Kev Qhia Txog Kev Hloov Kho ntawm EVA

Ethylene-vinyl acetate copolymer, luv ua EVA, yog ib hom yas uas muaj cov non-polarity, crystalline vinyl monomers thiab non-crystalline vinyl acetate (VA) monomers. EVA qhov yooj ywm, tawv, tiv taus kev ntxhov siab, pob tshab, thiab sib xws nrog cov khoom sau zoo dua li polyethylene (PE). EVA tuaj yeem ua rau ntau yam khoom los ntawm cov txheej txheem molding xws li extrusion.

Los ntawm kev siv tshuab hloov kho sib xyaw, kev ua tau zoo ntawm EVA tuaj yeem txhim kho tau zoo, thiab qhov dav thiab kev hloov pauv ntawm nws daim ntawv thov tuaj yeem nthuav dav. Txhawm rau kom txhua tus nkag siab txog kev sib xyaw thiab kev hloov kho ntawm EVA, Xiaobian tau sau cov ntaub ntawv tsim nyog rau txhua tus nyeem.

Cov yam tseem ceeb uas cuam tshuam rau kev ua tau zoo ntawm EVA.

01. Cov Nyhuv ntawm Cov Ntsiab Lus VA rau Kev Ua Haujlwm ntawm EVA

Qhov cuam tshuam ntawm VA cov ntsiab lus rau kev ua tau zoo ntawm EVA feem ntau yog pom tseeb hauv ob qho.

① Va sab pawg rhuav tshem thaj chaw crystalline tsim los ntawm polyethylene saw ntu, nrog rau kev nce ntawm VA cov ntsiab lus, qhov crystallinity ntawm EVA maj mam txo qis, thaum cov ntsiab lus VA txuas ntxiv mus txog 40% txog 50%, EVA copolymer dhau los ua cov qauv random kiag li;

② Vim tias VA yog ib pawg polar, nrog rau kev nce ntawm VA cov ntsiab lus, qhov polarity ntawm EVA loj dua, yog li ntau yam ntawm nws cov khoom tau hloov pauv, xws li lub zog tensile, kev ua kom sov deformation, kev ua kom tsis muaj zog tshuaj lom neeg thiab lwm yam khoom tau txo qis, thaum cov permeability friction coefficient, kev ntxhov siab ib puag ncig tawg tsis kam thiab lwm yam khoom tau zoo dua.

02. Cov nyhuv ntawm Molecular Weight Faib Tawm rau EVA Performance

EVA nrog rau qhov faib tawm ntawm qhov hnyav molecular dav, cov saw ntev yooj yim dua rau kev sib xyaw ua ke dua li cov saw luv, thiab cov saw ntev molecules tuaj yeem nqus tau feem ntau ntawm lub zog deformation thiab qhia txog kev teb elastic siab dua, yog li EVA nrog rau qhov faib tawm ntawm qhov hnyav molecular dav dua muaj viscosity loj thaum raug kev txiav tsawg dua, uas tsis yooj yim rau ntws, tab sis yooj yim rau ntws. Hauv kev ua tiav thiab kev tsim khoom tiag tiag, qhov kev sib raug zoo ntawm viscosity / shear no vim muaj kev faib tawm ntawm qhov hnyav molecular sib txawv yuav muaj qee qhov cuam tshuam rau kev xaiv cov khoom siv raw EVA.

Tsis tas li ntawd xwb, thaum qhov hnyav molecular ntawm EVA nce ntxiv, lub zog thermal weld, yaj viscosity, deflection, stiffness, kev ntxhov siab fracture resistance thiab lwm yam ntawm EVA tau zoo dua.

03. Qhov tseeb ntawm Kev Sib Nqus ntawm Cov Chains Molecular ntawm EVA Kev Ua Haujlwm

Piv nrog EVA thiab PE molecules, EVA cuam tshuam rau lub xeev crystallization thawj vim yog kev qhia txog cov ceg luv luv uas muaj cov pab pawg polar hauv cov saw hlau ntawm cov molecules, yog li EVA nyiam "plasticizing effect", ua rau qhov deb ntawm cov saw hlau polymer molecular nce ntxiv, yog li txo qhov crystallinity ntawm polymer, ua rau EVA mos dua thiab ywj dua PE; qhov kev cuam tshuam ntawm CH3COO-pab pawg tsim ntawm EVA molecular saw ua rau qhov crystallinity thiab glassing kub txawv ntawm qhov ntawm cov polyethylene qis-density (LDPE). Qhov ruaj khov thermal, kev laus thiab lwm yam khoom siv lub cev thiab tshuab ntawm EVA kuj raug cuam tshuam.

Txoj Kev Hloov Kho ntawm EVA

01. Kev Hloov Kho Dua Tshiab

Kev sau yog ib txoj kev hloov kho polymer yooj yim thiab zoo, uas tsis tsuas yog tuaj yeem tswj tau qhov zoo ntawm cov polymer nws tus kheej, tab sis kuj siv cov txiaj ntsig sib xyaw los txhim kho qhov tsis zoo, kom ua tiav lub hom phiaj ntawm kev txhim kho kev ua tau zoo ntawm cov polymer. Tam sim no, kev hloov kho sau ntawm EVA muaj kev hloov pauv mus rau nano-functionalization thiab filler surface modification technology.

① Sau EVA nrog cov pob zeb hydrotal (LDHs) tuaj yeem txhim kho lub zog khoov ntawm EVA.

② Kev sau EVA nrog magnesium hydroxide (Mg(OH)2) tuaj yeem txhim kho qhov thermal stability ntawm EVA, txhim kho lub zog tensile thiab kev ua haujlwm fluidity.

③ Kev hloov kho ntawm EVA kub yaj nplaum nrog ferric oxide (Fe3O4) cov khoom me me tuaj yeem txhim kho qhov nplaum ntawm kub yaj nplaum thiab txhim kho nws cov kua yaj hauv qee qhov ntau.

④ NANO-SiO2 nrog rau qhov ntim ntawm 4% tuaj yeem ua kom lub zog tensile ntawm EVA / SiO2 cov ntaub ntawv sib xyaw ua ke siab tshaj plaws.

Cov hom fillers siv rau EVA filler hloov kho ntxiv zuj zus, tab sis tseem muaj ntau yam teeb meem hauv kev hloov kho filler, yuav ua li cas txhim kho qhov kev sib kis ntawm cov fillers hauv EVA matrix, thiab lwm yam. Kev daws teeb meem ntawm cov teeb meem no pab txhim kho kev ua tau zoo ntawm EVA.

02. Kev Hloov Kho Sib Xyaws

Kev sib xyaw thiab hloov kho EVA tuaj yeem ua kom zoo dua qhov kev sib xyaw ua ke ntawm cov khoom ntawm cov polymers sib txawv, yog li EVA tuaj yeem tau txais cov khoom tshiab thiab txhim kho kev ua tau zoo ntawm qee yam. Kev sib xyaw EVA nrog lwm cov polymers uas muaj kev sib raug zoo yog ib qho tseem ceeb ntawm kev tshawb fawb hloov kho EVA hauv xyoo tas los no.

① Thaum ntxiv 15% EVA-g-MAH rau hauv EVA/halogen-free flame retardant copoly polyester (P-PET) blend system, nws qhov kev sib raug zoo, cov txheej txheem ntws thiab kev tiv thaiv hluav taws tuaj yeem txhim kho.

② Hauv EVA/high-density polyethylene (HDPE) blending system, thaum cov ntsiab lus HDPE yog 15%, cov khoom siv kho tshuab ntawm cov xov paj thiab cov xov sib xyaw yog qhov zoo tshaj plaws.

③ Hauv EVA/NBR blend system, qhov kub siab tshaj plaws ntawm kev lwj ntawm cov khoom siv hluav taws xob tuaj yeem tau los ntawm kev ntxiv oxidized diisobenzotride (DCP).

Nrog rau kev tsim kho ntawm tiam thib peb ntawm cov thev naus laus zis polymer alloy, xws li interpenetrated polymer network technology, dynamic vulcanization technology,kev siv tshuab extrusion reaction, cov thev naus laus zis sib xyaw ua ke, thiab lwm yam, ntau dua thiab zoo dua kev ua tau zoo EVA sib xyaw cov ntaub ntawv yuav raug tsim los ua kom tau raws li qhov xav tau ntawm ntau yam thev naus laus zis engineering rau cov ntaub ntawv.

03. Lwm Cov Kev Hloov Kho

Ntxiv rau kev tshawb fawb ib txwm muaj ntawm kev sau thiab sib xyaw ua ke ntawm EVA, kuj tseem muaj kev tshawb fawb zoo heev hauv kev sib txuas tshuaj thiab kev sib txuas ntawm EVA hauv xyoo tas los no, uas tau tso lub hauv paus zoo rau kev tsim ntau yam khoom EVA.

① Benzoyl peroxide (BPO) yog siv los ua tus neeg sawv cev crosslinking los txhim kho qhov rov qab zoo ntawm cov khoom.

② EVA-g-PU polymer tau txais los ntawm txoj kev yaj grafting, uas tau txais lub zog tensile zoo dua thiab elongation thaum tawg dua li cov khoom siv raw. Thiab ntxiv PU prepolymers kuj tseem tuaj yeem txhim kho kev ua haujlwm thermal stability ntawm EVA.