Cellulose

Torstensen, Jonathan; Johnsen, Per-Olav; Riis, Henrik; Spontak, Richard; Deng, Liyuan; Gregersen, Øyvind; Syverud, Kristin

2018 Cellulose

doi: 10.1007/s10570-018-1854-8

Artifact-free imaging of cellulose nanofibrils (CNFs) from aqueous nanocellulose suspensions is nontrivial due to frequent irreversible agglomeration and structure damage during the course of sample preparation, especially as water is solidified prior to freeze-drying. In this study, we have examined the morphologies of CNF suspensions prepared by rapid vitrification in two different liquid cryogens—nitrogen and ethane—followed by freeze-drying. Results obtained by scanning electron microscopy confirm that vitrification in liquid ethane not only greatly improves the survivability of fine-scale CNF structural elements but also significantly reduces the propensity for CNF to agglomerate.

Wang, Qianqian; Sun, Jianzhong; Yao, Qian; Ji, Chencheng; Liu, Jun; Zhu, Qianqian

2018 Cellulose

doi: 10.1007/s10570-018-1888-y

Khoo, R.; Chow, W.; Ismail, H.

2018 Cellulose

doi: 10.1007/s10570-018-1879-z

Lamanna, Leonardo; Rizzi, Francesco; Demitri, Christian; Pisanello, Marco; Scarpa, Elisa; Qualtieri, Antonio; Sannino, Alessandro; Vittorio, Massimo

2018 Cellulose

doi: 10.1007/s10570-018-1874-4

Chen, Pan; Ogawa, Yu; Nishiyama, Yoshiharu; Ismail, Ahmed; Mazeau, Karim

2018 Cellulose

doi: 10.1007/s10570-018-1860-x

The bending of rod-like native cellulose crystals with degree of polymerization 40 and 160 using molecular dynamics simulations resulted in a deformation-induced local amorphization at the kinking point and allomorphic interconversion between cellulose Iα and Iβ in the unbent segments. The transformation mechanism involves a longitudinal chain slippage of the hydrogen-bonded sheets by the length of one anhydroglucose residue (~ 0.5 nm), which alters the chain stacking from the monotonic (Iα) form to the alternating Iβ one or vice versa. This mechanical deformation converts the Iα form progressively to the Iβ form, as has been experimentally observed for ultrasonication of microfibrils. Iβ is also able to partially convert to Iα-like organization but this conversion is only transitory. The qualitative agreement between the behavior of ultrasonicated microfibrils and in silico observed Iα → Iβ conversion suggests that shear deformation and chain slippage under bending deformation is a general process when cellulose fibrils experience lateral mechanical stress.

Dimitrušev, N.; Fras Zemljič, L.; Saake, B.; Strnad, S.

2018 Cellulose

doi: 10.1007/s10570-018-1906-0

Jilal, Issam; El Barkany, Soufian; Bahari, Zahra; Sundman, Ola; El Idrissi, Abderahmane; Salhi, Amin; Abou-Salama, Mohamed; Loutou, Mohamed; Amhamdi, Hassan

2018 Cellulose

doi: 10.1007/s10570-018-1909-x

Hu, Yang; Thalangamaarachchige, Vidura; Acharya, Sanjit; Abidi, Noureddine

2018 Cellulose

doi: 10.1007/s10570-018-1863-7

In this study, we report on a new strategy using low-concentration acetic acid (LCAA) to promote cellulose dissolution. High-molecular-weight (HMW) cotton cellulose (DP > 5000) was simply soaked in a dilute acetic acid aqueous solution (1 vol%) prior to dissolution. Using N,N-dimethylacetamide/lithium chloride as the solvent system, the dissolution of LCAA-activated cellulose was significantly improved. Material characterization results indicated that no cellulose acetylation occurred during the dissolution process and the acetic acid could be easily removed during cellulose regeneration. It was also noticed that using LCAA to activate cellulose significantly reduced the viscosity of cellulose solution and promoted the dissolution of HMW cellulose. The crystallinity of LCAA-activated cellulose was not impacted, and the molecular weight of LCAA-activated cellulose was not significantly decreased as compared to cellulose without LCAA activation. The LCAA in cellulose played a pivotal role, by enhancing the solvation of the lithium cation. As a result, the initial free chloride concentration was able to increase and interact with inter and intra molecular hydrogen bonds of cellulose. Understanding the role of LCAA in the dissolution of cellulose is of particular interest in developing a new concept to design new solvents and effective strategies for cellulose dissolution.

Fareez, Ismail; Ibrahim, Nur; Wan Yaacob, Wan; Mamat Razali, Nur; Jasni, Ainil; Abdul Aziz, Fauziah

2018 Cellulose

doi: 10.1007/s10570-018-1878-0

Zhang, Haichuan; Qin, Chengrong; Nie, Shuangxi; Wang, Shuangfei

2018 Cellulose

doi: 10.1007/s10570-018-1883-3