between 2.8 and 3.5 ppm. On the basis of these results, it can
be postulated that the first weight loss during thermal degradation
of PMBeA is due to water elimination. This behavior is
similar to that exhibited by PMAA during its thermal degradation
in which elimination of water occurs at ca. 250 C [4,5]. It
should be mentioned that the theoretical amount obtainable in
converting all PMBeA to the corresponding anhydride is only
4.4%. The fact that the weight loss obtained at the first degradation
step (ca. 20%) exceeds the theoretical value supports
the hypothesis that indicates that some water is associated
with carboxylic groups. This behavior has been also reported
by Grant and Grassie [4] for PMAA.
Undegraded PMBeA (Fig. 9a) presents the following main
absorption bands: at 3427, 2669, 2539 and 1694 cm1 which
are characteristics for carboxylic group; at 3088, 1603 and
1504 cm1, attributed to aromatic structure; at 1753 cm1, assigned
to ester group from methacrylate; and finally, at 2997e
2854 cm1 corresponding to methyl and methylene groups.
The spectrum of PMBeA heated at 300 C (see Fig. 9b) was
very similar to that of undegraded polymer although subtle differences
were observed. The appearance of a shoulder at
1802 cm1 suggested the formation of an anhydride type