Modification of Bisphenol-A Based Bismaleimide Resin (BPA-BMI) with an Allyl-Terminated Hyperbranched Polyimide (AT-PAEKI)
CONNECTICUT UNIV STORRS INST OF MATERIALS SCIENCE
Pagination or Media Count:
As a continuation of previous work involving synthesis of an allyl-functionalized hyperbranched polyimide, AT-PAEKI, we have studied the use of this reactive polymer as a modifier of bisphenol-A based bismaleimide resin BPA-BMI. This was pursued in anticipation of improvements in processability as well as physical properties including glass transition temperature, elastic modulus, and fracture toughness. Apparent miscibility, indicated by optical clarity with a single Tg, was observed for compositions containing up to 16 wt AT-PAEKI. Additionally, we observed complete suppression of monomer crystallization and a slight increase in the overall cure exotherm. By rheological characterization, blends containing 4 wt AT-PAEKI were found to feature a dramatic 65-fold reduction in the viscosity minimum during heating. Dynamic mechanical analysis DMA showed that the addition of 2, 4, 8 wt AT-PAEKI increases the cured modulus by approximately 10 from a base value of 3.4 GPa, while adding 16 wt AT-PAEKI decreases the modulus slightly to 3.3 GPa. DMA also revealed that the cured glass transition temperature increases monotonically with the addition of AT-PAEKI. Our results showed a modest toughening effect upon the addition of AT-PAEKI. We conclude that AT-PAEKI may serve as an effective reactive processing aid with slight improvements in Tg, modulus, and fracture toughness.
- Polymer Chemistry