Fluorescence and UV techniques for studying neck growth and equilibration processes during latex film formation
✍ Scribed by Pekcan, Önder; Canpolat, Murat; Arda, Ertan
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 234 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0959-8103
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✦ Synopsis
Steady state Ñuorescence (SSF) and UVÈvisible techniques have been used to study neck growth and equilibration processes during the coalescence of hard latex particles. Latex Ðlms were prepared separately by annealing pyrene labelled and unlabelled poly(methyl methacrylate) (PMMA) particles above (P y ) their glass transition temperature. During the annealing processes, the optical clarity of the Ðlms increased considerably. Direct Ñuorescence emission of excited pyrene from labelled latex Ðlms was monitored as a function of annealing temperature to detect this change. Void closure temperature and time were (T c ) ( t c ) determined at the point where the Ñuorescence emission intensity became maximal. Below this point, the increase in Ñuorescence intensity against tem-(I op ) perature was used to determine the activation energy for viscous Ñow (*H B 47 kcal mol~1). The decrease in above the void closure temperature I op was used to determine the backbone activation energy (*E B 44 kcal mol~1) for the interdi †using chains. Unlabelled PMMA particles were used to prepare Ðlms for UVÈvis measurements. The transmitted photon intensity from these Ðlms (I tr ) increased as the annealing temperature was increased. This behaviour was also used to determine the backbone activation energy (*E B 35 kcal mol~1) for the interdi †using chains.