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The effects of cellulose nanowhiskers (CNWs) and irradiation dose on phase separation behavior as well as rheological and physical properties of Poly vinyl methyl ether (PVME) nanogels are investigated. Interactions between CNWs and polymer chains lead to the dehydration of PVME chains. Increasing the irradiation dose or CNW weight fraction enhances the VPTT, due to the decreased chain mobility. The phase separation behaviors of hybrid and nonhybrid nanogels are investigated at two different quench depths. At the shallow quench depth, the samples phase separate through nucleation and growth (NG) mechanism. However in the case of hybrid nanogels with a higher temperature, as a result of the enhanced dynamic asymmetry induced by the increased quench depth and the interaction of PVME chains with CNWs, the phase separation mechanism changes from NG to viscoelastic phase separation (VPS). The linear rheological behavior of nanogels was well correlated with the evolution of corresponding phase‐separating morphologies. At 40°C, a shoulder appeared in the storage modulus curve in the intermediate frequency range, due to shape relaxation of the droplets formed by NG mechanism. However, a solid‐like behavior was observed due to the existence of a percolated network structure induced by VPS at 60°C. POLYM. ENG. SCI., 59:899–912, 2019. © 2018 Society of Plastics Engineers

The evolution of rheological response, phase morphology, and electrical properties of PA6/POE blends (80/20) with graphene primarily localized inside the POE minor phase and at the interface are investigated during annealing under small-amplitude oscillatory shear (SAOS). Analysis of the dynamic viscoelastic response of these nanocomposites revealed that it is primarily governed by the graphene 3-dimensional structure, which evolves during the rheological measurement. Comparing isochronal frequency sweeps with frequency sweeps close to the equilibrium condition illustrates that graphene content and the evolution of its 3D structure have the same impact on rheological and electrical properties. Interestingly, regardless of different blend morphology, the linear and nonlinear viscoelastic behavior follow the fractal scaling theory indicating that the 3-dimensional graphene structure is self-similar. With increasing graphene content, the phase morphology changes from typical droplet-matrix morphology to droplet clusters and cocontinuous morphology. The stability of the blend morphology when annealing under SAOS (0.1 rad/s) depends on the balance between the rate of coalescence and shape relaxation. Interestingly, our morphological observation for nanocomposites containing 0.5% and 1% of graphene shows that while the presence of graphene slows down the shape relaxation, it increases the coalescence rate within the first 30 min of annealing as compared to the neat blend. The increased coalescence rate comes from the compressive deformation applied during sample loading along with a slow shape relaxation and graphene bridging between neighboring domains.