Low Density Polyethylene Production Method
Jul 05, 2023| 1. Txoj kev polymerization ntawm low-density polyethylene
Raws li txoj kev polymerization, low-density polyethylene tuaj yeem muab faib ua cov txheej txheem high-pressure thiab low-pressure method. Raws li hom reactor, nws tuaj yeem muab faib ua kettle txoj kev thiab raj txoj kev. Siv ethylene ua raw khoom, xa mus rau lub reactor, nyob rau hauv qhov kev txiav txim ntawm tus pib, lub polymerization cov tshuaj tiv thaiv yog nqa tawm los ntawm high-pressure compression, thiab cov khoom tawm los ntawm lub reactor yog tshem tawm los ntawm lub separator tom qab lub unreacted ethylene, thiab ces. granulated los ntawm yaj extrusion, qhuav, blended, thiab xa mus rau ntim.
2. Lub LDPE thiab LLDPE
Ob leeg LDPE thiab LLDPE muaj qhov zoo rheological lossis yaj flowability. LLDPE muaj tsawg dua shear rhiab heev vim nws muaj qhov nqaim molecular hnyav faib thiab luv ceg chains. Thaum lub sij hawm shearing txheej txheem (xws li extrusion), LLDPE tuav lub viscosity ntau dua thiab yog li ntawd nyuaj rau txheej txheem dua li LDPE nrog tib lub melting Performance index. Nyob rau hauv extrusion, LLDPE qhov qis shear rhiab heev ua rau kom muaj kev ntxhov siab sai dua ntawm cov saw hlau molecular, thiab yog li tsis tshua muaj rhiab heev ntawm lub cev rau kev hloov pauv hauv kev sib piv.
Hauv yaj txuas ntxiv, LLDPE feem ntau muaj qis dua viscosity ntawm ntau hom kab mob. Ntawd yog, nws yuav tsis tsim cov tawv tawv thaum ncab zoo li LDPE. Raws li tus deformation tus nqi ntawm polyethylene nce, LDPE qhia tau hais tias ib qho kev ceeb toom nce nyob rau hauv viscosity, uas yog tshwm sim los ntawm molecular saw entanglement.
Qhov tshwm sim no tsis tau pom nyob rau hauv LLDPE, qhov uas tsis muaj cov saw ntev ntev ua rau cov polymer tsis tangled. Cov cuab yeej no tseem ceeb heev rau kev siv cov yeeb yaj kiab, vim LLDPE cov yeeb yaj kiab yooj yim dua los ua cov yeeb yaj kiab thinner thaum tuav lawv lub zog thiab tawv. Lub rheology ntawm LLDPE tuaj yeem muab sau ua "nruj ntawm shear" thiab "soft on extension". Thaum hloov LDPE nrog LLDPE, zaj duab xis extrusion khoom thiab tej yam kev mob yuav tsum tau hloov. Lub siab viscosity ntawm LLDPE yuav tsum muaj lub zog ntau dua nyob rau hauv lub extruder thiab muab ntau dua melt kub thiab siab. Qhov sib txawv tuag qhov sib txawv yuav tsum tau nthuav dav kom tsis txhob txo cov txiaj ntsig vim qhov siab rov qab siab thiab yaj tawg.