## 2 Materials and Methods
Rectangular bars with a length of 127 mm, a width of 12.7 mm, and 3.2 mm high were built; all the specimens were maintained at a fixed temperature of 87 \({}^{\circ}\)C for 12 h before performing the mechanical tests. The tests determined the flexural strength, the elastic modulus, and flexural strain of samples. A test specimen with rectangular cross section was placed in a flat position on two supports; the span length between them was fixed to 51.2 mm in accordance with the test standard. The load was then applied by means of a loading nose located in the centre of the span length; a crosshead rate of 1 mm/min was used. The specimen was deflected until rupture occurred or until a maximum strain of 9.0% was reached. For both tensile and flexural properties average values and standard deviations were calculated. All data were statistically evaluated using one-way ANOVA. Post hoc Tukey's honestly significant difference(HSD) multiple comparison tests were then used to identify statistically-homogeneous subsets (\(\alpha\) = 0.05). The thermal stability of Ultem 9085 (in the form of filament and printed samples) was evaluated through thermal-gravimetric analyses (TGA/SDTA851 Mettler Toledo), which were carried out from 25 to 800 \({}^{\circ}\)C with a heating rate of 10 \({}^{\circ}\)C/min under both argon atmosphere and air (gas flowing at 50 mL/min). The presence of any crystalline phases in the solid residue obtained after the thermal degradation of Ultem 9085 in inert atmosphere was investigated by using X-ray diffraction (Panalytical X'PERT PRO PW3040/60, Cu K\(\alpha\) radiation at 40 kV and 40 mA, Panalytical BV, Almelo, The Netherlands). The spectrum was collected in 2 Theta range from 10\({}^{\circ}\) to 80\({}^{\circ}\) setting a step size of 0.013\({}^{\circ}\). The ageing behavior of Ultem 9085 was evaluated after three kinds of artificial ageing treatments:  
* Warm storage, which consisted of maintaining samples at a temperature of 100 \({}^{\circ}\)C and a zero percent relative humidity for a period of 7 days;
* Cyclic climate change, involving the constant and periodic variation of climate cell temperature between \(-\)40 and +90 \({}^{\circ}\)C using a thermal gradient of 1 \({}^{\circ}\)C/min. Both the maximum and minimum temperatures were maintained for 4 h; the relative humidity was also controlled reaching a maximum of 85% at 90 \({}^{\circ}\)C. This cycle was repeated for 10 times with a cumulative duration of 120 h;
* Thermal shock, consisting of two steps. Firstly, the samples were maintained at the temperature of 70 \({}^{\circ}\)C and zero relative humidity for 7 days. They then were subjected to a strong temperature variation up to \(-\)20 \({}^{\circ}\)C for 24 h.  
To the best of authors' knowledge, there is not a standard procedure to determine the thermal behavior of a car component in different environmental conditions. However, some studies in the literature investigated the vehicle cabin temperatures that can be reached in various weather conditions and during the different periods of the year [26; 27; 28]. The testing conditions adopted for the three previously-described ageing treatments aim to simulate the environmental conditions (in term of temperature and relative humidity variations) that an internal vehicle component experiences during its life cycle. They are currently used for the qualification and validation of internal components in automotive industry. Bars for flexural tests were subjected to the three kinds of previously-described environmental tests--sets of four samples were subjected to a single ageing treatment and a fourth one underwent all the treatments. The influence of the ageing treatments on the mechanical behavior of Ultem 9085 was investigated by carrying out flexural tests to samples which underwent a single ageing cycle (samples set A, after warm storage; samples set B, after cyclic climate change; and samples set C, after thermal shock) or all the three treatments (samples set D).