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A comparative study between the leaching behavior of inhibitive ions from conventionally pigmented and smart (with encapsulated pigments) epoxy coatings has been conducted. Leaching of calcium phosphate as an inhibitive pigment from epoxy coatings was tested in 3.5 wt % NaCl solution. The results showed that pigment encapsulation contributed to a more uniform and stable coating microstructure based on the Scanning Electron Microscopy–Energy-Dispersive X-ray Spectroscopy (SEM-EDX) analysis and a higher leaching rate of the inhibitive pigment via the Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis, thereby enhancing both the active corrosion protection and the barrier properties of the coating film. This was further verified by the Electrochemical Impedance Spectroscopy (EIS) measurements. After 7 days of immersion in 3.5 wt % NaCl solution, the coating resistance of the smart epoxy coating with mesoporous silica nanoparticle encapsulated calcium phosphate (MSN-CP3%) was 2 × 109 Ω·cm2 compared to 1.1 × 106 Ω·cm2 and 2.6 × 106 Ω·cm2 for the conventional epoxy coatings pigmented with 3 wt % and 5 wt % calcium phosphate (CP3% and CP5%), respectively.

Silica aerogel-encapsulated biocide crystals can potentially enhance the protection efficiency of antifouling coatings, thereby lowering the impact on nontarget aquatic life. In the present study, copper pyrithione (CuPT) crystals are encapsulated by silica aerogel to obtain loadings of 50-80 wt % CuPT. For optimal design of the heterogeneous particles and mapping of the underlying biocide release mechanisms, the aerogel-encapsulated biocide crystals are characterized by scanning (transmission) electron microscopy, energy-dispersive X-ray spectroscopy, thermal gravimetric analysis, mercury intrusion porosity, Brunauer-Emmett-Teller analysis, and light scattering. The microscopic examination demonstrates that the elongated CuPT crystals are encapsulated by a thin highly porous silica layer. When varying the CuPT loading of the aerogels, it is possible to tune the particle size, pore volume, and specific surface area of the aerogels. Furthermore, this study suggests that the hydrophilic aerogel-encapsulated CuPT, when used in antifouling coatings, attracts seawater and contributes to an efficient controlled release of active CuPT.

The Selective Non-Catalytic Reduction process was investigated through experiments and modelling in a bench scale cyclone reactor. Outlet and internal profiles of NO and NH3 concentrations were measured at varying operating conditions. Cyclone inlet temperatures between 866 and 1023 °C were used, while the inlet NO concentration was kept at ~500 ppm. Gaseous ammonia was injected in the cyclone inlet, with nitrogen carrier gas. 60-69% NO reduction was achieved at inlet temperatures of 975-982 °C, and stoichiometric ratio NH3/NO β ≈ 1.6, with no ammonia slip. The main reaction zone was the inlet and upper cyclone chamber. The experiments was modelled using simple and detailed kinetics combined with simple reactor models and a compartment model suggested in this work. The qualitative trends of NO reduction and ammonia slip were predicted by the models. However, the ammonia slip was significantly over-predicted in most cases. The outlet concentrations were insensitive to choice of reactor model, while sensitive to temperature and kinetics. The compartment model quantitatively reproduced the cyclones NO concentration profiles, through its simplified representation of the cyclone flow and temperature gradients, while the NH3 profiles were only qualitatively predicted. The choice of bypass fractions showed a large influence on the ammonia profiles.

Biofouling on ship hulls can cause increased fuel consumption and the global spread of nonindigenous species. The shipping industry utilizes fouling control coatings (FCC) to prevent biofouling from occurring on the ship hull. The evaluation standards for the performance of FCC are based on manual inspections, which unavoidably induce some degree of subjectivity. A standardized biofouling recognition model using image analysis would provide a more objective basis for the evaluation of FCC. For this purpose, several coated panels were immersed in the ocean at CoaST Maritime Test Centre for an exposure period of six weeks, whereafter, the panels were fully covered with biofouling. The program ilastik was then successfully used to train a pixel classification model, which could provide a simple segmentation of the different biofouling categories detected on a coated surface. From the simple segmentation, a coverage percentage of biofouling was determined. The percentages can stand alone to provide information on the degree of biofouling or be used in combination with the guidelines from the European Chemicals Agency to calculate a fouling resistance rating (FRR). The FRR obtained from the model was compared with FRR values obtained from the manual evaluation of the panels.

To protect structural steel in the event of a hydrocarbon fire, epoxy-based intumescent coatings, which expand to form a multicellular char layer, are increasingly used. Consequently, to improve formulations and understand the performance of such coatings, it is of great industrial and scientific interest to establish relationships between the char properties and the critical heating times of coated steel plates. In this work, a so-called Stratification Parameter (SP) that combines the relative expansions and insulation efficiencies of individual char layers (termed the sponge-like, the macroporous, and the compact phase, respectively), is introduced to characterize the properties of the multilayered intumescent coating char. An approximate linear relationship was revealed between the SP of the char and the fire-resistance performance (i.e. critical times to 400 and 550 oC) of the intumescent coating. Furthermore, owing to the mapped-out exponential relationship between the dynamic viscosity minimum and the char appearance, it was discovered that the SP of the char can be effectively used to point out the required dynamic viscosity change of an intumescent coating to form a given char. Finally, results of thermogravimetric analyses suggest that constraining the coating mass loss during char degradation (to less than 28 wt.% for the coatings of the present work) may prevent the formation of the less efficient sponge-like phase. The stratification methodology developed, can be used to estimate expected thermal insulation properties of non-uniform hydrocarbon intumescent coating chars

In the recent decade, a strong push toward development of more biobased binders for coating applications as part of the transition toward independence from nonrenewable fossil-based raw materials has been seen. Here we present a biobased epoxy lignin/rapeseed fatty acid derivative (eFA-L), which has been applied in coating systems, leading to coatings with >97% biobased content and Y = 130 MPa. To approach the strength of classical epoxy systems, a series of bimodal systems, containing low molecular weight adducts of biobased diglycidyl furan-2,5-dicarboxylate (DGFDC) and fossil-based diglycidylether bisphenol A (DGEBA) were prepared. In these bimodal systems, it was shown that DGEBA contributes to higher mechanical strength compared to DGFDC at equivalent cross-linking density, which was attributed to increased π–π stacking interactions. The biobased bimodal binder system composed of eFA-L and DGFDC (30 wt %) resulted in a coating with a biobased content of 93 wt %, Y = 440 MPa, and Tg > 50 °C. Better mechanical properties (Y = 700 MPa) were achieved by use of DGEBA (30 wt %), but it results in a significant reduction in biobased content to 62 wt %.

A new method for testing materials under simulated fire conditions is introduced. The fundamentally new approach relies on the movement of the sample through zones with a spatially increasing temperature. Adjusting the velocity profile with which the sample is moved makes it possible to expose it to practically any temperature-time curve defined in fire safety standards, from extremely rapid hydrocarbon to more gradual cellulosic fire conditions. This manuscript presents a prototype named CoaST-Fire that capitalises on this concept by combining a vertical tube furnace with a vertical motion system. The methodology to calibrate the furnace temperature profile, as well as to calculate the velocity profiles are discussed. The velocity profiles are then used to replicate a range of temperature-time curves with exceptional accuracy and reproducibility. A numerical model is developed in COMSOL Multiphysics to study heat fluxes towards the steel substrate as a function of time and thermal insulation. Finally, proof-of-concept experiments with two commercial intumescent coatings are presented. The experiments are shown to be highly repeatable while images of the coatings during the experiments can provide additional insights into the occurring reaction steps. Furthermore, CoaST-Fire makes it possible to conduct experiments under various O-2 concentrations and could later be extended with a gas outlet analysis system. The study is in line with recent efforts to develop cheaper and more rapid testing methods for early research and development of intumescent coatings and the setup could potentially also be used to test other types of materials.

Using a three-phase batch reactor with coated steel panels, this investigation studies the influence of carbon dioxide (CO2), present in the gas phase at conditions of high pressure and high temperature (HPHT), on the degradation of an amine-cured epoxy novolac coating (EN). The combined effect of a gas, a hydrocarbon, and a seawater phase compromises the coating and leads to underfilm corrosion. Consequently, an understanding of the role of each of the phases is essential for the effective design of superior epoxy-based coatings for HPHT applications in the petroleum and other industries. On exposure to the three phases individually, at a low pressure of N2, the EN network remained unaffected and impervious. However, in the hydrocarbon-exposed zone, a combination of para-xylene, representing the hydrocarbon phase, and CO2 at HPHT, initiated a glass transition temperature depression with subsequent softening of the EN network. This allowed dissolved CO2 gas to diffuse into the EN network, thereby generating pinholes at the coating surface. The seawater-exposed zone, in the presence of CO2 at HPHT, suffered from an increased seawater ion diffusion, leading to blister formation.Moreover, the most detrimental subzone for the EN network was when CO2, para-xylene, and seawater were synergistically interacting at its hydrocarbon-seawater interface. This combination resulted in an increased chain motion of the EN network, subsequently allowing CO2 and seawater ions to diffuse into the EN network to the steel substrate, imposing underfilm corrosion. In the absence of CO2, blisters were formed at the interface subzone, but no corrosion was detected. The results are of high relevance to the petroleum industry, but also for the protection of transport pipelines and process equipment in the next-generation Carbon Capture and Storage (CCS) technologies.

Phosphorus (P) from biomass can cause operational problems in thermal conversion processes. In order to explore the release mechanism of P to the gas phase, carbothermic reduction of meta-, pyro-, and orthophosphates of ash elements commonly found in biomass; sodium, potassium, magnesium, and calcium was investigated. Mixtures of each phosphate and activated carbon were heated to 1135 °C in a laboratory-scale reactor, with the CO and CO2 evolving from the sample monitored, and the chemical composition of selected residues analyzed to quantify the release of P. Thermal gravimetric analysis was also performed on selected samples. The alkaline earth phosphates were reduced in steps, following the sequence meta → pyro → ortho → alkaline earth oxide. However, the alkali metaphosphates appear to be reduced in one step, in which both alkali and P are released. Alkali pyro- and orthophosphate appear to undergo a two-step process. In the first step, mainly alkali is released and in the second step both alkali and P. An intermediate is produced in the first step, which has a K:P:O atomic ratio of about 2:1:2.7, indicating it might be a phosphite with the overall stoichiometry; K4P2O5. The reduction of alkaline earth phosphates could be interpreted using available thermodynamic data, whereas thermodynamic equilibrium calculations for the alkali phosphates did not correspond well to the experimental observations. Kinetics were derived for the different reduction reactions, and can be used to compare the reactivity of the phosphates. The work suggests that carbothermic reduction reactions are important for the release of P in the temperature range 850–1135 °C and relevant for biomass combustion, pyrolysis and gasification.

For high performance of hydrocarbonintumescent coatings, interactions between the acid source ammoniumpolyphosphate (APP) and inorganic fillers can be critical. In the present work,low-borate concentration (i.e., 1 wt.% zinc borate) intumescent coatings with different concentrationratios of CaCO3 to APP were studied in an attempt to map thereaction mechanisms. The analysis of the coating performance was conductedusing thermal insulation assessment according to the UL1709 fire curve(disregarding substrate load, geometrical diversity, and other full-scaleimplications of the complete standard), rheological measurements,thermogravimetric analyses (TGA), Fourier transform infrared spectrometer(ATR-FTIR), and X-ray diffraction (XRD). Results show that a coating with a CaCO3/APPmass ratio of 0.3 gives the best performance (i.e., the longest critical time ofsteel substrates to reach both 400 and 550 oC in the thermalinsulation assessment). The dependency on the CaCO3/APP ratio of thedynamic viscosity minimum points to significant interactions between CaCO3and APP during the softening state (i.e., the intumescence process) of thecoating. Due to an enhanced anti-oxidation property, the degradation zone ofthe intumescent char and the residual weight of the coating after exposure wereboth improved when increasing the CaCO3/APP ratio. The compositionaldevelopment of the intumescent char showed that CaCO3 and APP reactto form a new polymeric phase, calcium catena-polyphosphate (CaP2O6).This polyphosphate may contribute to the formation of a compact phase in theintumescent char and benefit the thermal insulation performance of low-borateconcentration hydrocarbon intumescent coatings.

In this study, a rapid and versatile methodology for quantitative pore structure characterization is described taking the example of intumescent char. The char porosity and pore structure tend to be difficult to quantify but are decisive for the material’s thermal conductivity and thus performance. The methodology described here uses a fluorescent dye containing epoxy to impregnate the char. After curing, the sample is cut and polished, followed by imaging with a fluorescence microscope. The recorded images are segmented using an open-source interactive machine learning program, followed by automated pore size and porosity measurements. Volume-based three-dimensional (3D) pore size distributions are calculated via stereography and compared to X-ray microcomputed tomography (μ-CT) results. The pore aspect ratio and tortuosity of the solid char phase are also discussed. It is shown that the fluorescence microscopy methodology produces high-resolution images with excellent contrast, while similar pore metrics (porosity of 81.8%, average volume-based pore size of 70.5 μm) to those for μ-CT are obtained.

Biomass can be used to generate heat, power, or biofuels in thermal conversion processes such as combustion, gasification and pyrolysis. However, some types of biomass contain high levels of phosphorus, which can be released to the gas phase and cause operational or environmental problems. The mechanism(s) responsible for phosphorus release has not been convincingly established. Understanding the high-temperature phosphorus chemistry is also important in order to enable efficient recovery of phosphorus in residues from thermal conversion of biomass. In this work, the release of phosphorus from wheat bran char and sunflower seed char in different gas environments (100 % N2, 1–20 % O2, and 10 % CO2) and temperatures (900–1100 °C) was studied. The chars were converted in a horizontal tube reactor and characterized using ICP-OES, XRD, SEM-EDS, and 31P NMR. The release of ash-forming elements was determined using ICP-OES analysis of the char and sample residues, whereas the release of carbon was determined using CO and CO2 gas analysis. In both chars, phosphorus was present primarily together with potassium and magnesium, mainly as pyrophosphates in the wheat bran char, and largely as orthophosphates in the sunflower seed char. For wheat bran char, the release of phosphorus increased from 27 % at 900 °C to 71 % at 1100 °C in N2, whereas the release was at least 20 % lower in the oxidizing atmospheres (1–20 % O2, or 10 % CO2). The sunflower seed char reached a maximum release of 55 % at 1100 °C in N2. For wheat bran char, the molar ratio of released carbon/phosphorus was close to 2.5, which fits well with the theoretical value for carbothermic reduction of phosphates (P2O5(s, l) + 5C(s) → P2(g) + 5CO(g)). At 1100 °C, in N2, the release of phosphorus, potassium and sodium occurred mainly during the first 10 min. It was shown that KMgPO4, used as a model compound, could be reduced by carbon starting from 950 °C, but that some of the phosphorus remained in the condensed phase. The work provides a better understanding of phosphorus release and presents evidence showing that carbothermic reduction reactions can be an important phosphorus release mechanism for seed- and grain-based biomass char.

The Hansen solubility parameters (HSP) are frequently used for solvent selection and characterization of polymers, and are directly related to the suspension behavior of pigments in solvent mixtures. The performance of currently available group contribution (GC) methods for HSP were evaluated and found to be insufficient for computer-aided product design (CAPD) of paints and coatings. A revised and, for this purpose, improved GC method is presented for estimating HSP of organic compounds, intended for organic pigments. Due to the significant limitations of GC methods, an uncertainty analysis and parameter confidence intervals are provided in order to better quantify the estimation accuracy of the proposed approach. Compared to other applicable GC methods, the prediction error is reduced significantly with average absolute errors of 0.45 MPa1/2, 1.35 MPa1/2, and 1.09 MPa1/2 for the partial dispersion (δD), polar (δP) and hydrogen-bonding (δH) solubility parameters respectively for a database of 1106 compounds. The performance for organic pigments is comparable to the overall method performance, with higher average errors for δD and lower average errors for δP and δH.

The effect of gasification reactions on biomass char conversion under pulverized fuel combustion conditions was studied by single particle experiments and modelling. Experiments of pine and beech wood char conversion were carried out in a single particle combustor under conditions of 1473-1723 K, 0.0-10.5% O2, and 25-42% H2O. A comprehensive progressive char conversion model, including heterogeneous reactions (char oxidation and char gasification with CO2 and H2O), homogeneous reactions (CO oxidation, water-gas shift reaction, and H2 oxidation) in the particle boundary layer, particle shrinkage, and external and internal heat and mass transfer, was developed. The modelling results are in good agreement with both experimental char conversion time and particle size evolution in the presence of oxygen, while larger deviations are found for the gasification experiments. The modelling results show that the char oxidation is limited by mass transfer, while the char gasification is controlled by both mass transfer and gasification kinetics at the investigated conditions. A sensitivity analysis shows that the CO oxidation in the boundary layer and the gasification kinetics influence significantly the char conversion time, while the water-gas shift reaction and H2 oxidation have only a small effect. Analysis of the sensitive parameters on the char conversion process under a typical pulverized biomass combustion condition (4% O2, 13% CO2, 13% H2O), shows that the char gasification reactions contribute significantly to char conversion, especially for millimeter-sized biomass char particles at high temperatures.

An isothermal model is commonly used in computational fluid dynamics (CFD) modeling of biomass devolatilization in fluidized beds. However, the particle internal heat transfer, which is neglected by the isothermal model, influences significantly the devolatilization process for large biomass particles. To consider the effect of internal heat transfer, a heat-transfer-corrected isothermal model is introduced by comparing the differences between an isothermal model and a nonisothermal model. Two correction coefficients for external heat transfer, HT, and reaction rate, HR,i, were defined to correct the conventional isothermal model. The predictions of the heat-transfer-corrected isothermal model and the nonisothermal model were in good agreement with the experimental data for both thermally thick (Biot number, Bi ≥ 1.0) and thermally thin (Bi < 1.0) biomass particles, while the conventional isothermal model gave reasonable results only for thermally thin biomass particles. The heat-transfer-corrected isothermal model was further implemented in a CFD model to simulate biomass devolatilization in a batch bubbling fluidized bed. Compared to the conventional isothermal model, the heat-transfer-corrected isothermal model had similar computational efficiency, but it predicted a lower heating rate and a lower devolatilization rate, which were in good agreement with the observations from single-particle modeling.

The development and performance in practice of a commercial automatically controlled wood stove is described. The digital control system controls the three combustion air inlets individually, based on the combustion phase, measured flue gas temperature, measured O2 outlet concentration and desired room temperature. The control system ensured a well-controlled combustion cycle with respect to temperature and oxygen concentration, yielding improved thermal efficiency and minimized carbon monoxide emissions. A minimum in CO emissions was identified for the oxygen operation range 10–13% O2. The improved performance has been verified by field tests in 5 private homes, demonstrating more stable and optimal O2 concentrations and temperatures compared to manual operation. This resulted in significant lower CO concentrations (up to 27%) alongside higher thermal efficiency (up to 20%) when comparing manually and automatically controlled wood stoves. This new technology has a great potential for improving the stove efficiency/biomass utilisation and reducing the emissions of pollutants at low altitude close to private homes.

There is an immense potential for the computer-aided tools in the design of paints and coatings. Significant advances have been made, involving also the use of thermodynamic and in general property models for the study and theoretical formulation of these products. Algorithms and tools based on such models enable the formulation chemist to speed up the design process, by allowing them to focus their experimental efforts on a selected number of reliable constituents for the coating formulation. Even though model-based methods and tools can save resources and time required for the design, service life prediction and formulation of new products, the experimental validation cannot be done away with; as certain interactions in these complex systems can be accounted for only by using practical design procedures. Machine learning algorithms can, however, be used to improve the accuracy of predictive methods, if sufficient data on observed anomalies from physicochemical based theoretical predictions, is available.

Waterborne epoxy‑silicone coating formulations are prepared by combining selected ingredients in optimum quantities to produce ~250–275 μm films (dry film thickness, DFT) applied on polyester, sandblasted steel, smooth steel, acrylic, polypropylene and aluminum substrates. The self-stratification of the applied coatings is then evaluated using Fourier Transform Infrared spectroscopy – Attenuated Total Reflectance (FTIR–ATR) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analysis. The difference in the absorption spectra of the top and bottom surfaces of these films as well as a significant difference in topography seen from the SEM images and elemental mapping through an EDX analysis of the cross-section has confirmed the occurrence of stratification on polyester substrate. The observed stratification results are subsequently compared with a theoretical model where the primary mechanism driving the separation is assumed to be the surface free energy difference of the resins and their respective wetting of the substrate. The influence of using two different theories, Wu's Harmonic Mean Method and Owens-Wendt Method for the interfacial surface tensions and the solid surface free energy computations, on the predictions from this model is also tested. The theoretical predictions support the observed results for most cases of the formulated waterborne systems; except for the case of sandblasted steel, the observed results do not match the predictions. The possible reasons for the difference in between the prediction and observation for this specific case has also been elucidated.

Calcium phosphate was encapsulated into mesoporous silica nanoparticles (MSN). The effect of pH on the structure and morphology of the MSN and the release of calcium phosphate from the MSN was investigated. Epoxy coatings with encapsulated (3 wt%) and non-encapsulated (3 wt% and 5 wt%) calcium phosphate were formulated and their anti-corrosive performance was evaluated by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Results showed that encapsulation of the calcium phosphate as inhibitive pigment in the coating can enhance the anti-corrosive performance by preventing spontaneous pigment dissolution and controlling the pigment's release from the coating.

Formulated products represent a particular class of complex chemical products, and their design is typically based on experience and extensive experimentation. Though still at an early stage, and despite that their potential is not fully accessed and not fully utilized by industry, Computer-aided design (CAD) methods and tools offer many possibilities in the design of formulated products. The CAD methodology based on computerized models enables the formulation chemists to speed up the design process, without completely replacing experiments. In this work, we summarize previous studies in the field and present important elements of the CAD framework, emphasizing estimation methods for key target properties, link to specifications and finally, some case studies will illustrate how the CAD framework can be used in practice for formulated products.

Organic coatings have been widely applied for the protection of marine structures from corrosion. Usually, the coating systems for the marine environment are specified to last more than 20 years. However, degradation of the coating system starts already as it is commissioned and repair and maintenance are usually needed before the planned service lifetime of the structure. Rust creep is one of the most important criteria for the prequalification of an anti-corrosive coating system for offshore applications, as established in ISO 12944-9. This evaluation method is destructive in nature which means that one panel only gives one reading of rust creep because the coating beyond the rust area must be removed. Non-destructive methods allow for the evaluation of coating performance in an more efficient and cost-effective way where the same coated panel can be tested over time so that the early changes/breakdowns of the coatings and the propagation of the rust creep can be detected and monitored, which will lead to a better understanding of the mechanism behind. In this present work, three methods based on ISO 12944-9, optical 3D Profilometry and Scanning Acoustic Microscopy (SAM) for the rust creep assessment are compared and results show that the optical 3D Profilometry and SAM can act as the non-destructive test methods providing more efficient and accurate rust creep evaluation.

Photocatalytic coatings have potential as an air purifying technology for removal of pollutants such as NOx gases, which are converted into and immobilized as nitrate via photo-oxidation. This work is an investigation of the photocatalytic conversion of nitrite into nitrate in the aqueous phase. The study of this reaction is important to understand the mechanism through which the immobilization of the NOx species as nitrates takes place during NOx conversion, especially in humid environments. We investigate the photocatalytic performance of TiO2 nanoparticles (Aeroxide® P25) and the corresponding photocatalytic coatings prepared using acrylic binder (TiO2 NP-acrylic) towards the photo-conversion of nitrite. The combination of a simple colorimetric method (Griess test) for nitrite quantification and UV–vis spectroscopy for nitrite and nitrate analysis is shown to be a useful method for monitoring the nitrite conversion. Photocatalytic tests with suspended TiO2 nanoparticles show that the nitrite conversion benefits from lower pH, higher temperature and higher concentration of the photocatalyst. The advantage of lower pH is attributed to electrostatic attraction between TiO2 with adsorbed H3O+ and NO2−, which facilitates transport of nitrite to the active surface. When the photocatalyst is immobilized in a coating the factor of primary significance is the pigment volume concentration relative to critical pigment volume concentration (λ), as the nitrite conversion increases linearly with λ in the range 0.6–1.2. This is attributed to the creation of a more porous structure that facilitates the access of nitrite and light to the active TiO2 surface sites.

Physical cleaning, an important factor in maintaining ships' hulls free from biofouling, can help to prolong the lifetime of fouling-control coating systems. This study investigated how mechanical cleaning parameters (cleaning force, duration and frequency) affected antifouling coatings' performance including fouling resistance property and cleaning efficiency using a specially designed manual cleaning system. Meanwhile, coating surface conditions, including visual appearance condition, roughness, contact angle were evaluated in detail. Biocide release rates of copper-based soluble antifouling paint (Cu-AF) under different cleaning conditions were also assessed by Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX) analysis. Results from the field testing in Danish sea area showed that cleaning frequency affected more than cleaning force and duration on antifouling coating performance. Algae glue attachment increased the difficulty in the cleaning of non-coated acrylic surface (A-BS) and fluorine-based copper free insoluble antifouling paint (F-AF). For Cu-AF coated panels, no significant mechanical damages were observed after cleaning. For F-AF, scratches formed on the coating surface after cleaning were more related to cleaning force and cleaning frequency. The biocide release rates of Cu-AF under various cleaning condition were between 15.7 and 24.6 μg Cu cm−2 day−1. Gentle cleaning of Cu-AF with proper frequency has little influence on the copper release rate. This study provides guidance on cleaning strategies for antifouling coatings.

Hydrocarbon intumescent coatings are an efficient means to passive fire protection of steel structures in high-risk environments such as petrochemical plants and offshore platforms. In the present study, the effects of zinc borate on the performance of hydrocarbon intumescent coatings were investigated. The analyses include steel temperature-time relationships and char expansion, as well as structural investigations and compositional profiles of the char. Furthermore, transient rheological coating behaviors and thermal degradation of the coatings were measured and analyzed. Results of furnace experiments, conducted under a standard hydrocarbon fire curve (UL1709), showed that a formulation containing 15 wt.% zinc borate gave the best performance. Fully expanded char measurements and the associated rheological recordings, evidenced that adjusting the zinc borate content from 0 to 20 wt.% increased the dynamic viscosity minimum of the incipient char from 6.2 to 5671.4 Pa⋅s. The increased dynamic viscosity resulted in a more uniform, but less expanded char layer. Compositional profiles of intumescent chars, measured using X-ray Diffraction, showed an increasing phosphate (especially BPO 4 ) content with increasing levels of zinc borate in the intumescent coatings. Finally, the thermogravimetric analyses revealed that zinc borate can help to reduce epoxy binder degradation and oxidation of the carbon-inorganic residue. Due to the health risks associated with borate and its compounds, there is a requirement to find alternatives. The present work has mapped out some of the beneficial properties of zinc borate, and the results may provide some insight as to how to formulate without these compounds in the future.

The mixing and segregation behaviour of binary solid mixtures has been extensively studied through various experiments, while accurate CFD simulations are difficult to achieve due to process complexity and a lack of reliable constitutive relations. In this study, CFD simulations of a dense fluidized bed with glass and polystyrene particles were performed in order to identify a universal set of simulation parameters and models for simulating binary mixtures with different mixed and segregation behaviour. Through a comparison to experimental data, it was found that the EMMS drag model coupled with the Ma‐Ahmadi solid pressure and radial distribution models predicted more a reasonable axial distribution of solid phases than the Syamlal O´Brien drag model coupled with the Lun et al. solid pressure and radial distribution models. The increase in the solid‐solid drag further improved the simulation results.

The handling of sticky raw material can cause problems during operation of process equipment in the cement production industry. These handling problems are generally observed when raw material (e.g. wet clay) sticks to machine walls and causes blockage of outlets. This leads to frequent production shutdowns and expensive cleaning operations. In this work, the effects of surface material and process parameters on the friction forces between wet clay and surface were investigated. Various surface materials and clay impact speeds were investigated.The results demonstrate that not only the equipment surface material but also the surface roughness influences the observed frictional behavior. The ranking of the materials in terms of effective static friction coefficients fell in two groups with equal performance within the group: 1) Two Teflon-based coatings (Accofal 2G54 and Accolan LB), polished AISI 304 stainless steel, Matrox lining, and a polyurethane-based coating (best performing surfaces), 2) Mild steel, a silicone-based coating, and AISI 304 stainless steel (worst performing surfaces). However, the friction coefficients of the two groups only varied by a factor of two, suggesting that adhesion of wet clay to surfaces is difficult to avoid by the use of coatings.

Dispersion of a saturated gas in a supersaturated solution has been previously reported to promote nucleation rates during batch crystallization, leading to the exploration of this technique as a cost-effective method to control crystal size distributions. Despite the mechanisms are still unknown, it has been hypothesized that the presence of a flowing gas could promote variations in the flow pattern inside the crystallizer, leading to improved mass transfer and higher rates of secondary nucleation through an increased number of crystal collisions. In this work, we have constructed a lab-scale MSMPR crystallizer with self-induced gas dispersion to investigate the applicability of this technique in continuous crystallization. The effect of different gas hold-ups has been evaluated at high supersaturations and for two different suspension densities. Results show a very limited variation in the overall mass deposition rate, and reductions in the mean FBRM chord length not exceeding 5 μm for the highest investigated gas hold-up (12%). Studying the effect of impeller speed under the same conditions, we found that an increased mixing intensity has a similar impact as gas dispersion, with a mean chord length reduction of 4 μm when the impeller speed was increased from 800 to 950 rpm. These results suggest that the promotion of nucleation kinetics with gas dispersion is limited to systems where crystallization kinetics can be significantly affected by mixing, and demonstrate a limited applicability for crystal size distribution control in continuous MSMPR crystallizers.

Solid blasting waste generated from coating removal during ship repair and maintenance poses environmental challenges. This paper presents a review of the generation, characterization, and treatment of blasting waste in the ship repair industry. The quantities, properties, and environmental impacts of the generated blasting waste are summarized and analyzed, and the results indicate that blasting waste has a high generation rate and/or high toxicity. As alternatives to landfill, available blasting waste treatment methods include hydrometallurgical leaching, physical/physicochemical separation, thermal treatment, and direct utilization in the production of building materials. The advantages and disadvantages of these treatments are reviewed and compared. The production of building materials from blasting waste is currently attractive owning to its economic benefits and technical simplicity, whereas recycling blasting waste for high-value applications is gradually gaining research interest. The high dependence of the choice and performance of treatment methods on the waste type and characteristics is highlighted. The results emphasize the interest in conducting more research on physiochemical and thermal properties and the environmental effects of blasting waste. This review suggests that future research should focus more on paint waste management because of the restricted application of dry abrasive blasting and the development of nonabrasive blasting methods in the ship repair industry.

When a substrate-bonded silicone dielectric elastomer (DE) is subjected to high voltage, creasing, wrinkling, and cratering instabilities can be formed at the surface of the DE. This deformation, has been already demonstrated for the prevention and detachment of biofouling from the surface of DEs. In this work we add sensing capabilities to the anti-biofouling effect of active DE surfaces. The capacitance of the sensor is measured as a function of applied voltage, and the threshold voltage at which instabilities occur is identified. The formation of instabilities increases the capacitance of the device. When stiff biofouling material attach to the surface of the silicone, the threshold voltage necessary to develop instabilities on the surface of the silicone will increase and this can be used as a measure of attached species to the surface.

In this work, the curing and hardness evolution of a two-component polyurethane (PU) coating in four different environments, three of which were solvent evaporation-suppressed conditions, were studied.In contrast to previous studies, the simultaneous use of Fourier-transform infrared spectroscopy, gravimetric analysis, and pendulum hardness, allowed a transient mapping of the degree of isocyanate conversion, solids concentration, and coating hardness. Furthermore, to explore in more detail the coupling of the underlying mechanisms, the evolution in the average coating glass transition temperature was estimated by dynamic mechanical analysis, and the data simulated using the so-called Kelley-Bueche equation.For the curing conditions investigated, the final coating hardness differed by a factor of two, with the lowest values obtained for the evaporation-suppressed conditions. Due to the isocyanate groups reaching full conversion for all four series, the reason for the lower hardness was attributed entirely to the plasticizing effect of residual solvent. Using a Kα value of 0.687 in the Kelley-Bueche equation, the coating glass transition temperature as a function of the PU volume fraction could be successfully simulated, and was found to increase from about 282 K at a volume fraction of 0.79 to 319 K at one of 0.93. In addition, when the experimental temperature was lower than the coating glass transition temperature, a proportional increase of the pendulum hardness with the reciprocal loss factor was seen.The effects of catalyst concentration in the coating were also investigated, and this parameter was found to have a strong influence on both the surface conversion, the solids concentration, and the coating hardness. A too fast curing rate shortens the time to vitrification, after which the solvent evaporation rate becomes diffusion-controlled and very low, leading to higher residual solvent contents and significantly lower hardness values.The results obtained provide guidelines for how to optimize ventilation conditions during the curing of solvent-based, thermoset PU coatings.

Biochar nanoparticles (BCN) derived from spruce wood and wheat straw were prepared, characterized and incorporated into zinc-rich epoxy coatings, with the aim of improving the zinc powder utilization and the anticorrosion performance. Formulations with different BCN and commercial carbon black dosages (0.4wt.%, 0.8wt.% and 1.6wt.%) were compared to a zinc-rich epoxy paint (ZRP) without carbon addition. After immersion and salt spray exposure, coated steel panels were characterized with optical, electrochemical and spectroscopy techniques to evaluate the anticorrosive performance. BCN and carbon black addition enhanced the local electrochemical reactions and the barrier effects were promoted by an increased amount of zinc corrosion products (Zn5(OH)8Cl2 and ZnCO3). The formulation with 0.8 wt.% of spruce wood BCN performed equivalently well compared to the ones with carbon black. The degraded area and rust accumulation around the artificial scribe for the formulation with 0.8 wt.% of spruce wood BCN were 29.8% and 27.8% less than ZRP, respectively, which is attributed to the good electrical conductivity and high specific surface area of spruce wood char. These results suggest a promising and sustainable option for improving the anticorrosive performance of zinc-rich epoxy coatings by the incorporation of BCN.

Curing of coatings under solvent evaporation-suppressed conditions, can lead to trapping of solvents and subsequent solvent migration into mid- or topcoats in a multilayer coating system. Such migrations may have adverse effects on the coating mechanical properties, hardness in particular. Using a two-layer epoxy-polyurethane (PU) coating system with a strong practical significance for the heavy industry, the aim of the present work was to quantify the migration-reaction phenomenon for selected alcohols (co-solvents), and map the underlying mechanisms. In the experimental series undertaken, the evaporation rate of solvents was measured gravimetrically, and the urethane group formation quantified by the use of Fourier-transform infrared spectroscopy (FTIR). Simultaneously, the transient hardness development of the epoxy-PU system was followed and the coating surface morphology studied with a three-dimensional profilometer. In addition, to estimate the required coating curing time for dry-to-handle conditions, high-pressure compression measurements were conducted. As expected, due to solvent build-up in a closed exposure chamber, the amount of residual solvents in the epoxy-PU coating system increased under the evaporation-suppressed conditions. In particular, the residual 1-butanol in the epoxy primer migrated to the PU topcoat, where it reacted with the isocyanate reactants. The reduced cross-linking density, as a consequence of this undesired reaction, and the simultaneous suppressed solvent evaporation, resulted in an insufficient hardness development of the PU topcoat, despite continuous evaporation of solvents and consumption of isocyanates were indeed observed. To elucidate the underlying mechanisms, a kinetic study on the reactivity of 1-butanol with the isocyanate crosslinker was also conducted, and it showed a two orders of magnitude higher reaction rate than for the polyol reactant in the PU system, which explains the negative effects of the 1-butanol migration. In comparison, 2-butanol was less reactive towards isocyanates, and could substitute 1-butanol, whereby, under the evaporation-suppressed conditions, the hardness development of the epoxy-PU coating system was significantly improved and the curing time required for high-pressure dry-to-handle conditions reduced from more than eight to four days. The results of this work provide insight and guidelines for how to optimize a formulation to obtain adequate curing of the epoxy-PU coating system under evaporation-suppressed conditions.

Projections of continued growth in the global hydrocarbon demand and fast depleting resources push the oil and gas industry to explore and produce in geological formations with abnormal high pressures and temperatures, so-called HPHT conditions. In the present study, the largely unexplored degradation mechanisms for amine-cured epoxy novolac (EN) and bisphenol F (BPF) epoxy resins at HPHT are investigated at lower limits of HPHT.Using a batch-like reactor encompassing the three relevant phases (a gas mixture of nitrogen and carbon dioxide, a hydrocarbon phase of aromatic para-xylene, and an artificial seawater phase), the conditions of high pressures and high temperatures were simulated. The EN and BPF coated steel panels were placed inside the batch reactor.In the gas phase-exposed zone, both EN and BPF remained essentially intact with no major defects. However, due to para-xylene uptake that resulted in a free volume increase (i.e. lowering of the glass transition temperature), the hydrocarbon-exposed zones of EN and BPF were partly covered by an oxide of iron, the origin of which was found to be diffusion of anodically-dissolved iron from the steel-coating interface. The enhanced resin chain mobility at the hydrocarbon-seawater interphase allowed higher rates of diffusion of seawater ions to the steel-coating interface with clear signs of coating degradation. Finally, the seawater phase induced small blisters in the EN coating, whereas for BPF, a complete loss of adhesion between the coating and the substrate was observed.Simulation of Rapid Gas Decompression (RGD), uncovered the role of RGD in the iron oxide formation process for both EN and BPF coatings.In summary, when compared to BPF, the EN network showed superior performance under conditions of HPHT.

Phosphorus-rich biomass can cause operational problems in combustion units. Na-phytate, a model compound used to simulate phosphorus in biomass, was studied in a laboratory-scale reactor under temperature and gas atmosphere conditions relevant for pyrolysis, combustion, and gasification in fixed bed or fluidized bed reactors to understand the P and Na release behavior. Solid residues from Na-phytate thermal conversion were analyzed using ICP with optical emission spectrometry in order to quantify the P and Na release. The release mechanism was evaluated based on FTIR spectroscopy analysis of the residues, measurement of the flue gas CO/CO2 concentration, characterization of flue gas particles using SEM with EDS, and thermodynamic equilibrium calculations. Na-phytate decomposed in several steps under a nitrogen atmosphere, starting with condensation of the phosphate OH groups, followed by carbonization in the temperature range 300–420 °C. In the carbonization process, the phosphate units detached from the carbon structure and formed cyclic NaPO3. Above 800 °C, the C in the char reacted with the melted NaPO3 to form CO and gaseous elemental P. When the char produced from flash pyrolysis of Na-phytate at 800 °C for 10 min was exposed to 1% O2, 10% CO2, or 10% H2O (in N2), the release of Na and P to the gas phase in the temperature range 800–1000 °C was around 0–7%. However, the release of P in an inert atmosphere, with a holding time of 2 h or until full char conversion had been achieved, increased from around 4% at 800 °C to almost 30% at 1000 °C. The results indicated that carbothermic reduction reaction is responsible for the release of P and that NaPO3 vaporization is not the dominating mechanism for P and Na release at temperatures below 1000 °C. A small amount of P was released in the O2, CO2, and H2O containing gases because these gas species consumed the char and thereby inhibited the release of P.

On a global scale, methanol is one of the most important feedstocks and is used widely as solvent and co-solvent. However, due to the polar nature and associated ability to conduct current, the small molecule can take part in galvanic corrosion of metal storage tanks and degrade the barrier properties of protective coatings. In the present work, we investigated the degradation of two novolac epoxy coatings and a polyurethane (PU) coating exposed to methanol with the aim of quantifying the various degradation paths. Absorption and desorption rates were measured and the thermomechanical properties followed by dynamic mechanical analysis. For evaluation of the coating barrier properties (i.e., breakthrough time and steady state permeation rates of methanol), permeation cells were applied. During methanol absorption, simultaneous leaching of certain coating ingredients and bonding of methanol to the binder matrix via hydrogen bonds was evidenced. In terms of classification, the bonding of methanol took place by two types of mechanisms. In Type I, the methanol molecule forms a single hydrogen bond to the coating network, thereby acting as a plasticizer, which decreases the coating storage modulus and glass transition temperature. For Type II bonding of methanol, on the other hand, two hydrogen bonds to the coating network form per molecule, resulting in so-called physical crosslinking. The Type I mechanism boosted segmental mobility and contributed to the leaching of the plasticizer benzyl alcohol from the novolac epoxy coatings and residual solvents (i.e., naphtha and xylene) from the PU coating. Following the methanol desorption, and attributed to an increased effective crosslinking density from Type II bound methanol, the novolac epoxy and PU coatings exhibited significant increases in the glass transition temperatures. In addition, for the three coatings, a gradual decline in the permeability rate of methanol was observed over time. These enhanced (and unexpected) barrier properties result from a combination of effects ascribed to Type II bound methanol and the leaching process.

Silicones are typically cured at room temperature by means of metal catalyst such as tin or platinum. When networks are formed the catalyst become unrecoverable, which is of economic as well as environmental concern. Very few methods for producing metal catalyst-free room-temperature vulcanised (RTV) silicones exist and require conditions unavailable in industrial settings. Through the study of organic polysilazane (PSz) reactivity with simple alcohols by NMR, we discovered an unexpected fragmentation preference for breaking the Si-N bond rather than the Si-H; thereby, casting a new light on the fragmentation mechanism of polysilazanes. Utilising the polysilazane fragmentation as a silyl ether coupling agent for multifunctional carbinol silicones, we present a method of producing catalyst free RTV silicone networks at ambient conditions. These silicone networks were proven chemically similar to a standard condensation cured silicone and stoichiometric variations of PSz content demonstrated adjustable network properties.

Calcium tannate was synthesized, characterized, and dispersed into an epoxy coating as an inhibitive pigment. Electrochemical Impedance Spectroscopy (EIS) was employed to monitor the anti-corrosive performance of the coating formulated with the as-prepared pigment after exposure to the salt spray chamber. Reference coatings with the commercial calcium phosphate pigment and unpigmented coating were also evaluated for comparison reasons. EIS results showed that epoxy coating pigmented with calcium tannate has higher coating impedance after 21 days of exposure compared with reference coatings, either unpigmented or calcium phosphate pigmented coatings. XPS analysis was employed for a deeper understanding of the inhibitive action of calcium tannate towards corrosion protection and verified the incorporation of tannate molecules in the protective film formed on the steel substrate under the calcium tannate pigmented coating.