Migration of volatile compounds through stacked sheets of paper during accelerated ageing Part II:: Variable temperature studies

In order to investigate the effects of diffusion during paper ageing an alum-rosin sized, fully bleached, kraft paper was aged in stacks, at three different conditions, and four different intervals. The stacks were open at the top to allow diffusion of volatile products to take place. Tests, including grammage, moisture content, brightness, yellowness, L*a*b*, zero-span tensile strength, pH and the degree of polymerization show less change in paper properties at the top of the stack than in the centre. This indicates a diffusion effect where volatile compounds escape from the paper at the top of the stack, but remain trapped towards the centre, where more severe degradation occurs. More work is required to determine if this diffusion effect is the same at ambient conditions as it is at the elevated temperatures used in this study.