Rheology and pressure-volume-temperature behavior of the thermoplastic poly(acrylonitrile-butadiene-styrene)-modified epoxy-DDS system during reaction induced phase separation

The rheology and volume shrinkage characteristics of an epoxy matrix based on diglycidyl ether of bisphenol-A (DGEBA) cured with 4,4'-diaminodiphenylsulfone (DDS) and those containing poly( acrylonitrile-butadiene-styrene) (ABS) at compositions ranging from 0 to 12.9 wt% were monitored in situ using rheometry and pressure-volume-temperature (PVT) analysis. This investigation has focused on the importance of cure rheology on microstructure formation, using rheometry. The relationship between rheological properties and the phase separation process was carefully explored. The evolution of storage modulus, loss modulus, and tan delta was found to be closely related to the evolution of complex phase separation. It was found that complex viscosity profiles follow an exponential growth with curing at various temperatures. The characteristic relaxation time of viscosity growth can be described by the WLF equation. In the second part of this manuscript PVT measurements carried out to understand the volume shrinkage of the blend matrix with respect to cure are described. Volume shrinkage is highest for a neat epoxy system, the volume shrinkage decreased linearly up to 6.9 wt% ABS then it shows a different trend for the 10 and 12.9 wt% ABS modified epoxy blend. Investigation of the volume shrinkage behavior in these blends by various techniques confirms that the shrinkage behavior is influenced by thermoplastic phase separation during cure.