Rheological properties of microfibrillated cellulose and hydroxypropyl methylcellulose blends in ethanol/water solvent systems

Microfibrillated cellulose (MFC) and hydroxypropyl methylcellulose (HPMC) were employed as gelling agents in hydroalcoholic solutions. However, a limited number of studies have explored the interactions between MFC and cellulose derivatives in organic solvents. Most of these studies have primarily focused on either the interactions between MFC and polymers in aqueous solutions. To investigate their collaborative effect, phase diagrams were constructed by varying the concentration of the constituent elements, confirming phase separation, and identifying liquid-like and gel-like properties through oscillatory rheological measurements. Oscillatory amplitude, frequency, oscillatory swing temperature and viscosity were performed. Additionally, aerogels were fabricated with and without ethanol for microscopic analysis. It was demonstrated that ethanol significantly influences the rheological characteristics of MFC and MFC + HPMC dispersions, resulting in an increase in the elastic modulus (G'), decreased thixotropic behavior, and increased stability. Tests were also conducted with urea, a strongly chaotropic agent, providing evidence of the types of interactions governing the systems, and demonstrating that intermolecular hydrogen bond interactions play a predominant role.