MORPHOLOGICAL CHANGES OF JACK PINE LATEWOOD AND EARLYWOOD FIBERS IN THERMOMECHANICAL PULPING

Abstract

The morphological changes of jack pine (Pinus banksiama) earlywood (EW) and latewood (LW) in thermomechanical pulping (TMP) were studied by light microscopy and scanning electronic microscopy. The results indicate that: under the mechanical forces in refining, the EW fibres tend to separate in the P/S1 interface, while separation of the LW fibres takes place commonly in the P/S1 and S1/S2 regions. The thick-walled LW fibres exhibit much more external fibrillation than the thin-walled EW. As a result, the LW fines contain more fibrillar component than EW fines. The EW fibers suffer more fiber cutting and splitting than the LW fibers. In addition, the thin-walled EW fibres show higher collapsibility and conformability than the LW counterparts.

Keywords

• Jack Pine (Pinus banksiana)
• Earlywood
• Latewood
• Thermomechanical Pulping
• Morphology