Pressing of polyacetylene films before (or after) sorption of dopant can reduce significantly the rate of sorption (or desorption) due to reduced effective surface area and pore sue, as is found in the experiments of vapour sorption and desorption of hexane and iodine. On exposure to air, the pressed films have significantly lower oxidation rates at 120°C than the unpressed ones.
ZUSAMMENFASSUNG:Das Pressen von Polyacetylenfilmen vor (oder nach) der Sorption von Dotierungsagentien kann die Geschwindigkeit der Sorption (oder Desorption) wegen der verringerten effektiven OberflBche und der PorengrODe sehr stark reduzieren. Dies wurde in Versuchen iiber die Sorption und Desorption von Hexan und Jod nachgewiesen. Bei der Einwirkung von Luft zeigen die geprefiten Filme wesentlich geringere Oxidationsgeschwindigkeiten bei 120 "C als die ungeprefiten.
Dynamic viscoelasticity measurements at 90 "C suggest an oxidation process for pristine polyacetylenes (PA's). For &rich PA, the oxidation can be divided into three regions: surface oxidation, bulk oxidation, and crosslinking. Crosslinking also occurs at the end of the surface oxidation period but does not occur in the bulk reaction period. For frans-rich PA, oxygen doping was complete after the first 15 min and occurred to a smaller extent than that of the cisrich PA. The rate of reaction of trans PA chains with oxygen is slow in comparison to that of crosslinking by radical combination or addition reactions with the PA chains. In the case of trans PA the concentration of radical chains formed by reaction with oxygen retains a steady value after the initial period up to the end of oxidation. 0025-1 16X/84/$03 .OO
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.