Master of Engineering Science
Mechanical and Materials Engineering
Wood, Jeffrey T.
Variation in glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is addressed, specifically for composites of poly(methyl methacrylate) (PMMA) and freeze-dried cellulose nanocrystals; mortar-and-pestle grinding use for creating solventless PMMA/cellulose nanocomposites is evaluated. Experimentally, solvent-containing and solventless PMMA and PMMA/cellulose composite samples (prepared using mortar-and-pestle grinding, melt-pressing, and acetone addition) were tested by DSC in hermetically-sealed pans using one of two maximum first heating scan temperatures; post-DSC samples were photographed. Mortar-and-pestle-ground cellulose was imaged by Field Emission Scanning Electron Microscopy (FE-SEM). Post-DSC samples had different shapes, some corresponding to greater increases in Tg from first to second heating, associated with Tg variation. A shape classification is proposed. Second heating Tg was affected by first heating peak temperature in solvent-containing samples. FE-SEM showed only low aspect ratio microscale cellulose particles. Visual analysis of samples after DSC testing is recommended; mortar-and-pestle grinding is found unsuitable for solventless PMMA/cellulose nanocomposite preparation.
Mamycheva, Elena, "Sources of Glass Transition Temperature Variation in Poly(methyl methacrylate)/Cellulose Composites" (2018). Electronic Thesis and Dissertation Repository. 5418.