Thaum muas cov kav dej insulated, ntau tus neeg xav tias qhov nyuaj sab nrauv qhia tias muaj ntau dua ntawm cov khoom siv thiab cov khoom zoo dua. Thaum lub tswv yim no suab zoo, nws tsis tas yuav yog txoj hauv kev los ntsuas cov txheej txheem ntawm cov kav dej insulated. Lub luag haujlwm tseem ceeb ntawm lub qhov rooj sab nrauv yog kev tiv thaiv dej thiab tiv thaiv cov khoom sab nraud. Lub hardness ntawm siab - ntom polyethylene (HDPE) yog qhov tseeb txuas rau nws cov qauv molecular; ntau dua crystallinity ua rau ntau dua hardness thiab rigidity. Txawm li cas los xij, hardness tsuas yog ib qho ntawm ntau qhov ntsuas ntawm cov khoom siv. Qhov muag tsis pom kev ua ntej qhov nyuaj thaum tsis quav ntsej lwm qhov kev ntsuas tseem ceeb tuaj yeem ua rau muaj kev pheej hmoo tshiab.
Raws li tus qauv GB / T 29047, cov casings sab nrauv yuav tsum ua tau raws li ntau qhov kev ua tau zoo: lub zog tensile tawm los tsawg kawg yog 19 MPa, qhov elongation ntawm qhov tawg ntawm yam tsawg kawg nkaus 500%, thiab qhov ntev rov qab tsis tshaj 3%, nrog rau cov kev xav tau rau qhov ntom ntom, cov ntsiab lus carbon dub, thiab kev tiv thaiv ib puag ncig kev ntxhov siab. Ntawm cov no, elongation ntawm kev so yog qhov tseem ceeb ntawm kev hloov pauv yooj yim- sawv cev rau qhov uas cov khoom tuaj yeem ncav cuag ua ntej tawg; tus nqi siab dua qhia tau yooj yim dua. HDPE txheej txheej txheej ua tiav ua tiav qhov elongation ntawm kev tawg ntau tshaj 500%, muab cov deformability txaus kom haum rau thermal expansion thiab contraction nrog rau hauv av kev sib haum xeeb thaum lub sij hawm ua haujlwm kav dej.
Yog hais tias lub sab nrauv yog ua heev "nyuaj," nws brittleness nce. HDPE muab nws cov tawv tawv los ntawm qis- thaj chaw crystallinity thiab nws cov rigidity los ntawm siab - cheeb tsam crystallinity; Raws li crystallinity nce, yog li brittleness. Cov casings sab nrauv nrog cov brittleness siab yog ua rau tawg thaum lub sij hawm installation los yog cia rau hauv cheeb tsam txias. Qhov kub hloov pauv ntau dua ua rau muaj kev sib txuas ntxiv ntawm cov kav dej; Thaum lub casing lub yas deformation muaj peev xwm yog tas lawm thiab tsis tuaj yeem them rov qab rau qhov contraction, cov yeeb nkab lub cev tawg. Thaum cov kab nrib pleb tshwm nyob rau sab nrauv, cov dej hauv av tuaj yeem nkag mus rau hauv cov txheej txheem polyurethane ua npuas ncauj, ua kom cov thermal rwb thaiv tsev ua tau zoo thiab muaj peev xwm ua rau cov kav xa dej corrosion - qhov tshwm sim loj dua qhov kev ntsuam xyuas thawj zaug ntawm seb lub casing yog "nyuaj" lossis tsis. Tsis tas li ntawd, kev ua tau zoo ntawm cov yeeb nkab tiv thaiv sab nraud yog nyob ntawm ntau dua li cov khoom siv raw; molding parameters -xws li extrusion kub, txias npaum li cas, thiab thauj -off ceev- yog qhov tseem ceeb sib npaug. Kev tswj tsis raug ntawm cov txheej txheem extrusion tuaj yeem ua rau qhov tsis sib xws ntawm crystallinity faib ntawm cov txheej txheem sab hauv thiab sab nrauv ntawm cov yeeb nkab, uas ua rau muaj zog brittleness.
Yog li, kev ntsuam xyuas qhov zoo ntawm cov yeeb nkab tiv thaiv sab nrauv yuav tsum tau saib tshaj qhov "hardness" thiab tsom mus rau qhov sib npaug ntawm cov kev qhia dav dav, xws li lub zog tensile, elongation ntawm kev tawg, thiab kev tiv thaiv ib puag ncig kev ntxhov siab tawg. Tsis tas li ntawd, xaiv cov chaw tsim khoom uas ua raws li cov qauv nruj me ntsis thiab xav txog lawv lub sijhawm ntev - kev ua tau zoo nyob rau hauv cov kev ua haujlwm zoo sib xws yog qhov tseem ceeb hauv kev ua kom zoo. Ib lub raj xa dej peb caug- xyoo kev pabcuam lub neej tsis yog txhawb nqa los ntawm lub plhaub nruj ib leeg, tab sis tau lees paub los ntawm kev sib xyaw ntawm cov khoom siv tau zoo thiab cov txheej txheem tsim khoom ruaj khov.