(464f) Dependence of Physical Properties and Morphology of Acrylate/Epoxy Ipns

Interpenetrating polymer networks of polyethylene glycol (200)diacrylate and diglycidyl ether of bisphenol A were formed over a range of compositions and with different reaction orders. The reaction order was controlled by thermally initiating the cationic polymerization of the epoxy and by photoinitiating the free radical polymerization of the acrylate and by changing the processing order. The materials were evaluated for conversion by photoDSC and IR spectroscopy. Mechanical testing and rheology tests revealed information on the strength and hardness of the materials. Initial and final sample glass transition temperature was estimated from modulated differential scanning calorimetry. Optical microscopy and scanning electron microscopy was used to explore morphology and phase separation. All of the physical properties were dependent on composition. For example, the glass transition temperature and Young's modulus increase with epoxy concentration. Some of the material properties and the morphology were also dependent on reaction sequence. Large differences in glass transition temperatures were observed at the same composition but formed by different reaction sequence. Partially phase separated samples exhibiting maximum damping, correlating between the morphology and material properties. The experiments indicate that the relationships between phase morphology and physical properties of IPNs are complex and not readily predictable a priori.