Aqueous emulsions, dispersions and solutions of polyurethanes; synthesis and properties

Dieterich, Dieter

doi:10.1016/0033-0655(81)80002-7

Cited by 375 publications

(158 citation statements)

References 28 publications

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“…The suspensions investigated here are designed for a shelf-life of more than six months. According to the manufacturer, the polyurethane dispersion is synthesized by solution polymerization and subsequent precipitation without the use of surfactants [75]. The polyurethane particles are electrostatically stabilized by surface charges due to ionized sulfonate groups.…”

Section: Highly Concentrated Polymer Dispersionsmentioning

confidence: 99%

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

Georgieva

Dijkstra

Fricke

et al. 2010

Journal of Colloid and Interface Science

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We have investigated the phenomenon of flow-induced aggregation in highly concentrated colloidal dispersions exposed to strongly converging flow fields. This phenomenon is relevant not only for classical technical operations like coating, pumping or filtration, but also for the application of concentrated suspensions in upcoming processing technologies based on microfluidic devices. A ring-slit device (gap height 10 micrometers to 25 micrometers), which allows for a variation of flow kinematics in a wide range, has been developed in order to investigate this phenomenon. Various polymer dispersions with different particle surface properties have been used as model systems. Our experiments exclude, that channel clogging is due to retention of pre-existing aggregates, fouling or hydrodynamic bridging. Instead, we demonstrate that clogging of the microchannel is induced by hetero-coagulation between primary colloidal particles and micron-sized impurities present at concentrations on the order of 100 ppm to 1000 ppm. Clogging can occur even if the diameter of these impurities is less than a tenth of the gap height. Aggregation takes place in the converging flow field at the channel entrance, but not in the shear field within the slit. It can be suppressed by appropriate stabilization of the primary particles

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Section: Highly Concentrated Polymer Dispersionsmentioning

confidence: 99%

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

Georgieva

Dijkstra

Fricke

et al. 2010

Journal of Colloid and Interface Science

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“…In the early 1970s, while the first polyurethane dispersions (in water) were patented [15], more than 90% of the paint and coatings sold worldwide were low solids (5-20% by weight) solventbornecoatings. The increased demands for improved technical performance and/or minimized environmental contamination have motivated research on the development of new PU coating systems.…”

Section: Historymentioning

confidence: 99%

Polyurethane coatings used in twentieth century outdoor painted sculptures. Part I: comparative study of various systems by means of ATR-FTIR spectroscopy

2017

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Like acrylics and alkyds, polyurethanes (PUs) represent an important class of industrial paints adopted by 20th and 21st artists; primarily by those creating outdoor painted sculptures (OPS). Because PU coatings offer a compromise between aesthetic and performance expectations, unachievable with other types of paints, they are commonly recognized as the most appropriate option for painted artworks intended for an outdoor setting. However, the PU class includes various systems and subgroups possessing very different properties. Through the FTIR-ATR study of 137 PU coating references from the Getty Conservation Institute (GCI) reference collection, this paper outlines the differences and the similarities existing, in terms of the composition, of two package solvent-borne, two package waterborne, one package water-borne and fluoropolymer polyurethanes. The comparison of the obtained FTIR-ATR results allowed determining markers helpful to discriminate specific PU subgroups by means of ATR-FTIR spectroscopy. The goals of this paper are to provide to the conservation professionals a better understanding of the versatility and diversity of PU coatings and to facilitate the identification of the various types initially used by the artists.

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“…Study has shown that the particle size of dispersion depends on the content of DMPA. Therefore, increased amount of DMPA leads to more ionic centres in the PUD backbone and thereby increasing hydrophilicity of the polymer and hence reductions in particle size (Dieterich, 1981;Jacobs & Yu, 1993;Rosthauser & Nachkamp, 1986). …”

Section: Ingredients For Water-based Pudmentioning

confidence: 99%

Thermal Analysis of Polyurethane Dispersions Based on Different Polyols

Cakić¹,

Ristić²,

Ristić³

2012

Polyurethane

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Aqueous emulsions, dispersions and solutions of polyurethanes; synthesis and properties

Cited by 375 publications

References 28 publications

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

Polyurethane coatings used in twentieth century outdoor painted sculptures. Part I: comparative study of various systems by means of ATR-FTIR spectroscopy

Thermal Analysis of Polyurethane Dispersions Based on Different Polyols

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