Ulwazi Lwezinto Zokupakisha - Yini Ebangela Ukushintsha Kombala Kwemikhiqizo Yepulasitiki?

• Ukuwohloka kwe-oxidative yezinto zokusetshenziswa kungase kubangele ukushintsha kombala lapho kubumba ezingeni lokushisa eliphezulu;
• Ukushintsha umbala kombala ekushiseni okuphezulu kuzodala ukushintsha kombala kwemikhiqizo yepulasitiki;
• Ukusabela kwamakhemikhali phakathi kombala nezinto ezingavuthiwe noma izithasiselo kuzodala ukuguquguquka kombala;
• Ukusabela phakathi kwezithasiselo kanye ne-oxidation ezenzakalelayo yezithasiselo kuzodala ushintsho lombala;
• I-Tautomerization yombala wombala ngaphansi kwesenzo sokukhanya nokushisa kuzodala izinguquko zombala wemikhiqizo;
• Izinto ezingcolisa umoya zingadala izinguquko emikhiqizweni yepulasitiki.

1. Ibangelwa Ukubumba Kwepulasitiki

I-1) Ukuwohloka kwe-oxidative yezinto zokusetshenziswa kungase kubangele ukushintsha kombala lapho kubumba ezingeni lokushisa eliphezulu

Lapho indandatho yokushisa noma ipuleti yokushisa yemishini yokucubungula ukubumba ipulasitiki ihlale isesimweni sokushisa ngenxa yokuphuma kokulawula, kulula ukubangela ukushisa kwendawo ukuba kube phezulu kakhulu, okwenza izinto eziluhlaza zi-oxidize futhi zibole ekushiseni okuphezulu. Kulawo mapulasitiki angezwani nokushisa, njenge-PVC, kulula uma kwenzeka lesi simo, uma sibucayi, sizoshisa futhi sibe phuzi, noma sibe mnyama, sihambisane nenani elikhulu lama-volatiles aphansi amangqamuzana aphuphumayo.

Lokhu kwehlisa kuhlanganisa ukusabela okufana nalokhui-depolymerization, i-random chain scission, ukususwa kwamaqembu aseceleni kanye nezinto ezinesisindo esiphansi samangqamuzana.

• I-Depolymerization

Ukusabela kwe-cleavage kwenzeka kusixhumanisi sochungechunge lwetheminali, okubangela ukuthi isixhumanisi seketango siwe ngamunye ngamunye, futhi i-monomer ekhiqiziwe ishintshashintsha ngokushesha. Ngalesi sikhathi, isisindo samangqamuzana sishintsha kancane kakhulu, njengenqubo ehlehlayo ye-polymerization yeketango. Okufana ne-thermal depolymerization ye-methyl methacrylate.

• I-Random Chain Scission (Ukwehliswa)

Kwaziwa nangokuthi amakhefu angahleliwe noma amaketango aphukile angahleliwe. Ngaphansi kwesenzo samandla emishini, imisebe enamandla amakhulu, amaza e-ultrasonic noma ama-reagents amakhemikhali, iketango le-polymer liyaphuka ngaphandle kwephuzu eligxilile ukuze kukhiqizwe i-polymer enesisindo esiphansi. Kungenye yezindlela zokuwohloka kwe-polymer. Lapho uchungechunge lwe-polymer luwohloka ngokungahleliwe, isisindo samangqamuzana sehla ngokushesha, futhi ukulahlekelwa kwesisindo se-polymer kuncane kakhulu. Isibonelo, indlela yokuwohloka kwe-polyethylene, i-polyene ne-polystyrene ngokuyinhloko ukuwohloka okungahleliwe.

Lapho ama-polymers afana ne-PE abunjwa emazingeni okushisa aphezulu, noma yisiphi isikhundla seketanga eliyinhloko singase siphuke, futhi isisindo samangqamuzana siyancipha ngokushesha, kodwa isivuno se-monomer sincane kakhulu. Lolu hlobo lokusabela lubizwa ngokuthi i-random chain scission, ngezinye izikhathi ebizwa ngokuthi i-degradation, i-polyethylene Ama-radicals mahhala akhiwa ngemva kwe-chain scission asebenza kakhulu, azungezwe i-hydrogen yesibili eyengeziwe, ejwayele ukusabela kokudluliswa kweketanga, futhi cishe awekho ama-monomer akhiqizwayo.

• Ukususwa kwezinto ezibambele

I-PVC, i-PVAc, njll. ingabhekana nokusabela kokususwa lapho ishiswa, ngakho-ke ithafa livame ukuvela ejikeni le-thermogravimetric. Lapho i-polyvinyl chloride, i-polyvinyl acetate, i-polyacrylonitrile, i-polyvinyl fluoride, njll. Uma sithatha i-polyvinyl chloride (PVC) njengesibonelo, i-PVC icutshungulwa ezingeni lokushisa elingaphansi kuka-180 ~ 200°C, kodwa emazingeni okushisa aphansi (afana no-100~120°C), iqala ukukhipha i-hydrogen (HCl), futhi ilahlekelwa i-HCl kakhulu. ngokushesha cishe ku-200 ° C. Ngakho-ke, ngesikhathi sokucubungula (180-200 ° C), i-polymer ijwayele ukuba mnyama ngombala futhi ibe namandla aphansi.

I-HCl yamahhala inomphumela we-catalytic ku-dehydrochlorination, nama-chloride ensimbi, njenge-ferric chloride eyakhiwe isenzo se-hydrogen chloride nemishini yokucubungula, ikhuthaza i-catalysis.

Amaphesenti ambalwa ama-absorbents e-asidi, afana ne-barium stearate, i-organotin, ama-lead compounds, njll., kumele afakwe ku-PVC ngesikhathi sokucubungula okushisayo ukuze kuthuthukiswe ukuzinza kwayo.

Uma ikhebula lokuxhumana lisetshenziselwa ukufaka umbala kukhebula lokuxhumana, uma ungqimba lwe-polyolefin ocingweni lwethusi lungaqinile, kuzokwakhiwa i-carboxylate yethusi eluhlaza esibonakalayo se-polymer-copper. Lokhu kusabela kukhuthaza ukusakazeka kwethusi ku-polymer, kusheshise i-catalytic oxidation yethusi.

Ngakho-ke, ukuze kwehliswe izinga lokuwohloka kwe-oxidative lama-polyolefin, i-phenolic noma i-aromatic amine Antioxidant (AH) ivamise ukungezwa ukuze kuqedwe ukusabela okungenhla futhi kwenziwe ama-free radicals angasebenzi A·: ROO·+AH-→ROOH+A·

• Ukuwohloka kwe-Oxidative

Imikhiqizo ye-polymer evezwe emoyeni imunca umoya-mpilo futhi ingena kwi-oxidation yakhe i-hydroperoxides, iqhubeke nokubola ukuze ikhiqize izikhungo ezisebenzayo, yakhe ama-radicals mahhala, bese ibhekana nokusabela kwamahhala kweketango (okungukuthi, inqubo ye-auto-oxidation). Ama-polymers avezwa umoya-mpilo emoyeni ngesikhathi sokucubungula nokusebenzisa, futhi lapho kushisa, ukuwohloka kwe-oxidative kuyashesha.

I-oxidation eshisayo ye-polyolefin ingeye-free radical chain reaction mechanism, enokuziphatha kwe-autocatalytic futhi ingahlukaniswa ngezinyathelo ezintathu: ukuqalisa, ukukhula kanye nokuqedwa.

I-chain scission ebangelwa iqembu le-hydroperoxide iholela ekwehleni kwesisindo samangqamuzana, futhi imikhiqizo eyinhloko ye-scission ama-alcohol, ama-aldehydes, nama-ketones, agcina e-oxidized ku-carboxylic acid. Ama-Carboxylic acid adlala indima enkulu ekukhiqizeni i-oxidation yensimbi. Ukuwohloka kwe-oxidative kuyisizathu esiyinhloko sokuwohloka kwezakhiwo ezingokomzimba nezomshini zemikhiqizo ye-polymer. Ukuwohloka kwe-oxidative kuyahlukahluka ngesakhiwo samangqamuzana e-polymer. Ukuba khona komoya-mpilo kungabuye kuqinise umonakalo wokukhanya, ukushisa, imisebe namandla emishini kuma-polymer, okubangela ukusabela kokuwohloka okuyinkimbinkimbi. Ama-Antioxidants ayengezwa kuma-polymers ukunciphisa ukuwohloka kwe-oxidative.

2) Lapho ipulasitiki icutshungulwa futhi ibunjwa, umbala uyabola, ufiphele futhi ushintshe umbala ngenxa yokungakwazi ukumelana namazinga okushisa aphezulu.

Izingulube noma odayi abasetshenziselwa ukufaka imibala epulasitiki banomkhawulo wokushisa. Lapho lelizinga lokushisa elilinganiselwe lifinyelelwa, izimibala-bala noma odayi bazoshintsha amakhemikhali ukuze kukhiqizwe izinhlanganisela ezihlukahlukene zesisindo samangqamuzana aphansi, futhi amafomula awo okusabela ayinkimbinkimbi uma kuqhathaniswa; ama-pigments ahlukene anokusabela okuhlukile. Futhi imikhiqizo, ukumelana kwezinga lokushisa kwezingulube ezahlukene kungahlolwa ngezindlela zokuhlaziya ezifana nokuncipha kwesisindo.

2. Imibala Isabela Ngezinto Ezingavuthiwe

Ukusabela phakathi kwama-colorants nezinto zokusetshenziswa kubonakala ikakhulukazi ekucutshungulweni kwezingulube ezithile noma odayi nezinto ezingavuthiwe. Lokhu kusabela kwamakhemikhali kuzoholela ekushintsheni kwemibala kanye nokuwohloka kwama-polymers, ngaleyo ndlela kushintshe izakhiwo zemikhiqizo yepulasitiki.

• Ukusabela kokunciphisa

Amanye ama-polymers aphezulu, njengenayiloni nama-aminoplasts, angama-ejenti anamandla okunciphisa i-asidi esimweni esincibilikisiwe, anganciphisa futhi afiphale ama-pigments noma odayi abazinzile emazingeni okushisa okucubungula.

• I-Alkaline Exchange

Izinsimbi zomhlaba ezine-alkali kumapholima e-emulsion e-PVC noma ama-polypropylene athile azinzile angakwazi "ukushintshaniswa okuyisisekelo" nezinsimbi zomhlaba ezine-alkaline kuma-colorants ukuze kushintshwe umbala osuka obomvu-obomvu uye osawolintshi.

I-PVC emulsion polymer iyindlela lapho i-VC yenziwa i-polymerized ngokunyakaziswa ku-emulsifier (njenge-sodium dodecylsulfonate C12H25SO3Na) isixazululo samanzi. Ukusabela kuqukethe i-Na+; ukuze kuthuthukiswe ukumelana nokushisa nomoya-mpilo we-PP, 1010, DLTDP, njll. kuvame ukungezwa. I-oksijeni, i-antioxidant 1010 iyindlela yokusabela ye-transesterification eyenziwe yi-3,5-di-tert-butyl-4-hydroxypropionate methyl ester kanye ne-sodium pentaerythritol, futhi i-DLTDP ilungiswa ngokusabela isixazululo samanzi se-Na2S nge-acrylonitrile Propionitrile i-hydrolyodized futhi ekugcineni ikhiqize i-asidi etholwe nge-esterification nge-lauryl alcohol. Ukusabela nakho kuqukethe i-Na+.

Ngesikhathi sokubunjwa nokucutshungulwa kwemikhiqizo yepulasitiki, i-Na+ esele ezintweni ezingavuthiwe izosabela nge-pigment yechibi equkethe ama-ion ensimbi njenge-CIPigment Red48:2 (BBC noma 2BP): XCa2++2Na+→XNa2+ +Ca2+

• Ukusabela Phakathi Kwemibala Ne-Hydrogen Halides (HX)

Uma izinga lokushisa likhuphukela ku-170 ° C noma ngaphansi kwesenzo sokukhanya, i-PVC isusa i-HCI ukuze yakhe isibopho esiphindwe kabili esihlanganisiwe.

I-polyolefin ene-halogen-retardant flame-retardant polyolefin noma imikhiqizo yepulasitiki ekwazi ukumelana nelangabi enombala nayo i-dehydrohalogenated HX uma ibunjwa ezingeni lokushisa eliphezulu.

1) Ukusabela kwe-Ultramarine ne-HX

I-Ultramarine blue pigment esetshenziswa kakhulu ekwenzeni umbala wepulasitiki noma ukususa ukukhanya okuphuzi, iyinhlanganisela yesibabule.

2) I-Copper gold powder pigment isheshisa ukubola kwe-oxidative yezinto zokusetshenziswa ze-PVC

Imibala yethusi ingafakwa i-oxidized ku-Cu+ naku-Cu2+ ekushiseni okuphezulu, okuzosheshisa ukubola kwe-PVC.

3) Ukubhujiswa kwama-ion ensimbi kuma-polymers

Ezinye izingulube zinomphumela olimazayo kuma-polymers. Isibonelo, umbala wechibi we-manganese CIPigmentRed48:4 awufanele ukubunjwa kwemikhiqizo yepulasitiki ye-PP. Isizathu siwukuthi amanani aguquguqukayo ensimbi ye-manganese ions akha i-hydroperoxide ngokudluliswa kwama-electron ku-oxidation eshisayo noma i-photooxidation ye-PP. Ukubola kwePP kuholela ekugugeni okusheshayo kwe-PP; isibopho se-ester ku-polycarbonate kulula ukuba i-hydrolyzed futhi ibole lapho ishisa, futhi uma kukhona i-ion yensimbi ku-pigment, kulula ukukhuthaza ukubola; ama-ion ensimbi azophinde akhuthaze ukubola kwe-thermo-oksijeni ye-PVC nezinye izinto zokusetshenziswa, futhi kubangele ukushintsha kombala.

Ukufingqa, lapho ukhiqiza imikhiqizo yepulasitiki, kuyindlela engenzeka kakhulu futhi ephumelelayo yokugwema ukusetshenziswa kwezingulube ezinemibala ezisabela ngezinto ezingavuthiwe.

3. Ukusabela phakathi kombala nezithasiselo

1) Ukusabela phakathi kombala oqukethe isibabule kanye nezithasiselo

Imibala equkethe i-sulphur, njenge-cadmium yellow (isixazululo esiqinile se-CdS ne-CdSe), ayifanele i-PVC ngenxa yokungazweli kahle kwe-asidi, futhi akufanele isetshenziswe nezithasiselo ezinomthofu.

2) Ukusabela kwezinhlanganisela eziqukethe umthofu ezinezinza eziqukethe isibabule

Okuqukethwe okuholayo ku-chrome yellow pigment noma okubomvu kwe-molybdenum kuhlangana nama-antioxidants afana ne-thiodistearate DSTDP.

3) Ukusabela phakathi kwe-pigment kanye ne-antioxidant

Ngezinto ezingavuthiwe ezinama-antioxidants, njenge-PP, ezinye izingulube zizophinde zisabele nge-antioxidants, ngaleyo ndlela zenze buthaka umsebenzi wama-antioxidants futhi zenze ukuzinza kwe-oxygen eshisayo yezinto zokusetshenziswa kube kubi nakakhulu. Isibonelo, ama-antioxidants e-phenolic amuncwa kalula yi-carbon black noma asabelane nawo ukuze alahlekelwe umsebenzi wawo; ama-phenolic Antioxidants kanye ne-titanium ions emikhiqizweni yepulasitiki emhlophe noma enombala okhanyayo akha ama-phenolic anuka kamnandi e-hydrocarbon complexes ukuze abangele ukuphuzi kwemikhiqizo. Khetha i-antioxidant efanelekile noma wengeze izithasiselo ezisizayo, ezifana nosawoti we-zinc ophikisana ne-asidi (i-zinc stearate) noma i-P2 yohlobo lwe-phosphite ukuze uvimbele ukuguga kwe-white pigment (TiO2).

4) Ukusabela phakathi kwe-pigment ne-stabilizer yokukhanya

Umthelela wemibala neziqinisi ukukhanya, ngaphandle kokusabela kwemibala enesibabule kanye neziqinisi zokukhanya ezine-nickel njengoba kuchazwe ngenhla, ngokuvamile kunciphisa ukusebenza kahle kweziqinisi zokukhanya, ikakhulukazi umthelela wezinzinzisi zokukhanya ze-amine ezivinjiwe kanye ne-azo yellow and red pigments. Umthelela wokuwohloka okuzinzile usobala kakhulu, futhi awuzinzile njengokunganemibala. Ayikho incazelo eqondile yalesi simo.

4. Ukusabela Phakathi Kwezithasiselo

Uma izithasiselo eziningi zisetshenziswa ngendlela engafanele, ukusabela okungalindelekile kungase kwenzeke futhi umkhiqizo uzoshintsha umbala. Isibonelo, i-flame retardant i-Sb2O3 ihlangana ne-anti-oxidant equkethe isulfure ukuze ikhiqize i-Sb2S3: Sb2O3+–S–→Sb2S3+–O–

Ngakho-ke, kufanele kuqashelwe ekukhetheni izithasiselo lapho kucutshungulwa ukwakheka kokukhiqiza.

5. Izimbangela ze-Auto-oxidation ezisizayo

I-oxidation ezenzakalelayo ye-phenolic stabilizer iyisici esibalulekile sokuthuthukisa ukuguquguquka kwemikhiqizo emhlophe noma enombala okhanyayo. Lokhu kuguquguquka kombala kuvame ukubizwa ngokuthi “I-Pinking” emazweni angaphandle.

Ihlanganiswe nemikhiqizo ye-oxidation efana ne-BHT Antioxidants (2-6-di-tert-butyl-4-methylphenol), futhi yakheke njenge-3,3′,5,5′-stilbene quinone ukukhanya okubomvu komkhiqizo wokusabela okubomvu, Lokhu kuguquguquka kwenzeka. kuphela lapho kukhona umoya-mpilo namanzi futhi kungekho ukukhanya. Uma ichayeke ekukhanyeni kwe-ultraviolet, i-stilbene quinone ebomvu ekhanyayo ibola ngokushesha ibe umkhiqizo oyindandatho eyodwa ophuzi.

6. I-Tautomerization ye-Coloured Pigments Ngaphansi Kwesenzo Sokukhanya Nokushisa

Ezinye izimibalabala ezinemibala zithola i-tautomerization yokucushwa kwamangqamuzana ngaphansi kwesenzo sokukhanya nokushisa, njengokusetshenziswa kwezingulube ze-CIPig.R2 (BBC) ukushintsha kusuka ohlotsheni lwe-azo kuya ohlotsheni lwe-quinone, okushintsha umphumela wangempela wokuhlanganisa futhi kubangele ukwakheka kwamabhondi ahlanganisiwe. . ukuncipha, okuholela ekushintsheni kombala ukusuka kokubomvu okuluhlaza okwesibhakabhaka okumnyama ukuya kokubomvu ngokukhanyayo okuwolintshi.

Ngesikhathi esifanayo, ngaphansi kwe-catalysis yokukhanya, ibola ngamanzi, ishintsha amanzi e-co-crystal futhi ibangele ukufiphala.

7. Ibangelwa Izinto Ezingcolisa Umoya

Lapho imikhiqizo yepulasitiki igcinwa noma isetshenziswa, ezinye izinto ezisebenzayo, kungakhathaliseki ukuthi izinto ezingavuthiwe, izithasiselo, noma amabala ombala, zizosabela ngomswakama osemkhathini noma ukungcola kwamakhemikhali njengama-asidi nama-alkali ngaphansi kwesenzo sokukhanya nokushisa. Kubangelwa ukusabela okuhlukahlukene kwamakhemikhali okuyinkimbinkimbi, okuzoholela ekufipheleni noma ekushintsheni kombala ngokuhamba kwesikhathi.

Lesi simo singagwenywa noma sincishiswe ngokungeza izinza ezifanelekile zomoya-mpilo oshisayo, iziqinisi ukukhanya, noma ukukhetha izithasiselo zokumelana nesimo sezulu ezisezingeni eliphezulu nezinemibala.