Penetration of p-xylylene vapor into small channels prior to polymerization

Autor: W. Luijks, D. J. Broer
Rok vydání: 1981
Předmět:
Zdroj: Journal of Applied Polymer Science. 26:2415-2422
ISSN: 1097-4628
0021-8995
Popis: The penetration of p-xylylene gas into small rectangular channels has been studied by measuring the thickness of the formed poly(p-xylylene) films as a function of penetration distance. The experimental values are related to the theoretical penetration curves under various process conditions. At low monomer and residual gas pressures, meeting the Knudsen conditions for wall-to-wall collisions of the monomer, a molecular flow model is valid which shows large penetration distances and a gradual decrease in film thickness. At increasing monomer pressures and corresponding deposition rates the molecular flow at the entrance is disturbed in favor of a more viscous type of flow. Consequently an accumulation of poly(p-xylylene) has been observed in the first part of the channel. At increasing residual gas pressures the penetration can be described by a mass transfer model. Under our process conditions however, its ideal penetration characteristics could not be realized due to a visccus flow transition at the entrance of the channel. Polymerization of chloro-p-xylylene at low residual gas pressures showed a molecular flow controlled penetration, also at high deposition rates. Owing to its higher reactivity the penetration is less favorable than for p-xylylene.
Databáze: OpenAIRE
Externí odkaz: