NODIFICATION OF ACETATE OR TRIACETATE FIBER WITH TOLYLENE DIISOCIANATE BY THE VAPOUR PHASE METHOD

Abstract

Two acetate (acetic acid value: 52.55 and 54.23%) and a triacetate fibers were reacted with tolylene diisocynate (TDI) vapour at different temperatures under normal or reduced pressures. It is deduced that the hydroxyl groups of the acetate or the triacetate are reacted with isocyanate group and crosslinked together.This research was undertaken to modify the mechanical properties of acetate and triacetate fibers mainly by the vapour phase method. The reaction rates and the apparent activation energies of the reactions between acetate fibers and TDI were determined. The mechanical properties and the solubilities of the modified acetate and triacetate fibers were also measured.Results obtained are as follows:(1) The reaction rate increases with rise of reaction temperature and at 150°C for 1.5hr, the percentages of combined TDI become more than 40% and 10% for the acetate and for the triacetate respectively.(2) The apparent activation energies of the TDI-acetate reactions in a vapour phase are 12.8Kcal/mol for the acetate and 7.8Kcal/mol for the triacetate. This is probably due to higher affinity of the triacetate toward TDI than the acetate.(3) With an increase of the percentage of TDI combined, breaking load of the fiber remains almost constant, elongation decreases and initial modulus, yield value and elastic recovery increase.(4) Elastic recovery of the acetate fiber rises by grafting of poly (butyl acrylate) and increases further by successive TDI treatment.(5) The acetate and the triacetate combined with more than 7_??_8% of TDI become practically insoluble in acetone and methylene chloride.