Q5000 ir apparatus

The measurements were performed using a Q5000 IR apparatus (TA Instruments) under a nitrogen flow of 25 cm³ min⁻¹ for the sample and 10 cm³ min⁻¹ for the balance. The samples (ca. 6 mg) were heated from 25 to 700 °C. The heating rate was set at 20 °C min⁻¹. TG analyses were performed on the fillers loaded with flavonoid fractions and on the corresponding pristine components. The temperature calibration of the apparatus was conducted based on the Curie temperatures of standards (nickel, cobalt and their alloys) [72 (link)].

Solutions of VA (2% wt./wt.) and Q (0.2% wt./wt.) in ethanol were prepared and equilibrated overnight. Halloysite nanotubes, as a dry powder, were added to the ethanol solution of antioxidant (VA/HNT and Q/HNT mass ratios 1:5). The vacuum pumping strategy to enhance the loading efficacy into the halloysite nanotubes is described elsewhere [59 (link)]. The efficiency of loading was verified by means of thermogravimetric analyses (TGA; see Figure S1 in Supplementary Materials). The experiment was carried out by using a Q5000 IR apparatus (TA Instruments) under nitrogen flow (25 cm³/min) at a heating rate of 20 °C/min to 800 °C. The amount of antioxidant entrapped into the HNT was estimated from the residual mass at 750 °C taking into account for the residual mass of each component and assuming the rule of mixtures. The thermogravimetric curves are provided in the supporting files and the obtained loading efficacy expressed as antioxidant mass percent into the composite with HNT are 0.537% w/w and 2.59% w/w for HNT/VA and HNT/Q, respectively.

Thermogravimetric experiments were performed by using a Q5000 IR apparatus (TA Instruments, New Castle, DE, USA). The measurements were conducted under inert atmosphere using nitrogen flows for the sample and the balance (25 and 10 cm³ min⁻¹, respectively). The samples were heated (scanning rate of 20 °C min⁻¹) from 25 to 800 °C. According to the literature [62 (link),63 (link)], the temperature calibration was carried out by exploiting the Curie temperatures of specific standards (nickel, cobalt, and their alloys). Thermogravimetric measurements were repeated three times for all the investigated samples. The average values with the corresponding standard deviations for the thermogravimetric parameters are presented.

Thermal properties were tested with thermogravimetry (TGA) and differential scanning calorimetry (DSC). TGA measurements were performed with the Q5000IR apparatus (TA Instruments, New Castle, DE, USA). The samples were placed on platinum pans and heated up to 750 °C, at 10 °C/min heating rate and nitrogen flow rate amounting to 25 mL/min. DSC measurements used Q2000 apparatus (TA Instruments, New Castle, DE, USA). The samples were crimped in Tzero aluminium pans and tested according to a heat/cool/heat procedure in a temperature range between −50 °C and 180 °C, with a heating/cooling rate of 10 °C/min and nitrogen flow rate of 50 mL/min. The TGA and DSC results were processed and analysed with Universal Analysis software (version 4.5A, TA Instruments, New Castle, DE, USA). The samples used for the tests included non-weathered coatings (R), coatings weathered as a result of natural exposure for twenty and twenty-four months (N₂₀ and N₂₄, respectively), artificially weathered under neutral salt spray for 720 h (NSS₇₂₀) and according to original accelerated weathering cyclic test—three cycles and total exposure time of 1080 h (C3).

Thermogravimetry (TG) measurements were performed by using a Q5000 IR apparatus (TA Instruments, Milan, Italy) under nitrogen flows of 25 and 10 cm³ min⁻¹ for the sample and the balance, respectively. Each sample (approximately 5 mg) was heated from room temperature to 800 °C at a rate of 10 °C min⁻¹. The loading efficiency was provided using the rule of mixtures on neat HNTs, pure SA and SA/HNTs composites [48 (link)]. The apparatus was calibrated by the Curie temperature of standards [54 (link)]. In order to study the release kinetics obtained from the prepared materials, UV–Vis spectra in quartz cuvettes were recorded by a Specord S600 (Analytik, Jena, Germany). Optical images were produced by using a DIGITUSs (DA-70351) microscope and processed by using the Digital Viewer software. Dimensions were measured by using ImageJ as software [55 (link)]. Scanning electron microscopy was conducted by using a microscope ESEM FEI QUANTA 200F. Before each experiment, each sample was coated with gold in argon by means of an Edwards Sputter Coater S150A to avoid charging under the electron beam. The measurements were carried out in high vacuum mode (<6 × 10⁻⁴ Pa) for the simultaneous secondary electron; the energy of the beam was 10 kV, and the working distance was 10 mm.

Thermogravimetry (TG) experiments were carried out by means of a Q5000 IR apparatus (TA Instruments) under the nitrogen flows of 25 cm³ min^–1 for the sample and 10 cm³ min^–1 for the balance. The mass of each sample was ca. 5 mg. TG measurements were conducted between 25 and 600°C using a constant heating rate of 20°C min^–1. The temperature calibration was carried out by means of the Curie temperatures of standards (nickel, cobalt, and their alloys) (Blanco et al., 2014 (link)). The encapsulation efficiency into HNTs was determined by considering the rule of mixtures for the residual mass at 600°C. Details are provided in literature (Lisuzzo et al., 2019 (link)).