CNFs from softwood pulp fibers containing hemicellulose and lignin

• The energy demand to produce cellulose nanofibrils, CNFs, is high and additionally the cost of the starting material, the pulp, is substantial as high purity cellulose dissolving pulp is generally used. Pulps aimed for board and paper are produced at higher yield as they contain hemicelluloses and, in the case of unbleached pulp, lignin, and would be a more economical starting material for CNFs. It is of interest to understand how the presence of hemicellulose and lignin affects the fibrillation process and CNF properties. Kraft cooks of softwood were performed as well as kraft cooks with addition of polysulfide to increase the hemicellulose content. Part of the pulps were bleached to remove residual lignin, thus making it possible to compare pulps with and without lignin. Higher amount of hemicellulose had an obstructive effect on the enzymatic pre-treatment whereas lignin had no adverse effect on enzyme accessibility. Increased amount of charged groups improved the accessibility for enzymes. Both hemicellulose and lignin were carboxymethylated when pre-treatment by carboxymethylation was employed. However, carboxymethylation partly dissolved hemicelluloses. The tensile strength of CNF films was independent of the chemical composition of the pulp and the pre-treatment strategy. However, since the enzymatic pre-treatment decreased the cellulose DP more, CNF films from enzymatically pre-treated pulps had generally lower tensile strength. © 2022, The Author(s).

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

Nyckelord

Carboxymethylation

CNF film

Enzymatic pretreatment

Nanocellulose

Bleaching

Cellulose films

Dissolution

Enzymes

Lignin

Softwoods

Cellulose nanofibrils

Energy demands

High purity

Kraft cook

Pre-treatments

Pulp fibers

Softwood Pulps

Tensile strength

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)