Kuyambira pomwe idayamba Nkhondo Yachiwiri Yapadziko Lonse komanso pambuyo pa Nkhondo Yachiwiri Yapadziko Lonse, makampani azamalonda opangira ma polima - mamolekyu opangidwa ndi unyolo wautali omwe "pulasitiki" ndi dzina lolakwika lodziwika bwino - lakula mwachangu.Mu 2015, matani opitilira 320 miliyoni a ma polima, kuphatikiza ulusi, adapangidwa padziko lonse lapansi.
[Tchati: Zokambirana]Mpaka zaka zisanu zapitazi, opanga zinthu za polima nthawi zambiri samaganizira zomwe zingachitike akatha kutha kwa moyo wawo woyamba.Izi zikuyamba kusintha, ndipo nkhaniyi idzafuna kuti anthu ambiri aziganizira kwambiri zaka zikubwerazi.
NTCHITO YA PLASTICS
"Pulasitiki" yakhala njira yolakwika yofotokozera ma polima.Nthawi zambiri amachokera ku petroleum kapena gasi, awa ndi mamolekyu amtaliatali okhala ndi maulalo mazana mpaka masauzande mu unyolo uliwonse.Unyolo wautali umapereka zinthu zofunika kwambiri, monga mphamvu ndi kulimba, zomwe mamolekyu aafupi sangafanane.
"Pulasitiki" kwenikweni ndi mawonekedwe ofupikitsa a "thermoplastic," mawu omwe amafotokoza zipangizo za polymeric zomwe zingathe kupangidwa ndi kukonzanso pogwiritsa ntchito kutentha.
Makampani amakono a polima adapangidwa bwino ndi Wallace Carothers ku DuPont m'ma 1930.Ntchito yake yowawa pa ma polyamides idapangitsa kuti nayiloni agulitse malonda, chifukwa kuchepa kwa silika panthawi yankhondo kunakakamiza amayi kuyang'ana kwina kuti apeze masitonkeni.
Zida zina zitayamba kusowa pa nthawi ya nkhondo yachiwiri ya padziko lonse, ofufuza anayang'ana ma polima opangidwa kuti atseke mipata.Mwachitsanzo, kuperekedwa kwa mphira wachilengedwe wamatayala agalimoto kudathetsedwa ndi kugonjetsa kwa Japan ku Southeast Asia, zomwe zidapangitsa kuti pakhale chofanana ndi polima.
Kupita patsogolo kochitidwa ndi chidwi mu chemistry kudapangitsa kuti ma polima apangidwe, kuphatikiza ma polypropylene omwe amagwiritsidwa ntchito kwambiri masiku ano komanso polyethylene yolimba kwambiri.Ma polima ena, monga Teflon, anapunthwa mwangozi.
Pamapeto pake, kuphatikiza kwa zosowa, kupita patsogolo kwa sayansi, komanso kusakondana kudapangitsa kuti pakhale ma polima ambiri omwe tsopano mutha kuwazindikira ngati "pulasitiki."Ma polima awa adagulitsidwa mwachangu, chifukwa chofuna kuchepetsa kulemera kwazinthu komanso kupereka zotsika mtengo m'malo mwa zinthu zachilengedwe monga mapadi kapena thonje.
MITUNDU YA PLASTIKI
Kupanga ma polima opangidwa padziko lonse lapansi kumayendetsedwa ndi polyolefins-polyethylene ndi polypropylene.
Polyethylene imabwera m'mitundu iwiri: "high density" ndi "low density".Pa molekyulu ya molekyulu, polyethylene yotalika kwambiri imawoneka ngati chisa chokhala ndi mano aafupi nthawi zonse.Komano, mtundu wocheperako umaoneka ngati chisa chokhala ndi mano otalikirana mosiyanasiyana atali otalikirapo mwachisawawa—mofanana ndi mtsinje ndi matsiridwe ake ngati awonedwa kuchokera pamwamba.Ngakhale onse ndi polyethylene, kusiyana kwa mawonekedwe kumapangitsa kuti zinthuzi ziziyenda mosiyana zikapangidwa kukhala mafilimu kapena zinthu zina.
[Tchati: Kukambitsirana]
Polyolefins ndi olamulira pazifukwa zingapo.Choyamba, amatha kupangidwa pogwiritsa ntchito gasi wachilengedwe wotchipa.Chachiwiri, ndi ma polima opepuka kwambiri opangidwa pamlingo waukulu;kachulukidwe kawo ndi kochepa kwambiri moti amayandama.Chachitatu, ma polyolefin amapewa kuwonongeka ndi madzi, mpweya, mafuta, zosungunulira zosungunulira—zinthu zonse zomwe ma polimawa amatha kukumana nawo akagwiritsidwa ntchito.Pomaliza, ndizosavuta kuzipanga kukhala zinthu, pomwe zimakhala zolimba kotero kuti zoyikapo sizingasokonezeke m'galimoto yobweretsera itakhala padzuwa tsiku lonse.
Komabe, zida izi zili ndi zovuta zake.Amawononga pang'onopang'ono, kutanthauza kuti ma polyolefin adzakhala ndi moyo m'chilengedwe kwa zaka zambiri mpaka zaka zambiri.Panthawiyi, mafunde ndi mphepo zimawawononga, n'kupanga tinthu ting'onoting'ono tomwe tingalowe m'thupi ndi nsomba ndi nyama, n'kuyamba kukwera m'zakudyazo n'kupita kwa ife.
Kubwezeretsanso ma polyolefin sikolunjika monga momwe munthu angafunira chifukwa chotolera ndi kuyeretsa.Oxygen ndi kutentha kumayambitsa kuwonongeka kwa unyolo panthawi yokonzanso, pamene chakudya ndi zinthu zina zimawononga polyolefin.Kupita patsogolo kwa chemistry kwapanga ma polyolefin atsopano okhala ndi mphamvu komanso kulimba, koma izi sizingagwirizane nthawi zonse ndi magiredi ena panthawi yobwezeretsanso.Kuphatikiza apo, ma polyolefin nthawi zambiri amaphatikizidwa ndi zida zina muzopaka zamitundu yambiri.Ngakhale ma multilayer awa akugwira ntchito bwino, ndizosatheka kukonzanso.
Nthawi zina ma polima amatsutsidwa chifukwa chopangidwa kuchokera kumafuta osowa kwambiri komanso gasi.Komabe, kachigawo kakang'ono ka gasi kapena mafuta achilengedwe kamene kamagwiritsidwa ntchito popanga ma polima ndi ochepa kwambiri;Ochepera 5% amafuta kapena gasi omwe amapangidwa chaka chilichonse amagwiritsidwa ntchito kupanga mapulasitiki.Komanso, ethylene ikhoza kupangidwa kuchokera ku nzimbe ethanol, monga momwe amachitira malonda ndi Braskem ku Brazil.
MMENE PLASTIC AMAGWIRITSA NTCHITO
Kutengera dera, zonyamula zimadya 35% mpaka 45% ya polima yopangidwa yonse, pomwe ma polyolefins amalamulira.Polyethylene terephthalate, poliyesitala, imayang'anira msika wamabotolo a zakumwa ndi ulusi wa nsalu.
Kumanga ndi kumanga kumadya 20% ya ma polima onse opangidwa, pomwe chitoliro cha PVC ndi msuwani wake wamankhwala amalamulira.Mapaipi a PVC ndi opepuka, amatha kumamatidwa m'malo mogulitsidwa kapena kuwotcherera, ndipo amakana kwambiri kuwononga kwa chlorine m'madzi.Tsoka ilo, maatomu a klorini omwe amapereka PVC mwayiwu amapangitsa kuti zikhale zovuta kuzikonzanso-zambiri zimatayidwa kumapeto kwa moyo.
Ma polyurethanes, banja lonse la ma polima ogwirizana, amagwiritsidwa ntchito kwambiri pakutchinjiriza thovu m'nyumba ndi zida zamagetsi, komanso zokutira zomanga.
Gawo lamagalimoto limagwiritsa ntchito kuchuluka kwa ma thermoplastics, makamaka kuti achepetse kunenepa kuti akwaniritse bwino kwambiri mafuta.European Union ikuyerekeza kuti 16% ya kulemera kwa galimoto wamba ndi zida zapulasitiki, makamaka zamkati ndi zida.
Oposa matani 70 miliyoni a thermoplastics pachaka amagwiritsidwa ntchito mu nsalu, makamaka zovala ndi carpeting.Zoposa 90% za ulusi wopangidwa, makamaka polyethylene terephthalate, amapangidwa ku Asia.Kukula kwa ulusi wopangira zovala mu zovala kwabwera chifukwa cha ulusi wachilengedwe monga thonje ndi ubweya, zomwe zimafunikira minda yambiri kuti ipangidwe.Makampani opanga ma fiber awona kukula kwakukulu kwa zovala ndi carpeting, chifukwa cha chidwi ndi zinthu zapadera monga kutambasula, kupukuta chinyezi, komanso kupuma.
Monga momwe zimakhalira pakuyika, nsalu sizimasinthidwanso.Nzika wamba yaku US imatulutsa zinyalala zokwana mapaundi 90 chaka chilichonse.Malinga ndi Greenpeace, munthu wamba mu 2016 adagula zovala zochulukirapo 60% chaka chilichonse kuposa momwe munthu wamba amachitira zaka 15 m'mbuyomu, ndipo amasunga zovalazo kwakanthawi kochepa.
Nthawi yotumiza: Jul-03-2023