Influence of Pretreatment on Physical Properties of Oxidized Rayon Fabrics

Strips of polynosic rayon cloth, pretreated with inorganic salts that act as catalysts in pyrolysis, are pyrolyzed in air by a continuous process to a desired temperature (250°C). TGA thermograms of selected samples are examined and reveal that inorganic salts alter the course of decomposition and form more residues. Variations in char yield, breaking strength, and filling shrinkage of charred rayon fabrics are examined, and the results indicate that the physical properties of charred fabrics are determined by the species and concentration of inorganic salts. Nevertheless, it is almost impossible for a single inor ganic salt to achieve all the desirable physical properties of charred fabrics. Therefore. there appears to be a potential for developing mixtures of inorganic salts to be applied in pretreatment to improve most of these properties. For instance, a rayon precursor impreg nated with a solution containing a mixture of NH4Cl (3% w/v) plus ZnCl2 (7% w/v) produces better results than one impregnated with single inorganic salts.