Sdt q600 analyser

The starting materials and nanofibers were characterised using the following physicochemical techniques: absorption spectroscopy in the infrared region, X-ray diffraction and thermal analysis. In the infrared analysis, a Perkin Elmer spectrum GX spectrophotometer was used; the samples were prepared with KBr and readings were made in the 4000–400 cm⁻¹ region. The crystallographic profile of both raw materials and fibres was obtained by X-ray diffraction. The X-ray diffraction pattern of the nanofibers was analysed using a Shimadzu XRD-700-X-Ray diffractometer, equipped with a copper tube and CuKα (λ = 1.5405 Å) radiation. Data were processed in the 2θ angles ranging from 4 to 60° and the scanning rate was 4θ min⁻¹. Thermogravimetric (TG) profiling was performed using a TA Instruments SDT Q600 analyser, in N₂ atmosphere with a constant flow rate of 50 mL.min⁻¹, in the temperature range of 25–800 °C using a heating rate of 10 °C min⁻¹. The morphology and diameter of the fibres were studied by scanning electron microscopy: portions of the fibres were deposited directly on copper sample holders inside the electrospinning equipment. The micrographs were taken with a FEG Quanta 2000 electron microscope using an acceleration voltage of 10 kV under reduced pressure.

The free water (i.e., non-chemically combined water) content of all pastes at all ages was calculated by analysing the thermogravimetric traces of all arrested-hydration pastes. An SDT-Q600 analyser (TA Instruments, New Castle, DE, USA) was used to perform these analyses. Some milligrams of arrested-hydration pastes were placed in open platinum crucibles under air flow and heated from room temperature (RT) to 1000 °C (at 10 °C/min). The free water was calculated as detailed in [38 (link)] by considering the weighed loss from RT to 600 °C as chemically bounded water and the one from 600 to 1000 °C as CO₂.

A SDT-Q600 analyser from TA instruments (New Castle, DE, USA) was used to collect the thermogravimetric (TGA) traces for the four samples, i.e., two hydration-arrested and two neat pastes. The temperature was varied (10 °C/min) from RT to 40 °C, held at 40 °C for 30 min and then raised up to 1000 °C at the same rate. Measurements were made in open platinum crucibles under synthetic air flow. The weight loss from 45 to 550 °C was assigned to chemically bounded water [37 (link),38 (link)] and the loss from 550 to 1000 °C was considered as CO₂. The free water (FW, wt%) was calculated from the TGA traces of the hydration-arrested pastes by assuming that the chemically combined water was responsible for the weight loss from 45 to 550 °C. The FW was obtained by subtracting this value from the total added water (nominal value).