XRD analysis was used to characterize the fillers (d-spacing of the clay platelets) before their addition into polyester and forming the films. The X-ray diffraction (XRD) patterns of the catalysts were recorded by an Empyrean PANalytical (Malvern, UK) X-ray diffractometer using Cu K (λ = 0.154 nm) as the radiation source in the 2θ range 1-15° with a step size of 0.052. D-spacings were calculated using the Braggs equation (1):