Effect of microgel content on the shear and extensional rheology of polyacrylonitrile solution

Abstract

Crosslinked polyacrylonitrile (cPAN) particles with uniform size were synthesized through precipitation polymerization. The as-formed cPAN nanoparticles were dispersed in polyacrylonitrile (PAN) solutions to form microgels with various contents, which were used as model to study the influence of the microgels on the shear and extensional rheology of PAN solutions. Flow curves of steady shear viscosity displayed shear thinning and followed time-temperature superposition principle. The dependency of activation energy on the content of cPAN microgels indicated that introduction of microgels weakened the temperature sensitivity of PAN solutions. For extensional rheology study, we utilized the capillary thinning rheometry to characterize the elongation relaxation time and apparent extensional viscosity. Study of filament thinning dynamics with a series of system strains confirmed that the higher content of cPAN microgels the lower extensional strength and worse spinnability of the PAN solution.

Thermal Transformation of Polyacrylonitrile Accelerated by the Formation of Ultrathin Nanosheets in a Metal–Organic Framework

“…To elucidate the influence of topology on the transformation reaction, a 3D cross-linked PAN, termed 3D-PAN, was synthesized by emulsion polymerization with a cross-linking ratio comparable to that of 2D-PAN (see the Supporting Information). 40 The transformation reaction of PAN proceeds at approximately 280 °C, in which PAN converts to LP through cyclization and dehydrogenation reactions catalyzed by oxygen molecules. 10 Thus, PAN with 1D, 2D, and 3D topologies was heated at 280 °C under air, affording LP with different dimensionalities, denoted as 1D-LP, 2D-LP, and 3D-LP, respectively.…”