| 1. |
- Brännström, Sara, et al.
(författare)
-
Biobased UV-curable coatings based on itaconic acid
- 2017
-
Ingår i: Journal of Coatings Technology Research. - : Springer-Verlag New York. - 1945-9645 .- 1547-0091 .- 1935-3804. ; 14:4, s. 851-861
-
Tidskriftsartikel (refereegranskat)abstract
- A series of renewable unsaturated polyesters were synthesized from itaconic acid (IA), succinic acid, and 1,4-butanediol by solvent-free polycondensation. Previous studies utilizing IA to make polyesters for coating applications have shown great potential; however, the curing and material properties have not been investigated in detail. The aim of this study was to investigate how the curing is affected by the amount of unsaturations and how well itaconate-based polyesters crosslink without the addition of any other unsaturated monomers or reactive diluents. The chemical structures of the polyesters were confirmed with FTIR, 1 HNMR, and THF-SEC. The degree of curing was studied with FTIR, and the mechanical properties of the crosslinked polyesters were evaluated with DMA, pendulum hardness, and microindentation. The degree of curing was found to be up to 75%, and furthermore, it was found that the final mechanical properties of the crosslinked coatings could be tuned by modifying the IA content in the monomer composition. The results from DMA showed that there is a clear trend between mechanical properties and crosslinking density.
|
|
| 2. |
- Cznotka, E., et al.
(författare)
-
3D laser scanning confocal microscopy of siloxane-based comb and double-comb polymers in PVDF-HFP thin films
- 2016
-
Ingår i: Journal of Coatings Technology Research. - : Springer Science and Business Media LLC. - 1935-3804 .- 1547-0091. ; 13:4, s. 577-587
-
Tidskriftsartikel (refereegranskat)abstract
- Currently, atomic force microscopy is the preferred technique to determine roughness on membrane surfaces. In this paper, a new method to measure surface roughness is presented using a 3D laser scanning confocal microscope for high-resolution topographic analysis and is compared to conventional SEM. For this study, the surfaces of eight samples based on a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) host polymer with different liquid interpenetrating components were analyzed. Polymethylhydrosiloxane, triethylene glycolallylmethyether, (3,3,3-trifluoropropyl) methylcyclotrisiloxane (D-3-C2H4CF3), polysiloxane-comb-propyloxymethoxytriglycol (PSx), poly-siloxane-comb-propyl-3,3,3-trifluoro (PSx-C2H4CF3), poly [bis(2-(2-methoxyethoxy) ethoxy) phosphazene, or poly [bis(trifluoro) ethoxy] phosphazene was chosen as interpenetrating compound to investigate the impact of comb and double-comb-structured polymer backbones, as well as their dipolar or fluorous residues on the PVDF-HFP-miscibility. Different phases of the constituting ingredients were identified via their thermal properties determined by DSC. Additionally, the COSMO-RS method supported the experimental results, and with regard to computed sigma-profiles, new modified structures for polysiloxane and polyphosphazene synthesis were suggested.
|
|
| 3. |
- Even, Anais, et al.
(författare)
-
Influence of radical photoinitiator content on UV curing process and UV-cured hybrid sol–gel films
- 2020
-
Ingår i: JCT Research. - : Springer. - 1547-0091 .- 2168-8028. ; 17:2, s. 333-343
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid sol–gel coatings are widely used as protective layers for aluminum alloys because of their barrier abilities. This study aims at explaining the barrier properties of a sol–gel coating based on alkyltrimethoxysilane and methacrylate resin by its film structure. This approach was examined by modifying one photopolymerization parameter, e.g., by varying the content of radical photoinitiator. By neutral salt spray test and electrochemical impedance spectroscopy, the barrier properties are highlighted. The film structure is related to thermomechanical properties of films whose glass transition temperature and elastic modulus are measured by dynamic mechanical analysis and nanoindentation, respectively. On a finer scale, conversion of methacrylate functions calculated from Fourier transform infrared spectroscopy has given information on the chemical structure of films. The morphology of these coatings is studied by scanning electron microscopy, transmission electron microscopy, atomic force microscopy operating in tapping mode, and X-ray diffraction. Results revealed that formulations containing between 3 and 9 wt% of radical photoinitiator exhibit the maximal conversion of methacrylate functions and, at a microscopic scale, a homogeneous coating where the two organic and inorganic networks are well interpenetrated. This hybrid sol–gel microstructure corresponds to the highest glass transition temperature and the highest mechanical characteristics (elastic modulus, E and hardness, H) and the highest protection performance. This results in the best barrier properties, and thus the highest corrosion resistance.
|
|
| 4. |
- Fuaad, P. A., et al.
(författare)
-
Simulation of slot-coating of nanocellulosic material subject to a wall-stress dependent slip-velocity at die-walls
- 2022
-
Ingår i: JCT Research. - : Springer Nature. - 1547-0091 .- 2168-8028. ; 19:1, s. 111-120
-
Tidskriftsartikel (refereegranskat)abstract
- Bio-based nanocellulosic materials are non-toxic, renewable, exhibit excellent barrier properties, and are suitable candidates for sustainable food packaging applications. Sizing and designing coating parameters for slot-coating process using nanocellulose suspensions is challenging due to complex shear-thinning rheology and the presence of a water-rich boundary layer, effecting significant apparent slip at the wall. Previous studies have shown that the flow inside the coating bead can be complex, with occasional stagnation regions and a rheological model incorporating yield stress which should be considered while analyzing slot coating of nanocellulosic flows. This work extends earlier investigations by including the effects of the particle depleted water-rich boundary layer. The suspension is modeled as a Casson fluid with a shear-thinning viscosity, and the particle depletion at the wall is represented by an infinitely thin layer modeled as a local shear-dependent nonlinear slip law. The resulting two-phase flow equations are solved using a Finite Volume Method (FVM) coupled with the Volume of Fluid (VoF) method for tracking the free surface interface. It is observed that slip alters the flow’s dynamics in the coating bead, and the effect of slip cannot be ignored, especially at high shear rates. For thin films, the presence of slip enhances the flow, leading to more material coated on the substrate. In contrast, for thicker coatings, apparent slip leads to an augmentation in stagnant, non-yielded regions, potentially generating uneven surfaces.
|
|
| 5. |
- Harra, Juha, et al.
(författare)
-
Characteristics of nFOG, an aerosol-based wet thin film coating technique
- 2018
-
Ingår i: JCT Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 2168-8028 .- 1935-3804. ; 15:3, s. 623-632
-
Tidskriftsartikel (refereegranskat)abstract
- An atmospheric pressure aerosol-based wet thin film coating technique called the nFOG is characterized and applied in polymer film coatings. In the nFOG, a fog of droplets is formed by two air-assist atomizers oriented toward each other inside a deposition chamber. The droplets settle gravitationally and deposit on a substrate, forming a wet film. In this study, the continuous deposition mode of the nFOG is explored. We determined the size distribution of water droplets inside the chamber in a wide side range of 0.1–100 µm and on the substrate using aerosol measurement instruments and optical microscopy, respectively. The droplet size distribution was found to be bimodal with droplets of approximately 30–50 µm contributing the most to the mass of the formed wet film. The complementary measurement methods allow us to estimate the role of different droplet deposition mechanisms. The obtained results suggest that the deposition velocity of the droplets is lower than the calculated terminal settling velocity, likely due to the flow fields inside the chamber. Furthermore, the mass flux of the droplets onto the substrate is determined to be in the order of 1 g/m3s, corresponding to a wet film growth rate of 1 µm/s. Finally, the nFOG technique is demonstrated by preparing polymer films with thicknesses in the range of approximately 0.1–20 µm.
|
|
| 6. |
- Idris, Alamin, et al.
(författare)
-
A review on predictive tortuosity models for composite films in gas barrier applications
- 2022
-
Ingår i: JCT Research. - : Springer. - 1547-0091 .- 2168-8028. ; 19, s. 699-716
-
Tidskriftsartikel (refereegranskat)abstract
- Different types of impermeable fillers are usually incorporated into polymeric coating film to enhance the gas barrier properties. For instance, impermeable fillers are commonly used in barrier coating due to their larger surface, which in turn serve as barrier inclusions restricting the penetrant gas to diffuse through a longer tortuous pathway. Modeling gas transport in barrier coating can help determine the shelf-life of packaged food and reduce product development resources and time. In this paper, related tortuosity-based models corresponding to different filler geometries are outlined. This review emphasizes the emerging trends in modeling the tortuous pathway and the respective relative permeability model to predict the gas barrier performance in composite films used for barrier coating applications. We review models incorporating a range of factors, including different shapes, geometries, angular orientations, alignments, randomness in distribution, stacking, interspacing, and the polydispersity of fillers. The approaches employed to develop the tortuosity-based phenomenological models starting with simplified filler geometry and orientations to more complex morphological features of the composite films are elaborated.
|
|
| 7. |
- Johansson, Jimmy, et al.
(författare)
-
NMR-measurements for determination of local moisture content of coated wood
- 2013
-
Ingår i: JCT Research. - : Springer Berlin/Heidelberg. - 1547-0091 .- 2168-8028. ; 10:5, s. 601-607
-
Tidskriftsartikel (refereegranskat)abstract
- Local increased moisture content (MC) in wood constructions may result in different kinds of mechanical and, especially, biological degrading problems. Therefore, it is of great importance to control the MC of the material. However, there is at present no appropriate method for determining local MC in wood without destroying the product itself. Nondestructive measurements of local MC in wood is significant for the possibility of, for instance, monitoring the in situ MC in wood constructions over time, and thereby predicting potential problems. The nuclear magnetic resonance (NMR) technique has been shown to be valuable for the measurement of MC in wood. In this study, the possibility of utilizing this technique for local MC measurement in wood has been tested on wood samples exposed to water absorption for 72 h. The samples came from three different wood species treated with paint systems available on the market. In the wood samples an artificial “crack” had been created in the paint to introduce an area where the water could easily gain access to the wood. The results show the possibility of using the NMR technique for local MC measurements in wood. The measurement area, however, must be related to the properties of the material. In the case of wood, the measurement spot must be related to the early/latewood proportions. Further, a calibration of the NMR measurement must be made in relation to the expected density variations of the material.
|
|
| 8. |
- Karlson, L., et al.
(författare)
-
Influence of added surfactant on particle flocculation in waterborne polymer-particle systems
- 2008
-
Ingår i: Journal of Coatings Technology and Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 1935-3804. ; 5:4, s. 447-454
-
Tidskriftsartikel (refereegranskat)abstract
- Polymer-particle interactions can cause particle flocculation and phase separation problems in waterborne coatings. The problems can be the result of interactions that are either too weak or too strong. It is known by empirical work that addition of surfactants can minimize these problems. In this study, the authors have investigated how different types of surfactants influence the polymer-particle interactions. Both hydrophobic and hydrophilic particles were included in the study, and nonionic, anionic, and cationic surfactants were used. A simple model is suggested that can be used to predict the surfactant concentration needed to stabilize the system. The model considers the cmc (critical micelle concentration) of the surfactant, the adsorption to the polymer, and the adsorption to the particles.
|
|
| 9. |
- Karlsson, Mikael, 1978, et al.
(författare)
-
Characterization of paint formulated using secondary TiO2 pigments recovered from waste paint
- 2019
-
Ingår i: JCT Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 2168-8028 .- 1935-3804. ; 16:2, s. 607-614
-
Tidskriftsartikel (refereegranskat)abstract
- The paint industry is continuously striving to reduce its environmental impact, especially when it comes to the major virgin white pigment, titanium dioxide (TiO2). In this work, recycled TiO2 pigment was used in a paint formulation as a replacement for pigment made from virgin raw materials. The paint was evaluated based on pH, Stormer and ICI viscosities, gloss, hiding power, and color characteristics. The paint films were also characterized by LVSEM–EDS, AFM, and profilometry. The most significant difference between a paint based on recycled pigments and a paint based on virgin pigments was the agglomeration of pigment particles which gave a reduction in gloss and a rougher surface of the dried paint film based on recycled pigment, and it could be concluded that the recycled pigment could not be used without accepting a small decrease in paint quality. This points toward two main directions: (1) the use of recycled pigment in applications with less demand on surface finish and gloss, such as ceiling paints, and (2) that further work on formulation should be carried out with the recycled pigment as for any other new pigment introduced in a paint formulation to optimize its performance. © 2018, The Author(s).
|
|
| 10. |
- Karlsson, Mikael, 1978, et al.
(författare)
-
Recovery of titanium dioxide and other pigments from waste paint by pyrolysis
- 2015
-
Ingår i: Journal of Coatings Technology Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 1935-3804. ; 12:6, s. 1111-1122
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a model paint containing several types of inorganic pigments was pyrolyzed in a microwave-heated unit. The goal of the pyrolysis process was to recover and recycle the inorganic components in the paint, most importantly titanium dioxide (TiO2). The solid residue remaining after pyrolysis was further heat treated in air to remove most of the char in the TiO2-containing product. The recovered TiO2-containing product was used in two types of paint formulation as a replacement for virgin pigments. The properties of the paints containing recycled TiO2 pigment and extenders were evaluated and compared with a standard paint formulation containing only virgin TiO2 pigment and virgin extenders. A reduction in paint whiteness was observed but the opacity, gloss, and durability were nearly equivalent to that of the standard paint. Another consequence of using recycled pigments was that the recycled mix of TiO2 pigments and extenders was harder to disperse in the paint than the mix based on virgin materials, thus giving the painted surface a somewhat rough texture. The recycled material has shown promising results as a pigment/extender but further work is needed to optimize the recycled product to meet whiteness and dispersion requirements for incorporation in paint formulations on an industrial scale.
|
|
