Morphological, thermal, and structural aspects of dried and redispersed nanofibrillated cellulose (NFC)

Abstract

The effects of various drying techniques, such as air, oven, freeze, and spray drying, on the morphological, thermal, and structural behaviors of two different nanofibrillated cellulose (NFC) materials were investigated. Field emission scanning electron microscopy (FE-SEM) observations indicated an interlaced network formation of predominantly in-plane fibrillar orientation for air-and oven-dried samples, while freeze and spray drying resulted in the formation of coarse and fine powder fractions. Comparison of redispersed powders obtained by freeze and spray drying indicated that aggregation phenomena are significantly reduced in freeze-dried specimens. Rheological and sedimentation analysis revealed that the freeze-dried NFC powders are more stable than spray-dried NFC powders when redispersed in water. Aggressive dehydration processes, such as freezing or heating, significantly influence the thermal stability of the dried cellulose samples. On the contrary, the crystallinity properties of dried NFC materials are very similar regardless of the drying treatment.

Rheology of aqueous dispersions of Laponite and TEMPO-oxidized nanofibrillated cellulose

“…All rheological investigations have shown that TEMPO-NFC hydrogels exhibit shear thinning and thixotropic behavior (Benhamou et al, 2014;Lasseuguette et al, 2008;Mendoza, Gunawardhana, Batchelor, & Garnier, 2018a;Mendoza et al, 2018b;Saito et al, 2007). Despite important reduction of particle swelling ability and suspension viscoelasticity that have been observed when nanocelluloses of different types were dried and re-dispersed in water (Hubbe et al, 2017;Naderi, Lindström, Sundstrom, & Flodberg, 2015a;Okiyama, Motoki, & Yamanaka, 1993;Peng, Gardner, & Han, 2012;Voronova, Zakharov, Kuznetsov, & Surov, 2012;Zepic et al, 2014;Zimmermann et al, 2016), the accessibility of dried nanocellulose offers potentials for novel TEMPO-NFC hydrogel blends and applications. In our previous publication (Šebenik, Krajnc, Alič, & Lapasin, 2018), development of rheological properties of hydrogels prepared from a commercially available freeze-dried TEMPO-NFC powder was investigated.…”

Nanofibrillar cellulose hydrogels and reconstructed hydrogels as matrices for controlled drug release

“…wound healing applications. Previous studies have mainly focused on the evaluation of redispersibility and rheological properties of dilute 0.5 -1% NFC suspensions after spray drying or freeze-drying (Missoum, et al 2012;Žepič, et al 2014).…”

Forming and Dewatering of a Microfibrillated Cellulose Composite Paper

“…It has been shown in many studies that aqueous suspensions of MFC/NFC are highly shear thinning and show gel-like properties, especially at increased concentrations (Herrick et al 1983;Pääkko et al 2007;Agoda-Tandjawa et al 2010;Rezayati Charani et al 2013;Saarikoski et al 2015;Žepic et al 2014). The rheology of a high consistency furnish that contains large amount of MFC/NFC together with fillers and cellulose fibers was also observed to be governed by the swelling and gel-like properties of the MFC/NFC, as described by Dimic-Misic et al (2013).…”