Nyob rau hauv hluav taws xob teb, ib qho tseem ceeb ntawm cov hluav taws xob xaim thiab cables yog insulating thiabjacketing cov ntaub ntawv.Tau ntau xyoo, cov khoom siv hluav taws xob ua ntej rau cov hluav taws xob hluav taws xob yog cov ntawv roj-impregnated vim nws cov khoom hluav taws xob zoo heev.Nws kuj tseem muaj peev xwm tiv taus qib siab ntawm thermal overload yam tsis muaj kev cuam tshuam ntau dhau.Txawm li cas los xij, vim nws cov hygroscopicnature, hlau sheath yog noo noo corroded.Yog li ntawd, muaj qhov xav tau ntev ntev rau cov khoom siv hluav taws xob hluav taws xob, uas muaj kev sib xyaw ua ke ntawm cov khoom tsis yog-hygroscopic ntawm thermoplasticmaterials.
Kev tshawb fawb tsis tu ncua rau cov khoom siv npau suav no thaum kawg ua rau pom qhov sib txuas ntawm polyethylene.Kev sib txuas ntawm cov polymers yog hais txog kev hloov kho ntawm cov khoom siv polymer los ntawm kev tsim cov tshuaj sib txuas ntawm ib tus neeg macromolecules.Los ntawm kev sib txuas ntawm cov polymers xws li aspolyethylene, ib qho kev sib txuas ntawm peb-seem ntawm cov ntawv cog lus yog tsim los ntawm cov saw hlau polymer uas ua rau qhov hnyav molecular.Qhov no yog analogous rau lub mechanism ntawm 'vulcanising roj hmab'.
Cov txheej txheem ntawm 'vulcanisation' entails cua sov thiab ntxiv sulfur los yog lwm yam tshuaj los tsim crosslinks ntawm tus yam ntxwv ntev chains ntawm elastomer molecules.Cov txheej txheem no tau pib ntev dhau los thiab tseem siv tau.Cov cuab yeej ntawm cov khoom siv polymer yog nyob ntawm tus nqi ntawm leej faj siv.Feem ntau cov leej faj siv yog, qhov nyuaj dua yog cov khoom, uas tiv taus qhov kub thiab txias, kev nyuaj siab thiab kev sib tw rau nws txoj kev ncaj ncees.Tab sis sulfur vulcanisation muaj teeb meem loj nrog kev hwm rau tib neeg kev noj qab haus huv thiab ib puag ncig thiab muaj qee qhov kev lag luam tsis zoo.Tsis tas li ntawd, nws xav tau qhov kub thiab txias los pib cov tshuaj tiv thaiv thiab emissions odorous thiab toxic gases nrog rau tsim ntau yam tsis xav tau cov tshuaj residues uas yuav tsum tau muab tshem tawm ntawm cov khoom kawg.
'Radiation crosslinking' yog txoj kev ua pov thawj zoo uas hla tag nrho cov kev tsis zoo ntawm cov txheej txheem thevulcanisation.Nws yog ib qho kev ntsuas kub hauv chav tsev uas muaj nyob rau hauv nws tus kheej tus nqi tseem ceeb.Nws tswj tau yooj yim thiab cov khoom xav tau ntawm cov polymer tau yooj yim los ntawm kev hloov cov koob tshuaj (lub sijhawm irradiation).Cov ntaub ntawv hloov pauv tsis muaj txoj hauv kev tsis zoo rau cov uas ua los ntawm sulfurvulcanisation.
Lub hom phiaj tseem ceeb ntawm crosslinking yog txhim kho cov thermal resistivity.Feem ntau, qhov siab tshaj plaws uas tau tso cai rau hauv qhov luv luv yog 140⬚C rau qhov tsis yog-crosslinked polyethylene cable tuaj yeem hloov kho mus rau 250⬚C los ntawm cov txheej txheem hluav taws xob sib txuas.Lub hom phiaj thib ob feem ntau yog qhov kev nco zoo xws li tso tawm los ntawm cov hlab ntsws.Qhov no yog qhov txawv txav thiab muaj txiaj ntsig cov cuab yeej ntawm irradiated polyethylene thiab nws tau khaws cia tsis tu ncua nyob rau hauv lub polymer tsis hais lub sij hawm thiab ntawm ib qho tom qab deformations.Yog li, yog tias polyethylene yog irradiated nyob rau hauv ib feem ntawm crystalline daim ntawv (piv txwv li hauv qab nws melting point) thiab ces rhuab kom tshem tawm cov crystals, nws yuav deformed considerably deformed (xws li stretch-ing) thiab ces txias dua rau crystals kom hloov nyob rau hauv nws cov duab tshiab.Yog hais tias cov khoom yog rhuab dua saum toj no melting, cov crystals ploj thiab cov roj hmab zoo li polyethylene yuav zoo li yuav rov qab mus rau cov duab yog hais tias nws yog khaws cia thaum lub sij hawm irradiation tej zaum lub hli los yog xyoo ua ntej.Shrink tubing yog tsim los ntawm extruding tshwj xeeb formulated polymer rau hauv ib lub raj thiab tom qab crosslinking lub raj no.Tom qab crosslinking, lub raj yog rhuab, nthuav thiab txias nyob rau hauv daim ntawv nthuav.Qhov no nthuav dav raj, ib zaug reheated yuav shrink rov qab mus rau nws cov qub duab, uas yog vim nco nyhuv ntawm crosslinking.Txij li thaum cov polymermolecules yog cov tshuaj sib txuas rau ib leeg thiab tsis tuaj yeem txav mus los ntawm qhov tsis sib xws, cov khoom sib txawv xws li kub tsis kam, tsis kam tiv taus, qhov ntev stability, adhesion khoom thiab lwm yam.Yog li, crosslinking tuaj yeem muab cov khoom tsim nyog rau cov khoom siv polymer, xws li toughness, elasticity, cuam tshuam tsis kam, tshuaj tsis haum thiab lwm yam. Irradiated polyethylene yog siv dav heev rau cov cua sov shrinkable films rau ntim, encapsulation thiab rau kev sib txuas hluav taws xob, uas tuaj yeem hloov tau yooj yim tshav kub mus rau lwm yam khoom. .Rau qhov yooj yim, crosslinked xaim / cableinstallation yog yooj yim dua thiab nws tsis muaj qhov siab txwv.Ntxiv mus, tsis muaj metallic sheath yuav tsum tau kho.Tsis tas li ntawd, cov khoom tensile yog nruab nrab ntawm cov thermoplastic thiab anelastomer.
Post lub sij hawm: Feb-18-2017