Kev Ua Kom Muaj Polymerization
Pendahuluuan
Cov polymers yog cov tshuaj sib xyaw ua ke uas muaj cov molecule loj, ntev uas ua los ntawm cov units rov ua dua hu ua monomers. Polymerization yog cov txheej txheem tshuaj uas cov monomers no sib xyaw ua ke los ua cov polymers. Cov txheej txheem no tseem ceeb heev hauv kev lag luam tshuaj lom neeg thiab pab txhawb rau kev tsim ntau yam khoom siv muaj nqis, suav nrog cov yas, roj hmab, thiab cov xov hluavtaws.
Tsab xov xwm no lub hom phiaj yog piav qhia txog cov txheej txheem, hom, thiab kev siv ntawm cov tshuaj tiv thaiv polymerization. Cov txheej txheem polymerization tuaj yeem tshwm sim los ntawm ntau yam txheej txheem, nrog rau ob pawg tseem ceeb: kev ntxiv polymerization thiab condensation polymerization.
Hom Kev Ua Polymerization
Kev Ntxiv Polymerization
Kev sib ntxiv polymerization yog ib qho txheej txheem uas cov monomers nrog ob lossis peb lub bonds sib xyaw ua ke los tsim cov polymer yam tsis tsim cov khoom seem. Cov polymers tsim los ntawm hom polymerization no hu ua cov polymers ntxiv.
Cov Kauj Ruam:
1. Kev Pib: Qhov kev ua tshuaj pib thaum tus neeg pib tsim cov free radicals, ions, lossis catalysts uas tuaj yeem rhuav tshem ob daim ntawv cog lus hauv monomers.
2. Kev nthuav dav: Cov free radicals lossis ions tsim tawm tsam nrog cov monomers, tsim cov kawg tshiab uas tuaj yeem tawm tsam nrog lwm cov monomers.
3. Kev xaus: Qhov kev ua haujlwm nres thaum ob lub free radicals sib ntsib thiab tsim ib daim ntawv cog lus sib koom ua ke, lossis thaum qee yam mechanism txwv tsis pub nthuav dav.
Piv txwv:
– Poly(ethylene): Ethylene monomer (C2H4) reacts los ntawm ib txoj saw ntawm cov free radicals los tsim poly(ethylene).
– Poly(vinyl chloride) (PVC): Vinyl chloride monomers (C2H3Cl) raug koom ua ke los ntawm kev pib, kev nthuav dav, thiab kev xaus.
Kev sib xyaw ua ke ntawm cov kua dej
Kev sib xyaw ua ke ntawm cov polymerization suav nrog cov monomers uas muaj tsawg kawg yog ob pawg ua haujlwm reactive thiab tsim cov polymer nrog cov khoom tsim tawm, xws li dej lossis methanol.
Cov Kauj Ruam:
1. Kev pib: Cov monomers uas muaj cov pab pawg ua haujlwm reactive sib xyaw ua ke.
2. Kev Tsim: Kev tsim cov kev sib txuas ntawm cov monomers, nrog rau kev tso tawm cov molecules teeb, xws li H2O lossis HCl.
3. Kev Loj Hlob ntawm Cov Saw: Cov txheej txheem no txuas ntxiv mus txog thaum cov monomers tag lossis cov xwm txheej ntawm cov tshuaj tiv thaiv tsis zoo lawm.
Piv txwv:
– Nylon-6,6: Ua los ntawm kev sib xyaw ntawm hexamethylenediamine thiab adipic acid, uas tsim cov dej ua cov khoom seem.
– Polyester: Tsim los ntawm kev sib xyaw ntawm terephthalic acid thiab ethylene glycol, nrog dej ua cov khoom seem.
Txoj Kev Ua Kom Polymerization
Kev Ua Polymerization Dawb Radical
Kev ua kom cov dawb radical polymerization yog ib qho ntawm cov txheej txheem polymerization feem ntau. Cov txheej txheem no pib nrog kev tsim cov dawb radicals uas muaj zog heev, feem ntau yog los ntawm thermal lossis photoinitiation.
1. Kev Pib: Cov tshuaj pib xws li benzoyl peroxide lossis azobisisobutyronitrile (AIBN) raug rhuav tshem kom tsim cov free radicals.
\[ \text{(Note, AIBN) → 2 \cdot (Radical, )} \]
2. Kev nthuav dav: Cov free radicals ua rau cov monomers tsim cov monomer radicals ntev:
\[ \text{(Radical + Monomer) → (R-Polymer)} \]
3. Kev Txiav: Ob lub free radicals sib xyaw ua ke los tsim ib lub molecule uas tsis yog radical thiab nres qhov kev sib txuas ntawm cov saw hlau:
\[ \text{(R + R ) → Tsis Muaj Kev Hloov Pauv Siab} \]
Ionic Polymerization
Qhov polymerization no cuam tshuam nrog kev tsim cov ions (cations lossis anions) ua cov hom tshuaj reactive. Ionic polymerization kuj tseem tuaj yeem faib ua ob hom tseem ceeb, uas yog:
– Kev Ua Polymerization ntawm Cationic: Yuav siv cov cationic ua tus pib. Feem ntau siv nrog cov monomers uas muaj cov pab pawg pub electron xws li isobutylene.
– Anionic Polymerization: Muaj cov ions uas muaj nqi tsis zoo (anions) ua cov pib. Siv rau ntawm cov monomers uas muaj cov pab pawg txais hluav taws xob xws li styrene.
Kev sib koom tes polymerization
Hom polymerization no yog mediated los ntawm kev hloov pauv hlau complex catalysts, piv txwv li Ziegler-Natta polymerization siv los ua stereo-regular polyethylene thiab polypropylene.
1. Cov tshuaj catalysts: Cov hlau hloov pauv xws li titanium chloride yog siv ua ke nrog cov khoom sib xyaw organometallic xws li txhuas triethyl (AlEt3).
2. Kev Ua Tshwm Sim: Cov Monomers sib xyaw ua ke ntawm qhov chaw nquag ntawm cov hlau sib xyaw.
Cov Ntawv Thov Polymerization
Kev Lag Luam Yas
Cov yas yog cov khoom polymer uas paub zoo tshaj plaws thiab siv dav tshaj plaws. Lawv yog ua los ntawm kev ntxiv thiab cov txheej txheem polymerization condensation. Piv txwv ntawm cov khoom yas polymerization feem ntau suav nrog polyethylene, polypropylene, PVC, thiab PET (polyethylene terephthalate). Cov yas yog siv rau hauv kev tsim cov ntim khoom, cov khoom ua si, cov kav dej, thiab ntau yam khoom siv rau cov neeg siv khoom.
Cov Khoom Siv Fiber
Cov xov paj rwb ua los ntawm cov khoom siv hluavtaws xws li nylon thiab polyester yog qhov tshwm sim ntawm kev sib xyaw ua ke ntawm cov dej noo. Lawv siv rau hauv kev tsim cov ntaub, khaub ncaws, thiab cov khoom siv hauv tsev xws li cov ntaub pua plag thiab hlua. Cov xov paj rwb feem ntau raug xaiv rau lawv lub zog, kev tiv taus kev sib txhuam, thiab kev ywj pheej.
Roj Hmab Ua Los Ntawm Khoom Siv
Cov roj hmab ua los ntawm cov khoom siv hluavtaws, xws li polybutadiene thiab styrene-butadiene (SBR), yog cov khoom ntawm kev sib ntxiv ntawm cov monomers uas muaj diene. Cov roj hmab no yog siv rau hauv kev tsim cov log tsheb, cov foob, thiab ntau yam kev siv hauv kev lag luam vim lawv tiv taus kev puas tsuaj thiab kev hloov pauv.
Cov Epoxy Resins thiab Cov Polymers Thermosetting
Cov epoxy resins yog qhov tshwm sim ntawm kev sib xyaw ua ke ntawm cov dej noo uas tshwm sim ntawm chav tsev kub lossis nrog cua sov. Lawv siv rau hauv cov nplaum, xim, thiab cov ntaub ntawv sib xyaw uas xav tau kev tiv thaiv cua sov thiab tshuaj lom neeg. Cov thermosetting polymers no tsis tuaj yeem yaj dua tom qab kho, tsis zoo li thermoplastic polymers.
Kev kho mob biomedical
Cov polymers siv rau hauv kev siv biomedical suav nrog polylactide (PLA) thiab poly(tetrahydrofurane) (PTHF), uas yog siv los tsim cov khoom siv bioresorbable implant. Cov polymers no yog tsim los biodegradable hauv lub cev, txo qhov xav tau kev phais thib ob.
Cov Khoom Siv Hluav Taws Xob
Cov polymers hluav taws xob yog cov polymers uas hloov pauv cov duab nyob rau hauv kev cuam tshuam ntawm lub zog hluav taws xob, feem ntau siv rau hauv cov actuators thiab sensors. Piv txwv li suav nrog poly (3,4-ethylenedioxythiophene) (PEDOT), uas yog siv rau hauv cov khoom siv hluav taws xob xws li touchscreens.
Xaus
Cov tshuaj tiv thaiv polymerization yog cov txheej txheem tshuaj lom neeg tseem ceeb hauv kev lag luam tshuaj lom neeg niaj hnub no, uas yog txoj hauv kev rau ntau yam khoom thiab kev siv uas hloov peb lub neej txhua hnub. Los ntawm kev nkag siab txog cov txheej txheem thiab hom polymerization, nrog rau lawv cov kev siv, peb tuaj yeem tsim cov khoom siv tshiab nrog cov khoom zoo dua rau yav tom ntej. Kev ntxiv polymerization thiab condensation polymerization txhua tus ua lub luag haujlwm tshwj xeeb hauv kev tsim cov ntaub ntawv no, thiab kev tshawb fawb txuas ntxiv mus nrhiav cov hauv kev tshiab los ua kom zoo dua cov txheej txheem no thiab nrhiav cov ntawv thov tshiab rau polymers.
