Loss of tensile strength in cellulose tissue on the surface of spruce (Picea abies) caused by natural photodegradation and delignification

For the degraded and nondegraded samples, the tensile strength of the z-span was always twice that for the t-span. In addition, the time-dependent loss of strength always demonstrated the same tendency for both testing methods. This observation indicates a similar degree of degradation of lignin and cellulose in terms of strength loss.