Application of gpc to studies of the viscose process. III. Effect of various treatments of rayon print cloth on the molecular weight distribution of cellulose

Gel permeation chromatography (GPC) has been used to determine the molecular weight distribution of cellulose in rayon print cloths. The fabrics were made from a regular and a high wet modulus rayon with staple length of 1 9/16 inches in an 80 × 80, 31 × 41 singles construction. The effects of various treatments of the print cloths including bleaching exposure to UV and abrading on the yarn properties and the molecular weight distribution were determined. With chemical treatments, the changes in the molecular weight distribution in both warp and fill were similar. The chemical reactions with the fabric immersed in solution were fairly uniform throughout the yarn and in the filaments. In this group, bleaching drastically reduced the average molecular weight. Degradation due to abrasion and flexing was severe. Results indicate that the larger molecules are particularly susceptible to mechanical degradation. The detritus from abrasion of the high wet modulus and the regular rayons had similar, relatively narrow molecular weight distribution. The changes in yarn properties and distribution on washing were primarily the result of mechanical damage. Heating at 400°F for 30 min substantially changed the staining characteristic of cross sections of the yarns. The molecular weight distribution width increased on heating and for these samples, the weight average molecular weight determined from GPC was significantly greater than the value determined viscosimetrically.