Surface hydrophobization of TEMPO-oxidized cellulose nanofibrils (CNFs) using a facile, aqueous modification process and its effect on properties of epoxy nanocomposites

Autor: Jeffrey P. Youngblood, Reaz A. Chowdhury, Daniela Betancourt, Francisco Montes, Michael D. Toomey, Shikha Shrestha
Rok vydání: 2019
Předmět:
Zdroj: Cellulose. 26:9631-9643
ISSN: 1572-882X
0969-0239
DOI: 10.1007/s10570-019-02762-w
Popis: This work investigates the effects of surface modified cellulose nanofibrils (CNFs) on the mechanical, thermal, and morphological properties of epoxy nanocomposites. CNFs (extracted from wood pulp) were modified by using a two-step water-based method, where tannic acid (TA) acts as a primer with CNF suspension and reacts with hexadecylamine (HDA), forming the modified product as CNF-TA-HDA. The modified (-m) and unmodified (-um) CNFs were filled into hydrophobic epoxy resin with a co-solvent (acetone), which was subsequently removed to form a solvent-free two component epoxy system, followed by addition of hardener to cure the resin. Better dispersion and stronger adhesion between fillers and epoxy were obtained for m-CNFs than the um-CNFs, resulting in better mechanical properties of nanocomposites at the same loading. Elastic modulus, tensile strength, and work-of-fracture improved with increasing m-CNFs, with the most remarkable improvement observed for 0.5 wt% content, indicating good reinforcement of epoxy. um-CNFs showed incompatibility and lack of dispersion with epoxy leading to insignificant changes in the mechanical properties. Thermal stability and the degradation temperature of m-CNF/epoxy improved when compared to neat epoxy. The glass transition temperature ($$ T_{g} $$) also increased substantially up to 5 °C for m-CNFs, while um-CNFs showed decrease in $$ T_{g} $$.
Databáze: OpenAIRE
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