Anthu akhala akugwiritsa ntchito zinthu zachilengedwe za polymeric monga nkhuni, zikopa ndi ubweya kuyambira chiyambi cha mbiri yakale, koma ma polima opangidwa adakhala otheka pambuyo pa chitukuko chaukadaulo wa labala m'zaka za m'ma 1800.Zoyamba zopanga polima za Ž, celluloid, zidapangidwa ndi John Wesley Hyatt mu 1869, kuchokera ku cellulose nitrate ndi camphor.Kupambana kwakukulu mu ma polima opangidwa ndi kupangidwa kwa Bakelite ndi Leo Hendrik Baekeland mu 1907. Ntchito ya Hermann Staudinger m'zaka za m'ma 1920 ikuwonetseratu chikhalidwe cha macromolecular cha maunyolo aatali a mayunitsi obwerezabwereza.1 Mawu oti 'polima' amachokera ku Chigriki, ndipo amatanthauza 'ambiri magawo'.Kukula kofulumira kwa makampani a polima kunayamba itangotsala pang'ono Nkhondo Yachiwiri Yapadziko Lonse, ndikukula kwa ma polima a acrylic, polystyrene, nayiloni, polyurethanes ndi kukhazikitsidwa kotsatira kwa polyethylene, polyethylene terephthalate, polypropylene ndi ma polima ena m'ma 1940 ndi 1950.Ngakhale kuti matani pafupifupi 1 miliyoni okha ndi omwe anapangidwa mu 1945, kupanga mapulasitiki ambiri kuposa zitsulo mu 1981, ndipo kusiyana kwakhala kukukulirakulirabe kuyambira pamenepo.
Ma polima oyera nthawi zambiri samakonzedwa okha.Amaphatikizidwa ndi zinthu zina, makamaka pogwiritsa ntchito makina osakanikirana kapena kusungunuka kwa dziko kuti apange ma pellets, ufa kapena akes kuti agwiritsidwe ntchito pokonzekera.Mankhwalawa angaphatikizepo Ž llers (kuchepetsa mtengo), zolimbitsa thupi, ma polima ena, ma colorant, ame retardants, stabilizer (kuteteza kuwonongeka kwa kuwala, kutentha kapena zinthu zina zachilengedwe) ndi zida zosiyanasiyana zopangira.
Ma polima opangidwa akhoza kugawidwa m'magulu awiri.Thermoplastics (ndi voliyumu yayikulu kwambiri) imatha kusungunuka ndi kutentha, kulimba ndi kuziziritsa ndi kusungunuka mobwerezabwereza.Mitundu yayikulu ndi polyethylene (PE), polypropylene(PP), polystyrene (PS), polyvinyl chloride (PVC), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET) ndi polyamide (PA, nayiloni).Ma thermosets amawumitsidwa ndi kugwiritsa ntchito kutentha ndi kukakamiza, chifukwa cha kuphatikizika, mwachitsanzo, kupanga maukonde okhazikika amitundu itatu.Sangafewetsedwe ndi kutentha kuti akonzenso.Bakelite, epoxies ndi polyurethanes ambiri ndi thermosets.
Chidule chapano chimangoperekedwa pakukonza ma thermoplastics.Ma thermoplastics amalonda amagawidwa malinga ndi momwe amagwirira ntchito ngati 'chinthu' (ntchito yotsika, monga PE, PP, PS ndi PVC), 'Engineering' (monga PC, nayiloni ndi PET) kapena 'pamwamba' (ntchito yapamwamba kwambiri, monga ma polima amadzimadzi a crystal (LCPs), polyphenylene sulphide (PPS) ndi polyetheretherketone (PEEK)).Kukula kwamphamvu komwe kumayembekezeredwa mu engineering ndi ma polima apamwamba sikunachitike.Kugwiritsa ntchito mapulasitiki kwakhala kukukulirakulira m'zaka makumi atatu zapitazi, koma makamaka m'gulu lazinthu.Pakadali pano, ma polima azinthu amafika ~ 88% ya voliyumu yopangidwa, mapulasitiki a engineering 3 ~ 12% ndipo apamwamba osakwana 1%.Ngakhale mitengo ya ma polima apamwamba pa kilogalamu ndiyokwera kwambiri kuposa ya ma polima azinthu, mtengo wawo wapadziko lonse pachuma udakali wochepa kwambiri.
Mapulasitiki amtengo wapatali amakhala ndi mphamvu zochepa komanso zowuma poyerekeza ndi zitsulo kapena zoumba, ndipo amakonda kuwonetsa kukwapula pansi pa mphamvu yogwiritsidwa ntchito.Amakhalanso ndi malire a kutentha pa ntchito yawo monga zolimba (zambiri zimasungunuka mu 100-250 ° C).Ma moduli olimba a mapulasitiki azinthu ndi ~ 1 GPa (poyerekeza ndi 210 GPa yachitsulo).Kusintha kwa Signi-Ž cant kumatha kutheka polumikizana ndi maunyolo a polima.Kwenikweni, ma carbon-carbon bonds ndi amphamvu kwambiri, ndipo polyethylene imodzi ya Ž lament yapangidwa ndi modulus modulus modulus modulus modulus modulus modulus.Kuwongolera kwakukulu kungapezeke mwa njira zapadera zopangira, mwachitsanzo extrusion ndi kujambula wotsatira pa kutentha kochepa.Pakutentha kotsika, maunyolo a polima amakhala ndi zoyenda pang'ono, ndipo mawonekedwe ake amakhalabe atatambasula.Zomwe zatulukira posachedwapa ndi chitukuko cha malo amodzi, zothandizira za metallocene zachititsa kuti ma polima apangidwe atsopano azitha kulamulira kamangidwe ka maselo ndi zinthu zabwino.
Kupanga kwa ma polima padziko lonse lapansi kudakwera3 kuchoka pa matani 27 miliyoni mu 1975 kufika ~ matani 200 miliyoni pachaka mu 2000 ndipo kukukulirakulirabe.Malinga ndi lipoti laposachedwa, katundu 4 wa zinthu zamapulasitiki ku USA mu 2000 zidakwana $330 biliyoni, ndipo mafakitale opangira zinthu zakumtunda adagulitsa $90 biliyoni, zomwe zidapangitsa kuti ndalama zonse zapachaka zikhale $420 biliyoni.Ntchito yonse inayerekezedwa kukhala 2 .4 miliyoni - pafupifupi 2% ya ogwira ntchito ku US.Kukula kwa mafakitale a polima ndi chifukwa cha kuphatikiza kwapadera kwa zinthu zapulasitiki, zomwe zimaphatikizapo kupangidwa kosavuta ndi kupanga, kachulukidwe kakang'ono, kukana dzimbiri, kutchinjiriza kwa magetsi ndi matenthedwe, komanso nthawi zambiri kukhazikika komanso kulimba pamtundu uliwonse.
Nthawi yotumiza: Feb-04-2018