Rashin lalacewa na PVC yana faruwa ne ta hanyar bazuwar ƙwayoyin chlorine masu aiki a cikin kwayoyin halitta a ƙarƙashin dumama da oxygen, wanda ya haifar da samar da HCI. Saboda haka, PVC zafi stabilizers yawanci mahadi ne da za su iya daidaita da chlorine atom a cikin PVC kwayoyin da kuma hana ko yarda da saki na HCI. R. Gachter et al. an rarraba tasirin masu daidaita zafi a matsayin rigakafi da gyarawa. Na farko yana da ayyuka na ɗaukar HCI, maye gurbin ƙwayoyin chlorine marasa ƙarfi, kawar da tushen ƙonewa, da hana iskar oxygen ta atomatik. Nau'in gyaran na ƙarshe yana nufin ƙarawa zuwa tsarin polyene, amsa tare da sassan da ba a cika ba a cikin PVC, da lalata carbocation. Musamman, kamar haka:
(1) Sha HC1 da aka cire daga PVC don hana aikin motsa jiki. Samfura irin su gishirin gubar, sabulun ƙarfe na acid Organic, mahaɗan organotin, mahadi na epoxy, amines, ƙarfe alkoxides da phenols, da thiols na ƙarfe duk na iya amsawa tare da HCI don hana de HCI dauki na PVC
Ni (RCOO) 2+2HCI MeCl+2RCOOH
(2) Sauya ko kawar da abubuwa marasa ƙarfi kamar allyl chloride atoms ko atom ɗin carbon chloride na uku a cikin kwayoyin PVC, da kuma kawar da wurin farawa na cire HCI. Idan kwano atom na Organic tin stabilizers daidaita tare da m chlorine atom na PVC kwayoyin, da sulfur atom a Organic tin daidaita tare da daidai carbon atom a cikin PVC, da sulfur atom a cikin daidaitawa jiki maye gurbin da m chlorine atoms. Lokacin da HC1 ke nan, haɗin haɗin gwiwar ya rabu, kuma ƙungiyar hydrophobic ta ɗaure da ƙarfi tare da atom ɗin carbon a cikin kwayoyin PVC, don haka hana ƙarin halayen cire HCI da samuwar shaidu biyu. Daga cikin sabulun ƙarfe, sabulun zinc da sabulun tukunya suna da mafi saurin musanya halayen tare da atom ɗin chlorine mara ƙarfi, sabulun barium shine mafi hankali, sabulun calcium yana sannu a hankali, sabulun gubar yana tsakiyar. A lokaci guda kuma, chlorides na ƙarfe da aka samar suna da nau'i daban-daban na tasirin catalytic akan cire HCI, kuma ƙarfin su shine kamar haka:
ZnCl> CdCl>> BaCl, CaCh> R2SnCl2 (3) an kara zuwa biyu bonds da kuma conjugated biyu bond don hana ci gaban polyene Tsarin da kuma rage canza launi. Gishirin acid ɗin da ba a cika ba ko rukunin gidaje suna da ɗakuna biyu, waɗanda ke jure yanayin ƙari tare da ƙwayoyin PVC, ta haka ya rushe tsarin haɗin gwiwar su kuma yana hana canjin launi. Bugu da ƙari, sabulun ƙarfe yana tare da canja wurin haɗin gwiwa sau biyu yayin maye gurbin allyl chloride, yana haifar da lalacewa ga tsarin polyene kuma don haka yana hana canjin launi.
(4) Ɗauki radicals na kyauta don hana iskar oxygen ta atomatik. Idan ƙara phenolic zafi stabilizers iya toshe kau da HC1, shi ne saboda hydrogen atom free radicals bayar da phenols iya biyu tare da lalatar da PVC macromolecular free radicals, forming wani abu da ba zai iya amsa tare da oxygen kuma yana da thermal stabilization sakamako. Wannan ma'aunin zafi yana iya samun tasiri ɗaya ko da yawa.
Lokacin aikawa: Maris 29-2024
