Dsc25

The anti-freezing ability of the gel samples was characterized via differential scanning calorimetry (DSC) (DSC 25, TA Instruments) with a refrigerated cooling system (TA Instruments, RCS90), the cooling cycle was executed from 20°C to −70°C at a rate of 2°C min⁻¹. Rheological test was performed on a rotational rheometer (DHR-2, TA Instruments) under a fixed strain of 0.1% and fixed frequency of 1 Hz, this temperature-sweep was cooled from 25°C to −40°C at a rate of 2°C min⁻¹. The storage modulus (G′) and loss modulus (G″) were recorded. Besides, the stretching behavior of different gels at −40°C was tested using a tensile tester (Instron 3369, United States) with a separate frozen chamber.

The thermal and decomposition (TGA) characteristics of different semi-IPNs were determined on a Setaram Setsys Evolution 16 apparatus by heating the samples at a rate of 10 °C.min⁻¹ from 20 to 600 °C under atmospheric air and normalized to the C=O band at 1732 cm⁻¹.
Differential scanning calorimetry (DSC) measurements were recorded on TA Instruments DSC25. A first heating run from −80 °C to 200 °C with a heating rate of 10 °C/min was performed to determine the melting temperature and the fusion enthalpy. This was followed by a cooling run to −80 °C with a cooling ramp of 200 °C/min. The T_g was obtained in a second heating run from −80 °C to 200 °C at 10 °C/min.

DSC analysis was performed using a thermal analyzer (DSC25, TA instruments, Inc., New Castle, DE, USA). Prior to each analysis, temperature and heat capacity calibration were performed using high purity indium and aluminum oxide sapphire, respectively, with a temperature range of 0 to 390 °C, a modulation rate of 0.6 °C/min every 40 s, and a scan speed of 5 °C/min. Next, 2–4 mg of sample was weighed and placed in a pre-weighed aluminum hermetic pan, then sealed with an aluminum cover. Closed, empty aluminum pans were used as reference samples. Analysis was carried out by heating samples from 0 to 350 °C at a heating rate of 10 °C/min under a nitrogen purge of 400 mL/min.

The thermal properties of the polymers were analysed using differential scanning colorimetry (DSC) using a TA Instruments DSC 25 (New Castle, DE, USA). Approximately 9–11 mg of resin or polymer powder sealed in Tzero Pans with Tzero lid with pin hole (TA instruments, USA) were subjected to a heating-cooling-heating cycle at a rate of 10 °C/min. The measurement for the polymers PCL, PBAT, PBS and PHBH was performed from 0 to 180 °C, starting for 5 min at 0 °C, heating up to 180 °C and kept for 5 min for the first run, cooling down to 0 °C and kept for 5 min and heated up to 180 °C for the second heating run. For the polymers with a higher Tm, PLLA, PHB, PHBV and PLLA/PCL blend, the measurement was conducted from 0 to 220 °C.
To determine the degree of crystallinity of the sample, the following formula was used: Xc = ΔHm0 × 100% [24 ]. Xc is the degree of crystallinity. ΔHm is the enthalpy during the melting. ΔHm0 is the enthalpy for the normalized enthalpy values (J/g) for 100% crystalline polymer, as reported in the literature: for PHB = 146 J/g [25 (link)], PLLA = 93.1 J/g [26 (link)], PBAT = 114 J/g [27 (link)], PBS = 110.3 J/g [28 (link)], PCL = 139.5 J/g [29 (link)] and PHBH = 146 J/g [29 (link)]. PHBV was assumed to have the same enthalpy as PHB [30 (link)].

The calorimetric measurements of the samples were carried out using a differential scanning calorimeter DSC25 (TA Instruments, New Castle, DE, USA) and sealed aluminum Tzero pans. The measurements were carried out in a nitrogen atmosphere at a flow rate of 70 mL/min in the temperature range from −20 to 200 °C with a heating rate of 10 °C/min. The first heating continued up to 190 °C at a rate of 20 °C/min and then the sample was cooled down to −20 °C at a rate of 3 °C/min. The results were processed using the TRIOS v. 5.00.44608 software package (TA Instruments, New Castle, DE, USA).

A differential scanning calorimeter (DSC 25, TA instruments, New Castle, DE, USA) was employed to observe the melting and the recrystallization behavior of the drug with the excipients. The samples for the DSC analysis include TA and physical mixture of the lipid phase (with similar ratio as for formulation) melted and solidified. Approx. 5 mg of the samples, individually sealed in the aluminum pans, were placed over the sample platform. The reference pan, empty sealed aluminum pan, was placed on the reference platform. The pans were heated from 25 to 320 °C at the rate of 20 °C/min under nitrogen purge (20 mL/min).