Water permeability of pigmented waterborne coatings

Donkers, Paj Pim; Huinink, HP Henk; Erich, Sjf Sebastiaan; Reuvers, Njw Nico; Adan, Ocg Olaf

doi:10.1016/j.porgcoat.2012.08.011

Cited by 27 publications

(13 citation statements)

References 20 publications

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“…the water content. NMR Imaging has been proven to be an excellent tool to determine the distribution and the concentration of water in wood during drying (Quick et al 2007;Stenström et al 2014;Dvinskikh et al 2011a, b), and during uptake (Robertson and Packer 1999;Van Meel et al 2011;Donkers et al 2013). In situ determination of local moisture content has been achieved by portable NMR devices (Casieri et al 2004;Dvinskikh et al 2011b).…”

Section: Introductionmentioning

confidence: 99%

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

et al. 2016

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Knowledge on moisture transport in wood is important for understanding its utilization, durability and product quality. Moisture transport processes in wood can be studied by Nuclear Magnetic Resonance (NMR) imaging. By combining NMR imaging with relaxometry, the state of water within wood can be identified, i.e. water bound to the cell wall, and free water in the cell lumen/vessel. This paper presents how the transport of water can be monitored and quantified in terms of bound and free water during water uptake and drying. Three types of wood from softwood to hardwood were selected covering a range of low to high density wood; pine sapwood and oak and teak. A calibration is performed to determine the different water states in each different wood type and to convert the NMR signal into moisture content. For all wood types, water transport appeared to be internally limited during both uptake and drying. In case of water uptake, free water was observed only after the cell walls were saturated with bound water. In case of drying, the loss of bound water starts only after vanishing of free water, irrespective of the position. Obviously, there is always a local thermodynamic equilibrium of bound and free water for both uptake and drying. Finally, we determined the effective diffusion coefficient (D eff ). Experimentally determined diffusion constants were compared with those derived by the diffusion models for conceptual understanding of transport mechanism. We found that diffusion in the cell wall fibers plays a critical role in the transport process.

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Section: Introductionmentioning

confidence: 99%

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

et al. 2016

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“…NMR spectroscopy and relaxometry analysis have similarly been used to characterize water molecules in latex films during the drying process and have identified three different environments for water: (1) isolated in the surfactant layers or aggregated in pockets; (2) interfacial layers between nanoparticles; and (3) dissolved in the polymer . In an NMR profiling study, the presence of interfaces between the polymer phase and inorganic pigments was determined to provide a pathway for diffusion and to increase the kinetics of transport …”

Section: Introductionmentioning

confidence: 99%

Explanations for water whitening in secondary dispersion and emulsion polymer films

Liu

Gajewicz

Rodin

et al. 2016

J Polym Sci B Polym Phys

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The loss of optical transparency when polymer films are immersed in water, which is called “water whitening,” severely limits their use as clear barrier coatings. It is found that this problem is particularly acute in films deposited from polymers synthesized via emulsion polymerization using surfactants. Water whitening is less severe in secondary dispersion (SD) polymers, which are made by dispersing solution polymers in water without the use of surfactants. NMR relaxometry in combination with optical transmission analysis and electron microscopy reveal that some of the water sorbed in emulsion polymer films is contained within nanosized “pockets” or bubbles that scatter light. In contrast, the water in SD polymer films is mainly confined at particle interfaces, where it scatters light less strongly and its molecular mobility is reduced. The addition of surfactant to a SD creates a periodic structure that displays a stop band in the optical transmission. The total amount of sorbed water is not a good indicator of polymers prone to water whitening. Instead, the particular locations of the water within the film must be considered. Both the amount of water and the size of the local water regions (as are probed by NMR relaxometry) are found to determine water whitening. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1658–1674

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“…Thus, the processing wastewater composition often varies considerably, also in terms of its quantities [1][2][3]. Typical components of the contamination load are the ingredients of parent paints, eg filling substances such as chalks (with major components: CaCO 3 and MgCO 3 ), barite (containing mainly BaSO 4 ), talk (containing mainly magnesium hydroxysilicate Mg 3 (OH) 2 Si 4 O 10 ), kaolin (containing mainly kaolinite -alkaline aluminium silicate (Al 4 [Si 4 O 10 ](OH) 8 ) and fused quartz and mica), silica (mainly SiO 2 ), mica (mainly alkaline aluminates such as: AB 2-3 (OH,F) 2 (Si,Al 4 O 10 ), where: A -mainly potassium, sodium and calcium, whereas Bmainly iron, magnesium, manganese, lithium and aluminium), titanium white (containing mainly TiO 2 ), siccatives, pigments, thickeners and surfactants, as well as defoaming agents [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Technological effluents generally contain significant concentrations of colloids and suspensions of a different degree of dispersion fastness, which is also a function of quantity and type of cross-linking agents added to semi-finished products, such as polyalcohols, polyurethanes, phenol-formaldehyde resins, urea-formaldehyde resins, amine-formaldehyde resins etc.…”

Section: Introductionmentioning

confidence: 99%

Research on physico-chemical pretreatment of wastewater from the production of wood coating materials

Żak

Rauckyte-Żak

Laurinavičius

et al. 2014

Ecological Chemistry and Engineering S

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This paper presents the results of the research conducted on the installation designed for physico-chemical pretreatment of technological wastewater in the volume of up to 5.0 m 3 /day discharged from the production of protective and decorative coating materials used for wooden surfaces. The subject-matter installation constructed on a mobile pallet, consisted of a storage-averaging tank where concentrations were equalised with the use of circulation aeration and mixing. A variant, preliminary pre-oxidation with the use of hydrogen peroxide was conducted in this tank. A substantial installation set for the wastewater treatment plant consisted of two preliminary tube reactors, one cylindrical-conical processing reactor, stations for preparing and dispensing reagents and the sediment dewatering station. Considerable reductions in main chemical indicators of water pollution were obtained in the installation: both total suspended solids (TSS) and ether extract (EE) -more than 98%, chemical oxygen demand (COD) -46-54%, biochemical oxygen demand (BOD5) -39-46%, and free formaldehyde (HCHO) -14-27% due to the use of pre-oxidation and the acid -alkaine double coagulation by applying the ALCAT 105 -SAX 25 system. The use of pre-oxidation with hydrogen peroxide in doses 250.0-450.0 mg/l and then two-stage coagulation resulted in an increase in the reduction of: COD and BOD5 by ca 10-15%, and HCHO by ca 58-66% with reference to the water pretreatment without pre-oxidation. The assessment of sediments formed during the process of pretreatment was made determining the leachable forms of metals (Cu, Ni and Ti) according to methodology of TCLP in compliance with the US EPA Method 1311.

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Water permeability of pigmented waterborne coatings

Cited by 27 publications

References 20 publications

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

Explanations for water whitening in secondary dispersion and emulsion polymer films

Research on physico-chemical pretreatment of wastewater from the production of wood coating materials

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