UV-visible technique for studying powder coatings and their dissolution
Küçük Resim Yok
Tarih
2001
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Federation Soc Coating Tech
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
UV-Visible (UVV) technique was used to monitor powder coating and its dissolution processes from hard latex particles. Three sets of latex coatings were prepared from poly(methyl methacrylate) (PMMA) particles. The first set of coatings was annealed at elevated temperatures in various time intervals during which reflected photon intensity, I-rf, was measured. The second set of coatings was annealed at various temperatures in 10 min time intervals during which transmitted intensity, I-tr, was measured. I-rf first decreased and then increased as the annealing temperature was increased. Decrease in I-rf was explained with the void closure mechanism due to viscous flow. Increase in I-tr and I-rf against time and temperature were attributed to an increase in crossing density at the junction surface. The activation energy of viscous flow, DeltaH was measured and found to be around 8 kcal/mol and the back and forth activation energies (DeltaE(rf) and DeltaE(tr)) were measured and found to be around 49 and 53 kcal/mol for a reptating polymer chain across the junction surface. Diffusion of solvent molecules (chloroform) into the annealed latex coatings was followed by desorption of PMMA chains for the third set of films. Desorption of pyrene, P, labeled PMMA chains was monitored in real-time by the absorbance change of pyrene in the polymer-solvent mixture. A diffusion model with a moving boundary was employed to quantify realtime UVV data. Diffusion coefficients of desorbed PMMA chains were measured and found to be between 2 and 0.6 x 10(-11) cm(2) s(-1) in the 100 and 275 degreesC temperature range.
Açıklama
79th Annual Meeting of the Federation-of-Societies-for-Coatings-Technology -- NOV 04-07, 2001 -- ATLANTA, GEORGIA
Anahtar Kelimeler
T Latex-Particles, Film Formation, Energy-Transfer, Poly(Methyl Methacrylate), Polymer Dissolution, Photon Transmission, Fluorescence, Diffusion, Kinetics, Coalescence
Kaynak
Journal Of Coatings Technology
WoS Q Değeri
Q3
Scopus Q Değeri
N/A
Cilt
73
Sayı
923
