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Significant effect of cellulose nanofibers (CNFs) on cure‐induced phase separation in dynamically asymmetric system is reported. An epoxy/polysulfone blends with typical layered structure formation was chosen as the polymer matrix, and morphology evolution and rheological behavior of systems with different nano‐size fiber loadings upon curing reaction were investigated using optical microscopy and rheological measurement. CNF distributed uniformly in the polymer matrix and had good interaction with polymer chains. Curing reaction of epoxy was promoted by CNF, making the system gel and phase separate earlier. Meanwhile, system viscosity was increased with CNF addition, and the movement of polymer chains and component diffusion were constrained, as a result, the structure evolution process was slowed down. The CNF altered the final morphologies, resulting in refined structures with smaller characteristic length scales or even completely change the morphologies from the layered structures to a bicontinuous structure when the CNF concentration reached to a relatively high level. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1357–1366 [ABSTRACT FROM AUTHOR]

The steady rheological behavior of phenol-liquefied cellulose product (LCP) at varying liquefaction times was investigated at three testing temperatures. The LCP presented interesting rheological behavior. When liquefaction time was longer than 45 min, the LCP showed stronger shear-thinning behavior with increasing temperature, and the viscosity at high testing temperature was higher than that at low testing temperature at low shear rates. An experiment with a heating and cooling cycle indicated that LCP would form reversible association structures when temperature increased. The mechanism of the reversed rheological behavior of LCP may be attributed to the association of alkyl chain parts of liquefied cellulose when heating. [ABSTRACT FROM AUTHOR]

In order to develop the potential application of industrial alkali lignin, its acrylonitrile-butadiene-styrene (ABS) composites were fabricated via melt blending in the absence/presence of a compatibilizer. The lignin can uniformly disperse in the ABS matrix with number-average dispersed-phase domains of sub-micron scale, ranging from 150–250 nm, as observed by scanning electron microscopy. Infrared spectroscopy reveals that strong intermolecular interactions, mainly hydrogen bonding, were responsible for their good interfacial compatibility. Rheological behaviors show that the presence of lignin restricts to some extent the relaxation of polymer chains without affecting the processing properties of ABS resin. The presence of lignin increases storage modulus and glass transition temperature (T g) of ABS. Incorporating small amounts of lignin, e.g. 5 wt%, can produce ABS composites with enhanced tensile strength and modulus, while higher loading of lignin will reduce mechanical properties. The latter, however, can be improved by reactive compatibilization. [ABSTRACT FROM AUTHOR]