<Note>Some Physical Properties of Wood and Cellulose Irradiated with Gamma Rays

Abstract

The effect of gamma irradiation from cobalt-60 on specific gravity, degree of crystallinity, thermal softening temperature, tensile strength and torsional creep behavior of wood and cellulose were investigated and the following results were obtained. 1) A dosage up to about 10^8 rad had little effect on the specific gravity of wood and cellulose. 2) The degree of crystallinity of wood and cellulose remained almost unchanged up to 3×10^7 rad, but started to decrease rapidly at about 1×10^8 rad. 3) The softening temperature of cellulose shifted gradually to a lower temperature region up to about 3×10^7 rad and abruptly in the range exceeding 3×10^7 rad. 4) Strength of wood decreased with increasing irradiation dosage, depending remarkably on loading modes. 5) The value of creep compliance of wood at time 0.1 min did not change up to 1×10^7 rad, but increased markedly in the range exceeding about 3×10^7 rad.