Photoacoustic characterization of bleached wood pulp and finished papers

We have carried out photoacoustic measurements of the thermal diffusivity o n samples of laboratory produced chemically bleached wood pulps, as well as on samples of several commercially available papers. Our results for bleac hed pulps indicate that the thermal diffusivity is correlated to each of th e chemical bleaching controlling parameters (the kappa number, viscosity an d brightness) measured during distinct phases of the bleaching processes. A lso, the values of the thermal diffusivities for the commercial papers were found to be adequate for their end uses. It tumid out that photoacoustic m easurements can be a valuable research laboratory and/or industrial plant t ool for comparing and controlling the properties of pulp and paper and for evaluating the effects of processing parameters upon these properties.