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 npaj ntawm crosslinked polymers tuaj yeem ua tau los ntawm ob txoj kev sib txawv.Ib qho yog chemical method thiab lwm qhov yog txoj kev ionizing.Txawm hais tias qhov kev paub txog qhov cuam tshuam ntawm crosslinking muaj hnub nyoog tshaj 150 xyoo, qhov cuam tshuam crosslinking ntawm ionizing hluav taws xob tau pom tseeb rau thawj zaug los ntawm Charlesby.Txoj kev sib txuas hluav taws xob hluav taws xob yog qhov ua tau zoo tshaj plaws rau cov xov hlau me me thiab nyias nyias thiab yog li cov xov hlau siv hluav taws xob thiab cov khoom siv hluav taws xob tau tsim los ntawm txoj kev hluav taws xob sib txuas.Txoj kev yog qhov zoo vim tias siv hluav taws xob tsawg thiab xav tau qhov chaw me me.Cov txheej txheem hluav taws xob tau yooj yim tswj tau thiab muaj peev xwm txuag hluav taws xob nrog rau kev tswj cov pa phem.Cov yam ntxwv tshwj xeeb ntawm kev sib txuas hluav taws xob hluav taws xob tau sau tseg raws li hauv qab no: (1) Cov kab ntau lawm tuaj yeem tswj tau.Kev kub ceev npog (extrusion) yog ua tau, raws li tsis muaj qhov yuav tsum tau ntawm crosslinking tus neeg sawv cev.Los ntawm kev siv lub accelerator nrog lub zog siab thiab lub zog qis, kev ua kom nrawm tuaj yeem ua tiav.(2) Crosslinking uniformity yog zoo heev.Cov khaubncaws sab nraud povtseg los ntawm kev xaiv lub tshuab tsim nyog thiab siv cov qauv zoo tshaj plaws rau kev pub hlau tuaj yeem nqa tawm.(3) Ntau yam ntawm cov polymers tuaj yeem npaj tau, nyob ntawm qib ntawm kev sib txuas los ntawm hluav taws xob crosslinking txheej txheem.Tsis tas li ntawd, cov txheej txheem hluav taws xob tua hluav taws xob yog qhov zoo dua li cov txheej txheem ua kom sov.Hauv cov txheej txheem kho cua sov, cov dej nkag mus rau hauv cov txheej txheem polymer nyob rau hauv lub zog siab ua rau muaj pes tsawg tus 'microvoids', uas tuaj yeem ua rau tsob ntoo zoo li ib feem ntawm cov paug tawm thaum lub cable yog kev pabcuam.Txawm hais tias qhov tshwm sim yog qhov nyuaj heev, cov ntoo tuaj yeem loj hlob thiab ua rau txo qis hauv dielectric zog ntawm cov cables.Sib nrug los ntawm cov no, cov txheej txheem ua kom sov muaj qee qhov tsis zoo los ntawm qhov pom ntawm kev siv lub zog: (a) lub zog siab yog xav tau kom tau txais lub siab tempera-ture;(b) qhov ua tau zoo ntawm thermal conduction los ntawm sab nraud ntawm lub cable yog tsawg thiab (c) cov khoom siv hluav taws xob ntau yog siv los ntawm tus neeg xyuas hluav taws xob cable, uas ua rau cov thermal efficiency qis dua thiab siv sijhawm ntev dua rau kev sib txuas sib txuas.Radiation curing yog tus neeg sib tw rau cov txheej txheem qhuav.Txawm li cas los xij, nws muaj qhov teeb meem uas tsim cov electrons nres thiab / los yog tsim nyob rau hauv lub rwb thaiv tsev txheej los ntawm irradiation canals kuj induce tsob ntoo zoo li ib feem puas thaum lub sij hawm thiab tom qab irradiation.Nws txawv kiag li ntawm 'txoj kev tsis muaj dej'.Raws li cov polymer cable muaj cov dej noo thiab cov voids loj, cov txheej txheem kho yog tsim nyog.Sib nrug los ntawm cov txiaj ntsig saum toj no, cov khoom siv semiconductor tuaj yeem qhia tau yooj yim hauv cov txheej txheem hluav taws xob tua hluav taws xob uas tsis yooj yim thaum cov txheej txheem ua kom sov vim tias feem ntau ntawm cov ntaub ntawv tsis tuaj yeem tiv taus qhov kub thiab txias.
Radiation grafting txheej txheem kuj tseem cuam tshuam cov conductivity rau matrix.Qhov no yog txoj kev tshwj xeeb ntawm kev sib txuas ntawm kev coj ua matrix rau ntawm insulating ib qho.Cov txheej txheem no cuam tshuam nrog deactiva-tion ntawm cov pob txha pob txha polymer nrog lub monomer tsim nyog los ntawm grafting thiab tom qab tso tawm ntawm cov khoom siv polymer hla cov pob txha pob txha.Sib nrug los ntawm tus cwj pwm insulating, qhov no polymer tuaj yeem coj tus cwj pwm ua ib qho.Txawm hais tias nws tseem tsis tau tsim, nws tuaj yeem nthuav tawm ntau cov ntawv thov xws li EMI shielding, ua cov txheej txheem thiab cov tshuaj tiv thaiv kab mob.Bhattacharya etal.tau npaj cov khoom sib xyaw polymer-FEP-g-(AA)-PPY thiab polymer-FEP-g-(sty)-PPY.Thaum xub thawj, cov polymer-FEP tau irradiated daim ntawv Co-60 qhov chaw thiab cov zaj duab xis ces dipped nyob rau hauv sib txawv feem pua ntawm cov monomers.PPy tau muab tso rau saum npoo ntawm grafted los ntawm oxidative polymerization ntawm pyrrole siv ferric chloride ua oxidant.Qhov kev tiv thaiv saum npoo yog txo qis thiab yog qhov kev txiav txim ntawm 104-105ohm / cm2.Qhov saum npoo kuj nyob ntawm qhov feem pua ntawm grafting ntawm monomers.Siv cov txheej txheem no, nto conductivity ntau dua li cov conductivity tuaj yeem nce ntxiv.Photoconducting coj tus cwj pwm ntawm zaj duab xis kuj tuaj yeem muab los ntawm cov txheej txheem grafting.Cellulose acetate-g-(N-vinyl carbazole) thiab cellulose acetate-g-(N-vinyl carbazole-methyl methacylate) yog cov piv txwv ntawm thephotoconducting film.
Hauv kev lag luam hluav taws xob cable, feem ntau yog polyethylene, polyvinyl chloride (PVC), EPDM roj hmab siv.Polyethylene yog siv vim nws cov khoom siv hluav taws xob zoo heev thiab nws lub sijhawm ntev.Tsawg-density polyethylene yog nyiam dua cov high-densitypolyethylene vim yog ob peb yam.Cov laj thawj muaj raws li hauv qab no: (a) ntau dua;(b) siab zog dielectric dua li high-density polyethylene;(c) lub neej ntev dua HDPE;(d) tsis yooj yim rau txheej txheem dua li HDPE thiab (e) tsis tshua muaj kev pheej hmoo ntawm kev suav nrog cov voids hauv rwb thaiv tsev ntawm LDPE, uas ua rau ionisation.Txawm hais tias tag nrho cov txiaj ntsig zoo li no, LDPE muaj nws tus kheej txwv raws li cov khoom siv hluav taws xob cable.Ua ib qho thermoplastic polymer, nws muaj qhov kub thiab txias nyob ib puag ncig 105-115 ⬚C thiab muaj qhov ua rau muaj kev ntxhov siab tawg tshwm sim thaum nws nyob rau hauv kev sib cuag nrog qee qhov chaw ua haujlwm.Crosslinking ntawm polyethylene molecules txhim kho cov thermal thiab lub cev muaj zog thaum nws cov khoom hluav taws xob feem ntau tsis hloov pauv.Crosslinked polyethylene yog, muaj-ua ntej, tsis yog thermoplastic polymer lawm.Nws softens ntawm crystalline melting point ntawm polyethylene thiab assumes elastic, zoo li roj hmab sib xws, ib yam khoom uas nws khaws cia thaum lub sij hawm ntxiv nce ntawm tempera-ture, kom txog rau thaum nws ua carbonised yam tsis melting ntawm 300⬚C.Txoj kev xav rau kev ntxhov siab-cracking ploj mus thiab zoo heev tiv thaiv kev laus hauv huab cua kub tau txais.Crosslinked polyethylene cables yog dav nyiam vim nws cov hluav taws xob zoo heev thiab lub cev muaj zog.Nws muaj peev xwm nqa cov dej ntws loj, tiv taus lub vojvoog me me dabtsi yog khoov thiab lub teeb hauv qhov hnyav, tso cai rau kev yooj yim thiab txhim khu kev qha, piv txwv li nws tsis muaj qhov siab txwv vim nws tsis muaj cov roj thiab yog li tsis muaj qhov tsis ua tiav vim cov roj tsiv teb tsaws hauv cov roj. kab kab.Nws kuj tsis feem ntau yuav tsum tau ib tug metallic sheath.Yog li ntawd, nws yog dawb los ntawm cov tsis ua hauj lwm peculiar rau metallic sheathed cables, corrosion thiab qaug zog.Tam sim no-ib-hnub, hluav taws xob crosslinking yog industrially siv tsis tau tsuas yog polyethylene tab sis kuj muaj lwm yam polymers xws li polyvinyl chloride, polyisobutylene thiab lwm yam. Ntawm nws tus kheej PVC yog tsis ruaj tsis khov polymer.Nws pib tau txais txiaj ntsig kev lag luam tsuas yog tom qab kev txhim kho cov txiaj ntsig zoo ntawm kev ruaj khov.Nrog kev pab los ntawm kev hloov kho cov neeg ua haujlwm (stabilizers, plasticizers, fillers thiab lwm yam additives), PVC tuaj yeem ua kom pom ntau yam ntawm cov khoom, xws li nruj heev mus rau qhov yooj yim heev.Kev sib txawv ntawm nws daim ntawv thov thiab nws cov nqi qis yog lub luag haujlwm rau nws qhov tseem ceeb hauv kev ua lag luam hauv ntiaj teb.
Txhawm rau ua kom cov kev sib txuas ua tau zoo, cov polymers tsis tshua muaj siv hauv lawv daim ntawv ntshiab.Plasticisers, antioxidants, fillers muaj lawv lub luag haujlwm hauv lawv txoj hauv kev los faib cov khoom tsim nyog.Qhov ntxiv yog zoo dua thaum lub sij hawm crosslinking txheej txheem.Plasticisers tau ntxiv rau cov polymers kom txo tau cov brittleness ntawm cov khoom polymer.Lawv cuam tshuam rau crosslinking thaum twg lawv koom nrog hauv tiam ntawm freeradicals lossis nkag mus rau cov kev tawm tsam.Dibutyl phthalate, tritolyl phosphate thiab diallyl phosphate yog cov piv txwv ntawm cov yas yas rau PVC.Flexibility thiab elasticity, uas yog ib qho tseem ceeb heev nyob rau hauv hluav taws xob rwb thaiv tsev, yog txhim kho los ntawm kev ntxiv cov yas rau PVC.Tiag tiag nyob rau hauv cov ntaub ntawv ntawm PVC, uas yog polar vim lub unbalanced qauv, ua rau kom muaj zog intermolecular bonds, uas koom nrog macromolecular chains rigidly, ua ke ua rau nws inflexible.Antioxidants yog lwm pab pawg ntawm additives, uas yog tsim nyog rau tej crosslinked sib tov tsim rau lub tswv yim ntawm com-paring dua thermooxidative stability ntawm ib tug polymer ntau lawm.Feem ntau lawv cuam tshuam rau crosslinking byscavenging radicals, uas yuav tsim crosslinks.RC (4,4-thio-bis (6-tert-butyl-3-methyl phenol), MB (Mercapto benzoimidazole) yog cov piv txwv ntawm cov tshuaj antioxidants uas siv los ntawm Ueno li al. Raws li cov hlau rwb thaiv tsev cov ntaub ntawv tau siv tshwj xeeb tshaj yog rau cov khoom siv, cov xim rau cov yas muaj ntau yam inorganic thiab organicmaterials, cov khoom siv tsis muaj xim tsis nyiam nyob rau hauv daim teb no, feem ntau muab ntxiv rau kev txhim kho lawv lub cev-txheej txheem thiab kev ua tau zoo. Nws tau pom tias cov txiaj ntsig ntawm radicals hauv polyethylene tau nce los ntawm 50%, thaum ntxiv me me (0.05%) ntawm aerosil. Polyethylene, qhov twg macromolecules tuaj yeem nyob rau hauv lub xeev tsis sib npaug ntawm cov kab mob tsis sib haum. Nrog rau cov ntsiab lus siab dua ntawm cov filler, kev hloov hluav taws xob los ntawm cov khoom ntim rau hauv cov txheej txheem polymer tuaj yeem tshwm sim thiab yog li ua rau muaj txiaj ntsig ntau dua ntawm cov tshuaj dawb radicals.Tsis tas li ntawd, kev sib xyaw ntawm irradiation nrog reactive admixture tuaj yeem cuam tshuam rau thaj chaw ntawm kev sib txuas ntawm cov saw hlau polymer.
Nyob rau hauv luv luv, hluav taws xob ua lub luag hauj lwm tseem ceeb nyob rau hauv lub polymer ua nyob rau hauv hluav taws xob teb.Nws yog txoj kev zoo tshaj plaws xws li 'vulcanisation' dais qee qhov kev txwv.Txoj kev sib txuas sib txuas tuaj yeem txhim kho los ntawm kev xaiv cov monomers tsim nyog.Nyob rau hauv cov txheej txheem hluav taws xob crosslinking, cov plasticisers, fillers thiab nplaim taws retardant ntxiv tau zoo heev hauv cov txheej txheem hluav taws xob sib txuas.Txoj kev radiationcrosslinking kuj tseem ceeb heev hauv kev npaj cov khoom siv semiconductor.Tsis tas li ntawd, cov txheej txheem hluav taws xob grafting tuaj yeem ua haujlwm los npaj cov yeeb yaj kiab ua yeeb yaj kiab thiab cov yeeb yaj kiab nrog tus cwj pwm photoconducting.
Post lub sij hawm: May-02-2017