Jj. Singh et al., MICROSTRUCTURAL CHARACTERIZATION OF SEMIINTERPENETRATING POLYMER NETWORKS BY POSITRON LIFETIME SPECTROSCOPY, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 134(1), 1998, pp. 113-120
Citations number
11
Categorie Soggetti
Instument & Instrumentation","Nuclear Sciences & Tecnology","Physics, Atomic, Molecular & Chemical
Thermoset and thermoplastic polyimides have complementary physical/mec
hanical properties. Whereas thermoset polyimides are brittle and gener
ally easier to process, thermoplastic polyimides are tough but harder
to process. II is expected that a combination of these two types of po
lyimides may help produce polymers more suitable for aerospace applica
tions. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset La
RC(TM)-RP46 and thermoplastic LaRC(TM)-IA polyimides were prepared in
weight percent ratios ranging from 100:0 to 0:100. Positron lifetime m
easurements were made in these samples to correlate their free volume
features with physical/mechanical properties. As expected, positronium
atoms are not formed in these samples. The second life time component
has been used to infer the positron trap dimensions. The ''free volum
e'' goes through a minimum at about 50:50 ratio, suggesting that S-IPN
samples are not merely solid solutions of the two polymers. These dat
a and related structural properties of the S-IPN samples have been dis
cussed in this paper. Published by Elsevier Science B.V.