the influence of refining on the mechanical and optical properties of recycled newspaper

this study was performed to investigate the effects of refining on the mechanical and optical properties of waste newspaper. waste newspapers were prepared from gorgan ettelaat newspaper agency and were cut to 5 centimeter pieces, and then were soaked with sufficient distillated water. after 1 day fibers were separated by disintegrator and freeness values for each pulp before and after refining were measured. waste newspaper was refined by pfi mill at 1000, 2000, 3000, 6000, 9000 revolutions, respectively. handsheets were made from each revolution according to tappi standard t 205om-97, and then compared with control sample. analysis of variance was conducted using completely randomized design, then mean values were compared usingduncan’s test, and finally the normalization equations were used to determine the best treatment. the results showed that increasing refining revolution increased burst, tensile and folding strength, brightness and density but decreased freeness, bulk, thickness, tear strength and opacity. normalization equations showed that the best paper can be made from refining revolution of 9000.