Ukuwohloka kwe-PVC kubangelwa kakhulu ukubola kwama-athomu e-chlorine asebenzayo ku-molecule eshisa kakhulu nomoya-mpilo, okuholela ekukhiqizweni kwe-HCI. Ngakho-ke, iziqinisi zokushisa ze-PVC ikakhulukazi ziyizinto ezingakwazi ukuzinzisa ama-athomu e-chlorine kuma-molecule e-PVC futhi zivimbele noma zamukele ukukhishwa kwe-HCI. U-R. Gachter nabanye bahlukanise imiphumela yeziqinisi zokushisa njengezokuvimbela kanye nokulungisa. Eyokuqala inemisebenzi yokumunca i-HCI, ukufaka esikhundleni sama-athomu e-chlorine angazinzile, ukususa imithombo yokushisa, kanye nokuvimbela i-oxidation ezenzakalelayo. Uhlobo lokugcina lokulungisa luhlose ukwengeza esakhiweni se-polyene, ukusabela nezingxenye ezingagcwalisiwe ku-PVC, nokubhubhisa ama-carbocation. Ngokukhethekile, kanje:
(1) Umunca i-HC1 ekhishwe ku-PVC ukuze uvimbele umsebenzi wayo wokuzivuselela. Imikhiqizo efana nosawoti we-lead, insipho yensimbi ye-organic acid, ama-organotin compounds, ama-epoxy compounds, ama-amine, ama-alkoxide ensimbi nama-phenols, kanye nama-metal thiols konke kungasabela ne-HCI ukuze kuvinjelwe ukusabela kwe-de HCI kwe-PVC.
Mina (RCOO) 2+2HCI MeCl+2RCOOH
(2) Faka esikhundleni noma ususe izinto ezingazinzile njenge-athomu ye-allyl chloride noma ama-athomu e-tertiary carbon chloride kuma-molecule e-PVC, bese ususa indawo yokuqala yokususwa kwe-HCI. Uma ama-athomu e-tin e-organic tin stabilizers ehlangana nama-athomu e-chlorine angazinzile ama-molecule e-PVC, kanye nama-athomu e-sulfur ku-organic tin ehlangana nama-athomu e-carbon ahambisanayo ku-PVC, ama-athomu e-sulfur emzimbeni wokuxhumana angena esikhundleni sama-athomu e-chlorine angazinzile. Uma i-HC1 ikhona, isibopho sokuxhumana siyahlukana, futhi iqembu le-hydrophobic libopha ngokuqinile nama-athomu e-carbon kuma-molecule e-PVC, ngaleyo ndlela livimbele ukusabela okuqhubekayo kokususwa kwe-HCI nokwakheka kwezibopho ezimbili. Phakathi kwensipho yensimbi, insipho ye-zinc kanye nensipho yebhodwe kunempendulo esheshayo yokufaka esikhundleni nama-athomu e-chlorine angazinzile, insipho ye-barium iyona ehamba kancane, insipho ye-calcium ihamba kancane, kanti insipho ye-lead iphakathi. Ngesikhathi esifanayo, ama-chloride ensimbi akhiqizwayo anezinga elihlukahlukene lomphumela wokukhipha i-HCI, futhi amandla awo angokulandelayo:
I-ZnCl>CdCl>>I-BaCl, i-CaCh>I-R2SnCl2 (3) yengezwa kuma-double bond futhi ihlanganiswe nama-double bond ukuvimbela ukuthuthukiswa kwezakhiwo ze-polyene nokunciphisa umbala. Ama-unsaturated acid salts noma ama-complexes ane-double bond, adlula ekusabeleni kwe-diene addition nama-molecule e-PVC, ngaleyo ndlela aphazamise isakhiwo sawo se-covalent futhi avimbele ushintsho lombala. Ngaphezu kwalokho, insipho yensimbi ihambisana nokudluliselwa kwama-double bond ngenkathi ithatha indawo ye-allyl chloride, okubangela umonakalo esakhiweni se-polyene futhi ngaleyo ndlela kuvimbele ushintsho lombala.
(4) Bamba ama-free radicals ukuze uvimbele i-oxidation ezenzakalelayo. Uma ukwengeza iziqinisi zokushisa ze-phenolic kungavimba ukususwa kwe-HC1, kungenxa yokuthi ama-free radicals e-hydrogen athomu anikezwa ama-phenol angahambisana nama-free radicals e-PVC awonakele, akhe into engakwazi ukusabela nomoya-mpilo futhi enomphumela wokuzinza kokushisa. Lesi siqinisi sokushisa singaba nomphumela owodwa noma eminingana.
Isikhathi sokuthunyelwe: Mashi-29-2024
