Cov Txheej Txheem Tsim Khoom Siv Polyethylene thiab Nws Daim Ntawv Thov Hauv Cov Kav Dej
Polyethylene (PE) yog ib qho ntawm cov yas siv dav tshaj plaws thoob ntiaj teb vim nws muaj ntau yam siv tau, pheej yig, yooj yim ua, thiab tiv taus tshuaj lom neeg. Hauv lub neej txhua hnub, polyethylene muaj nyob rau hauv ntau hom: hnab khw, ntim khoom noj, lub raj mis, thiab txawm tias cov khoom siv engineering xws li cov kav dej rau dej huv, roj, thiab cov dej ntws. Tsab xov xwm no tham txog cov txheej txheem tsim polyethylene los ntawm cov khoom siv raw mus rau cov khoom tiav, thiab tom qab ntawd qhia txog vim li cas cov khoom siv no tseem ceeb heev hauv kev lag luam kav dej.
Kawm Paub Txog Polyethylene: Hom thiab Cov Yam Ntxwv Tseem Ceeb
Polyethylene yog ib qho polymer uas muaj ethylene monomers (C₂H₄). Thaum ethylene monomers raug polymerized, lawv cov bonds ob npaug tawg qhib, tsim cov saw ntev - (CH₂–CH₂) - uas tsim lub hauv paus ntawm polymer. Qhov sib txawv ntawm cov txheej txheem polymerization, catalysts, thiab cov xwm txheej ua haujlwm ua rau muaj kev hloov pauv ntawm cov qauv saw thiab qib ntawm kev sib cais, uas cuam tshuam rau cov khoom siv kho tshuab thiab kev siv.
Cov hom polyethylene feem ntau muaj xws li:
1. LDPE (Low-Density Polyethylene): muaj ntau ceg, yoog tau yooj yim dua, muaj qhov melting qis dua, siv dav rau cov yeeb yaj kiab/ntim khoom.
2. HDPE (High-Density Polyethylene): cov saw hlau ntau dua, muaj crystallinity siab, tawv dua thiab muaj zog dua, siv dav rau lub raj mis, cov kaus poom jerry thiab cov kav dej.
3. LLDPE (Linear Low-Density Polyethylene): linear nrog cov ceg luv luv, muaj zog rau cov yeeb yaj kiab thiab cov ntawv thov uas xav tau kev tiv thaiv kua muag.
4. PE-RT (Polyethylene of Raised Temperature Resistance): tsim los rau kev tiv taus kub zoo dua, feem ntau siv rau hauv qee lub tshuab dej kub.
5. PE100/PE80 (qib rau cov kav dej): kev faib tawm cov khoom siv yeeb nkab raws li lub zog ntev (MRS) thiab kev ua tau zoo; PE100 feem ntau zoo dua hauv lub zog thiab kev ua haujlwm ntawm phab ntsa.
Rau cov ntawv thov yeeb nkab, qhov tseem ceeb tshaj plaws yog HDPE thiab cov yeeb nkab qib xws li PE80 lossis PE100 vim lawv tiv taus siab, ruaj khov tshuaj lom neeg, thiab lub neej ua haujlwm ntev.
Cov Khoom Siv Raw: Los ntawm Roj lossis Roj mus rau Ethylene
Hauv kev lag luam, ethylene ua cov khoom siv tseem ceeb rau polyethylene feem ntau yog los ntawm:
- Roj av (naphtha) los yog
- Cov roj av (ethane/propane)
Cov txheej txheem feem ntau rau kev tsim cov ethylene yog kev tawg ua npuas dej. Hauv cov txheej txheem no, naphtha lossis ethane raug cua sov rau qhov kub siab (kwv yees li 750–900 ° C) rau lub sijhawm luv luv hauv lub cub tawg nrog cov pa. Lub hom phiaj yog rhuav cov hydrocarbon molecules ua cov me dua, suav nrog ethylene, propylene, thiab lwm yam sib xyaw.
Tom qab tawg lawm, cov khoom sib tov yuav txias sai sai (quenched) kom tsis txhob muaj kev cuam tshuam ntxiv. Tom qab ntawd, nws raug cais los ntawm kev siv kev nias, kev txias, thiab kev sib cais ua feem kom tau txais cov ethylene uas muaj cov khoom ntshiab heev. Cov ethylene no mam li nkag mus rau hauv chav polymerization.
Cov Txheej Txheem Polymerization: Tsim Cov Polyethylene Chains
Cov txheej txheem ntawm kev ua polyethylene yog qhov tseem ceeb ntawm polymerization ntawm ethylene. Feem ntau, muaj peb txoj hauv kev tseem ceeb uas tau lees paub dav dav:
1. Kev Hloov Pauv Hloov Pauv (Feem ntau rau LDPE)
LDPE feem ntau yog ua los ntawm cov txheej txheem polymerization siab siv cov radical initiators. Lub siab tuaj yeem siab heev (txog li ntau txhiab bars) thiab qhov kub tuaj yeem siab heev. Cov xwm txheej hnyav no txhawb kom muaj kev sib txuas ntawm cov saw polymer, ua rau muaj qhov ceev qis dua thiab muaj kev ywj pheej ntau dua.
2. Kev Siv Tshuaj Polymerization Siv Catalyst (HDPE thiab LLDPE)
Rau HDPE thiab LLDPE, kev lag luam siv ntau yam catalysts xws li:
– Ziegler–Natta
- Phillips catalyst (chromium)
- Metallocene (niaj hnub dua, kev tswj hwm cov qauv meej dua)
Cov txheej txheem tuaj yeem tshwm sim ntawm qhov siab qis dua LDPE thiab tuaj yeem ua tiav hauv ntau hom reactors:
- Cov txheej txheem slurry (polymer ncua hauv cov kuab tshuaj)
- Cov txheej txheem roj-theem (kev ua haujlwm hauv theem roj, uas feem ntau siv rau kev tsim khoom loj)
- Cov txheej txheem daws teeb meem (polymer yaj hauv cov kuab tshuaj ntawm qee qhov kub)
Cov txheej txheem xaiv yog txiav txim siab los ntawm cov hom phiaj khoom: qhov ceev, qhov hnyav ntawm cov molecular faib, kev tiv thaiv tawg, thiab yooj yim ntawm kev ua ntxiv.
Theem Tom Qab Polymerization: Los ntawm Hmoov rau Pellets
Cov khoom ntawm lub tshuab polymerization feem ntau yog hmoov lossis cov granules loj. Ua ntej ua cov khoom kawg, cov khoom siv yuav tsum dhau los ntawm ntau theem tseem ceeb:
1. Kev sib cais thiab kev ntxuav
Cov monomers seem, cov kuab tshuaj, lossis cov catalysts yuav tsum tau tshem tawm lossis txo kom txog rau qib uas muaj kev nyab xeeb. Qhov no cuam tshuam rau qhov zoo ntawm cov khoom, tsw, thiab kev ruaj khov.
2. Ntxiv cov khoom ntxiv (kev sib xyaw)
Cov polyethylene ntshiab tsis tshua siv yam tsis muaj cov khoom ntxiv. Rau kev siv cov yeeb nkab, cov khoom ntxiv feem ntau suav nrog:
- Cov tshuaj antioxidants: tiv thaiv kev puas tsuaj thaum lub sijhawm ua thiab siv mus sij hawm ntev.
– UV stabilizer / carbon dub: tseem ceeb rau cov kav dej sab nraum zoov kom tiv taus lub hnub ci.
- Kev pab ua tiav: pab kom ruaj khov cov dej ntws thaum lub sijhawm extrusion.
– Cov xim: piv txwv li kab xiav rau dej huv, kab daj rau roj (nyob ntawm tus qauv/lub teb chaws).
3. Kev rho tawm thiab pelletizing
Cov khoom siv no raug yaj hauv lub tshuab extruder, sib xyaw ua ke nrog cov khoom ntxiv, thiab tom qab ntawd txiav ua cov pellets. Cov pellets no ces raug xa mus rau cov chaw tsim khoom uas tsim cov khoom xws li cov kav dej.
Kev Tsim Yeeb Nkab Polyethylene: Cov Txheej Txheem Extrusion Yeeb Nkab
Cov kav dej polyethylene feem ntau yog tsim los ntawm kev rho cov kav dej tawm. Cov kauj ruam tseem ceeb suav nrog:
1. Pub cov pellets rau lub hopper
PE pellets nkag mus rau hauv extruder tas li.
2. Yaj thiab sib tov hauv lub extruder
Lub tshuab extruder ntsia hlau ua kom sov thiab yuam cov khoom kom yaj ua homogeneous. Kev tswj qhov kub thiab txias yog qhov tseem ceeb kom tiv thaiv kev puas tsuaj los ntawm cua sov.
3. Kev tsim cov yeeb nkab hauv lub pwm (pwm)
Cov yaj tawm los ntawm lub pwm zoo li lub nplhaib los ua ib lub raj.
4. Kev kho thiab txias
Cov yeeb nkab uas tseem mos dhau los ntawm chav ntsuas (feem ntau siv lub tshuab nqus tsev) kom tswj tau qhov loj thiab qhov tuab ntawm phab ntsa kom raws li cov lus qhia. Tom qab ntawd cov yeeb nkab raug txias nrog dej.
5. Thauj thiab txiav
Lub tshuab rub tawm rub lub yeeb nkab nrog qhov ceev ruaj khov. Lub yeeb nkab raug txiav kom ntev lossis dov (rau cov kab uas me me).
6. Kev cim thiab kev tshuaj xyuas
Cov kav dej muaj cov cim hauv qab no: hom, txoj kab uas hla, SDR, qib siab, tus qauv, thiab hnub tsim khoom. Tom qab ntawd, kev tshuaj xyuas qhov ntev thiab kev ntsuam xyuas zoo tshwj xeeb raug ua tiav.
Vim li cas Polyethylene Zoo Tshaj Plaws rau Cov Kav Dej?
Cov yeeb nkab siv yuav tsum muaj ntau yam khoom sib xyaw ua ke uas lwm cov khoom siv tsis yooj yim ntsib. Polyethylene, tshwj xeeb yog HDPE/PE100, nrov vim tias:
1. Tiv taus xeb thiab tshuaj lom neeg
Tsis zoo li hlau, PE tsis xeb. Nws tiv taus ntau yam tshuaj lom neeg, ua rau nws haum rau dej, dej khib nyiab, lossis qee yam kua dej hauv kev lag luam.
2. Yooj yim thiab tawg tsis kam
Cov kav dej PE tuaj yeem tiv taus kev hloov hauv av thiab cov khoom thauj dynamic zoo dua li cov khoom siv khov kho. Qhov no tseem ceeb heev rau thaj chaw uas muaj av qeeg lossis cov av tsis ruaj khov.
3. Qis qis, kev thauj mus los yooj yim thiab kev teeb tsa
Nws sib dua li hlau lossis pob zeb ua vaj tse, ua rau kev faib khoom thiab kev teeb tsa yooj yim dua.
4. Kev sib txuas ua tau nruj heev
Cov kav dej PE tuaj yeem sib txuas los ntawm kev sib xyaw ua ke lossis electrofusion, ua rau muaj qhov sib koom ua ke uas, thaum ua kom raug, tuaj yeem muaj zog dua li cov kav dej nws tus kheej, thaum txo qis qhov xau.
5. Lub neej ua haujlwm ntev
Yog tias tsim thiab teeb tsa kom raug, cov kav dej PE tuaj yeem siv tau ntev txog ntau xyoo. Ntau tus qauv teev tseg lub neej tsim qauv txog li 50 xyoo nyob rau hauv qee qhov xwm txheej.
Cov Kev Siv Cov Yeeb Nkab Polyethylene Hauv Ntau Qhov Chaw
Cov kav dej polyethylene siv dav, suav nrog:
- Kev faib dej huv: cov kav dej hauv nroog, kev sib txuas hauv tsev, cov kav xa dej thiab cov kav xa dej.
– Cov kav roj: HDPE tshwj xeeb rau cov roj nrog cov qauv nruj, feem ntau cim nrog xim tshwj xeeb.
- Kev ywg dej ua liaj ua teb: tiv taus cov chiv thiab tshuaj lom neeg, yoog tau rau thaj chaw loj ntawm thaj av.
- Cov kab ke pov tseg thiab cov kav dej ntws: suav nrog cov kav dej corrugated rau kev ntws dej.
- Kev lag luam thiab kev khawb av: rau cov slurries, cov dej ua haujlwm, lossis qee yam kua vim nws zoo tiv taus kev sib txhuam thiab tshuaj lom neeg (nyob ntawm cov xwm txheej ua haujlwm).
Kev kaw
Cov txheej txheem tsim cov polyethylene pib nrog kev tsim cov ethylene los ntawm kev tawg ntawm cov pa dej, ua raws li kev sib xyaw ua ke siv cov txheej txheem thiab cov tshuaj catalysts uas txiav txim siab hom PE, ua raws li kev sib xyaw ua ke thiab pelletization. Rau cov ntawv thov yeeb nkab, polyethylene tom qab ntawd raug ua tiav los ntawm kev rho tawm yeeb nkab nrog kev tswj hwm qhov ntev. Kev sib xyaw ua ke ntawm kev tiv thaiv corrosion, kev ywj pheej, lub zog ntev, thiab lub peev xwm los tsim cov pob qij txha nruj ua rau cov yeeb nkab polyethylene - tshwj xeeb tshaj yog HDPE / PE100 - qhov kev xaiv tseem ceeb rau cov khoom siv niaj hnub xws li dej huv, roj, thiab dej.
Yog tias koj xav tau, kuv tuaj yeem hloov kho tsab xov xwm no kom ua raws li cov qauv tshwj xeeb (piv txwv li SNI / ISO), lossis ntxiv ib ntu tshwj xeeb rau cov qauv tsim yeeb nkab xws li SDR, PN, thiab kev sib xyaw ua ke vs electrofusion vuam.
