A Sealed Pressing System and its Use to Explore the Ammonia Plasticization of Natural Fiber Mats

Authors

  • Mohammed Jahangir A. Chowdhury
  • Philip E. Humphrey

Keywords:

Natural fiber mats, ammonia plasticization, sealed pressing, gas injection

Abstract

The effectiveness of gaseous ammonia as a softening agent for natural fiber and particle composite mats has been examined. A miniature digitally controlled sealed pressing system with provision for chemical injection and removal through permeable graphite platens was developed for this and other purposes. The pressing system is described, along with its use to examine the softening action of anhydrous ammonia on 97-mm-diameter thermomechanical pulp (TMP) mats. This was done principally in terms of treatment time (0 to 900 s) and partial pressure (0.0345 to 0.7444 MPa). Ammonia applied at moderate partial pressures (0.42 MPa) was found to rapidly penetrate and soften (within 4 s) mats compressed to a density of 525 kg m-3 at near-room temperatures (29°C). The results suggest that judicious injection of ammonia in sealed pressing arrangements may provide an attractive alternative to our current dependency on heat- and moisture-induced softening in conventional composite pressing methods—both in terms of production speed and providing the ability to optimally sequence rheological and adhesion mechanisms

References

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Published

2007-06-05

Issue

Number 1 / January 2005

Section

Research Contributions

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