Effect of chemically reduced graphene oxide on the isothermal and non-isothermal phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) binary polymer blends

Abstract

The effect of a small amount of chemically reduced graphene oxide (CRGO) on the isothermal and nonisothermal phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/ SAN) blends was investigated by using time-resolved small angle laser light scattering (SALLS). During the non-isothermal process, a quantitative logarithm function can be established to describe the relationship between the cloud point T c and heating rate k as given by T c ¼ A ln k + T 0 for the unfilled and filled CRGO-filled PMMA/SAN systems. During the isothermal process, the TTS principle and WLF function are applicable to describe the temperature dependence of nonlinear phase separation behaviors at the early and late stages of spinodal decomposition (SD) for such unfilled and filled systems, indicating that the introduction of CRGO hardly changes the viscous diffusion essence of macromolecular chains during phase separation. However, the mechanical barrier effect of CRGO on the macromolecular viscous diffusion may result in the delay of their phase separation behavior. Furthermore, the effect of CRGO on the isothermal and non-isothermal phase-separation behavior of the blend matrix is found to be dependent on the composition of the blend matrix. CRGO may act as a nucleating agent to result in the decrease of T c for the PMMA/SAN 37/63 system, while the mechanical barrier effect of CRGO on the macromolecular segment may retard the concentration fluctuation at the early stage of SD phase separation to cause the increase of T c for the PMMA/SAN 57/43 system. Besides, when SAN is the minority of the blend matrix (PMMA/SAN 57/43), the selective location of CRGO may result in the more obvious viscosity increment and then the more remarkable hindering effect on the SD phase separation behavior of blend matrix.

Designing triple‐shape memory polymers from a miscible polymer pair through dual‐electrospinning technique

“…Additionally, it can be seen from Figure (b) and Table that embedding of graphene into the PLA and PVAc matrices led to a considerable reduction in the intensity (tan δ max ) and area of the loss factor peak of PLA, implying that less amount of energy can be dissipated during the deformation process and, as a result, more elastic energy can be stored in graphene‐loaded nanocomposite samples …”

Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends: Separation of thermodynamic aspects from kinetics

“…In order to determine the “true” phase‐transition temperatures, the critical points determined from the G ′ slope change are linearly extrapolated to the ramp rate of zero . However, it is stated that the apparent phase‐transition temperatures versus the ramp rate deviate from a linear relationship by reducing the cooling/heating rates . Thus, the extrapolated results as well as the data related to the lowest cooling rate are shown in Figure .…”

“…The nanoparticles have been classified as beneficial compatibilizers in immiscible polymer blends, which can effectuate the formation of finer morphology, improved toughness, lower interfacial tension, larger miscibility window, slower phase separation kinetics, and the enhanced solubility of polymeric phases . As one of the key characteristics of the multicomponent polymer mixtures containing nanofillers, the phase separation behavior has been the main issue of lots of researches over the last decades …”

“…Along with the theoretical works, the effects of nanofillers on the phase behavior of polymer blends have been critically investigated by using different experimental approaches . Small‐angle light scattering (SALS) and optical microscopy have been widely applied to determine the phase‐transition points of binary polymer blends and filled polymer mixtures . The refractive indices of polymers, film transparency, and thickness are the most important parameters in SALS and optical microscopy measurements that can affect the validity of the results .…”

“…Considering the correlation between the measured rheological functions and the kinetics of phase separation/dissolution, the rheologically determined phase‐transition points can be markedly influenced by the heating/cooling rate of the dynamic temperature sweeps . The competition between the timescales of the dynamic measurements and phase separation/dissolution provokes the dependence of the determined critical points of polymer blends on the heating/cooling rates of the experiments . For the nanosilica‐filled polymer mixture, it has been detected that the rheologically determined phase‐transition points and optically determined cloud point are higher than the equilibrium phase boundary and the kinetic aspects profoundly impact the phase boundary of the filled systems .…”