Rheological investigation of complex micro and nanofibrillated cellulose (MNFC) suspensions: Discussion of flow curves and gel stability

Abstract

Micro and nanofibrillated cellulose in aqueous suspension presents many challenges when considering its use, for example, in forming nanocomposites. The inclusion of filler particles either as extender or as functional additive allows the range of strength and deformation properties to be extended. These properties, however, are linked in many cases to the rheological properties of the raw material mix. Interactions under dynamic shear or under controlled stress at low amplitude reveal the potential to generate functional interactions, not only between the cellulose components themselves but also between the cellulose and polymer additives, as well as surface modified pigment fillers. Examples are given demonstrating the action of adding cellulosic polymer in the form of carboxymethyl cellulose (CMC) to micro and nanofibrillated cellulose (MNFC). Rheological studies show how these combinations with CMC, added either in free form or preadsorbed onto calcium carbonate filler particles, lead to a variety of responses. Dispersability of the MNFC is increased by the use of free CMC polymer addition, and the usually expected flocculating action on added filler is seen not to occur. Alternatively, the preadsorbed CMC on the calcium carbonate pigment filler leads to an interaction between the fibrillar cellulose and the surface modified calcium carbonate pigment filler, to which incorporation of cationic polymer leads to a reduction of interaction, provided theaddition level does not exceed the isoelectric point of the mix. The observations are viewed in the context of a combination of proposed physical contact dynamics in the form of disordered and ordered alignment.

Co-exfoliation and fabrication of graphene based microfibrillated cellulose composites – mechanical and thermal stability and functional conductive properties

“…As graphene is exfoliated, the cellulosic species are exposed to the fresh graphene surface and, in most cases, the surface energy of a fresh surface is higher than on an aged surface, which in turn has adsorbed other stabilising species prior to the exposure to cellulose. This effect has been seen for co-grinding and co-homogenising of MNFC with pigments 59 , where the mechanical properties of the composite were enhanced. The decrease in the mechanical properties at higher graphene content can be explained as being due to the aggregation of graphene in the polymer matrix.…”

Acid dissociation of surface bound water on cellulose nanofibrils in aqueous micro nanofibrillated cellulose (MNFC) gel revealed by adsorption of calcium carbonate nanoparticles under the application of ultralow shear

“…In the forest bioproducts industry, nanofibrillated (NFC), sometimes referred to as cellulose nanofibres (CNF), and microfibrillated cellulose (MFC) have drawn much attention in the past decades due to their strength giving property potential not only in paper and board manufacturing but also in other industrial value chains, such as nanocomposites [1,2]. An emerging variant of such fibrillated material is micro nanofibrillated cellulose (MNFC), so-called because it contains a distribution of microfibrils which, in turn, have nanofibrils emanating from their surface formed by mechanical nanofibrillation [3,4]. This material is chosen because it is endowed with some interesting intrinsic properties, exhibiting particularly high specific surface area, long range structural integrity, regions of internal structural crystallinity and surface chemistry presenting hydroxyl groups for possible chemical modification [2].…”

Microfluidic Lateral Flow Cytochrome P450 Assay on a Novel Printed Functionalized Calcium Carbonate‐Based Platform for Rapid Screening of Human Xenobiotic Metabolism

“…FCC is prepared by etching the surface particles of calcium carbonate pigment with phosphoric acid and then reprecipitating them to create a highly porous plate‐like, nanometer thick lamellar structure resulting in a pigment with inter‐ and intraparticle porosity (Table S2, Supporting Information). Two types of MFC, a commercially available Arbocel MF‐40‐7 (J. Rettenmaier & Söhne GmbH + Co KG, Rosenberg, Germany), termed MFC A, and a mechanically produced micro nanofibrillated cellulose (Omya International AG, Oftringen, Switzerland), termed MFC B, were evaluated as binders. SuperYUPO (Yupo Corporation, Tokyo, Japan), pigment filled polypropylene film (thickness 80 µm), was used as the inert base substrate for the coatings.…”