Maurizio Fiorini
Maurizio Fiorini
Professor, Bologna University, DICAM & CIRI MAM
Talk WEDNESDAY, SEPTEMBER 12, 2018
Inventing the Future of Performance Nonwovens for Health and Personal Care
Combined Raman Spectroscopy and Rheology to Study PLA Stereocomplex Formation Dynamics
The formation of stereocomplex between PLLA and PDLA (PLA-sc) offers an outstanding opportunity to increasing thermo-mechanical properties of polylactides, which enables them to compete with well established techno polymers such as PP, PBT and PA-6 in durable applications.
Scaling up PLA-sc production from lab-scale solvent casting techniques to a larger scale requires a deep understanding of thermal and rheological processing conditions. Thanks to a unique lab facility, which combines a dispersive Raman microscope with a modified parallel plate rheometer, simultaneous rheological and spectroscopic analysis could be carried out. We were able to investigate the effects of several parameters, namely: polylactide molecular weight, temperature, cooling rate, and shear stress on the kinetics of PLA-sc formation.
Data on rheological parameters: G’, G” and eta* (under small amplitude oscillatory shear, SAOS) were collected during on-line Raman spectra acquisition. Formation of PLA-sc and its crystallization induced a very sharp increase in eta* values, while G”/G’ ratio changed from values typical of a viscoelastic melt to those of a viscoelastic solid. Two indices of PLA-sc formation, induction time and G’/G” crossover were derived from flow curves under SAOS. At the same time, in the Raman spectra, the intensity of PLA-sc carbonyl band at 1749 cm-1 increased whereas the intensity of the homopolymer carbonyl band at 1772 cm-1 decreased. From these two band ratios, a spectroscopic index of PLA-sc formation was calculated. The evolution of the rheological and Raman indices with time were showed to be in a very good agreement.
About Maurizio Fiorini
Education: University of Bologna, Master and Ph.D. in Industrial Chemistry.
Academic position: 1989-2001: Research Assistant; 2001 -: Associate Professor, University of Bologna
Research interests: Synthesis, modification and characterization of polymeric materials; polymer blends and nanocomposites. Flame resistance of polymer from renewable resources. Bio-based packaging.
Experience in collaborative research with foreign companies (Global Research Center, General Electric 1997-2008 on several topics concerning polymer science) and national companies (since 2013, Head of Lab4Pack, a joint laboratory Bologna Univ. – Sacmi for research on polymer processing for packaging; other collaboration with IMA, G.D., Tetrapak, Philip Morris).
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