Activation energy dependencies obtained by isoconversional analysis of TGA data for pristine and aged PP with thickness (a) PP01 (L = 0.25 mm), (b) PP02 (L = 0.39 mm), and (c) PP03 (L = 0.69 mm), and PP-MWCNT composites with thickness (d) PP41 (L = 0.35 mm), (e) PP42 (L = 0.50 mm), and (f) PP43 (L = 2.27 mm).