Polyethylene yog cov khoom siv uas siv ntau yam kev lag luam. Cov khoom siv los ntawm nws kuj tseem siv tau hauv lub neej txhua hnub. Ordinary polyethylene khaws nws lub zog mus txog qhov kub ntawm 130 degrees. Txawm li cas los xij, nws feem ntau dhau los ua qhov tsim nyog siv cov khoom no hauv cov xwm txheej hnyav dua, ntawm qhov kub thiab txias siab dua, piv txwv li, hauv cov cua kub thiab dej kub.
Qhov kev xav tau no coj mus rau kev tshawb nrhiav txoj hauv kev kom tau txais cov khoom siv ruaj khov dua. Cov thev naus laus zis pom tau ua rau nws tuaj yeem tau txais kev sib txuas ntawm polyethylene, uas muaj qhov hnyav dua molecular piv rau cov khoom siv thiab muaj cov yam ntxwv zoo dua. Kev sib txuas sib txuas tau nkag siab tias yog txheej txheem uas cov kev sib txuas ntawm cov molecules txuas rau hauv peb-dimensional wide-mesh network vim yog tsim cov kab sib txuas.
Nyob ntawm qhov cuam tshuam rau kev siv, tshuaj lom neeg thiab lub cev sib txuas yog qhov txawv. Nyob rau hauv rooj plaub tom kawg, cov kav dej (cross-linked polyethylene yog siv los tsim cov khoom no) yog irradiated nrog x-ray nyuaj.rays. Cov tshuab no ua tau zoo heev, thiab tuaj yeem ncav cuag 80 meters ntawm cov khoom siv hauv ib feeb.
Qhov tsis zoo ntawm txoj kev no yog qhov cross-linked polyethylene tsis sib npaug hauv qhov tuab ntawm cov yeeb nkab. Sab hauv muaj qhov feem pua ntawm kev sib txuas molecular qis tshaj plaws, thaum sab nraud, ntawm qhov tsis sib xws, muaj qhov siab tshaj.
Raws li, cov khoom ntawm cov khoom hauv ntim kuj txawv. Qhov tshwm sim yog cross-linked polyethylene ntawm qeb C (PEX).
Thaum siv cov tshuaj, cov tshuaj tshwj xeeb silane yog siv los hloov cov hydrogen atoms hauv cov molecules. Raws li, silane crosslinked polyethylene tau txais. Cov kav dej thaum lub sijhawm tsim khoom dhau los ntawm chav da dej tshwj xeeb uas muaj cov khoom siv. Qhov no ua rau nws muaj peev xwm ua kom cov txheej txheem stitching tsis sib xws los ntawm sab hauv thiab sab nrauv sib sib zog nqus rau hauv cov yeeb nkab phab ntsa. Cov thev naus laus zis no ua rau nws tuaj yeem tau txais cov kav dej nrog qhov feem pua ntawm kev ua tiav, thiab cov khoom siv tau raug xaiv PEX-B.
Muaj ib txoj hauv kev ua cov polyethylene nrog nitrogen radicals, cov khoom tsim tau raug xaiv PEX-D. Txawm li cas los xij, cov thev naus laus zis no tsis siv vim qhov ua haujlwm qis.
Hla-txuas nrog peroxides kuj tau ua. Hauv qhov no, cov txheej txheem tsim khoom suav nrog kev sib xyaw peroxide thiab polyethylene, tom qab ntawd, nyob rau hauv lub xeev molten thiab nyob rau hauv lub siab kub, cross-linked polyethylene ntawm pawg PEX-A tau txais.
Cov kav dej ua los ntawm cov khoom siv (pab pawg B, C) yog siv rau kev siv dej thiab cua sov, txawm li cas los xij, lawv muaj ntau qhov kev txwv uastxuam nrog lub zog thiab ductility ntawm cov khoom.
Qhov kev vam meej tshaj plaws yog cov kav dej ua los ntawm pab pawg A polyethylene, lawv muaj zog qaug zog, tawg tsis kam, zoo li ruaj khov, yoog raws, cuam tshuam tsis kam.
XLPE cov kav dej cua sov yog siv dav rau kev tsim kho tus kheej, pej xeem thiab kev lag luam. Nrog lawv cov kev pab, cov xov hluav taws xob hauv pem teb yog nqa tawm thiab cov cua sov hauv pem teb raug tsim.
