CHARACTERIZATION AND RHEOLOGICAL INVESTIGATION OF POLYMER MICROGELS USED IN AUTOMOTIVE COATINGS

Citation
Lj. Boggs et al., CHARACTERIZATION AND RHEOLOGICAL INVESTIGATION OF POLYMER MICROGELS USED IN AUTOMOTIVE COATINGS, JCT, Journal of coatings technology, 68(855), 1996, pp. 63-74
Citations number
45
Categorie Soggetti
Chemistry Applied","Materials Science, Coatings & Films
ISSN journal
03618773
Volume
68
Issue
855
Year of publication
1996
Pages
63 - 74
Database
ISI
SICI code
0361-8773(1996)68:855<63:CARIOP>2.0.ZU;2-4
Abstract
The mechanism by which polymer microgels impart shear-thinning behavio r and a yield stress to the Newtonian, low molecular weight resin of h igh-solids solvent-borne automotive coatings is not well understood. T oward identifying this mechanism, we measured the viscosity of several microgel dispersions as a function of particle volume fraction as wel l as the size and polydispersity of the particles. Variations in the r elative ''softness'' of the particles, due to differences in the steri c layer thickness or crosslink density of the particles, gave rise to differences in the viscometry behavior. When dispersed in acrylic poly mer solutions, the microgels induced a yield stress that displayed a p ower-law dependence on particle concentration. Dynamic oscillatory mea surement were used to investigate the nature of the structure formed b y the microgels. The mechanism of structure formation can be attribute d to depletion flocculation when the polymer does not absorb to the mi crogels and to bridging flocculation when the polymer does adsorb.