Ukutshatyalaliswa kwe-PVC kubangelwa ikakhulu ukuchithwa kwe-athomu ye-chlorine esebenzayo kwi-molecule phantsi kokufudumala kunye ne-oksijini, okubangelwa ukuveliswa kweHCI. Ngoko ke, i-PVC i-heat stabilizers ikakhulu i-compounds enokuzinzisa i-athomu ye-chlorine kwii-athomu ze-PVC kunye nokuthintela okanye ukwamkela ukukhululwa kwe-HCI. R. Gachter et al. yahlula iziphumo zezinzisi zobushushu njengokuthintela kunye nokulungisa. Owokuqala unemisebenzi yokufunxa iHCI, ukubuyisela iiathom zeklorini ezingazinzanga, ukuphelisa imithombo yokutshisa, kunye nokuthintela i-oxidation ngokuzenzekelayo. Uhlobo lokugqibela lokulungisa lujolise ukongeza kwisakhiwo se-polyene, siphendule kunye neengxenye ezingabonakaliyo kwi-PVC, kwaye zitshabalalise i-carbocations. Ngokukodwa, ngolu hlobo lulandelayo:
(1) Funxa i-HC1 ekhutshwe kwi-PVC ukunqanda umsebenzi wayo wokuzenzela. Iimveliso ezifana neetyuwa ezikhokelayo, iisepha ze-asidi zesinyithi, i-organotin compounds, i-epoxy compounds, i-amines, i-allkoxides yensimbi kunye ne-phenols, kunye ne-metal thiols zonke zinokusabela nge-HCI ukuvimbela ukuphendula kwe-HCI ye-PVC.
Mna (RCOO) 2+2HCI MeCl+2RCOOH
(2) Ukubuyisela okanye ukuphelisa izinto ezingazinzanga ezifana ne-athomu ye-alyl chloride okanye i-athomu ye-carbon chloride ephezulu kwii-athomu ze-PVC, kunye nokuphelisa indawo yokuqaliswa kokususwa kwe-HCI. Ukuba i-athomu ye-tin ye-organic tin stabilizers ilungelelanisa kunye ne-athom yeklorin engazinzanga ye-athom ze-PVC, kunye ne-athom yesulfure kwi-organic tin ilungelelanisa kunye ne-athom ye-carbon ehambelanayo kwi-PVC, ii-athom zesulfure kumzimba wolungelelaniso zithathe indawo ye-athom yeklorin engazinzanga. Xa i-HC1 ikhona, i-coordination bond yahlukana, kunye neqela le-hydrophobic libophelela ngokuqinileyo kunye ne-athomu ye-carbon kwii-athomu ze-PVC, ngaloo ndlela inqanda ukusabela okungaphezulu kokususwa kwe-HCI kunye nokwakhiwa kweebhondi ezimbini. Phakathi kweesepha zentsimbi, isepha ye-zinc kunye nesepha yembiza ineempendulo ezikhawulezayo zokutshintsha indawo kunye neeathom zeklorini ezingazinzanga, isepha ye-barium yeyona icothayo, isepha ye-calcium iyacotha, kwaye isepha yelothe iphakathi. Kwangaxeshanye, iikloridi zetsimbi ezenziweyo zinemigangatho eyahluka-hlukeneyo yefuthe le-catalytic ekususweni kweHCI, kwaye amandla abo ami ngolu hlobo lulandelayo:
ZnCl>CdCl>>BaCl, CaCh>R2SnCl2 (3) yongezwa kwiibhondi eziphindwe kabini kunye ne-co conjugated double bonds ukukhusela ukuphuhliswa kwezakhiwo ze-polyene kunye nokunciphisa umbala. Iityuwa ze-asidi ezingaxutywanga okanye ii-complexes zinezibophelelo eziphindwe kabini, ezifumana i-diene yokongeza i-molecule ye-PVC, ngaloo ndlela iphazamisa isakhiwo sabo sokubambisana kunye nokuthintela utshintsho lombala. Ukongeza, isepha yesinyithi ihamba kunye nokuhanjiswa kwebhondi kabini ngelixa ithatha indawo ye-alyl chloride, ibangela umonakalo kwisakhiwo se-polyene kwaye ngaloo ndlela inqanda ukutshintsha kombala.
(4) Thatha i-radicals yamahhala ukukhusela i-oxidation ngokuzenzekelayo. Ukuba ukongeza i-phenolic heat stabilizers kunokuthintela ukukhutshwa kwe-HC1, kungenxa yokuba i-athomu ye-hydrogen i-radicals yamahhala enikezelwa yi-phenols inokutshata kunye ne-PVC ethotyiweyo ye-macromolecular free radicals, yenze into engakwazi ukusabela nge-oksijeni kwaye ibe nefuthe lokuzinza kwe-thermal. Lo mzinzisi wobushushu unokuba nesiphumo esinye okanye ezininzi.
Ixesha lokuposa: Mar-29-2024
