Complex Phase Separation in Poly(acrylonitrile−butadiene−styrene)-Modified Epoxy/4,4′-Diaminodiphenyl Sulfone Blends: Generation of New Micro- and Nanosubstructures

Abstract

The epoxy system containing diglycidyl ether of bisphenol A and 4,4'-diaminodiphenyl sulfone is modified with poly(acrylonitrile-butadiene-styrene) (ABS) to explore the effects of the ABS content on the phase morphology, mechanism of phase separation, and viscoelastic properties. The amount of ABS in the blends was 5, 10, 15, and 20 parts per hundred of epoxy resin (phr). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to investigate the final morphology of ABS-modified epoxy blends. Scanning electron microscopic studies of 15 phr ABS-modified epoxy blends reveal a bicontinuous structure in which both epoxy and ABS are continuous, with substructures of the ABS phase dispersed in the continuous epoxy phase and substructures of the epoxy phase dispersed in the continuous ABS phase. TEM micrographs of 15 phr ABS-modified epoxy blends confirm the results observed by SEM. TEM micrographs reveal the existence of nanosubstructures of ABS in 20 phr ABS-modified epoxy blends. To the best of our knowledge, to date, nanosubstructures have never been reported in any epoxy/thermoplastic blends. The influence of the concentration of the thermoplastic on the generated morphology as analyzed by SEM and TEM was explained in detail. The evolution and mechanism of phase separation was investigated in detail by optical microscopy (OM) and small-angle laser light scattering (SALLS). At concentrations lower than 10 phr the system phase separates through nucleation and growth (NG). However, at higher concentrations, 15 and 20 phr, the blends phase separate through both NG and spinodal decomposition mechanisms. On the basis of OM and SALLS, we conclude that the phenomenon of complex substructure formation in dynamic asymmetric blends is due to the combined effect of hydrodynamics and viscoelasticity. Additionally, dynamic mechanical analysis was carried out to evaluate the viscoelastic behavior of the cross-linked epoxy/ABS blends. Finally, apparent weight fractions of epoxy and ABS components in epoxy- and ABS-rich phases were evaluated from T(g) analysis.

High performance HTLNR/epoxy blend—Phase morphology and thermo‐mechanical properties

“…The log E ′ of the blends remains same to that of the unmodified epoxy network until the T g of the epoxy phase. A sharp decrease in the log E ′ was observed for all blends near the glass transition of the epoxy network; the values thereafter remained constant in the rubbery plateau region, which is typical for cross‐linked polymers 22. It is interesting to note that the T g of epoxy rich phase slightly shifts towards the low temperature side with the addition of HTLNR.…”

Effect of Cure Conditions on the Generated Morphology and Viscoelastic Properties of a Poly(acrylonitrile–butadiene–styrene) Modified Epoxy–Amine System

“…19−23 Depending on the thermoplastic content and curing conditions, dispersed, co-continuous, or phase-inverted morphologies can be generated. 24,25 The mechanical properties of the blends depend on the generated blend morphology. 11 The ABS/epoxy mixture used for these studies is heterogeneous before curing; SAN-g-polybutadiene (PB) exists in a homogeneous epoxy/SAN phase [polystyrene (PS) and SAN are miscible with the epoxy prepolymer, unlike PB].…”

Discovering and Developing Molecules with Optimal Drug-Like Properties

“…However, DMA results clearly demonstrated subtle differences in the tanδ between the samples prepared by the two distinct methods and this, in part, helped to explain exceptional difference in performance of the two materials (Karabanova et al 2008). Additional examples showing the utility of DMA in understanding the phase behavior of complex (i.e., multicomponent) systems can be consulted for further explanation (Jyotishkumar et al 2009;Tsuji and Ikada 1996). Moreover, although not considered a primary tool for measuring noncooperative motions in the pharmaceutical arena, secondary relaxation processes are often measured in the polymer sciences using DMA.…”