Dynamics of Phase Separation in Poly(acrylonitrile-butadiene-styrene)-Modified Epoxy/DDS System: Kinetics and Viscoelastic Effects

Abstract

The dynamics of phase separation and final morphologies of poly(acrylonitrile-butadiene-styrene) (ABS)-modified epoxy system based on diglycidyl ether of bisphenol A (DGEBA) cured with 4,4'-diaminodiphenylsulfone (DDS) have been monitored in situ throughout the entire curing process by using optical microscopy (OM), differential scanning calorimetry (DSC), rheometry, and small-angle laser light scattering (SALLS). The evolution of phase separation and final morphologies with substructures were explored by OM. The final morphologies of the blend cured at 150 and 165 °C are of phase-inverted type and are quite different from the final morphologies of the same blend cured at 180 °C, in which the final morphologies are cocontinuous. AFM observations of the fully cured sample confirmed the existence of three different phases, the epoxy continuous phase, SAN (styrene/acrylonitrile) continuous phase, and PB droplets at the interface, with a strong tendency to stay at SAN continuous phase. Furthermore, the continuous epoxy phase contains SAN particles and the continuous SAN phase contains epoxy particles. Cure kinetics and rheological results correspond well with the viscoelastic phase separation revealed by OM. The SALLS results display clearly that the phase separation takes place according to nucleation and growth mechanism followed by spinodal decomposition. The development of light scattering patterns during the second stage phase separation follows the Cahn-Hilliard model of spinodal demixing. Furthermore, the evolution of the scattering vector follows a Maxwell-type relaxation equation establishing the viscoelastic behavior of phase separation. The relaxation time of phase separation can be described by the Williams-Landel-Ferry equation for viscoelasticity. As a whole, the dependence of phase separation on cure temperature and the development of final morphologies and the associated mechanisms were explored in detail for the complex epoxy/ABS system.

Investigation of Cure Reaction, Rheology, Volume Shrinkage and Thermomechanical Properties of Nano-TiO2 Filled Epoxy/DDS Composites

“…This is followed by a crossover point (gelation point) where equals that means the system acts as both elastic and viscous, storing and dissipating an identical amount of energy at this point [14,42]. Epoxy composites with, 0.7, 3.6, and 6.9 wt% TiO 2 follow a similar trend.…”

“…In this processes, polymer synthesis and shaping take place in a single operation; this involves the conversion of liquid monomers or polymers into solid crosslinked polymers [14,15]. In addition, tendency of polymers to expand or contract during processing is a problem that has been widely recognized, especially for epoxy systems [16,17].…”

Polymerization‐induced phase separation and resulting thermomechanical properties of thermosetting/reactive nonlinear polymer blends: A review

“…The microstructural evolution of the PIPS process can be successfully monitored and has been studied extensively by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), optical microscopy (OM), rheological dynamic analysis, small-angle laser light scattering, and the combination of the aforementioned analyses. [23][24][25][26][27][28][29] In addition to these methods, cloud-point, dielectric relaxation spectroscopy, and temperature-jump light-scattering and rheometry measurements have also been widely used to investigate PIPS in thermosets. [30][31][32][33][34] Jyotishkumar et al 24 traced the dynamics of phase separation and the final morphologies of a poly(acrylonitrile-butadiene-styrene) (ABS) modified diglycidyl ether of bisphenol A (DGEBA) epoxy system in situ with OM, DSC, rheometry, and small-angle laser light scattering.…”

Curing kinetics of nanostructured epoxy blends toughened with epoxidized carboxyl-terminated liquid rubber

“…The addition of fillers to the epoxy resin systems will alter their morphology and curing kinetics [23][24][25][26][27]. Vijayan et al [26] have investigated the effects of nanoclay and carboxyl-terminated (butadiene-co-acrylonitrile) (CTBN) rubber on the reaction induced phase separation and curing kinetics of an epoxy/cyclic anhydride system using dynamic and isothermal differential scanning calorimetry (DSC), and found that nanoclay surfactant accelerated the cure reaction, whereas the phase-separated CTBN hindered the cure reaction.…”