Ukuphazamisa Kwesilinganiso Polycarbonate: Amatheshweli Okulindela Isishushu

Ukufunda Umbhedlelo Wephondo le-polycarbonate: Umkhuba Wophazamiso, iTg, Nezimo Zokulahlekwa

Kungani i-polycarbonate ayinakuphazamiso okucacile ngoba yasendaweni yamorphous

I-Polycarbonate, noma kunguvikela ngokuthi yi-PC njengoba kuthiwa khona ngokujwayelekile embangweni, ikhona ekugxekenzeni kwezinhlayiya ezingaphambili lapho izimolekyuli zihamba phantsi esikhathini zingakhethi kakade njengalokho kuzimolo ezinezinhlangothi. Ngokungahleli kwazo okungavamile, akukho xesha eliqondile lokuthi i-PC ichanjeni kuqiniso kusolid kuya kumfula xa kuthathelwa isimo sezulu. Esikhathini senzima, sengathi isimo siyashisa ngokanda kakhulu njengakho kusemva kwalokho kuyadinga ukuba kwenzeke ngendlela efanelekileyo kumaqondo wokwakha. Lokho kubangelwa ngoku kuyindlela engcono: umfanekiso ophumelela kuququzelelo kokuqhubeka kanye nokulungiswa kwezixhumanisi. Uma ungasebenzi nge-PC ngendlela ethembekileyo, ukulawula isimo sezulu ngokucophele kuyayingililo. Uma kuthathelwa isimo sezulu esiphezulu kakhulu, umfanekiso udlule, kodwa uma kushiswe kancane kakhulu, ukudala kungafanele kangako. Ukufinyelela kulesi simo esifanelekileyo kudinga ukuziphatha nokulungiswa kwebhloko.

Ukuhlukanisa isilinganiso sokuthathwa (295°C–315°C) kusilinganiso sokuguquka kweglasi (Tg ~ 145–150°C)

Ukuphakama kwe-glass transition temperature, noma Tg, okwesibonelo kungu-145 kusuka ku-150 degrees Celsius kwi-polycarbonate engcono, lapho izimolekuli ziqala ukuhamba kakhulu. Lapho izinto zifinyelela leli xesha, ziyahlaza kusuka kumzimba obomvu ukuze kube yinkinga, kanye ne-leather noma i-rubber, futhi zilahle 80% yobukhokho bazo. Qaphela lokhu: akuyona umlamlilo, kodwa indawo ebalulekile lapho kuzoba khona ukungatholakali xa kugcinelwa ubunzima. Umhlamo wasebenza kakhulu kusuka ku-295 kusuka ku-315 degrees Celsius, lapho i-polycarbonate iyakhiqizwa into esebenzayo kumthetho we-extruding noma injection molding. Ukuchaphazela lezi zintambo ezimbili kuzothinta kumodeli. Izinxenye zingasanda noma zihlaziywe ngaphambi kokufinyelela lezi zintambo zomlamlilo uma zisebenza edondweni le-Tg. Ukulindela izintambo zokusebenza ngezansi kwe-315 degrees kusiza ekukhomeni kwendalo ngokuhlisa kwezindleko.

Ukuqala kokuwohloka okushisayo nemiphumela yokuphepha kokucubungula nobuqotho bempahla

Ipolikhabhonethi iqala ukuthulwa uma kuthathelwa phambili kakhulu kunezingozi eziphakade 350. Ngaleso sikhathi, imolayuli iqala ukwahlulwa futhi libuze izinto ezihlukile njenge-bisphenol A ne-monoxide yekhabhoni. Kubantu bonke abasebenzisa lolu hlelo, kubalulekile ukugcina amathephe ethulwini ngezansi kwe-340C. Abazali beshintsha kungabi phezulu kwe-320C xa kusekelwa kuzinto njenge-extrusion noma izindlela zokwakha. Uma kuhamba phambili kuleso simo esiphilwayo, imiphatlalalo ihlala kusabela kakhulu. Amadwane afaka kakhulu. Kutheni? Imithombo yepolyma ihlulwa ngendlela eyaziwa ngiyoe hydrolytic chain scission. Izimodi ziya kuba ngemitya, zibuke izigaba ze-carbonyl, futhi zilahle kanye nesiseko semandla yangaphakathi phakathi kwe-40% kuya kuma-60%. Uma le miphindzelo ivela, ayikwenzeki ukubuyisela futhi kuzoba kuhlaza kakhulu ekuphileni kwesinqumo ngokudla. Lokho kusobala ukuthi ukusika kwegumbi kumele kubaluleke kangakanani. Ukulawula amathephe ethulwini ngokuphelele kumsebenzi kunceda ukugcina ubude bomthamo nomkhiqizo wonke amathulwa okumele kutholakale.

Amatheshwado Okwehla Kwezindlela: Ukwakha Izindlela Ezifaneleka Ukusebenza Ngazo Ngokuphila

I-Polycarbonate isebenza ngokugcwele uma isebenza ngaphakathi kwe-120–130°C. Ngaphandle kwalokho, ukwephuka kusabela, kubangela ukuncipha okubonakalayo kwezinkalo zomsebenzi. Isibonelo, ukuthi kuthathelwe kwi-135°C ngemizuzwana engu-100 kungakhusela ubunzima bomthelela ngalokho ku-40% (Indiketha Yempilo Yomthwalo 2023). Izinto ezintathu eziphatha ukusebenza ngokwesithunzi:

Ukuphazamisa kwesithuthi emanzini ngaphezu kwemizuzu engu-145 kusho iqiniso elilodwa kwezinhlayiya. Uma kuqukethwe le phakathi, izinkuni ezinde zemolekyuli ziqala ukuhamba ngokwazo, okwakhiwa ukuguquka kwezenzo esikhohlwayo okungakwenzekanga. Izikhathi eziphazanyayo apho amanzi ahlanzela ngaphezu kuka-130C sizukulungile, kodwa uma amanzi abuya ngaso konke kanye no-Tg ngemva yokuphazanya, izinhlayiya ziqaqa futhi ziphele ukuba yinto eyayifanele. Nakuba siyakhumbula izimo ngaphandle kokuphazanya, ikhabonathi iphila kakhulu kwizinkinga zakho, iphila ngezinhlangothi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi ezinephansi......

Isebenzo Ngaphansi Kwesimo Nomhla: HDT, Ukusetshenziswa Okuphakade, Nama-Escursions Amakhambi

Ukuphazamiseka Kwesithunzi (HDT) ngemuva ngesikhathi 1.8 MPa kunalokungu-0.45 MPa: Imithiphako Efanayo Ekusebenzisweni Kwesithunzi

Umbiko wokukhazimula kwezulu, noma HDT ngokufuphi, kusenza sibone konke ukuthi yini indlela engcono okunye okwenziwa kuzofaka umfanekiso walo xa kuthathelwa kakhulu emva kwegazi elikhulu. Xa sibheka ngqo izinto ezinzima, sibona ukuthi i-HDT yazo iyahluka kakhulu ngokwesidingo esithile esizofakela phezu kwazo. Ngaphansi kwegazi elilodwa elincane ngaphezu kwe-0.45 MPa, i-HDT isafika ku-145 digri eSelsiyasi, okuyisilinganiso sesilinganiso se-glass transition temperature (Tg). Kodwa izinto ziyavutha lapho igazi lihlanza ku-1.8 MPa lapho i-HDT ihlulela ku-132°C. Oku kugcwele ukukhohlwa kwe-13°C kwenza uhlu olukhulu kubo bonke abadesigner abasebenza kumakhasi okuhlola kwezimali noma amakhambi ebhokisi yezinhlelo zezixhumaneko. Lokhu kumele kube khethiwe ngokulingana negazi eliphezulu le-1.8 MPa engaphansi kwaloko elincane. Uma into ethile isebenza ngaphandle kwalokho, ingadinga ukuthi ikhuluke emfanekenini, ibe yingcinga yokulinganisa, noma ngaphezulu, iphule kabonke nakuba izulu akalikholwa kakhulu kulesi simo se-Tg. Abenginje abagqimani bahlala behlanganisa izici ze-HDT nezidingo eziphilayo zokusebenza ukuqinisekisa ukuthi konke kuhlinzeka ngokuphila.

Isilinganiso Sempilengweni (Ukuya kuya ku-130°C) Ngokulinganisa Ngezikhathi Ezincane – Ukulungiselela Indima Nenkinga Yeminyaka Emininingwane

Izinto ezinzululwane zika-polycarbonate zihandlela kahle umsebenzi ophakade emakhelwini okwanda ngaphezu kwamadigri-130. Kufaneleke kube khona iziqhamo ezingaphansi kwezinsuku ezimbili ku-150, ikakhulukazi xa zisetshenziswa izinto njengezivivinyo ze-medical noma imithambo eyakhiwa kakhulu. Kodwa qaphela ukuthi kutheni uma lezinto ziphakamiselwa ngaphezulu futhi zibe ngaphakade kakhulu. Izinto ziqala ukuphazanyiswa ngendlela ethiwa yilokho hydrolysis, lokhu kwenza kuba kukhula ngokushesha ngokwesilinganiso kwezintathu eziyishumi ngesilinganiso ngema-100 amahora apho aphindwa ngaphezu kwamadigri-135 ngokuvamile kusayensi ye-Polymer Degradation Studies engu-2023. Lokhu kusho ukuthini? Umfanekiso wasebenza, iphlasiya ihlukile kakhulu ngemva kokusebenza futhi isiphazanyise amandla akhe ekuvikela izinkinga ngamathuba angu-30 kuya ku-40% kuphela ngemaqemu amashumi amabili ngesikhathi esingaphansi kwezinsuku ezimbili uma isebenza ngokuchaza izimo eziphakeme kangaka ngaphezu kwebheji ezingama-5 ngokugcwele kwasempilweni yakhe. Kubo bonke abadesignaya izinto ngokusebenzisa ipolycarbonate, ukulawula umsebenzi phansi kwalokho umkhawulo wezinsuku ezingama-130 kuyindlela eqondisayo kunezimali nezibopho. Futhi xa kusebenzwa ngokudondelayo kuma-140, ukusebenzisa izindlela zobuhlungu okufanelekile njengoko manje kanye nokublowa amanzi kumakampunyoni kuyadingeka kakhulu ukuze kuthintelwe le ndlela yokuhlukana.

Imiphumela Yekhala Ngokudala Kwemvula Kugcina Okudala Kude

Ukuphila okuqhubekayo kwezimali zomthunzi nokukhathazeka kwemvula phaya kuka-100°C

Ipolikhabhonethi ikhuluma izinkomba zokugcoka kwezintsho uma kuphakanywa kumathelelo aphezu kwe-100 degrees Celsius. Uma kushaywa kulezi zimo ngexesha elide, umongo uphazamisa ngendlela eyaziwa ngokuthi hydrolysis ne-oxidation. Lokhu kukhupha ubunzima bokutshisa kabusha nge-40 iphesenti futhi kube yilapha okungaphezulu kwesibili emva kokusetshenziswa ngexesha elide. Ngaphezu kwe-110 degrees, umongo ukuqina kakhulu emva kwe-1,000 amahora e-sebenzo, lokhu kwenza kube lula ukuthinta uma kunikelwa ukumelana nokumelana komthwalo. Lokhu kubaluleke kakhulu emakhinini nemisebenzi yezinhlelo zezimali lapho kunezindleko ezihlukene eziphakama ngexesha. Abasebenzi besayensi abasebenzela ukusiza kumele bakhathaze lokhu kuchitha kancane ngenkathi bamele ixesha lefane letholakala. Ukugcina amathelelo phansi kwezimali ezifanayo ngasempilweni kusiza ekugcineni ubunzima bomongo ngexesha lefane letholakala.

Imithombo yokubona nokwehla kwesakhiwo: ukuluhlaza, ukuguda, nokwethulwa kweguni ngaphandle komthombo wokuthembeka

Izinkomba ezintathu ebonakalayo zibonisa ukuthutha okuphindekayo kwe-polycarbonate:

• Ukuluhlaza : Kusohlwa ngemiphumela yendima engaqediyo eyenzela ukwakha kweekhomophore, okwephinde kakhulu ngokwanguquko komusa nok exposure kwe-UV
• Umbhalo : Kusohlwa kusindiso sokuthula kweguni ngokungena kwebhantsheli, kujula ubunzima bokubona futhi kusho ukwethulwa kwegunya elikhulu
• Ukwethulwa kweguni : Kudala emakhathini apholile ekugcineni, nangempawu engaphansi kuka-0.5µm ethola izindlela zokuchithwa kabili

Kakhulu sithola lezi ngqamuzana ngemva kweminyaka engu-6 kuya ku-12 emva kokusebenzisa izixhobo ngokuphindaphindiweyo kwi-100 degrees Celsius. Izikhumba ezincinci zibonakala kumongo owaziwayo osebenza njengendawo yokuthembeka yezikhumba ezinkulu eziphinde ziphinde ziphinde, ekugcineni kuthintela ukungahleli kwesixhobo. Ukulandela le mazwi amacala kuvumela amathimba okulungiselela ukuthola iingxaki ngokuqala kwaye acwangcise izinto ngaphambi kokuba zihlele kabani. Xa iintempiletha ziyaphakama ngaphezulu kwezo esithatha njengesiphumo, izinto ziyaphila ngokukhawuleza kakhulu. Ngoko ke ukulawula kahle kwezibusiso kubaluleke kangangoko kuyo yonke indlela eyenzelwe ukuba isebenze iminyaka engakanani ngokusasala.

Isikhombisi Sokuqala

Uyintoni intempiletha yokuguquka kweglasu (Tg) yepolikhabhonethe?

Intempiletha yokuguquka kweglasu yepolikhabhonethe iphakathi kwe-145 kunye ne-150 degrees Celsius. Kule tempiletha, ipolikhabhonethe iguquka kuthiwa ngu-ntempiletha ebucayisayo kuthiwa ngu-ntempiletha enobumbeko obuninzi kunye nobushushu.

Kwintempiletha epho ipolikhabhonethe iqala ukuchitha?

Ipolikhabhonethi icubungela ukuchithwa kwayo ngokunxibelelana ngezinkeleni ezingu-350 ezingu-Celsius. Kukhululwa ukulondoloza izinkeleni ngezantsi kwe-340 ukuze kuthintelwe ukuchithwa.

Kutheni okuthile kungaba yisiphumo xa kudlulwa izinkeleni eziphathelene ngokuphelele kwe-polycarbonate?

Ukudlula izinkeleni eziphathelene ngokuphelele kwe-polycarbonate, ikakhulu ngaphezu kwe-130°C ngeminyaka engaphezu, kungakhotha ekunxibeleleni kwayo okuchitha ubunzima bawo, ukukhathazeka kwayo, nokuthi umkhondo wawo ube ngumthwalo.

Ngani angikwazi ukubona ukuthi ipolikhabhonethi yayinxa yachithwa ngokunxibelelana?

Izibonakaliso zokuchithwa kwayo ngokunxibelelana kwi-polycarbonate zifaka ukubomdaka, ukuthi kube ngumfudliso, nokuthi kube nenqwelo yasephansi, okungakhotha ekuphazanyiseni kwayo nokuthula kwayo.