Effect of surface-modified montmorillonite on viscosity and gelation behavior of cellulose/NaOH solution

In this work, rheological properties of cellulose solution incorporated with different concentration of surface-modified montmorillonite (SM-MMT) were investigated. Thermal behavior analyses of cellulose solutions were performed using rheological tests; including determination of various factors to estimate the gelation temperature and time. The results showed lower viscosities for composite samples compared to pristine cellulose solution which can be regarded as a result of good dispersion of SM-MMT through cellulose matrix. Moreover, gelation point was dependent on SM-MMT concentration. There was a tendency for an increase in gelation temperature with SM-MMT content from 0 to 10 wt%. Also, gelation time significantly increased with incorporation of nanoparticles, indicating SM-MMT effect on weakening of hydrogen bond strength between cellulose chains which limited cellulose aggregation. Fourier transform infrared and Raman spectroscopy were also used to evaluate structural differences between composite foams prepared from cellulose solutions. FTIR and Raman spectra confirmed hydrogen bond formation between cellulose matrix and SM-MMT.