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

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering.

In this study, acacia (Acacia mangium) and mixed tropical hardwood (MTH) pulps from Indonesia were compared to birch (Betula pendula & pubesceus) pulp from Scandinavia, to obtain the potential dewatering, retention properties at web forming and related handsheets prope1ties of these pulps for fine paper. Drainability and retention properties of these hardwoods pulps are compared at the constant tensile strength level. Schopper-Riegler device, drainage time, water retention value, high pressurized dewatering in handsheet mold and Moving Belt Former (MBF) are used to study the drainage properties. Acacia is proved superior in light-scattering ability and formation, higher filler-retention ability that are critical quality requirements for fine paper. The drawbacks are acacia's low drainage rate and low wet web strength, which are bottleneck to the high paper machine speed especially at the web forming. Birch has the much faster drainage rate, highest solids content and low retention properties at the same tensile strength level. MTH is morphologically close to birch, but most of its properties fall between acacia and birch. Acacia and birch are the suitable hardwoods for fine paper though there are further improvements needed. Acacia is a promising raw material if the drainage properties can be improved fmther.