Qhov sib txawv tseem ceeb ntawm kev sib txuas ntawm cov khoom sib txuas polymer thiab cov kab hluav taws xob yog cov monomer units ntawm cov kab hluav taws xob cov kab hluav taws xob muaj qhov txuas kawg-rau-kawg, zoo li cov hlaws dai hauv ib lub caj dab, qhov sib txuas ntawm cov khoom sib txuas yog tsim los ntawm cov saw hlau uas txuas nrog. ua ke los ntawm cov nyiaj sib koom ua ke, hu ua cross-links.
Polymers yog cov tebchaw uas muaj cov me me rov ua dua tshiab txuas ua ke los tsim cov saw hlau ntev. Qhov rov ua dua los yog lub tsev thaiv ntawm cov polymer yog monomers. Polymers tuaj yeem muab faib ua peb ntu raws li lawv cov tshuaj thiab thermal xwm, uas yog; (a) thermoplastic polymers, (b) thermosetting polymers, thiab (c) elastomers. Thermoplastics yog cov yas uas tuaj yeem hloov cov duab raws li kev siv cua sov. Tsis zoo li cov thermoplastics, cov thermosets tsis tuaj yeem zam lub voj voog cua sov dua. Elastomers yog cov roj hmab uas muaj cov khoom elastic zoo, tsis zoo li ob hom uas tau hais los saum no. Raws li cov qauv, muaj peb hom polymers li linear, branched thiab cross linked polymers. Thermoplastic polymers yog linear molecules, whereas thermosets thiab elastomers yog cross linked polymers.
Cross Linked Polymer yog dab tsi?
Ib tug ntoo khaub lig txuas polymer yog ib tug polymer uas muaj chains txuas ua ke los ntawm lub network ntawm covalent bonds. Hla kev sib txuas tuaj yeem luv lossis ntev, tab sis feem ntau ntawm cov polymers, cov ntawv cog lus luv luv. Thermosets thiab elastomers muaj kev sib txuas. Cov khoom ntawm cross linked polymers feem ntau yog nyob ntawm qhov kev sib txuas ntawm kev sib txuas. Yuav kom paub meej, yog tias qib ntawm kev sib txuas ntawm qhov sib txuas qis qis, cov polymer yuav coj tus cwj pwm tsis sib xws ntawm cov polymer thiab qhia tus cwj pwm softening. Txawm li cas los xij, yog tias qhov kev sib txuas ntawm qhov sib txuas yog siab, qhov kev ua kom zoo ntawm cov polymer yuav nyuaj dua. Ib qho piv txwv zoo ntawm kev siv kev sib txuas los txhim kho cov khoom ntawm cov roj hmab yog cov txheej txheem vulcanization.
Daim duab 1: Hla-txuas polyisoprene (vulcanized natural rubber siv sulfur ua tus neeg sawv cev sib txuas)
Thaum lub sijhawm vulcanization, ntxiv cov vulcanization cov neeg ua haujlwm xws li sulfur, hlau oxides, thiab lwm yam, ua rau kev sib txuas ntawm cov roj hmab saw molecules. Thiab yog li, txhim kho lub zog tensile thiab hardness ntawm rubbers. Ntau cov khoom siv roj hmab tsim cov txheej txheem siv vulcanization. Tsis zoo li cov roj hmab, cov thermoset polymers xws li urea formaldehyde ua cov ntaub ntawv nyuaj thiab nkig thaum tus txheej txheem ntawm kev sib txuas. Qhov ntawd yog vim kev sib txuas sib txuas ua rau cov khoom siv tshuaj polymer, thiab cov tshuaj tiv thaiv no tsis tuaj yeem rov qab los. Tsis tas li ntawd, lub solubility parameter ntawm cross-linking polymers txawv nrog rau qhov sib txuas ntawm qhov ntom ntom. Yog hais tias ib tug polymer muaj ib tug tsawg degree ntawm cross-linking, nws yuav nyiam o nyob rau hauv cov kua.
Dab tsi yog Linear Polymer?
Ib kab hluav taws xob yog cov thermoplastic polymer uas muaj cov saw ntev ntev. Ntawm no, cov chav nyob monomer muaj qhov kawg-rau-kawg txuas, zoo li cov hlaws dai hauv caj dab. Polyethylene yog ib qho piv txwv ntawm linear polymer uas ethylene units ua raws li monomers. Qee lub sij hawm cov kab sib txuas no muaj cov qauv tsim. Feem ntau, linear thiab branched-chain lug ntawm tib lub polymer muaj cov khoom zoo sib xws.
Daim duab 02: Polyethylene
Vim lawv yog cov thermoplastics, cua sov tuaj yeem ua rau cov kab hluav taws xob zoo. Lub softening kub yog ib tug tshwj xeeb feature ntawm linear polymers. Lub softening kub ntawm cov roj hmab los yog cov kua viscous yog nyob rau hauv chav tsev kub, whereas cov tawv, brittle solids los yog ductile solids yog siab tshaj chav tsev kub. Ntxiv mus, ib tug linear polymer yog ib tug thermoplastic polymer uas muaj cov saw ntev molecules. Ntawm no, cov monomer units muaj qhov kawg-rau-kawg txuas, zoo li cov hlaws dai hauv caj dab.
Polyethylene yog ib qho piv txwv ntawm cov kab hluav taws xob uas muaj cov ethylene ua cov monomers. Qee lub sij hawm cov kab sib txuas no muaj cov qauv sib txawv. Feem ntau, linear thiab branched-chain lug ntawm tib lub polymer muaj cov khoom zoo sib xws.
Qhov txawv ntawm Cross Linked Polymer thiab Linear Polymer yog dab tsi?
Cross Linked Polymer vs Linear Polymer |
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| Cross linked polymer yog tsim los ntawm cov saw hlau uas tau koom ua ke los ntawm cov nyiaj sib koom ua ke. | Linear polymer yog tsim los ntawm monomers koom ua ke kawg-rau-kawg, zoo li cov hlaws dai hauv caj dab. |
| Thermoplastics | |
| Thermosets thiab elastomers | |
| cua sov ntawm Polymers | |
| Tsis tuaj yeem rov ua cua sov dua | Cam ua kom rov ua cua sov dua |
| Recyclability | |
| Tsis tuaj yeem rov ua dua (tsis tuaj yeem rov ua dua) | Cov khoom siv rov ua dua tshiab (tuaj yeem rov ua dua / rov ua dua) |
| Hom Bond Ntawm Molecular Chain | |
| Pib daim ntawv cog lus ruaj khov | Daim ntawv cog lus ib ntus ntu |
| Examples | |
| phenol-formaldehyde, polyurethanes, silicones, roj hmab ntuj, butyl roj hmab, chloroprene roj hmab | acetals, acrylics, acrylonitrile-butadiene-styrene (ABS), polyamides, polycarbonate, polyethylene |
Summary – Hla Linked Polymer vs Linear Polymer
Hauv luv luv, muaj ob pawg ntawm cov polymers raws li lawv cov qauv: linear polymers thiab cross linked polymers. Cov monomers ntawm linear polymers muaj qhov kawg-rau-kawg txuas, zoo li cov hlaws dai ntawm caj dab. Yog li ntawd, tag nrho cov thermoplastics yog cov linear polymers thiab tsis muaj kev sib txuas mus tas li ntawm cov saw hlau polymer. Txawm li cas los xij, crosslinked polymers muaj kev ruaj khov ntawm cov saw hlau uas nyob ib sab. Tag nrho cov elastomers thiab cov thermosets yog cov sib txuas sib txuas polymers. Yog li, qhov no yog qhov sib txawv ntawm cross linked polymer thiab linear polymer.
