Summary

The effect of hydrogen peroxide bleaching on the structure of thermomechanical (TMP) and chemothermomechanical (CTMP) wheat straw paper pulps was investigated. The results obtained by thioacidolysis indicated that the TMP treatment did not significantly affect the ß-0-4 structures of lignins whereas, the alkali conditions of sulfonation (CTMP) and bleaching induced the cleavage of the ß-0-4 bonds and an increase in the S/G ratio. Moreover, it was concluded that bleaching and sulfonation are responsible for the partial solubilisation of the p-coumaric and ferulic acid esters. The ethers of p-coumaric acid are not significantly affected by these treatments whereas, the ethers of ferulic acid are degraded, as shown by acidolysis data. These results underline the structural differences of wheat straw pulps compared to wood pulps.