Polyethylene terephthalate (PET) ndi polima wa semi crystalline wokhala ndi kukana kwamphamvu kwamankhwala, kusungunuka kwamadzi komanso kusinthasintha.Polima imapangidwa ndi mayunitsi obwerezabwereza monga momwe tawonetsera pa Chithunzi 1. Chigawo chilichonse chokhala ndi kutalika kwa thupi pafupifupi 1.09 nm ndi molekyulu yolemera ~ 200.Ikapangidwa kuchokera ku terephthalic acid ndi ethylene glycol, imayikidwa kumanzere ndi H- ndi kumanja ndi -OH.Polima motero amatsagana ndi kupanga madzi omwe amachotsedwa pansi pa kutentha kwakukulu ndi vacuum.Chifukwa chake, kukhalapo kwa madzi mumkhalidwe wosungunuka kumapangitsa kuti pakhale kusungunuka kwadongosolo kotero kuti kuyanika bwino kwa polima kusanasungunuke kupota ulusi ndikofunikira.

Mphete yonunkhira yophatikizidwa ndi tcheni chachifupi cha aliphatic imapangitsa polima kukhala molekyulu yowuma poyerekeza ndi ma polima ena monga polyolefin kapena polyamide.Kusasunthika kwa segmental mu maunyolo a polima kumapangitsa kuti pakhale kukhazikika kwamafuta ambiri.Polima kalasi ya nsalu adzakhala ndi chiwerengero cha mayunitsi obwereza 100 pa molekyulu kotero kuti kutalika kwa unyolo wa polima wamba kumakhala pafupifupi 100nm ndi molekyulu yolemera pafupifupi 20,000.Miyezo yapamwamba ya polymerization imapanga ulusi wamphamvu kwambiri koma kusungunuka kwa mamachulukidwe ndi kukhazikika kwa kusungunula mpaka kunyowa pang'ono kumayambitsa kuwonongeka kwa hydrolytic.Kuyeza pafupifupi digiri ya polymerization ikuchitika ndi kusungunuka mamasukidwe akayendedwe (poyesa kuthamanga dontho kudzera calibrated orifice) kapena mamasukidwe akayendedwe a kuchepetsedwa polima mu zosungunulira yoyenera.Chotsatiracho ndi muyeso wautali wautali wa polima wotchedwa Intrinsic viscosity kapena IV ndipo mtengo wa polima wamtundu wa fiber ndi 0.6 dl/g mu 60/40 w/w osakaniza a phenol ndi tetrachloroethane zosungunulira.IV muzosungunulira zotsirizirazi ndi zogwirizana ndi Mv (Viscosity average molecular weight) ya polima ndi Mark Howink equation (Equation 1).