The
effect of various solvents on the de-cross-linking reaction
of cross-linked polyethylene under subcritical and supercritical conditions
was studied. The gel content of the de-cross-linked polyethylene decreased
from 60 to 0.8–2.5% at 380 °C within 5 min in all of the
solvents tested in this study. When water, ethanol, and 2-propanol
were used, the M
w of the de-cross-linked
polyethylenes decreased from 349,000 to 200,000–227,000 g/mol,
and much lower M
w values of 70,000–90,000
g/mol were observed when acetone and diisopropyl ether were used.
The de-cross-linked polyethylenes treated in the different solvents
had a very similar chemical structure to raw polyethylene. According
to a kinetic study using a first-order reaction model, the de-cross-linking
rate in each solvent increased in the order 2-propanol < ethanol
< n-hexane < water < methanol ≪ diisopropyl
ether ≪ acetone at 350 °C.
De-crosslinking of silane-cross-linked
polyethylene (S-XLPE) in
supercritical methanol was investigated. Changes in gel content and
molecular weight with reaction temperature and reaction time were
analyzed in a batch reactor, and kinetic parameters were calculated
from the experimental data. The reaction time for de-crosslinking
shortened as the reaction temperature increased and the complete de-crosslinking
of S-XLPE was achieved at 320 °C and 20 min. The de-crosslinking
rate of S-XLPE fit well with the first order reaction model. In addition,
the molecular weight of de-cross-linked polyethylene (DXPE) decreased
further as reaction temperature and reaction time increased when the
reaction temperature exceeded 360 °C relative to that of the
original polyethylene before being cross-linked. The decreasing molecular
weight trend also fit well with the first order reaction model.
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.