High-strength cellulose nanofiber/graphene oxide hybrid filament made by continuous processing and its humidity monitoring

Abstract

Human-made natural-fiber-based filaments are attractive for natural fiber-reinforced polymer (NFRP) composites. However, the composites' moisture distribution is critical, and humidity monitoring in the NFRP composites is essential to secure stability and keep their life span. In this research, high strength and humidity sensing filament was developed by blending cellulose nanofiber (CNF) and graphene oxide (GO), wet-spinning, coagulating, and drying, which can overcome the heterogeneous mechanical properties between embedded-type humidity sensors and NFRP composites. The stabilized synthesis process of the CNF-GO hybrid filament demonstrated the maximum Young's modulus of 23.9 GPa and the maximum tensile strength of 439.4 MPa. Furthermore, the achieved properties were successfully transferred to a continuous fabrication process with an additional stretching process. Furthermore, its humidity sensing behavior is shown by resistivity changes in various temperature and humidity levels. Therefore, this hybrid filament has excellent potential for in-situ humidity monitoring by embedding in smart wearable devices, natural fiber-reinforced polymer composites, and environmental sensing devices.

Effect of graphitic additives on the rheology of cellulose solutions for the preparation of templated carbon fiber precursors

“…These results imply that the additive‐containing fibers may behave as ordered carbon; that is, their La is proportional to D:G peak intensity ratio, following the Tuinstra‐Koenig relation. This is reasonable considering that, assumedly, the carbon included in these fibers originates largely from well ordered GO, which is less prone to degradation during heating than cellulose 39 . Furthermore, the templating effect of GO 4 may cause even the cellulose to carbonize into a form that behaves like orderly carbon.…”

“…Comparison between the crystal sizes (Figure 4c,d) shows that the crystallites were approx. 50% smaller in both dimensions when incorporated in fibers than in plain ground GO flakes, even though the carbon present in fibers GO2% and GO5% can be expected to largely originate from the additive, as cellulose is more prone to degradation upon heating than GO 39 . Likewise, the interlayer spacing d 002 was wider in fiber samples than in ground GO flakes (Figure S6d).…”

“…50% smaller in both dimensions when incorporated in fibers than in plain ground GO flakes, even though the carbon present in fibers GO2% and GO5% can be expected to largely originate from the additive, as cellulose is more prone to degradation upon heating than GO. 39 Likewise, the interlayer spacing d 002 was wider in fiber samples than in ground GO flakes (Figure S6d). These findings suggest that the fiber preparation-including steps like sonication of the GO in ionic liquid and filtration-impacts the crystallinity of the GO in a way that leads to smaller and less densely packed crystallites in the resulting carbon fiber.…”

“…This is reasonable considering that, assumedly, the carbon included in these fibers originates largely from well ordered GO, which is less prone to degradation during heating than cellulose. 39 Furthermore, the templating effect of GO 4 may cause even the cellulose to carbonize into a form that behaves like orderly carbon.…”

Cellulose‐Based Sustainable Composites: A Review of Systems for Applications in EMI Shielding and Sensors

“…Kafy et al. [ 32 ] presented a simple fabrication approach (simple blending technique) for CNC−(graphene oxide) (GO) composite films and determined the humidity sensing performance of the produced films. These authors postulated that CNC–GO composite film benefits synergistically from the properties of cellulose GO functionality; as a result, unique properties of CNC–GO composite film were exploited to engineer flexible, renewable, and low‐cost humidity sensors.…”