Swelling and mass transport properties of nanocellulose-HPMC composite films

Abstract

Composite films were sprayed from mixtures of water soluble hydroxypropyl methylcellulose (HPMC) and either nanofibrillated cellulose (NFC) or cellulose nanocrystals (CNC). Fiber diameter was similar for both nanocelluloses but fiber length was several μm for NFC and about 200 nm for CNC. Films were characterized for morphology, swelling, mass loss and transport properties. NFC-HPMC films swelled less than CNC-HPMC films; with a HPMC content of 20 wt% NFC-HPMC and CNC-HPMC films presented swelling of 7 and 75 g/g, respectively. The swelling strongly influenced water transport across the films, with slower transport for CNC-based materials compared to NFC-based materials. The properties of NFC-based films were comparable to previous results using microfibrillated cellulose (MFC) with heterogeneous structural content and fiber lengths of ~ 10 μm. The findings have implications for using nanocellulose to modulate material properties in wet-state applications, with effects being in strong contrast when using as a hardening filler in dry materials.

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