Kuwonongeka kwa PVC kumachitika makamaka chifukwa cha kuwonongeka kwa maatomu a klorini yogwira mu molekyulu pansi pa kutentha ndi mpweya, zomwe zimapangitsa kuti HCI ipangidwe. Choncho, PVC kutentha stabilizers makamaka mankhwala amene angathe kukhazikika maatomu klorini mu PVC mamolekyu ndi kupewa kapena kuvomereza kutulutsidwa kwa HCI. R. Gachter et al. adayika zotsatira za kutentha kwa stabilizer ngati zodzitetezera komanso zowongolera. Yoyamba ili ndi ntchito zoyamwa HCI, m'malo mwa maatomu osakhazikika a klorini, kuchotsa magwero oyatsira, ndikuletsa makutidwe ndi okosijeni. Mtundu womaliza wokonzanso umafuna kuwonjezera pamapangidwe a polyene, kuchitapo kanthu ndi zigawo zopanda unsaturated mu PVC, ndikuwononga ma carbocation. Makamaka, motere:
(1) Bweretsani HC1 yotengedwa ku PVC kuti mulepheretse ntchito yake yodzithandizira. Zinthu monga mchere wamchere, organic acid zitsulo sopo, organotin mankhwala, epoxy mankhwala, amines, zitsulo alkoxides ndi phenols, ndi zitsulo thiols akhoza kuchita ndi HCI kuletsa de HCI anachita wa PVC.
Ine (RCOO) 2+2HCI MeCl+2RCOOH
(2) Bwezerani kapena kuchotsani zinthu zosakhazikika monga maatomu a allyl chloride kapena maatomu apamwamba a carbon chloride mu mamolekyu a PVC, ndikuchotsani poyambira kuchotsa HCI. Ngati maatomu a malata a organic tini stabilizers akugwirizana ndi kusakhazikika kwa maatomu a klorini a mamolekyu a PVC, ndi maatomu a sulfure omwe ali mu tini ya organic amagwirizana ndi maatomu a carbon mu PVC, maatomu a sulfure amalowa m'malo mwa maatomu a klorini osakhazikika. Pamene HC1 ilipo, mgwirizano wogwirizanitsa umagawanika, ndipo gulu la hydrophobic limamangiriza mwamphamvu ndi maatomu a carbon mu mamolekyu a PVC, potero kulepheretsa kuwonjezereka kwa HCI kuchotsa ndi kupanga zomangira ziwiri. Pakati pa sopo wazitsulo, sopo wa zinki ndi sopo wa mphika ndizomwe zimakhala zofulumira kwambiri m'malo mwa maatomu a klorini osakhazikika, sopo wa barium ndiye wochedwa kwambiri, sopo wa calcium ndi wochedwa, ndipo sopo wotsogolera ali pakati. Pa nthawi yomweyi, ma chloride opangidwa ndi zitsulo ali ndi magawo osiyanasiyana othandizira kuchotsa HCI, ndipo mphamvu zawo ndi izi:
ZnCl>CdCl>>BaCl, CaCh>R2SnCl2 (3) amawonjezedwa ku ma bond awiri ndi co conjugated double bond kuti ateteze kukula kwa mapangidwe a polyene ndikuchepetsa utoto. Unsaturated acid salt kapena ma complexes ali ndi ma bond awiri, omwe amakumana ndi diene kuwonjezera mamolekyu a PVC, potero amasokoneza mawonekedwe awo ogwirizana ndikulepheretsa kusintha kwa mtundu. Kuphatikiza apo, sopo wachitsulo amatsagana ndi kusamutsidwa kwamagulu awiri pomwe akulowa m'malo mwa allyl chloride, kuwononga kapangidwe ka polyene ndikuletsa kusintha kwamtundu.
(4) Gwirani ma radicals aulere kuti mupewe oxidation yokha. Ngati kuwonjezera phenolic kutentha stabilizers angalepheretse kuchotsedwa kwa HC1, ndi chifukwa chakuti atomu wa haidrojeni ma free radicals operekedwa ndi phenols akhoza kuphatikana ndi otsika PVC macromolecular free radicals, kupanga chinthu chimene sichingagwirizane ndi okosijeni ndipo chimakhala ndi kukhazikika kwa kutentha. Stabilizer yotentha iyi imatha kukhala ndi zotsatira imodzi kapena zingapo.
Nthawi yotumiza: Mar-29-2024
