Mechanical and morphological study of polyurethane/polystyrene interpenetrating polymer networks containing ionic groups

✍ Scribed by Douglas J. Hourston; Franz-Ulrich Schäfer; Nicholas J. Walter; Michael H. S. Gradwell

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 480 KB
• Volume: 67
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980321)67:12<1973::aid-app3>3.0.co;2-k

✦ Synopsis

The viscoelastic and mechanical properties and the morphology of polyurethane (PUR)/polystyrene (PS) interpenetrating polymer networks (IPNs) containing ionic groups have been investigated. Dynamic mechanical thermal analysis (DMTA) revealed a pronounced change in the viscoelastic properties upon the introduction of ionic groups. For the 70 : 30 and 60 : 40 PUR/PS IPN compositions, the DMTA data changed from a dominant PUR to a dominant PS loss factor peak. Higher intertransition loss factor values indicated a significant improvement of IPN component mixing with increasing ionic content. The stress at break values increased only moderately, whereas sharp rises in Young's modulus and hardness values were found at 2 wt % ionic groups. At the same time, the strain at break values decreased by half. Scanning and transmission electron microscopy (TEM) indicated a grossly phase-separated morphology for the 70 : 30 PUR/PS IPN without ionic groups. With increasing methacrylic acid (MAA) content, the PS phase domain sizes decreased. At 2 wt % of ionic groups, a TEM micrograph showed interconnected PS phase domains resembling a network structure.