Kuchitapo kanthu kwa polymerization
Pendauluan
Ma polima ndi mankhwala opangidwa ndi mamolekyu akuluakulu, aatali opangidwa ndi mayunitsi obwerezabwereza otchedwa ma monomers. Kupolima ndi njira ya mankhwala yomwe ma monomers awa amaphatikizidwira kupanga ma polima. Njirayi ndi yofunika kwambiri mumakampani opanga mankhwala ndipo imathandizira kupanga zinthu zosiyanasiyana zamtengo wapatali, kuphatikizapo mapulasitiki, rabala, ndi ulusi wopangidwa.
Nkhaniyi ikufuna kufotokoza njira, mitundu, ndi momwe zinthu zimagwiritsidwira ntchito polima. Njira zomangira polima zimatha kuchitika kudzera m'njira zosiyanasiyana, ndi magulu awiri akuluakulu: kuwonjezera polima ndi polima ya condensation.
Mitundu ya Polymerization
Kuwonjezera Polima
Kuonjezera polymerization ndi njira yomwe ma monomers okhala ndi ma bond awiri kapena atatu amachitapo kanthu kuti apange polima popanda kupanga zinthu zina. Ma polima opangidwa ndi mtundu uwu wa polymerization amatchedwa ma polima owonjezera.
Langkah-langkah:
1. Kuyambitsa: Kuchitapo kanthu kumayamba pamene woyambitsa amapanga ma free radicals, ma ion, kapena ma catalyst omwe amatha kuswa maubwenzi awiri mu ma monomers.
2. Kufalikira: Ma free radicals kapena ma ion opangidwa amakumana ndi ma monomers, ndikupanga malekezero atsopano omwe amatha kuchitapo kanthu ndi ma monomers ena.
3. Kutha: Kuchitapo kanthu kumasiya pamene ma free radical awiri akumana ndikupanga mgwirizano wa covalent, kapena pamene njira ina imasiya kufalikira.
Chitsanzo:
– Poly(ethylene): Ethylene monomer (C2H4) imachitapo kanthu kudzera mu unyolo wa ma free radicals kuti ipange poly(ethylene).
– Poly(vinyl chloride) (PVC): Vinyl chloride monomers (C2H3Cl) amalumikizidwa kudzera mu kuyambitsa, kufalitsa, ndi kutha.
Kupopera kwa Manyowa
Kupopera kwa madzi kumaphatikizapo ma monomers omwe ali ndi magulu awiri ogwira ntchito omwe amagwira ntchito ndipo amapanga polima yokhala ndi zotsatira za chinthu china, monga madzi kapena methanol.
Langkah-langkah:
1. Kuyambitsa: Ma monomers omwe ali ndi magulu ogwira ntchito omwe amachita zinthu mosiyanasiyana amakumana.
2. Kupanga: Kupanga ma bond pakati pa ma monomers, limodzi ndi kutulutsidwa kwa mamolekyulu owala, monga H2O kapena HCl.
3. Kukula kwa Unyolo: Njirayi imapitirira mpaka ma monomers atatha kapena momwe zinthu zimachitikira sizilinso bwino.
Chitsanzo:
– Nayiloni-6,6: Yopangidwa kuchokera ku momwe hexamethylenediamine imagwirira ntchito ndi adipic acid, yomwe imapanga madzi ngati chinthu china.
– Polyester: Yopangidwa kuchokera ku mgwirizano pakati pa terephthalic acid ndi ethylene glycol, ndi madzi ngati chinthu china.
Njira Yopangira Polima
Kupopera Kwaulere Kwambiri
Kupoletsa kwa ma free radical ndi njira imodzi yodziwika bwino yopoletsa ma free radical. Njirayi imayamba ndi kupanga ma free radicals omwe amagwira ntchito kwambiri, nthawi zambiri kudzera mu kutentha kapena kuwala kwa dzuwa.
1. Kuyambitsa: Mamolekyu oyambitsa monga benzoyl peroxide kapena azobisisobutyronitrile (AIBN) amagawidwa kuti apange ma free radicals.
\[ \text{(Note, AIBN) → 2 \cdot (Radical, )} \]
2. Kufalikira: Ma free radicals amachitapo kanthu ndi ma monomer kuti apange ma extended monomer radicals:
\[ \text{(Radical + Monomer) → (R-Polymer)} \]
3. Kutha: Ma free radical awiri amaphatikizana kupanga molekyulu yosasinthika ndikuyimitsa kayendedwe ka unyolo:
\[ \text{(R + R ) → Yopanda Mphamvu Kwambiri} \]
Kuponda kwa Ionic
Kupolima kumeneku kumaphatikizapo kupangidwa kwa ma ayoni (cations kapena anions) ngati mitundu yosinthika. Kupolima kwa ma ayoni kungagawidwenso m'mitundu iwiri ikuluikulu, yomwe ndi:
– Cationic Polymerization: Imagwiritsa ntchito mtundu wa cationic ngati choyambitsa. Nthawi zambiri imagwiritsidwa ntchito ndi ma monomers omwe ali ndi magulu opereka ma electron monga isobutylene.
– Anionic Polymerization: Imagwiritsa ntchito ma ayoni omwe ali ndi mphamvu yoipa (anions) ngati oyambitsa. Imagwiritsidwa ntchito pa ma monomers omwe ali ndi magulu olandirira ma elekitironi monga styrene.
Kugwirizanitsa Polima
Mtundu uwu wa polymerization umayendetsedwa ndi transition metal complex catalysts, chitsanzo chake ndi polymerization ya Ziegler-Natta yomwe imagwiritsidwa ntchito popanga stereo-regular polyethylene ndi polypropylene.
1. Zothandizira: Zitsulo zosinthira monga titanium chloride zimagwiritsidwa ntchito limodzi ndi zinthu za organometallic monga aluminium triethyl (AlEt3).
2. Kuyankha: Ma monomers amasakanikirana pamalo ogwirira ntchito a chitsulo.
Mapulogalamu Opangira Polima
Makampani Opanga Mapulasitiki
Mapulasitiki ndi zinthu zodziwika bwino komanso zomwe zimagwiritsidwa ntchito kwambiri ndi ma polima. Amapangidwa kudzera mu njira zowonjezera ndi zokometsera ma polymer. Zitsanzo za zinthu zodziwika bwino za pulasitiki monga polyethylene, polypropylene, PVC, ndi PET (polyethylene terephthalate). Mapulasitiki amagwiritsidwa ntchito popanga ma paketi, zoseweretsa, mapaipi, ndi zinthu zina zosiyanasiyana zogwiritsidwa ntchito ndi anthu.
Zipangizo za Ulusi
Ulusi wopangidwa monga nayiloni ndi polyester ndi zotsatira za condensation polymerization. Umagwiritsidwa ntchito popanga nsalu, zovala, ndi zinthu zapakhomo monga makapeti ndi chingwe. Ulusi nthawi zambiri umasankhidwa chifukwa cha mphamvu zake, kukana kukwawa, komanso kusinthasintha.
Mphira Wopangidwa
Ma rabala opangidwa, monga polybutadiene ndi styrene-butadiene (SBR), ndi zinthu zopangidwa ndi polymerization yowonjezera ya ma monomers okhala ndi diene. Ma rabala awa amagwiritsidwa ntchito popanga matayala a magalimoto, zisindikizo, ndi ntchito zosiyanasiyana zamafakitale chifukwa cha kukana kwawo kuvulala ndi kusinthika.
Ma Resin a Epoxy ndi Ma Polima Opoletsa Kutentha
Ma resini a epoxy ndi zotsatira za condensation polymerization yomwe imachitika kutentha kwa chipinda kapena kutentha. Amagwiritsidwa ntchito mu zomatira, utoto, ndi zinthu zophatikizika zomwe zimafuna kukana kutentha ndi mankhwala. Ma polima otenthetsera kutentha awa sangasungunukenso atasungunuka, mosiyana ndi ma polima a thermoplastic.
Biomedics
Ma polima omwe amagwiritsidwa ntchito mu ntchito zachipatala ndi monga polylactide (PLA) ndi poly(tetrahydrofurane) (PTHF), zomwe zimagwiritsidwa ntchito popanga zinthu zobzalidwa zomwe zimatha kubzalidwa m'thupi. Ma polima awa amapangidwira kuti awonongeke m'thupi, zomwe zimachepetsa kufunika kochitidwa opaleshoni kachiwiri.
Zipangizo zamagetsi
Ma polima amagetsi ndi ma polima omwe amasintha mawonekedwe awo motsogozedwa ndi mphamvu yamagetsi, omwe nthawi zambiri amagwiritsidwa ntchito mu ma actuator ndi masensa. Zitsanzo zikuphatikizapo poly(3,4-ethylenedioxythiophene) (PEDOT), yomwe imagwiritsidwa ntchito muzipangizo zamagetsi monga ma touchscreen.
Mapeto
Machitidwe a polymerization ndi njira zofunika kwambiri zamakemikolo m'makampani amakono a mankhwala, zomwe zimatsegula njira ya zinthu zosiyanasiyana ndi ntchito zomwe zimasintha miyoyo yathu ya tsiku ndi tsiku. Pomvetsetsa njira ndi mitundu ya polymerization, komanso momwe amagwiritsidwira ntchito, titha kupanga zinthu zatsopano zokhala ndi zinthu zowonjezera zosowa zamtsogolo. Kuphatikiza polymerization ndi polymerization ya condensation iliyonse imachita gawo lapadera pakupanga zinthuzi, ndipo sayansi ikupitilizabe kupita patsogolo kuti ipeze njira zatsopano zowongolera njirazi ndikupeza ntchito zatsopano zama polima.
