Cov Lus Nug Piv Txwv & Kev Sib Tham Txog Hom Polymers
Ib qho polymer yog ib lub molecule loj uas muaj cov molecule me me hu ua monomers. Cov polymers siv rau ntau yam kev siv, txij li cov yas thiab roj hmab mus rau cov fibers hluavtaws thiab cov ntaub ntawv siv hauv kev tsim kho. Kev nkag siab txog cov polymers yog qhov tseem ceeb hauv chemistry, cov ntaub ntawv tshawb fawb, thiab ntau yam lag luam. Tsab xov xwm no yuav tham txog ntau qhov piv txwv ntawm cov teeb meem hais txog cov hom polymers thiab muab cov kev daws teeb meem tob rau cov teeb meem no.
Cov Lus Nug Piv Txwv thiab Kev Sib Tham
Lo lus nug thib 1:
Sau peb hom polymers raws li lawv qhov chaw pib thiab muab piv txwv rau txhua hom.
Kev Sib Tham:
1. Cov Khoom Siv Polymer Ntuj:
Cov polymers ntuj tsim yog cov polymers uas tshwm sim ntuj tsim nyob rau hauv ib puag ncig. Piv txwv ntawm cov polymers ntuj tsim suav nrog:
- Cellulose: Pom muaj nyob rau hauv cov phab ntsa cell ntawm cov nroj tsuag.
- Roj Hmab Ntuj: Tau los ntawm cov kua txiv ntawm tsob ntoo Hevea brasiliensis.
- Cov protein: Xws li collagen pom muaj nyob rau hauv daim tawv nqaij thiab cov nqaij sib txuas ntawm cov tsiaj.
2. Cov Khoom Siv Polymer Ua Los Ntawm:
Cov polymers ua los ntawm cov khoom siv hluavtaws yog cov polymers uas tib neeg tsim los ntawm cov txheej txheem tshuaj lom neeg. Piv txwv ntawm cov polymers ua los ntawm cov khoom siv hluavtaws suav nrog:
– Polyethylene (PE): Siv rau hauv kev tsim cov hnab yas.
– Polypropylene (PP): Siv rau hauv kev lag luam tsheb thiab ntim khoom noj.
– Polyvinyl Chloride (PVC): Siv rau hauv kev tsim cov kav dej thiab cov xov hlau.
3. Cov Polymers Semi-synthetic:
Cov polymers semi-synthetic yog cov kev hloov kho ntawm cov polymers ntuj tsim los txhim kho lawv cov yam ntxwv. Piv txwv ntawm cov polymers semi-synthetic suav nrog:
– Cellulose Acetate: Ua los ntawm cellulose uas tau hloov kho siv acetic acid, siv rau hauv zaj duab xis thaij duab.
- Nitrocellulose: Tau los ntawm nitration ntawm cellulose, siv rau hauv kev tsim cov khoom tawg thiab cov txheej txheem.
Lo lus nug thib 2:
Piav qhia qhov txawv ntawm thermoplastic thiab thermoset polymers, thiab muab ob qho piv txwv ntawm txhua yam.
Kev Sib Tham:
1. Cov Khoom Siv Thermoplastic (Thermoplastics):
Cov polymer no mos thaum raug cua sov thiab tawv thaum txias, thiab tuaj yeem ua cov txheej txheem no ntau zaus. Qhov no ua rau nws yooj yim rau kev rov ua dua tshiab. Piv txwv li:
– Polyethylene (PE): Siv rau hauv kev tsim cov hnab yas thiab lub raj mis.
– Polystyrene (PS): Siv rau hauv kev tsim cov ntaub ntawv rwb thaiv tsev thiab cov ntim khoom noj.
2. Cov Polymers Thermosetting (Thermosets):
Cov polymers no, thaum ua los ntawm kev cua sov thiab txias, tsis tuaj yeem yaj dua. Lawv muaj cov qauv ruaj khov thiab tsis tuaj yeem rov ua dua ib yam li cov thermoplastics. Piv txwv li:
– Bakelite: Pom muaj nyob rau hauv cov qhov hloov hluav taws xob thiab cov tes tuav ua noj.
- Epoxy: Siv rau hauv cov nplaum, cov tshuaj pleev xim, thiab cov khoom sib xyaw ua ke ntev.
Lo lus nug thib 3:
Piav qhia txog cov txheej txheem ntawm kev ntxiv polymerization thiab muab piv txwv ntawm cov polymers tsim los ntawm cov txheej txheem no.
Kev Sib Tham:
Kev ntxiv polymerization yog cov txheej txheem ntawm kev tsim cov polymers los ntawm kev sib xyaw ua ke uas cov monomers muaj cov ntawv cog lus ob npaug (feem ntau yog carbon-carbon ob npaug) sib xyaw ua ke yam tsis tsim cov khoom lag luam.
Cov theem ntxiv polymerization muaj xws li:
1. Kev Pib: Kev tsim cov free radicals lossis ions uas pib qhov kev tawm tsam.
2. Kev nthuav dav: Cov free radicals lossis ions ua rau cov monomers sib xyaw ua ke, ua rau cov saw polymer ntev dua.
3. Kev xaus: Qhov kev sib xyaw ua ke xaus thaum ob lub free radicals sib xyaw ua ke.
Piv txwv ntawm cov polymers ntxiv:
– Polyethylene (PE): Ua los ntawm ethylene monomer (C2H4).
– Polypropylene (PP): Ua los ntawm propylene monomer (C3H6).
Lo lus nug thib 4:
Lub ntsiab lus ntawm condensation polymerization yog dab tsi thiab muab ob qho piv txwv ntawm cov polymers tsim los ntawm cov txheej txheem no.
Kev Sib Tham:
Condensation polymerization yog ib qho txheej txheem polymerization uas cov monomers sib xyaw ua ke los ntawm kev tshem tawm cov molecules me me xws li dej lossis methanol.
Piv txwv ntawm cov condensation polymerization yog:
1. Kev Tsim Nylon:
Nylon 6,6 yog tsim los ntawm kev sib xyaw ntawm hexamethylenediamine thiab adipic acid, tsim cov dej ua cov khoom lag luam.
\[ \text{H}_2\text{N}-(\text{CH}_2)_6\text{NH}_2 + \text{HOOC}-(\text{CH}_2)_4\text{COOH} \rightarrow (-\text{NH}-(\text{CH}_2)_6\text{NH-CO}-(\text{CH_2)_4 \text{H}_2\text{O} \]
2. Kev Tsim Polyester:
Cov Polyesters xws li polyethylene terephthalate (PET) yog tsim los ntawm kev sib xyaw ntawm terephthalic acid thiab ethylene glycol, tsim cov dej ua cov khoom seem.
\[ \text{HOOC-}\text{C}_6\text{H}_4\text{COOH} + \text{HO-CH}_2\text{CH}_2\text{OH} \rightarrow (-\text{O-CH}_2\text{CH}_2-\text{OCO-}\text{C}_6\text{H}_4\text{H}_2\text{CO-})_n
Lo lus nug thib 5:
Yuav ua li cas thiaj hloov tau cov yam ntxwv ntawm cov polymers los ntawm kev siv cov plasticizers? Muab ib qho piv txwv.
Kev Sib Tham:
Cov tshuaj plasticizers yog cov khoom ntxiv rau cov polymers kom ua rau muaj kev ywj pheej, txo qhov brittleness, thiab txo qhov kub hloov iav (Tg). Cov tshuaj plasticizers ua haujlwm los ntawm kev txo lub zog ntawm cov bonds intermolecular hauv cov polymer, cia cov saw polymer txav mus los ntau dua thiab ua rau cov khoom siv plasticity ntau dua.
Piv txwv ntawm kev siv cov plasticizers:
– PVC thiab cov tshuaj yas: Hauv kev tsim cov xov hluav taws xob, PVC yog sib xyaw nrog cov tshuaj yas xws li phthalates kom nws yoog tau thiab ruaj khov dua.
– Cellulose acetate thiab cov plasticizers: Siv rau hauv kev tsim cov yeeb yaj kiab thiab lacquers kom cov khoom tsis nruj.
Xaus
Cov polymers yog cov khoom siv tau ntau yam uas ua lub luag haujlwm tseem ceeb hauv lub neej txhua hnub thiab thev naus laus zis niaj hnub. Los ntawm kev nkag siab txog cov hom polymer thiab cov txheej txheem polymerization, peb tuaj yeem tsim cov khoom siv tshiab nrog cov khoom zoo thiab txhim kho lawv cov ntawv thov hauv ntau qhov chaw. Kev kawm txog polymer pib nrog kev daws cov teeb meem no thiab nkag siab tob txog cov ntsiab cai tseem ceeb ntawm kev tshawb fawb polymer. Tsab xov xwm no lub hom phiaj yog muab kev nkag siab thawj zaug txog cov hom polymer thiab txhawb kom cov neeg nyeem txuas ntxiv kawm thiab tshawb nrhiav tob dua txog cov polymers thiab lawv cov ntawv thov.
