PROPAGATION RATE COEFFICIENT OF VINYL NEO-DECANOATE BY PULSED-LASER POLYMERIZATION

The propagation rate coefficient (k(p)) for vinyl neo-decanoate has be en measured by pulsed laser polymerization (PLP) over the range -21 to +21 degrees C. The Mark-Houwink-Sakaruda constants required for GPC a nalysis were obtained using size-exclusion chromatography with an on-l ine viscosity detector, whose analysis required careful quantification of the uncertainties. The data, which satisfy various consistency tes ts for PLP (invariance of k(p) to laser pulse frequency, etc.), fit th e relation k(p) (dm(3) mol(-1) s(-1)) = 10(7.31) exp(-22.2 kJ mol(-1)/ RT); the joint confidence region for these Arrhenius parameters is als o given. These Arrhenius parameters are close to those for vinyl aceta te [10(7.16) exp(-20.7 kJ mol(-1)/RT)]; the small differences between these Arrhenius parameters are, however, statistically significant at the 95% confidence limit. The vinyl neo-decanoate used is actually a m ixture of isomers: CH2=CHOCOCR1R2CH3, where the total number of carbon s in R-1 and R-2 is 7; however, theory suggests that the k(p) values f or all these isomers should be very similar and polymerization of the mixture can be treated as a homopolymerization with a k(p) equal to th e average k(p).