Comparison of physical and chemical methods for analysing cellulose degradation following artificial ageing treatment

Cotton paper was impregnated with aluminium salts and aged thermally to ind uce degradation. Cellulose degree of polymerisation (DP) was determined by viscosimetry. End group analysis was determined by copper number measuremen ts. Fibre strength was assessed by wet zero-span tensile analysis. The data show all three measurements are highly correlated. Viscosimetric D P determination was sensitive mainly during the initial stages of ageing. A s degradation proceeded the tensile test became more sensitive. Copper numb er measurement showed no bias; it proved responsive at all levels of degrad ation. Data suggest zero-span strength is related more to the number of end s of cellulose molecules than to their molecular weight. Overall, the data show that chemical tests are necessary for assessing degr adation when ageing is to be characterised fully. However, physical tests h ave advantages regarding their rapidity and ease of use; they are useful wh en full characterisation of ageing phenomena is not required.