Photoacoustic characterization of bleached wood pulp and finished papers

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