
350 HIGH PERFORMANCE POLYMERS
The polyhedral oligomeric silsesquioxane structure
affects the rheological and cure characteristics but was
found to have no discernible influence on the proper-
ties in the cured state.
15.2.11 Bis(maleimide)s
The most common thermosetting PI resins are
bis(maleimide) resins. A wide variety of these resins
are known. Commercially available bismaleimide
thermoset compositions are well known for their
high modulus, and excellent resistance to thermal
degradation.
On the otherhand, these thermoset compositions are
also well known for their brittleness [52]. The utility of
the bismaleimide class of thermosets can be improved
by