Twisting of Fibers Balancing the Gel⁻Sol Transition in Cellulose Aqueous Suspensions

Optical Properties of Cellulose Nanofibre Films at High Temperatures

Nanocelluloses and their different designs, such as films and nanopapers, have gained considerable interest in many application areas due to their unique properties. For many purposes, such as packaging and electronics, the thermal stability and optical properties of nanocellulose materials are crucial characteristics. In this study, the effects of heat treatment (100 ºC, 150 ºC and 200 ºC) on the optical and mechanical properties of 2,2,6,6-tetramethylpiperidinyl-1-oxy radical-oxidised cellulose nanofibre (TO-CNF) films were investigated, especially the alteration of the colour, complex refractive index and birefringence. Exposing TO-CNF films to high temperatures (> 150 ºC) induced permanent transformations in the CNF structure, leading to an increase in the refractive index, decreases in the birefringence and crystallinity index, colour darkening and significant deterioration of the mechanical properties.

Graphical abstract

Role of the Exchange Interactions in the Stability of the Cellulose

The problem of the origin of biochirality and the related problem of the initial monomers' selection are still under discussion, and the main point here is not the mechanics of...

Zhurkov's Stress-Driven Fracture as a Driving Force of the Microcrystalline Cellulose Formation

Microcrystalline cellulose (MCC) is a chemically pure product of cellulose mechano-chemical conversion. It is a white powder composed of the short fragments of the plant cells widely used in the modern food industry and pharmaceutics. The acid hydrolysis of the bleached lignin-free cellulose raw is the main and necessary stage of MCC production. For this reason, the acid hydrolysis is generally accepted to be the driving force of the fragmentation of the initial cellulose fibers into MCC particles. However, the low sensibility of the MCC properties to repeating the hydrolysis forces doubting this point of view. The sharp, cleave-looking edges of the MCC particles suggesting the initial cellulose fibers were fractured; hence the hydrolysis made them brittle. Zhurkov showed that mechanical stress decreases the activation energy of the polymer fracture, which correlates with the elevated enthalpy of the MCC thermal destruction compared to the initial cellulose.