*Article* **Study of Curing Characteristics of Cellulose Nanofiber-Filled Epoxy Nanocomposites**

#### **Mohan Turup Pandurangan \* and Krishnan Kanny**

Department of Mechanical Engineering, Durban University of Technology, Durban 4001, South Africa; kannyk@dut.ac.za

**\*** Correspondence: mohanp@dut.ac.za; Tel.: +2-73-1373-2831

Received: 24 June 2020; Accepted: 13 July 2020; Published: 24 July 2020

**Abstract:** In recent years, much attention was focused on developing green materials and fillers for polymer composites. This work is about the development of such green nanofiller for reinforcement in epoxy polymer matrix. A cellulose nanofiber (CNF)-filled epoxy polymer nanocomposites was prepared in this work. The effect of CNF on curing, thermal, mechanical, and barrier properties of epoxy polymer is evaluated in this study. CNF were extracted from banana fiber using acid hydrolysis method and then filled in epoxy polymer at various concentration (0–5 wt.%) to form CNF-filled epoxy nanocomposites. The structure and morphology of the CNF-filled epoxy nanocomposites were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Curing studies shows CNF particles acts as a catalytic curing agen<sup>t</sup> with increased cross-link density. This catalytic effect of CNF particles has positively affected tensile, thermal (thermogravimetry analysis and dynamic mechanical analysis) and water barrier properties. Water uptake test of nanocomposites was studied to understand the barrier properties. Overall result also shows that the CNF can be a potential green nanofiller for thermoset epoxy polymer with promising applications ahead.

**Keywords:** thermoset polymer; epoxy; cellulose nanofiber; curing characteristics; thermal properties; mechanical properties
