Kusukela ekuqaleni kwayo phakathi nangemva kweMpi Yezwe II, imboni yezohwebo yama-polymers-ama-molecule okwenziwa amaketanga amade okuthi “amapulasitiki” okuyigama elingelona iqiniso elivamile—ikhule ngokushesha.Ngo-2015, amathani angaphezu kwezigidi ezingu-320 zama-polymers, ngaphandle kwemicu, akhiqizwa emhlabeni jikelele.
[Ishadi: Ingxoxo]Kuze kube yiminyaka emihlanu edlule, abaklami bomkhiqizo we-polymer ngokuvamile bebengacabangi ukuthi kuzokwenzekani ngemva kokuphela kwesikhathi sokuqala sokuphila somkhiqizo wabo.Lokhu sekuqala ukushintsha, futhi lolu daba luzodinga ukugxila okukhulayo eminyakeni ezayo.
IMBONI YEPlastiki
"Ipulasitiki" isiphenduke indlela engalungile yokuchaza ama-polymers.Ngokuvamile etholakala ku-petroleum noma igesi yemvelo, lawa ama-molecule amaketanga amade anamakhulu kuya ezinkulungwaneni zezixhumanisi kuchungechunge ngalunye.Amaketanga amade adlulisela izici ezibalulekile zomzimba, njengamandla nokuqina, ama-molecule amafushane awakwazi ukufana.
"Ipulasitiki" empeleni iwuhlobo olufushanisiwe lwe-"thermoplastic," igama elichaza izinto ze-polymeric ezingabunjwa futhi zibunjwe kabusha kusetshenziswa ukushisa.
Imboni yesimanje ye-polymer yadalwa ngempumelelo nguWallace Carothers eDuPont ngeminyaka yawo-1930.Umsebenzi wakhe onzima kuma-polyamides waholela ekuthengisweni kwenayiloni, njengoba ukushoda kukasilika ngesikhathi sempi kwaphoqa abesifazane ukuba babheke amasokisi kwenye indawo.
Lapho ezinye izinto zokwakha zintuleka phakathi neMpi Yezwe II, abacwaningi babheka kuma-polymer okwenziwa ukuze bavale izikhala.Isibonelo, ukuhlinzekwa kwenjoloba yemvelo yamasondo ezimoto kwanqanyulwa ukunqotshwa kwamaJapane aseNingizimu-mpumalanga ye-Asia, okuholela ekulinganeni kwe-polymer yokwenziwa.
Ukuphumelela okuqhutshwa ilukuluku kukhemistri kuholele ekuthuthukisweni okuqhubekayo kwama-polymers okwenziwa, okuhlanganisa i-polypropylene esetshenziswa kabanzi manje kanye ne-polyethylene ephezulu kakhulu.Amanye ama-polymer, njengeTeflon, akhubeka ngengozi.
Ekugcineni, inhlanganisela yesidingo, intuthuko yesayensi, kanye nokuzola kwaholela ekuhlanganisweni okuphelele kwama-polymer manje ongawabona kalula ngokuthi “amapulasitiki.”Lawa ma-polymer adayiswa ngokushesha, ngenxa yesifiso sokunciphisa isisindo somkhiqizo kanye nokuhlinzeka ngezinye izindlela ezingabizi kuzinto zemvelo ezifana ne-cellulose noma ukotini.
IZINHLOBO ZEPLASTIKI
Ukukhiqizwa kwama-polymers okwenziwa emhlabeni jikelele kwenganyelwe i-polyolefins-polyethylene ne-polypropylene.
I-Polyethylene iza ngezinhlobo ezimbili: "ukuminyana okuphezulu" kanye "nokuminyana okuphansi."Esikalini samangqamuzana, i-polyethylene ephezulu-density ibukeka njengekama elinamazinyo amafushane ahlukanisiwe njalo.Inguqulo ye-low density, ngakolunye uhlangothi, ibukeka njengekama elinamazinyo ahlukanisiwe obude obungahleliwe-ngandlela-thile njengomfula nemingenela yawo uma ibonakala phezulu.Nakuba zombili ziyi-polyethylene, umehluko wokwakheka kwenza lezi zinto ziziphathe ngendlela ehlukile uma zibunjwa zibe amafilimu noma eminye imikhiqizo.
[Ishadi: Ingxoxo]
Ama-Polyolefin abusa ngenxa yezizathu ezimbalwa.Okokuqala, zingakhiqizwa kusetshenziswa igesi yemvelo engabizi kakhulu.Okwesibili, angama-polymers okwenziwa alula kakhulu akhiqizwa ngezinga elikhulu;ukuminyana kwazo kuphansi kangangokuthi ziyantanta.Okwesithathu, ama-polyolefin amelana nokulimala kwamanzi, umoya, amafutha, izincibilikisi zokuhlanza—zonke izinto lawa ma-polymer angahlangabezana nazo lapho esetshenziswa.Okokugcina, kulula ukubumbeka abe yimikhiqizo, kuyilapho aqine ngokwanele kangangokuthi amaphakheji enziwe ngawo ngeke akhubazeke elolini lokulethwa elihlezi elangeni usuku lonke.
Kodwa-ke, lezi zinto zinezinkinga ezimbi kakhulu.Zehlisa kabuhlungu kancane, okusho ukuthi i-polyolefin izophila endaweni amashumi eminyaka kuya emakhulwini eminyaka.Phakathi naleso sikhathi, amagagasi nomoya kuyawagwaza, kwakheka izinhlayiyana ezincane ezingamuncwa izinhlanzi nezilwane, zikhuphukele kithi.
Ukugaywa kabusha kwama-polyolefin akuqondile ngendlela umuntu angathanda ngayo ngenxa yezinkinga zokuqoqwa nokuhlanza.Umoya-mpilo kanye nokushisa kubangela ukulimala kweketango ngesikhathi sokuphinda kucutshungulwe, kuyilapho ukudla nezinye izinto kungcolisa i-polyolefin.Intuthuko eqhubekayo kukhemistry idale amamaki amasha e-polyolefin enamandla athuthukisiwe nokuqina, kodwa lezi azikwazi ukuhlangana njalo namanye amabanga ngesikhathi sokugaywa kabusha.Ngaphezu kwalokho, ama-polyolefin avame ukuhlanganiswa nezinye izinto ekufakweni kwe-multilayer.Ngenkathi lezi zakhiwo ze-multilayer zisebenza kahle, azikwazi ukuphinda zisetshenziswe.
Ngezinye izikhathi ama-polymers agxekwa ngokuthi akhiqizwa kusukela ekuntulekeni kwe-petroleum negesi yemvelo.Nokho, ingxenye yegesi yemvelo noma i-petroleum esetshenziselwa ukukhiqiza ama-polymer iphansi kakhulu;ngaphansi kuka-5% kawoyela noma igesi yemvelo ekhiqizwa unyaka ngamunye kuqashwa ukukhiqiza amapulasitiki.Ngaphezu kwalokho, i-ethylene ingakhiqizwa nge-ethanol yomoba, njengoba kwenziwa ukuhweba ngabakwaBraskem eBrazil.
INDLELA I-PLASTIC ISETSHENZISWA NGAYO
Ngokuya ngesifunda, ukupakishwa kudla u-35% kuya ku-45% we-polymer yokwenziwa ekhiqizwa iyonke, lapho i-polyolefin ibusa khona.I-Polyethylene terephthalate, i-polyester, ibusa imakethe yamabhodlela esiphuzo nemicu yendwangu.
Ukwakha nokwakha kudla amanye ama-20% engqikithi yama-polymer akhiqizwayo, lapho kubusa ipayipi le-PVC kanye nabazala balo bamakhemikhali.Amapayipi e-PVC alula, anganameka esikhundleni sokudayiswa noma ashiselwe, futhi amelana kakhulu nemiphumela elimazayo ye-chlorine emanzini.Ngeshwa, ama-athomu e-chlorine anikeza i-PVC le nzuzo enza kube nzima kakhulu ukugaywa kabusha–iningi liyalahlwa ekupheleni kwempilo.
Ama-polyurethanes, umndeni wonke wama-polymers ahlobene, asetshenziswa kabanzi ekwakhiweni kwegwebu ezindlini nasezimpahleni zikagesi, kanye nasezimbotsheni zezakhiwo.
Umkhakha wezimoto usebenzisa amanani akhulayo we-thermoplastics, ikakhulukazi ukunciphisa isisindo futhi ngaleyo ndlela uzuze amazinga aphezulu okusebenza kahle kukaphethiloli.I-European Union ilinganisela ukuthi u-16% wesisindo semoto evamile izingxenye zepulasitiki, ikakhulukazi izingxenye zangaphakathi nezingxenye.
Angaphezu kwezigidi ezingama-70 amathani we-thermoplastics ngonyaka asetshenziswa ezindwangu, ikakhulukazi ezingutsheni kanye nakukhaphethi.Ngaphezu kwe-90% yemicu yokwenziwa, ikakhulukazi i-polyethylene terephthalate, ikhiqizwa e-Asia.Ukukhula kokusetshenziswa kwefayibha yokwenziwa ezingutsheni kufike ngenxa yezindleko zemicu yemvelo efana nekotini noboya, edinga inani elikhulu lendawo yokulima ukuze likhiqizwe.Imboni yefayibha yokwenziwa ibone ukukhula okumangazayo kwezimpahla zokugqoka kanye nokhaphethi, ngenxa yentshisekelo yezakhiwo ezikhethekile ezifana nokunwebeka, ukuxubha umswakama, kanye nokuphefumula.
Njengasendabeni yokupakishwa, izindwangu azivamisile ukugaywa kabusha.Isakhamuzi esijwayelekile sase-US sikhiqiza ngaphezu kwamakhilogremu angu-90 wemfucuza yendwangu unyaka ngamunye.Ngokusho kweGreenpeace, umuntu ojwayelekile ngo-2016 uthenge izingubo zokugqoka ezingu-60% ngaphezulu njalo ngonyaka kunomuntu ojwayelekile eminyakeni engu-15 ngaphambili, futhi ugcina izingubo isikhathi esifushane.
Isikhathi sokuthumela: Jul-03-2023