綿漁網腐朽に関する粘度的研究

Abstract

The weakening of cotton netting cords, being immersed in sea water, may be due mainly to bacterial decompositions of cellulose chains. A continuous reduction of average degree of polymerization (??) of the cellulose chains should then be expected to occur with increasing the period of immersion. In this investigation, such reduction of ?? occurring in cotton netting in cotton netting cords immersed in sea water was pursued by measuring intrinsic viscosities of cellulose nitrate om acetone and by comparing them with the tensile strengths of single yarns. It was found that the tensile strengths of single yarns began to decrease after 30 days immersion, reach one half of the initial value after 60 days and dropped to zero after 90 days; on the contrary, the average molecular weights showed slow reduction and reached no more than one half of the initial value for the peirod of 90 days. The linear relationship between the tensile strength and the reciprocal of average degree of polymerization which was often found to fit well for linear high polymers could not be obtained in the present investigation. It is considered that the tensile strength of cotton yarns may be responsible not only for the rupture of primary valence bond and the slippage of the cellulose chains with respect to each other, but also for the more macroscopic structures.