Modeling wood fiber deformation caused by vapor expansion during steam explosion of wood
Artikel i vetenskaplig tidskrift, 2014

Steam explosion is a process used to enhance enzyme penetration and digestibility of wood. Wood chips are processed with high-pressure steam for a limited time, and the bonding between polysaccharides and lignin is weakened. After this processing, the pressure is rapidly reduced to induce steam explosion where the vapor inside a fiber expands and exerts pressure on the fiber walls. This pressure causes fiber deformation and breakage. In this study, fiber deformation caused by vapor expansion was simulated by single wood fibers using finite element modeling. When pressure is applied inside a fiber, it is likely to break from the corner and midway between two adjacent corners. The fiber is modeled with four layers (P, S1, S2, and S3). Although the P, S1, and S3 layers are very thin, they significantly prevent fiber deformation. The fibers with a thin wall and a low micro-fibril angle (MFA) deform more than the fibers with a thick wall and a higher MFA. It was found that the shape of the fiber plays an important role in its deformation. The areas of localized strain are the most likely places for fiber splitting. Essentially, fiber wall damage is more likely to occur in (1) thin-walled fibers, i.e., earlywood, (2) fibers with damaged P and S1 layers, (3) fibers with low MFAs, and (4) fibers with irregular cross-sections. Different chemical pretreatments, fractionation procedures, and selections of raw materials can accordingly be considered to produce easily steam-exploded materials.

WALL

TRANSVERSE

ELASTIC-MODULUS

PRETREATMENT

TEMPERATURE

MOISTURE-CONTENT

BEHAVIOR

NORWAY SPRUCE

POLYMERS

MECHANICAL-PROPERTIES

COMPRESSION

Författare

Muhammad Muzamal

Chalmers, Kemi- och bioteknik, Kemisk reaktionsteknik

Erik Kristofer Gamstedt

Uppsala universitet

Anders Rasmuson

Wallenberg Wood Science Center (WWSC)

Chalmers, Kemi- och bioteknik, Kemisk apparatteknik

Wood Science and Technology

0043-7719 (ISSN) 1432-5225 (eISSN)

Vol. 48 2 353-372

Ämneskategorier

Pappers-, massa- och fiberteknik

DOI

10.1007/s00226-013-0613-0