Amorphous phenolphthalein-based poly(arylene ether)- modified cyanate ester networks: Effect of thermal cure cycle on morphology and toughenability

✍ Scribed by S. A. Srinivasan; J. E. McGrath

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 690 KB
• Volume: 64
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970404)64:1<167::aid-app15>3.0.co;2-1

✦ Synopsis

Reactive functional thermoplastic poly(arylene ether) toughness modifiers were demonstrated to enhance toughness of brittle thermosetting cyanate ester networks and also allowed retention of a highly desirable stability to solvent stress cracking and a moderately high modulus. Careful control of the heterophase morphological structure was necessary to achieve significant toughening. In contrast to the well-defined morphologies of the reactive thermoplastic-modified networks, the use of nonreactive simple physical blend modifiers of the same molecular weight and backbone chemistry produced a macrophase separation and no apparent control over the sizes of the phaseseparated domains. Macrophase-separated morphologies are inherently process-sensitive and less desirable from the point of performance control and prediction. Generation of controlled microphase-separated morphologies can be achieved by systematically varying thermal cure cycles in the case of the reactive thermoplastic-modified systems. Such a cure cycle dependence of the morphology was particularly demonstrated for the case of the 25 wt % 15,000 »M n … (15K) phenolphthalein-based hydroxy-functionalized poly(arylene ether sulfone) (PPH-PSF-OH)-modified networks. Morphologies that exhibit finer textures of the phase separated domains usually result in lower fracture toughness values.