| 1. |
- Claesson, Hans, et al.
(författare)
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Rheological behaviour during UV-curing of a star-branched polyester
- 2002
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Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 44:1, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- Using a rheometer coupled with an UV-light generator, the viscoelastic behaviour during the fast cure of star-branched polyester is investigated. The 32 arm star polymers consist of a hyperbranched polyester core, Boltorn(TM) and linear grafts of poly(E-caprolactone) (degree of polymerisation: 20-52) with methacrylate end groups. The resins are crystalline and the melting points range from 34 to 50degreesC; films can be formed and cured below 80degreesC. The crossover of G' and G was used as the gel point. The time to reach the gel point, a few seconds, increases linearly with molecular weight.
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| 2. |
- Johansson, Mats, et al.
(författare)
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Design of coating resins by changing the macromolecular architecture : solid and liquid coating systems
- 2003
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Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 48:2-4, s. 194-200
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Tidskriftsartikel (refereegranskat)abstract
- An increased demand for new and improved coating systems, both due to environmental as well as performance reasons, have appeared during the last decades. Techniques such low temperature curing powder coatings, radiation curable systems, and high solids have gained an increased interest and obtained significant market shares. Although improved in many aspects, these systems still have limited use in certain applications due to technical reasons. One way to change the properties of thermoset resins that has obtained significant interest during the last decade is by changing the molecular architecture of the resin. An example of polymers which exhibit different properties compared to conventional linear structures are highly branched, dendritic, polymers [1-3]. These polymers, for example, exhibit a higher solubility and lower melt viscosity compared to their linear counterparts. They can also be tailored with respect to functionality and polarity to adjust the properties for certain applications. Coating resins based on hyperbranched polymers have been described both for liquid UV-curable systems as well as powder coatings [4-6]. This presentation will focus on how properties of resins based on dendritic polymers can be tailored and how this can applied to coating systems such as powder coatings, radiation curable resins and no-solvent liquid systems. The correlation between resin structure and its properties both before and after cure will be discussed.
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| 3. |
- Krupicka, A., et al.
(författare)
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Mechanical response of ductile polymer coatings to contact and tensile deformation
- 2003
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Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 48:1, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Ductile polymer coatings were investigated in terms of their response to uniaxial deformation and contact deformation with respect to indentation and scratching. The effects of pigmentation, contact geometry, load and speed on the mechanical response were studied. The materials have been tested with extended spherical contacts deep into the coating layer and concentrated conical contacts close to the surface. The residual deformation pattern was examined with optical microscopy, white-light interferometry and atomic force microscopy. In the case of extended spherical contacts, corresponding to small effective strains, there was a correlation between the magnitude of residual deformation and the tensile strength. In the case of concentrated conical contacts, corresponding to larger strains, the materials were ranked differently. Reproducible failure transitions were detected with increased scratch load for the conical contacts. These failure transitions could not be directly linked to uniaxial break parameters. Stratification appears to be an issue in pigmented coatings. The effect of pigmentation was increased tensile stiffness and improved scratch resistance.
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| 4. |
- Krupicka, A., et al.
(författare)
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The effect of long-term recovery and storage on the mechanical response of ductile poly(urethane) coatings
- 2003
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Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 48:1, s. 14-27
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Tidskriftsartikel (refereegranskat)abstract
- The scope of this work has been to investigate storage and recovery processes in ductile polymer coatings. The effects of storage have been measured in terms of variations in mechanical response with time. The use of contact tests in combination with sophisticated surface imaging tools offered unique possibilities to monitor deformation recovery over long periods of time. The kinetics of the recovery processes has been monitored. Polyurethane coatings were found to recover in a similar fashion to a viscous liquid. By comparing the time scale of the recovery with transient tests, it was evident that this was not a viscoelastic effect. The effect of exposure to water and humidity on deformation response and recovery was significant for polyurethane coatings. In addition, high amounts of pigmentation had a great effect on recovery processes. Surface-, bulk-, and interfacial-properties were greatly affected by storage time.
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| 5. |
- Krupicka, A., et al.
(författare)
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Use and interpretation of scratch tests on ductile polymer coatings
- 2003
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Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 46:1, s. 32-48
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Tidskriftsartikel (refereegranskat)abstract
- The use and interpretation of contact scratch tests on polymer coatings has been investigated. The influences from test parameters such as scratch speed, contact geometry and load on the deformation response were examined. Two ductile polymer coatings of commercial grade tailored for pre-painted steel applications were used as model systems. The residual deformation pattern was examined with optical microscopy, white-light interferometry, and atomic force microscopy. Free-standing coating films were also subjected to static, transient and dynamic tensile testing to find a correlation between the intrinsic coating properties and the scratch behavior. The results indicate that the use of a single set of contact parameters is insufficient to reflect the overall response of a coating material to real contact conditions. A well-designed scratch test will however give a substantial amount of useful information.
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| 6. |
- Abbadessa, Anna, et al.
(författare)
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Layer-by-layer assembly of sustainable lignin-based coatings for food packaging applications
- 2023
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Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.
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| 7. |
- Abolhasani, Hasanali, et al.
(författare)
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Development of self-healable acrylic water-based environmental-friendly coating as an alternative to chromates coatings
- 2023
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Ingår i: Progress in organic coatings. - : Elsevier B.V.. - 0300-9440 .- 1873-331X. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- In this study, different coating systems, including solvent-based epoxy and water-based acrylic resins, were evaluated for their potential as an alternative to chromate coatings in order to avoid Cr(VI) toxic hazards. The resins were used as either pigment-free coatings or were formulated with 20-wt% zinc/aluminum pigments. The coatings were subsequently applied on galvanized ST12 steel plates and their corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) evaluations. The effect of the binder and pigment type on the impact resistance of two different polymeric coatings was also evaluated. The results of impact tests revealed completely peeled film from the substrate for epoxy coatings. However, under the same experimental conditions, very few small cracks were created in water-based acrylic coatings for both pigmented and pigment-free cases. In addition, some other parameters such as drying time and coating cost were taken into account to select a good alternative to chromate coatings. The results of this work can facilitate the introduction of an inexpensive environmentally friendly acrylic coating as a promising self-healing alternative to chromate coating.
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| 8. |
- Bonin, Pierre, et al.
(författare)
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Impedance analysis of the barrier effect of coil-coated materials : Water uptake and glass transition variations
- 2021
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Ingår i: Progress in organic coatings. - : Elsevier B.V.. - 0300-9440 .- 1873-331X. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, an industrial polyester coil-coated steel sample was characterized by electrochemical impedance spectroscopy. The diagrams were obtained for various immersion times in a 0.5 M NaCl solution for three different initial states of the same coil coating (as received, dried and dried after the impedance measurements). The aim of the study was to have a better knowledge of how the water uptake influences the coil coating physical properties and to extract relevant parameters of the ageing processes. From the high-frequency part of the impedance diagrams, the water uptake was calculated using a linear rule of mixtures. Two sorption regions were observed for the dried samples suggesting the presence of porosities already filled with ambient moisture for the as-received sample. It was shown that the water uptake was a slow process and, independently of the initial state of the sample, a saturation plateau was never reached, even after 456 h of immersion. A time constant, clearly visible on the phase angle of the impedance diagrams, was analysed through the dielectric permittivity formalism and attributed to the signature of the dielectric manifestation of the glass transition. This time constant was shifted to higher frequencies with increasing water fraction (increasing immersion time), consistent with a plasticization effect. This result was supported by differential scanning calorimetry measurements. Finally, the data obtained for the different initial states of the coating highlighted that, even if the water uptake was reversible, the sorption kinetics was different for the sample dried after the impedance measurements. This could be of importance in the degradation process of the coil coated steel.
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| 9. |
- Cairns, Mathew J., et al.
(författare)
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Tetraethylorthosilicate-containing barrier dispersion coatings-Mechanism of action
- 2020
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Ingår i: Progress in organic coatings. - : Elsevier. - 0300-9440 .- 1873-331X. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of tetraethylorthosilicate (TEOS) as a silica precursor for water barrier poly(styrenebutadiene) latex dispersion coating applications. The TEOS is adsorbed at the surface interface by the latex particles in the aqueous dispersion due to the hydrophobic nature of the surface and the TEOS. It then undergoes hydrolysis and condensation to the silica phase in the interstitial sites in the partially dry close-packed polymer structure. The fully cured film exhibits a greater degree of coalescence than films prepared from the unmodified latex binder. Large discrete silica particles are not formed within the cured film; rather the films contain homogenous silica dispersion with a probable particle size no larger than 10 nm. This higher degree of coalescence results in improvements in water vapour barrier performance from 121 - 20 g m(-2) d(-1), with direct water barrier performance (Cobb 120 s) improving from 25 to < 2 g m(-2), compared to the silica-free film.
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| 10. |
- Caussé, Nicolas, et al.
(författare)
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Ageing processes of coil-coated materials : Temperature-controlled electrochemical impedance analysis
- 2023
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Ingår i: Progress in organic coatings. - : Elsevier B.V.. - 0300-9440 .- 1873-331X. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, an industrial polyester coil-coated steel was characterized by electrochemical impedance spectroscopy (EIS) during immersion in a 0.5 M NaCl solution for different temperatures (30, 40, 50 and 60 °C). The objective was to propose a methodology to follow the ageing of the coil-coated system, from the first stage of water uptake until the blistering appearance. Relevant parameters were extracted from the EIS diagrams to analyse ageing processes of the polymer and of the metal/polymer interface. Water uptake was determined from the high-frequency part of the impedance diagrams using a linear rule of mixtures. By increasing the temperature, both the water uptake kinetics and the water content in the coating increased. The effect of water uptake on the physical structure of the coating (plasticization) was discussed through the analysis of a time constant corresponding to the dielectric manifestation of the polymer glass transition. At 40, 50 and 60 °C, appearance of corrosion was detected on the impedance spectra by a decrease, at low frequency, of the impedance modulus and of the phase angle. For 60 °C, the corroded surface area as a function of time, was assessed from the EIS data analysis with adapted equivalent circuits. The corroded surface areas followed similar trend as blister surface areas determined from images analysis.
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