EFFECTS OF RECYCLING ON PAPERMAKING PROPERTIES OF MECHANICAL AND HIGH-YIELD PULPS .1. HARDWOOD PULPS

Recycling characteristics of aspen mechanical and high-yield pulps, an d a spruce thermomechanical pulp have been studied using usual laborat ory procedures. The results indicate that the most obvious change in f iber properties occurs during the first drying cycle. The changes are irreversible. Subsequent rewetting-drying induces relatively little ef fect. Losses in water retention value and fiber bonding capacity are p articularly evident. Aspen TMP seems to behave differently from that m ade from spruce. Aspen commercial pulps have their own unique properti es. Repeated drying-rewetting of lignocellulosic fibers is a complex p henomenon and needs to be further examined.