
112 HIGH PERFORMANCE POLYMERS
influence the dielectric properties. Methods for sep-
arating the impurities from the capping reaction are
known [53].
A method that precipitates the capped poly
(phenylene ether) with an antisolvent [26] has been
described. The precipitated PPE resin containing a
residual aliphatic unsaturation has then lower levels of
residual impurities than the same compound isolated
by a devolatilization method.
A high yield of capped PPE with low levels of resid-
ual capping reagents can be obtained by a subsequent
liquid-liquid extraction with an alkanol/water wash.
The capping reaction mixtures can be purified by this
method with substantially ...