Aromatic polyhydrazides and polyamide-hydrazides

The usual amide solvent systems are used for the polymers from VIII and IX while the all-hydrazide polymer from X and terephthaloyl chloride has been repiorted to be insoluble in the usual organic solvents. 

More recently it has been found to dissolve in dimethyl sulphoxide-lithium chloride from which fibres can be spun. In the authors experience the polyamide-hydrazide from VIII and terephthaloyl chloride dissolves readily enough in sulphuric acid but the inherent viscosity of the polymer quickly falls, presumably owing to degradation of the polymer chains. 

The polymers do not melt or exhibit glass transitions but decompose at about 400-525 C (Ref. 14) and the spinning methods used are essentially the same as for the aromatic polyamides including dry-jet wet spinning.  

As in the case of the aromatic polyamides minimum values of /i h for the production of good fibres are quoted and the useful number average molecular weight range for the polymers based on VIII and IX is said to be 50000-100000. Spin stretch appears to be a factor in the development of the as-spun properties.  

Apparently this does not occur at the moderate temperature (300°Q and during the very short time involved in heat treating or hot drawing the fibres.  

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