Thesis (M.Sc.) - Asian Institute of Technology, 2002

A thesis submitted in pa1tial fulfillment of the requirements for the degree of Master of Science.

During recent years, there has been a continuous trend to lower the basis weight of newsprint. The reduction of transportation, raw materials and handling costs is the main reason that is motivating this development. With this consideration in view, the effects of basis weight reduction on sheet properties for deinked newsprint furnishes were evaluated. Raw materials used were old newspapers (ONP) from Thailand, East Coast and West Coast of U.S., old magazines (OMO) and chemi-thermomechanical pulp (CTMP). Mill's furnish was also used for comparison. Basis weights were varied from 35 g/m2 - 50 g/m2 . Nearly all paper properties are deteriorated with reducing basis weight, bending stiffness, tensile strength and opacity were found to be the most critical properties that needed to be concerned. In order to maintain or improve some of these critical prope1ties, the mixtures of furnish compositions and pulp refining can be one of the alternatives. By adding ONP from Thailand, the opacity can be improved, and adding OMO can enhance the paper strength. Fmthermore, adding CTMP fiber can improve bulk and stiffness. However, the deterioration of other properties should also be considered case by case.