Fourier transform infrared evaluation of autoclaved cellulose fibre pulps used in cement-based building materials

Preliminary studies on the effects of autoclaving cellulose fibre pulp used in fibre-cement building materials were conducted by Fourier transform infrared. Autoclaving at 180°C at different times in tap water showed little spectral differences. The use of lime solution under the same condition showed significant spectral differences in the regions of 3020 to 3800 cm⁻¹ and 800 to 1600 cm⁻¹. The former is the region corresponding to O—H stretch where the differences are the result of variations in the hydrogen bonding. The differences in the latter region correspond mainly to C—O stretching modes in COH and the acetal O—C—O—C groups. These results are rationalised in terms of susceptibility of the cellulose fibres to alkaline hydrolysis and oxidative alkaline hydrolysis under high temperature autoclaving conditions. Results from differential scanning calorimetry and environmental scanning electron microscopy also showed similar trends, confirming that only under the adverse alkaline and autoclave environment does the cellulose undergo significant degradation.