Processing and characterization of nanofibrillated cellulose/layered silicate systems

Abstract

Recently, nanofibrillated cellulose with cationic functional groups was synthesized. This trimethylammonium-modified nanofibrillated cellulose (TMA-NFC) was applied in this study for the preparation of composites with various layered silicates. These belonged to the groups of montmorillonite, kaolin, talc, vermiculite, and mica. The respective composites were prepared by high-shear homogenization followed by filtration and hot-pressing. Data on crystal structures, chemical compositions, cation exchange capacity, specific surface area, density, and morphology of all clays and micas themselves as well as structure information of the corresponding composites have been collected. Possible microstructural features responsible for the composite appearances were tentatively identified. Principally, the interactions between TMA-NFC and the layered silicates were pronounced, due to electrostatic attraction of cationic cellulose fibrils and anionic silicate layers. This mutual interaction between TMA-NFC and layered silicate, however, was influenced not only by layered silicate properties but also by the composite preparation method, as discussed in this study.

Effect of operational parameters and stress energies on stirred media milling of talc

“…Additionally, Song et al [14] ground talc particles with sand mill and observed an increased bending strength of the polypropylene matrix after grinding process. The use of talc in hybrid barrier films, together with nanofibrillar cellulose (NFC), was also examined in a few papers [15][16][17]. When the talc particles were mixed with NFC as a form of platelet aggregates, the mechanical properties of talc hybrids were lower, compared to those of mica, for instance [16].…”

Liquid ammonia treatment of (cationic) nanofibrillated cellulose/vermiculite composites

“…The received vermiculite was further ground in the dry state into particles smaller than 75 μm. Preliminary experiments have been conducted also with a muscovite mica (mica R120 from Minelco, UK) 28. However, the improvement regarding mechanical and water vapor barrier properties of TMA‐NFC/mica R120 was not as pronounced as of TMA‐NFC/vermiculite after liquid ammonia treatment.…”

“…NFC consists of high aspect ratio fibers and shows higher tensile strength and modulus, higher grade of homogeneity and higher quantity of surface OH groups compared to native cellulose fibers 25–27. Recently, composites of trimethylammonia‐modified NFC (TMA‐NFC) and various layered silicates (LSs) like montmorillonite, talc, kaolin, vermiculite, and mica have been produced,28–33 aiming at the creation of materials with enhanced water vapor barrier properties 29. One of the reasons for this improvement (reaching a factor of 30 compared to commercially used base paper) is most likely ionic interaction between cationic TMA‐NFC and anionic surfaces of the LSs 29.…”

Recent Developments in Cellulose and Cellulose Derivatives/Clay Nanocomposites

“…Fewer studies of cellulose/layered silicate nanocomposites are found in literature [35][36][37][38][39][40][41][42][43][44][45][46] than those reported for other polymeric matrices. The most relevant investigations explore the use of nanoparticulated clay as a low-cost flame-retardant filler for the production of regenerated cellulose fibers and the combination of clay and cellulose (cellulose fibers and cellulose micro-and nanocrystals) as reinforcement fillers for polymeric matrices.…”

“…Ho et al [46] prepared composites of nanofibrillated cellulose with cationic functional surface groups (trimethylammonium-modified nanofibrillated cellulose) and various anionic layered silicates (montmorillonite, vermiculite, and mica). The interactions between modified cellulose and layered silicates were expected to be effective due to the electrostatic interaction of the cationic cellulose fibrils and the anionic silicate layers.…”