Dielectric and thermal properties of handsheets made from recycled pulp and their relationship with deinking efficiency and pulp quality

This study evaluated the possibility of using dielectric and thermogravimetric analysis techniques as new procedures to profile deinking system efficiency and pulp quality. The procedures were applied to handsheets made from ONP/OMG deinked pulp sampled from two deinking systems at the Guangzhou Paper Mill, P.R. China. The dielectric properties (epsilon', epsilon", sigma) of handsheets made from pulp sampled at each deinking stage (pulping, flotation, screening and cleaning, and bleaching) were studied over the frequency range 1 kHz to 5 MHz at similar to25degreesC. The thermal analysis measurements, such as activation energy (E-a) and order of degradation (n), were calculated from non-isothermal thermogravimetric analysis, using the Coats-Redfern equation and the least square method. These results were successfully correlated with the conventional measurements of deinkability (ERIC, brightness, flakes) and breaking length. There was a relationship between the measurements of dielectric properties with the deinking factor, while the thermal analysis measurements correlated with breaking length.