PET ya firime ishushanya ni ubwoko bwa firime yatunganijwe hamwe na formula idasanzwe. Hamwe na tekinoroji yohejuru yo gucapa hamwe nubuhanga bwo gushushanya, irerekana uburyo butandukanye bwibara ryamabara hamwe nimiterere yo murwego rwohejuru. Igicuruzwa gifite ibiti bisanzwe byimbaho, ibyuma byo murwego rwohejuru, ubwiza bwuruhu rwiza, hejuru-yuzuye hejuru yubuso nubundi buryo bwo kwerekana.