Kev sib piv ntawm LLDPE thiab LDPE.

Polyethylene uas tsis muaj kab ncaj, cov qauv sib txawv ntawm cov polyethylene uas tsis muaj kab ncaj dav dav, vim tias tsis muaj cov ceg ntev. Qhov linearity ntawm LLDPE nyob ntawm cov txheej txheem tsim khoom sib txawv thiab kev ua tiav ntawm LLDPE thiab LDPE. LLDPE feem ntau yog tsim los ntawm kev sib txuas ntawm ethylene thiab alpha olefins siab dua xws li butene, hexene lossis octene ntawm qhov kub thiab siab qis dua. LLDPE polymer tsim los ntawm cov txheej txheem copolymerization muaj qhov faib tawm molecular nqaim dua li LDPE dav dav, thiab tib lub sijhawm muaj cov qauv linear uas ua rau nws muaj cov khoom sib txawv rheological.

cov yam ntxwv ntawm cov dej ntws

Cov yam ntxwv ntawm cov dej yaj ntawm LLDPE tau hloov kho rau cov kev xav tau ntawm cov txheej txheem tshiab, tshwj xeeb tshaj yog cov txheej txheem extrusion zaj duab xis, uas tuaj yeem tsim cov khoom lag luam LLDPE zoo. LLDPE siv rau hauv txhua lub khw muag khoom ib txwm muaj rau polyethylene. Kev ncab zoo dua, kev nkag mus, kev cuam tshuam thiab kev tsim kua muag ua rau LLDPE tsim nyog rau cov yeeb yaj kiab. Nws qhov kev tiv thaiv zoo heev rau kev tawg ntawm kev ntxhov siab ib puag ncig, kev cuam tshuam qis kub thiab kev tiv thaiv warpage ua rau LLDPE zoo nkauj rau cov yeeb nkab, daim ntawv extrusion thiab txhua daim ntawv thov molding. Daim ntawv thov tshiab ntawm LLDPE yog ua cov mulch rau cov chaw pov tseg thiab cov ntaub rau cov pas dej pov tseg.

Kev Tsim Khoom thiab Cov Yam Ntxwv

Kev tsim cov LLDPE pib nrog cov tshuaj catalysts hloov pauv hlau, tshwj xeeb tshaj yog hom Ziegler lossis Phillips. Cov txheej txheem tshiab raws li cov tshuaj catalysts cycloolefin hlau yog lwm txoj kev xaiv rau kev tsim LLDPE. Qhov kev tshuaj tiv thaiv polymerization tiag tiag tuaj yeem ua tiav hauv cov tshuaj thiab cov roj theem reactors. Feem ntau, octene yog copolymerized nrog ethylene thiab butene hauv cov tshuaj theem reactor. Hexene thiab ethylene yog polymerized hauv cov roj theem reactor. Cov LLDPE resin tsim tawm hauv cov roj theem reactor yog nyob rau hauv daim ntawv particulate thiab tuaj yeem muag ua hmoov lossis ua tiav ntxiv rau hauv pellets. Ib tiam tshiab ntawm super LLDPE raws li hexene thiab octene tau tsim los ntawm Mobile, Union Carbide. Cov tuam txhab xws li Novacor thiab Dow Plastics tau tsim tawm. Cov ntaub ntawv no muaj qhov txwv toughness loj thiab muaj peev xwm tshiab rau kev siv lub hnab tshem tawm tsis siv neeg. Cov roj PE qis heev (qhov ceev hauv qab 0.910g / cc.) kuj tau tshwm sim hauv xyoo tas los no. VLDPEs muaj kev ywj pheej thiab mos mos uas LLDPE tsis tuaj yeem ua tiav. Cov khoom ntawm cov resins feem ntau pom hauv cov ntsuas yaj thiab qhov ceev. Tus ntsuas yaj qhia txog qhov nruab nrab ntawm qhov hnyav molecular ntawm cov resin thiab feem ntau yog tswj los ntawm qhov kub ntawm cov tshuaj tiv thaiv. Qhov nruab nrab ntawm qhov hnyav molecular yog ywj pheej ntawm qhov faib tawm ntawm qhov hnyav molecular (MWD). Kev xaiv catalyst cuam tshuam rau MWD. ​​Qhov ceev yog txiav txim siab los ntawm qhov concentration ntawm comonomer hauv cov saw polyethylene. Qhov concentration ntawm comonomer tswj tus lej ntawm cov ceg luv luv (qhov ntev ntawm qhov ntev nyob ntawm hom comonomer) thiab yog li tswj qhov ceev ntawm cov resin. Qhov siab dua qhov concentration ntawm comonomer, qhov qis dua qhov ceev ntawm cov resin. Kev teeb tsa, LLDPE txawv ntawm LDPE hauv tus lej thiab hom ceg, high-pressure LDPE muaj cov ceg ntev, thaum linear LDPE tsuas muaj cov ceg luv luv xwb.

kev ua haujlwm

Ob leeg LDPE thiab LLDPE muaj rheology zoo heev lossis yaj ntws. LLDPE muaj qhov rhiab heev tsawg dua vim nws qhov kev faib tawm molecular nqaim thiab cov ceg luv luv. Thaum lub sijhawm txiav (piv txwv li extrusion), LLDPE khaws cia viscosity ntau dua thiab yog li ntawd nyuaj rau ua dua li LDPE nrog tib lub ntsuas yaj. Hauv extrusion, qhov rhiab heev qis dua ntawm LLDPE tso cai rau kev so kom sai dua ntawm cov saw hlau polymer molecular, thiab yog li txo qhov rhiab heev ntawm cov khoom siv lub cev rau kev hloov pauv hauv qhov piv txwv blow-up. Hauv kev nthuav dav yaj, LLDPE sib txawv nyob rau hauv ntau yam kab mob Feem ntau muaj viscosity qis dua ntawm qhov ceev. Ntawd yog, nws yuav tsis nruj thaum ncab zoo li LDPE. Nce nrog rau qhov deformation ntawm polyethylene. LDPE qhia txog kev nce ntxiv ntawm viscosity, uas yog tshwm sim los ntawm kev sib txuas ntawm cov saw hlau molecular. Qhov xwm txheej no tsis pom hauv LLDPE vim tias tsis muaj cov ceg ntev hauv LLDPE ua rau cov polymer tsis muaj kev sib txuas. Cov khoom no tseem ceeb heev rau cov ntawv thov zaj duab xis nyias. Vim tias LLDPE zaj duab xis tuaj yeem ua cov zaj duab xis nyias dua thaum tswj hwm lub zog siab thiab toughness. Cov khoom rheological ntawm LLDPE tuaj yeem sau ua "rigid in shear" thiab "mos hauv extension".