(PVC) ndi thermoplastic yotchuka yomwe ilibe fungo, yolimba, yonyezimira, ndipo nthawi zambiri imakhala yoyera.Panopa ili pa nambala yachitatu ya pulasitiki yomwe imagwiritsidwa ntchito kwambiri padziko lonse lapansi (kumbuyo kwa polyethylene ndi polypropylene).PVC imagwiritsidwa ntchito kwambiri popanga mipope ndi ngalande, ngakhale imagulitsidwanso ngati ma pellets kapena ngati utomoni waufa.
Kugwiritsa ntchito PVC
Kugwiritsiridwa ntchito kwa PVC kumakhala kofala kwambiri pantchito yomanga nyumba.Amagwiritsidwa ntchito nthawi zonse ngati m'malo kapena m'malo mwa mapaipi achitsulo (makamaka mkuwa, malata, kapena chitsulo chotayira), komanso m'malo ambiri pomwe dzimbiri zimatha kusokoneza magwiridwe antchito ndikukweza mtengo wokonza.Kuphatikiza pa ntchito zogona, PVC imagwiritsidwanso ntchito nthawi zonse pamatauni, mafakitale, ankhondo, ndi malonda.
Kawirikawiri, PVC ndiyosavuta kugwira ntchito kuposa chitoliro chachitsulo.Ikhoza kudulidwa mpaka kutalika kofunikira ndi zida zosavuta zamanja.Zopangira ndi mapaipi sayenera kuwotcherera.Mipope imalumikizidwa ndi kugwiritsa ntchito mfundo, simenti yosungunulira, ndi zomatira zapadera.Ubwino wina wa PVC ndikuti zinthu zina zomwe mapulasitiki adawonjezeredwa ndizofewa komanso zosinthika, mosiyana ndi zolimba, zomwe zimapangitsa kuti zikhale zosavuta kuziyika.PVC imagwiritsidwanso ntchito kwambiri mumitundu yonse yosinthika komanso yolimba ngati kutchinjiriza pazinthu zamagetsi monga waya ndi chingwe.
M'makampani azachipatala, PVC imatha kupezeka ngati machubu odyetsera, matumba amagazi, matumba a intravenous (IV), mbali za zida za dialysis, ndi zina zambiri.Kuyenera kudziŵika kuti kugwiritsa ntchito koteroko kumatheka kokha pamene phthalates-mankhwala omwe amapanga mapepala osinthika a PVC ndi mapulasitiki ena-awonjezeredwa ku mapangidwe a PVC.
Zogulitsa wamba monga malaya amvula, matumba apulasitiki, zoseweretsa za ana, makhadi a ngongole, mapaipi amunda, mafelemu a zitseko ndi mazenera, ndi makatani osambira - kutchula zinthu zochepa zomwe mungapeze m'nyumba mwanu-zinapangidwanso kuchokera ku PVC mu mawonekedwe amodzi kapena ena.
Momwe PVC imapangidwira
Ngakhale kuti mapulasitiki ndi zinthu zopangidwa ndi anthu, zinthu ziwiri zazikulu zomwe zimapita ku PVC - mchere ndi mafuta - ndi organic.Kuti mupange PVC, chinthu choyamba chimene muyenera kuchita ndikulekanitsa ethylene, chochokera ku gasi wachilengedwe, kuchokera ku zomwe zimatchedwa "feedstock."M'makampani opanga mankhwala, mafuta a petroleum ndi omwe amasankha mankhwala ambiri, kuphatikiza methane, propylene, ndi butane.(Zodyetsa zachilengedwe zimaphatikizanso ndere, zomwe ndi chakudya chodziwika bwino chamafuta a hydrocarbon, pamodzi ndi chimanga ndi nzimbe, zomwe ndi njira zina zodyeramo ethanol.)
Kupatula ethanol, mafuta amadzimadzi amatenthedwa mu ng'anjo ya nthunzi ndi kupanikizika kwambiri (njira yotchedwa thermal cracking) kuti abweretse kusintha kwa molekyulu ya mankhwala omwe ali mu feedstock.Mwa kusintha kulemera kwake kwa maselo, ethylene imatha kudziwika, kulekanitsidwa, ndi kukolola.Izi zikachitika, zimakhazikika kumadzi ake.
Gawo lotsatira la ndondomekoyi likuphatikizapo kuchotsa chigawo cha chlorine kuchokera ku mchere m'madzi a m'nyanja.Podutsa mphamvu yamagetsi yamagetsi kudzera mu njira yothetsera madzi amchere (electrolysis), electron yowonjezera imawonjezeredwa ku mamolekyu a chlorine, kachiwiri, kuwalola kuti adziwike, apatulidwe, ndi kuchotsedwa.
Tsopano muli ndi zigawo zikuluzikulu.
Ethylene ndi klorini zikakumana, zomwe amapanga amapanga ethylene dichloride (EDC).EDC imadutsa njira yachiwiri yowotcha, yomwe imapanga vinyl chloride monomer (VCM).Kenako, VCM imadutsa mu chothandizira chokhala ndi riyakitala, chomwe chimapangitsa kuti mamolekyu a VCM agwirizane (polymerization).Mamolekyu a VCM akalumikizana, mumapeza utomoni wa PVC - maziko azinthu zonse za vinyl.
Mapangidwe okhwima, osinthika, kapena osakanikirana a vinyl amapangidwa posakaniza utomoniwo ndi mitundu yosiyanasiyana ya ma plasticizer, zokhazikika, ndi zosintha kuti akwaniritse zomwe mukufuna zomwe zimaphatikizapo chilichonse kuyambira mtundu, mawonekedwe, ndi kusinthasintha mpaka kulimba nyengo yotentha komanso nyengo ya UV.
Ubwino wa PVC
PVC ndi chinthu chotsika mtengo chomwe ndi chopepuka, chosinthika, komanso chosavuta kuchigwira ndikuchiyika.Poyerekeza ndi mitundu ina ya ma polima, kupanga kwake sikumangogwiritsa ntchito mafuta osakanizika kapena gasi.(Ena amatsutsa kuti izi zimapangitsa PVC kukhala "pulasitiki yokhazikika" chifukwa sichidalira mphamvu zosasinthika.)
PVC imakhalanso yolimba ndipo simakhudzidwa ndi dzimbiri kapena njira zina zowonongeka, ndipo motero, imatha kusungidwa kwa nthawi yaitali.Mapangidwe ake amatha kusinthidwa mosavuta kukhala mitundu yosiyanasiyana kuti agwiritsidwe ntchito m'mafakitale osiyanasiyana ndikugwiritsa ntchito, zomwe ndi kuphatikiza kotsimikizika.PVC imakhalanso ndi kukhazikika kwa mankhwala, chomwe ndi chinthu chofunikira kwambiri pamene zinthu za PVC zimagwiritsidwa ntchito m'madera okhala ndi mitundu yosiyanasiyana ya mankhwala.Makhalidwewa amatsimikizira kuti PVC imasunga katundu wake popanda kusintha kwakukulu pamene mankhwala ayambitsidwa.Ubwino wina ndi:
● Biocompatibility
● Kulankhula momveka bwino
● Kukana kusokonezeka kwa mankhwala osokoneza bongo
● Low matenthedwe madutsidwe
● Simafunika kukonza bwino
Monga thermoplastic, PVC imatha kusinthidwanso ndikusinthidwa kukhala zinthu zatsopano zamafakitale osiyanasiyana, ngakhale chifukwa chamitundu yosiyanasiyana yomwe imagwiritsidwa ntchito popanga PVC, sizovuta nthawi zonse.
Zoyipa za PVC
PVC imatha kukhala ndi 57% chlorine.Mpweya wopangidwa kuchokera ku mafuta a petroleum umagwiritsidwanso ntchito popanga.Chifukwa cha poizoni omwe amatha kutulutsidwa panthawi yopangidwa, atayaka moto, kapena akawola m'malo otayira, PVC imatchedwa "pulasitiki yapoizoni."
Zodetsa nkhawa zokhudzana ndi thanzi la PVC sizinatsimikizidwebe, komabe, poizonizi zakhala zikugwirizana ndi zinthu zomwe zimaphatikizapo koma osati kokha ku khansa, kusokonezeka kwa fetus, kusokonezeka kwa endocrine, mphumu, ndi kuchepa kwa mapapu.Ngakhale kuti opanga amanena kuti mchere wambiri wa PVC ndi wachilengedwe komanso wosavulaza, sayansi imasonyeza kuti sodium-pamodzi ndi kutulutsidwa kwa dioxin ndi phthalate-ndizowonjezera zomwe zingayambitse kuopsa kwa chilengedwe ndi thanzi la PVC.
Tsogolo la PVC Plastics
Nkhawa zokhudzana ndi zoopsa zokhudzana ndi PVC ndipo zachititsa kuti afufuze kagwiritsidwe ntchito ka ethanol ya nzimbe m'malo mwa naphtha (mafuta oyaka omwe amapangidwa ndi malasha, shale, kapena petroleum).Maphunziro owonjezera akuchitidwa pa bio-based plasticizers ndi cholinga chopanga njira zina zopanda phthalate.Ngakhale kuyesaku kudakali koyambirira, chiyembekezo ndikukhazikitsa mitundu yokhazikika ya PVC kuti muchepetse zovuta zomwe zingawononge thanzi la anthu komanso chilengedwe panthawi yopanga, kugwiritsa ntchito, ndi kutaya.
Nthawi yotumiza: Apr-07-2022