Dr. Pekarovicova, professor, joined the Department of Chemical and Paper Engineering in 1997 as a visiting scientist. She teaches courses in the printing and chemical engineering programs.
Rheology of Glucomannan-Xylan Film-forming Solutions In the Process of Manufacturing Biofilms for Food Packaging
Kholoud Al-Ajlouni, Paul D. Fleming, and Alexandra Pekarovicova, Western Michigan University
Glucomannan-xylan blend films were prepared and their film-forming solutions ‘rheological properties were tested using Anton Paar Rheometer at 25°C at shear rates 0.1- 100 1/s. The viscoelastic properties were tested under constant shear strain 5% and frequency sweep 0.1-100 rad/s. Nano fibrillated cellulose (NFC) was added to the mixture to improve the strength property of the blend films. The viscosity of the film-forming solution of all samples showed that it is increased when the concentration of the glucomannan is higher and the NFC is added to the formulas. The solutions proved to be shear-thinning, their fluidity was visible at lower frequencies; gel formation was hindered by higher values of glucomannan concentrations in the blends which means longer drying time, but NFC addition contributed to gel formation in all samples.
Rotogravure Printing of Li Ion Battery Anodes
Kevin Mathew, Alexandra Pekarovicova, and Paul D. Fleming, III, Western Michigan University
Rotogravure inks were formulated for Li-ion battery anodes. Different polymer chemistries were tested such as polyvinylidene fluoride (PVDF ) with degree of polymerization of 1*106. It was found that the best printability can be achieved using mixed PVDF-PVP (polyvinylidene fluoride – polyvinylpyrrolidone) binders with commercial names of PVDF being Kureha 9100, 9300, and Solef 5300. As active materials, Philips 5, 10, 15 graphites (5 -15 micron) in combination with nanocarbon filler were used. Inks were dispersed in NMP (N-methyl-pyrrolidone) solvent. The particle size of graphite for most uniform printing was found to be 5 microns. Surface energy of copper foil substrate and surface tension of inks were determined. Printed copper foils were assembled into battery half cells and their irreversible capacity loss was tested.