Calculate the percentage of crystallinity of these PET plastic containers. Discuss why these PET plastics have different crystallinity.

Table 1 shows the heats of melting, Hm, and cold crystallization, Hc, of polyethylene terephthalate (PET) plastic containers from DSC analysis. Jadual 1 menunjukan haba peleburan, Hm, dan penghabluran sejuk, Hc, bagi bekas plastik polietilena tereftalat (PET) daripada analisis DSC. Table 1/Jadual 1 Table 1 shows the heats of melting, Hm, and cold crystallization, Hc, of polyethylene terephthalate (PET) plastic containers from DSC analysis. Jadual 1 menunjukan haba peleburan, Hm, dan penghabluran sejuk, Hc, bagi bekas plastik polietilena tereftalat (PET) daripada analisis DSC. Table 1/Jadual 1