A Role of Coagulant in Structure Formation of Fibers and Films Spun from Cellulose Solutions

Abstract

Replacing the aqueous coagulation bath with an alcoholic one during spinning cellulose fibers (films) from solutions in N-methylmorpholine-N-oxide leads to a radical restructuring of the hydrogen bonds net of cellulose and, as a result, to a change in the structure and properties of the resulting material. By the method of optical interferometry, it was possible to identify the intrinsic features of the interaction of the solvent and isomeric alcohols and to construct phase diagrams of binary systems describing the crystalline equilibrium. Knowledge of the phase states of the system at different temperatures renders it possible to exclude the process of solvent crystallization and conduct the spinning in pseudo-homogeneous conditions. The structure and morphology of samples were studied using X-ray diffraction and scanning electron microscopy methods for a specific coagulant. When the solution under certain conditions is coagulated at contact with alcohol, the solvent may be in a glassy state, whereas, when at coagulation in water, an amorphous-crystalline structure is formed. The structural features of cellulose films obtained by coagulation of solutions with water and alcohols help to select potential engineering or functional materials (textile, packaging, membranes, etc.), in which their qualities will manifest to the best extent.

Design and Fabrication of Membranes Based on PAN Copolymer Obtained from Solutions in N-methylmorpholine-N-oxide

“…On the contrary, the use of “soft” precipitators allows the process of solvent removal to be carried out smoothly. The forming pores during such precipitation have a small scatter in size; large (finger-like) pores are absent [ 26 , 27 , 58 ]. Another way of forming a membrane in which large pores will not form is the use of concentrated dopes [ 59 ].…”

“…Polymers 2022, 14, x FOR PEER REVIEW 9 of 14 (finger-like) pores are absent [26,27,58]. Another way of forming a membrane in which large pores will not form is the use of concentrated dopes [59].…”

“…For the first time, the phase inversion method of obtaining membranes was described in the 1960s of the last century in [ 25 ]. Upon contact of the precipitant with a thermodynamically equilibrium polymer solution, the system transforms from liquid to solid (non-fluid), with the formation of a polymer-rich phase and a phase with a low polymer content [ 26 ].…”

Measurements of Temperature and Humidity Responsive Swelling of Thin Hydrogel Films by Interferometry in an Environmental Chamber

“…Beyond proposing a new method for the measurement of humidity and temperature-dependent swelling, the novelty of the paper is also attributed to the use of the interferometer for the detection of thickness changes in situ. More commonly, interferometry is used for precipitation or dissolution studies [ 21 ].…”

N‐methylmorpholine‐N‐oxide molecules coated ammonium polyphosphates for dope spinning of flame‐retardant lyocell fiber

“…19 The spectrum of NAPP shows a new absorption band at 3062 cm À1 , which corresponds to the stretching vibration of C-H in NMMO molecules. 27 Moreover, the intensity of the broad absorption peak in the range 3500-2800 cm À1 for NAPP increases. This increase can be attributed to the hydrogen bond between the exposed hydroxyl of APP and the active oxygen of NMMO molecules.…”