ʻO ka polyethylene terephthalate (PET) kahi polymer semi crystalline nona ke kūpaʻa kemika maikaʻi loa, ka hoʻoheheʻe ʻana a me ka spinnability.Hoʻokumu ʻia ka polymer me nā ʻāpana hana hou e like me ka mea i hōʻike ʻia ma ke Kiʻi 1. ʻO kēlā me kēia ʻāpana he lōʻihi kino ma kahi o 1.09 nm a me ke kaumaha molekala o ~200.Ke hana ʻia ia mai ka hopena o ka ʻakika terephthalic a me ka ethylene glycol, ua uhi ʻia ia ma ka hema e H- a ʻo ka ʻākau e –OH.Hoʻopili pū ʻia ka polymerization me ka hana ʻana o ka wai i hoʻoneʻe ʻia ma lalo o ke kiʻekiʻe kiʻekiʻe o ka mahana a me ka vacuum.No laila, ʻo ka loaʻa ʻana o ka wai i loko o ka moku i hoʻoheheʻe ʻia e hoʻoheheʻe koke i ka hale i mea e pono ai ka hoʻomaloʻo pono ʻana o ka polymer ma mua o ka hoʻoheheʻe ʻana o ka wili o nā fibers.

ʻO ke apo ʻala i hui pū ʻia me ke kaulahao aliphatic pōkole e hana ai ka polymer i mole ʻoʻoleʻa i hoʻohālikelike ʻia me nā polymers aliphatic e like me ka polyolefin a i ʻole polyamide.ʻO ka nele o ka mobility segmental i nā kaulahao polymer ka hopena i ke kūpaʻa wela kiʻekiʻe.E loaʻa i kahi polymer papa textile ka helu awelika o 100 mau ʻāpana hou i kēlā me kēia mole no laila ʻo ka lōʻihi lōʻihi o ke kaulahao polymer maʻamau ma kahi o 100nm me ke kaumaha molekala ma kahi o 20,000.ʻO nā kiʻekiʻe kiʻekiʻe o ka polymerization e hoʻopuka i nā fiber ikaika kiʻekiʻe akā ʻo ka hoʻoheheʻe viscosity a me ka paʻa o ka hoʻoheheʻe ʻana a hiki i ka liʻiliʻi liʻiliʻi o ka wai ke kumu o ka hydrolytic degradation.Hana ʻia ke ana o ka degere awelika o ka polymerization ma o ka viscosity hehee ʻia (ma ke ana ʻana i ka hāʻule kaomi ma o ka puka calibrated) a i ʻole ka viscosity o ka polymer i hoʻoheheʻe ʻia i loko o kahi mea hoʻoheheʻe kūpono.ʻO ka hope ka ana o ka lōʻihi o ke kaulahao polymer i ʻike ʻia ʻo Intrinsic viscosity a i ʻole IV a ʻo ka waiwai no ka polymer grade fiber maʻamau he 0.6 dl/g i loko o 60/40 w/w hui ʻana o ka phenol a me ka solvent tetrachloroethane.ʻO ka IV i loko o ka mea hoʻoheheʻe hope e pili ana iā Mv (Viscosity average molecular weight) o ka polymer e ka hoʻohālikelike Mark Howink (Equation 1).