Characterization of micro fibrillation process of cellulose and mercerized cellulose pulp

Abstract

Here we detail the fibrillation process for cellulose and mercerized cellulose pulps. Native and mercerized cellulose showed high degree of purity as indicated by α -cellulose content measurement and XRD analysis. Furthermore, stark change in fiber morphology indicated aggregation of fibrils on the surface due to mercerization. Fibrillation of pulp was carried out in the in the following subsequent steps: Disintegration, PFI refining, microgrinding by 20 passes in SuperMassColloider, and 60 passes in SuperMassColloider. Fiber samples were collected at every stage and highly uniform films were made by ultrafiltration and hot press method. The fibers and films made from fibers were then characterized by measuring physical properties, contact angle, thermal, mechanical, and SEM analysis. The main objective was to characterize the physical properties of the films made from different degrees of fibrillation. The films obtained were of fairly close grammage approximately 35g/m 2 . The target grammage was 40g/m 2 , and the slightly lower grammage indicated some fiber loss during the fabrication process. Additionally, it was observed that the density of the films increased with increasing degree of fibrillation from about 180g/m 3 to 455g/m 3 for cellulose I and 95g/m 3 to 385g/m 3 for cellulose II. Cellulose I films showed some contact angle to begin with which increased at every stage (14° -64°), whereas cellulose II films did not display a contact angle until the final stage of fibrillation. The films also showed increasing strength and an evolution of tensile strength from initially displaying a tear behavior indicating poor bonding to typical micro fibrillated cellulose films behavior as the fibers became increasingly fibrillated. The ultimate tensile strength for cellulose changed from tear behavior with no defined break to 134.5MPa. While on the other hand, the same change for cellulose II was a maximum of 75.1MPa from tear behavior. Increasing fibrillation of fibrils in both cases showed a decrease in fiber size, well differentiated for the two types of pulps at every stage.

Morphological investigation of cellulose nanocrystals and nanocomposite applications

“…The raw WP fibers are long tortuous and sometimes twisted flat tubes with a relatively smooth surface (Figure 27a-c), whereas the MWP fibers are solid cylinders, the lumen having collapsed during the alkaline treatment (Figure 27d-f). The surface of the MWP fibers exhibits a sub-fibrillar structure that most likely corresponds to bundles of nanofibrils, which is consistent with what was observed for mercerized pinewood pulp (Sharma et al, 2015) and cotton fibers (Yue et al, 2013). The mercerization process also affects the tortuosity and swelling of the fibers (i.e., the fiber untwists and swells).…”

A Comparative Study on the Characterization of Nanofibers with Cellulose I, I/II, and II Polymorphs from Wood

“…CNFs with cellulose I, I/II, and II polymorphs were obtained by chemical purification and one mechanical grinding treatment. It resulted in a relatively high yield of approximately 80–85% after a simple grinding treatment, which showed less energy consumption compared to previous studies [17,18]. The obtained three types of CNFs have similar morphology with long lengths and a high aspect ratio.…”

“…Abe et al [16] obtained CNFs with cellulose I polymorph (CNF-I) from wood using a very simple mechanical grinding treatment. However, the extraction of CNFs with cellulose II polymorph (CNF-II) is complex and requires great energy consumption [17,18], which limits their application.…”

Cellulose II as bioethanol feedstock and its advantages over native cellulose

“…Mercerisation was introduced by J. Mercer in the 1850's where cellulose I was allowed to swell in a concentrated NaOH aqueous solution followed by dissolution and precipitation [45,46]. Ever since mercerisation was introduced, it has been used to produce cellulose II frequently [47][48][49][50][51][52][53][54][55]. Table 2 Yu et al tested the effect of a range of NaOH concentrations and temperatures on the mercerisation of cellulose I [54].…”