Q50 tga model

The molecular weight (M_w) as well as the molecular weight distribution, Ð_M = M_w/M_n, was determined by size exclusion chromatography, SEC, employing a modular instrument consisting of a Waters (Milford, MA, USA) model 510 pump, U6K sample injector, 401 differential refractometer, and a set of 5μ-Styragel columns with a continuous porosity range from 500 to 10⁶ Å. The carrier solvent was CHCl₃ and the flow rate 1 mL/min. The system was calibrated using nine polystyrene standards with molecular weights in the range of 970–600,000.
The NMR measurements were carried out on a 400 MHz Bruker Avance Neo instrument (Bruker BioSpin, Rheinstetten, Germany) using chloroform-d as a solvent at 298 K.
The Tg values of the copolymers were determined by a 2910 Modulated DSC Model from TA Instruments (New Castle, DE, USA). The samples were heated under nitrogen atmosphere at a rate of 10 °C/min from −10 °C up to 220 °C. The second heating results were obtained in all cases.
The thermal stability and the kinetics of thermal decomposition of the copolymers were studied by thermogravimetric analysis (TGA) employing a Q50 TGA model from TA Instruments (New Castle, DE, USA). The samples were placed in a platinum pan and heated from ambient temperatures to 600 °C in a 60 mL/min flow of nitrogen at heating rates of 3, 5, 7, 10, 15, and 20 °C/min.

The polymers were characterized by size exclusion chromatography, SEC, and ¹H-NMR spectroscopy. SEC was performed on a modular instrument consisting of a Waters model 510 pump, a Waters model U6K sample injector, a Waters model 410 differential refractometer, a Waters model 486 UV spectrophotometer and a set of 5 μ-Styragel columns. The columns were housed in an oven thermostated at 40 °C. Tetrahydrofuran was the carrier solvent at a flow rate of 1 mL/min. The system was calibrated with eight polystyrene, PS, standards having molecular weights in the range of 1000 to 500,000.
The ¹H NMR measurements were recorded on a Bruker Avance Neo (Billerica, MA, USA) V3–400 MHz spectrometer at room temperature in deuterated chloroform (CDCl₃).
The thermal stability and the kinetics of thermal decomposition of the copolymers were studied by Thermogravimetric Analysis, TGA, employing a Q50 TGA model from TA Instruments (New Castle, DE, USA). The samples were placed in a platinum pan and heated up to 600 °C in a 60 mL/min flow of nitrogen at heating rates of 3, 5, 7, 10, 15 and 20 °C/min.
The optical properties of the copolymers were investigated via circular dichroism. CD spectra were recorded in hexane solutions using a Jasco J-815 CD spectrometer (Easton, MD, USA).