Extrusion Pulping of True Hemp Bast Fibre (Cannabis Sativa L.), 1995 Pulping Conference Proceedings

Gerrit J. van Roekel, Steef J J. Lips,

Richard G. M. Op den Kamp and Gijs Baron

ATO-DLO Agrotechnology

Hemp was selected as an alternative crop for Dutch arable farming. Extrusion pulping of hemp bast was evaluated as a small scale, environmentally and economically viable alternative to the traditional chemical pulping technology for hemp. Laboratory trials are described producing unbleached (XP), unbleached alkaline-pretreated (AXP) and peroxide bleached alkaline-pretreated (APXP) hemp bast fibre pulps. Typical results are presented and discussed, and compared to softwood market pulps. It is concluded that extrusion pulping is a viable process to produce both unbleached and bleached pulps from hemp bast at a yield of 80% and higher, and at a specific energy consumption as low as half of that for mechanical softwood pulps. The AXP pulp quality can be compared to softwood CTMP pulps, and is considered for application as a reinforcement pulp for testliner production. The APXP pulp quality can be compared to softwood BCTMP pulps for use in printing and writing grade papers. APXP can also be considered to replace NBSK with a lower tensile strength but also a lower density and higher tear strength. Considering the low lignin content, hemp bast APXP can be regarded as a woodfree TCF pulp.