From the method section of the paper:

Materials and Property Characterization. From a popular US chain store, two brands of baby food containers made of polypropylene and one brand of reusable food pouch with- out material information on the label were purchased. The selection of polypropylene containers was based on its widespread use in baby food packaging. These choices aimed to showcase diverse types of baby food packaging. The food containers and the food pouch were analyzed for their semicrystalline structure and thermal stability by DSC using a Q200 differential scanning calorimeter (TA Instruments, New Castle, DE). Briefly, a small sample weighing between 3 and 8 mg was taken from each container or pouch, placed in a DSC aluminum pan/lid assem- bly, and crimped with a press. The samples were heated and cooled at a rate of 10 °C/min under a nitrogen atmosphere, resulting in calori- metric curves that indicate the heat transfer to and from the polymer sample during the thermal cycle, which was used to monitor phase transitions. H u s s a i n e t a l . i n E n v i r o n . S c i . T e c h n o l . 5 7 ( 2 0 2 3 ) 5 Transmission wide-angle X-ray diffraction (WAXD) of the reusable food pouch was performed at the 12-ID-B beamline at the Advanced Pho- ton Source (Argonne National Laboratory), using incident X-rays with energy 13.30 keV and a Pilatus 300k 2D detector mounted 0.4 m from the sample. WAXD patterns of the two plastic containers were acquired in reflection geometry with a Bruker-AXS D8 Discover equipped with a Cu Kα lab source (λ = 1.5406 A) and a Vantec 500 area detector. In all cases, the acquired 2D patterns were radially averaged to produce 1D intensity (I) vs scattering vector (q) plots