral resolution.

Polyaniline Inhibition of Corrosion-Driven Organic Coating Cathodic Delamination on Iron

The polyaniline emeraldine salt of paratoluenesulfonic acid (PAni-pTS) is dispersed in polyvinylbutyral coatings adherent to an iron surface. Such dispersions are shown to effectively inhibit corrosion-driven coating delamination (cathodic disbondment) when 5% w/v (0.86 M) aqueous chloride electrolyte contacts a penetrative coating defect. A scanning Kelvin probe is used to quantify the influence of PAni-pTS volume fraction on delamination rate and the potential of the intact (undelaminated) coated surface Secondary ion mass spectroscopy and atomic force microscopy are used to determine the time-dependent thickness of an oxide layer developing at the coating-iron interface. At 20°C, high relative humidity (93%), and the iron oxide layer grows at a constant rate of nm s−1. increases monotonically from 0.2 to 0.56 V vs. SHE, and coating delamination rates decrease by ca. 95% as is increased from 0 to 0.25. Addition of 0.01 M Na-pTS to the experimental electrolyte has no effect. An inhibition mechanism is proposed in which through-coating cathodic reduction is suppressed by the ennoblement of substrate potentials and the product of reduction is absorbed through PAni-pTS mediated pH buffering. © 2005 The Electrochemical Society. All rights reserved.