| 1. |
|
|
| 2. |
- Molenaar, F, et al.
(författare)
-
Rheological behaviour of latexes in-can and during film drying
- 1997
-
Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 30, s. 141-158
-
Tidskriftsartikel (refereegranskat)abstract
- In-can rheology was studied for sixteen model acrylate laticies and a commercial vinyl/acrylate copolymer latex. Following the model of Quemada the shear thinning behaviour, the effects of latex neutralisation and the copolymer composition could be described. Furthermore, the rheological effects of coalescing agents and thickeners (a cellulose and hydrophobically modified types thereof (HEC and HMEC), as well as associative urethanes (HEUR)) were studied. A special apparatus (the TNO Filmviscometer) was shown to be suitable to follow the rheological changes during drying of latex films. Effects of binder type, coalescent and thickener were investigated. The rheological effects of coalescents during drying could be related to the evaporation kinetics and latex particle swelling, while the effects of thickeners reflect the initial in-can rheology. The rheological changes during drying correlate to sagging and levelling behaviour and to the adsorption behaviour of associatice thickeners onto latex particles.
|
|
| 3. |
|
|
| 4. |
- Svanholm, T, et al.
(författare)
-
Adsorption studies of associative interactions between thickener and pigment particles
- 1997
-
Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 30, s. 167-171
-
Tidskriftsartikel (refereegranskat)abstract
- Adsorption of a HEUR thickener and a HMHEC thickener have been studied on two titanium dioxide pigment grades with and without dispersant previously adsorbed. One of the pigments had an acidic surface, mainly silica, and the other a more basic alumina/zirconia surface. Both associative thickeners adsorbed on pigments having a partially hydrophobic (alpha-olefinic maleic acid co-polymer) dispersant preadsorbed on the surface. No adsorption takes place when sodiumhexametaphosphate, a highly charged low molecular weight inorganic dispersant, was used. The alpha-olefinic-maleic acid co-polymer dispersant is shown to adsorb on a negatively charged silica surface. This is assigned to hydrogen bonding between unionised carboxylic groups from the dispersant and oxide ions on the pigment surface.
|
|
| 5. |
- Svanholm, T, et al.
(författare)
-
Associative thickeners: their adsorption behaviour onto latexes and the rheology of their solutions
- 1997
-
Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 30, s. 159-165
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between an associative thickeners in solution and an anionic surfactant has been studied with rheology and surface tension measurements. Both a HEUR thickener and low molecular weight HMHEC thickener interacted strongly with the surfactant. The addition of surfactant leads in both cases to a reinforced transient network at low and moderate levels of surfactant, whereas the structure is destroyed at higher levels. The HMHEC thickener was found more sensitive to high surfactant concentrations than the HEUR one. Surface tension measurements are complementary to the rheology studies and showed hydrophobic interaction between HEUR thickener and surfactant to be dominant over polyethylene oxide - surfactant interaction. Adsorption of thickener to latex was studied with monitoring of isotherms from depletion concentration, electrokinetic measurements and ellipsometry. The HEUR thickener used was found to adsorb more strongly to the latex than the surfactant in contrast to the HMHEC thickener.
|
|
