Modification on nanocellulose extracted from kenaf (Hibiscus cannabinus) with 3-aminopropyltriethoxysilane for thermal stability in poly (vinyl alcohol) thin film composites

Improvement in thermal stability with the aim of homogeneous distribution of the active side of nanocellulose in this study was done with silanization treatment, which started with the treatment of silylated kenaf nanocellulose (SKNC) using 3-aminopropyltriethoxysilane in an alcohol solution at 25 °C with pH 4 within 4 h. Then, SKNC with a varied content of 0.5–2% (w/w) was added to polyvinyl alcohol (PVA). The SKNC was characterized by FT-IR, XRD, TEM, and TGA. The peak at 1571 cm⁻¹ corresponding to N–H bending vibration was observed on SKNC spectra, indicating a successful silane treatment accompanied by a reduction of peak 1642 and 1425 cm⁻¹, respectively. The crystallinity index for SKNC with antiparallel units were increased to 70.34% as compared with kenaf nanocellulose (KNC) (61.73%). TEM showed a form of needle-like structure for both SKNC and KNC. The interaction between SKNC and PVA was characterized by FT-IR with an increment of peak 1089 and 1028 cm⁻¹, which shows the physical interaction that occurred between PVA and SKNC. The dispersion of SKNC was quite homogenous, as observed in FESEM. The SKNC exhibited a good thermal stability, and less amount of char was formed at 700 °C compared to kenaf extractive free. Furthermore, the TGA demonstrated better improvement after addition of 2% SKNC into PVA as well as for DSC results showed higher melting point of PVA composites.