Study of the supermolecular structure of concentrated poly- m-phenyleneisophthalamide solutions

Abstract

To characterize the supermolecular structure (SMS) of concentrated solutions of poly- m-phenyleneisophthalamide (phenylone) a method involving the turbidity spectrum was used. A range was found in the spectrum, in which the use of this method to characterize SMS of stained phenylone solutions appeared to be quite adequate. It was found that SMS had formed in phenylone solutions at increased temperature. Kinetics of formation of SMS were accepted as an index of stability. SMS was studied in concentrated (and viscous) solutions (syrups) of phenylone, according to several factors determined by conditions of synthesis. The stability of phenylone solutions decreases with an increase in concentration, polymer molecular weight and water content of the syrup specimen. Calcium and lithium chloride additives improve the quality of solvent (DMAA) and stabilize the syrup. The phenylone-DMAA system is determined as a system with a lower critical point of mixing with a critical temperature in the range of 30–40°. The behaviour of the system on varying the parameters of polymer synthesis was explained from the point of view of systems with LCTM. An inverse proportional relation was found between the strength of fibre formed from syrup and the dimensions of supermolecular particles. This fact indicates that supermolecular particles, of which the dimensions and concentration are determined by the extent to which conditions of treatment of the solution diverge from the binodal curve, cause a deterioration in the quality of the phenylone fibre.