Comparison of the degradation behavior of cotton, linen, and kozo papers

The long term degradation behavior of cotton, linen, and kozo papers was studied to compare changes to the chemical and physical properties with time. The elemental composition, α-content, β-content, γ-content, and lignin content (K number) of the three unaged controls were determined. The papers were then degraded at 90 °C and 50 % relative humidity for several thousand hours. Changes to the pH, carbonyl content, yellowness index (YI), moisture content, molecular weight, and tensile strength with aging were monitored. The general trends in degradation behavior of linen and kozo papers were similar to cotton in that all three showed decreases in pH, molecular weight, and strength as well as increases in carbonyl content and YI during hydrolysis. However, the kinetics of degradation differed between the three papers. The cellulose component of all three papers dominated measured changes to the molecular weight while the presence of hemicellulose in the linen and kozo papers led to unique measured moisture contents, carbonyl group, and YI values relative to cotton after the same amount of degradation had occurred.