Tsis zoo li cov thermoplastics, elastomers feem ntau yog siv los ntawm ntau qhov kub thiab txias tshaj lawv cov iav hloov kub (Tg). Qhov zoo ntawm elastomers tshaj cov thermoplastics yog lawv lub peev xwm los yuav luag tag nrho los ntawm lub xeev tensile (siab elasticity), nrog rau lawv cov elasticity, tsis tshua muaj hardness thiab tsis tshua muaj modulus zog. Thaum elastomers siv hauv qab chav tsev kub, lawv qhia qhov nce hauv hardness, nce hauv modulus, thiab txo qis elasticity. Thaum elastomers siv hauv qab chav tsev kub, muaj ib tug nyiam rau hardness nce, modulus nce, elasticity kom txo (tsawg tensile) thiab compression teem kom nce. Nyob ntawm qhov teeb meem nrog lub elastomer, ob qhov tshwm sim tuaj yeem tshwm sim nyob rau tib lub sijhawm - iav hardening thiab ib nrab crystallization - CR, EPDM, NR yog qee qhov piv txwv ntawm elastomers uas nthuav tawm crystallization.
1. Txheej txheem cej luam ntawm qhov ntsuas kub tsawg
Brittleness, compression mus tas li deformation, retraction, hardening thiab cryogenic hardening tau siv ntau xyoo thiaj li ua rau cov khoom siv polymer ntawm qhov kub thiab txias. Compressive kev nyuaj siab so yog qhov tshiab thiab tsom rau kev txiav txim siab sealing quab yuam ntawm cov khoom nyob rau lub sijhawm nyob rau hauv ntau yam ib puag ncig.
2. Qhov kub thiab txias
ASTM D 2137 txhais lub brittleness kub raws li qhov qis tshaj qhov kub ntawm cov roj hmab vulcanized yuav tsis pom puas los yog rupture nyob rau hauv tej yam kev mob. Tsib cov qauv roj hmab ntawm cov qauv kev txiav txim siab ua ntej tau npaj, muab tso rau hauv lub chamber lossis kua nruab nrab, raug rau qhov kub thiab txias rau 3 ± 0.5min, thiab tom qab ntawd muab qhov cuam tshuam nrawm ntawm 2.0 ± 0.2m / s. Cov qauv raug muab tshem tawm thiab raug cuam tshuam los yog kev sib tsoo. Cov qauv raug tshem tawm thiab kuaj xyuas qhov cuam tshuam lossis tawg, tsis muaj kev puas tsuaj. Qhov ntsuas tau rov ua dua mus txog qhov kub thiab txias - qhov kub qis tshaj plaws uas tsis pom muaj pob tawg yog ze rau 1 ° C.
3. Tsis tshua muaj kub compression teeb thiab qis kub hardening
Cov txheej txheem kev sim rau qhov kub qis compression teeb yog ze heev rau qhov txheej txheem compression txheej txheem, tshwj tsis yog tias qhov ntsuas kub yog tswj los ntawm qee txoj kev siv hluav taws xob, xws li cov dej khov qhuav, kua nitrogen, los yog cov txheej txheem siv tshuab, thiab tus nqi yog nyob rau hauv ± 1 ° C ntawm qhov preset kub. Tom qab rov qab los ntawm cov khoom siv, cov qauv no kuj tau muab tso rau ntawm qhov kub thiab txias thiab molded mus rau ib txoj kab uas hla ntawm 29 hli thiab thickness ntawm 12.5 hli. Low-temperature compression set yog ib txoj hauv kev tsis ncaj ncees rau kev sib khi daim ntawv thov ntawm qhov sib txuas hauv nqe lus nug. Compressive kev ntxhov siab so yog txoj kev ncaj qha thiab yuav tham tom qab. Tsawg kub hardening kuj feem ntau txiav txim siab siv lub vulcanized compression set qauv (29mm x 12.5mm), tab sis rov sim dua ntawm qhov ntsuas kub qis, uas yog tib yam li rau compression teeb, thiab tom qab ntawd dua ntawm qhov kub thiab txias raws li lawv qhov kub thiab txias. Hardening thiab low-temperature compression set yog cuam tshuam ncaj qha los ntawm kev ua kom txias, tab sis kuj los ntawm kev nyiam ntawm cov polymer rau crystallize, nrog rau tus nqi ntawm crystallization nyob ntawm qhov kub thiab txias, piv txwv li, CR crystallizes ceev tshaj plaws nyob ib ncig ntawm -10 ° C, thiab tom qab ntawd txo qis ntawm qhov kub thiab txias, feem ntau yog vim lub immobility ntawm polymer saw ntu (lub molecular rearranges).
4. Gehman Low Temperature Hardening
ASTM D 1053 piav qhia txog cov txheej txheem qis-kub hardening raws li hauv qab no: cov qauv ntawm cov ntaub ntawv elastic polymer yog tsau rau hauv cov hlau uas paub qhov torsional tas li, thiab lwm qhov kawg ntawm cov hlau txuas nrog lub taub hau torsion muaj peev xwm tso cai rau cov xaim sib tw. Cov hnoos qeev tau muab tso rau hauv qhov kub hloov mus rau qhov nruab nrab ntawm qhov kub thiab txias hauv qab ib txwm, thaum lub sij hawm lub taub hau torsion yog twisted los ntawm 180 °, thiab tom qab ntawd cov qauv yog twisted los ntawm tus nqi (tsawg dua 180 °) uas yog nyob ntawm qhov kev hloov ntawm cov qauv qhov yooj thiab tawv. Tom qab ntawd siv tus nqi ntawm goniometer los txiav txim seb tus nqi ntawm cov qauv twist, lub kaum sab xis ntawm twist thiab hardness ntawm cov khoom siv roj hmab. Qhov kub ntawm qhov system yog maj mam nce ntawm qhov no, thiab ib daim phiaj ntawm lub kaum sab xis ntawm qhov sib tw ntawm qhov kub thiab txias tau txais. Qhov kub ntawm qhov modulus nce mus txog T2, T10, thiab T100 feem ntau tau sau tseg raws li qhov sib npaug ntawm tus nqi modulus ntawm chav tsev kub.
5. Tsawg Kub Retraction (TR Test)
Kev ntsuas TR yog siv los ntsuas qhov muaj peev xwm ntawm cov qauv hauv lub xeev tensile thaum compressive tas li deformation thiab compressive kev ntxhov siab so txiav txim siab los ntawm compressive stress yog siv los txiav txim siab qhov kub thiab txias. Raws li tau hais dhau los, ntau cov polymers zoo li NR thiab PVC yuav crystallize ntawm qhov kub thiab txias, tab sis ncab tuaj yeem ua rau crystallize, ua rau muaj ntau yam ntxiv thaum saib cov khoom uas tsis tshua muaj kub. Rau kev soj ntsuam daim ntawv thov xws li tso pa tawm, TR nyob rau hauv nruj yog qhov tsim nyog thiab nquag siv. Hauv qhov kev sim no, tus qauv yog elongated (feem ntau yog 50% lossis 100%) thiab khov rau hauv lub xeev elongated. Cov qauv raug tso tawm, thaum lub sij hawm qhov kub thiab txias tau nce ntawm tus nqi txiav txim los ntsuas qhov rov qab ntawm cov qauv, qhov ntev ntawm qhov shrinkage yog ntsuas thiab elongation yog kaw. Qhov ntsuas kub ntawm qhov hnoos qeev los ntawm 10%, 30%, 50%, thiab 70% feem ntau yog sau tseg xws li TR10, TR30, TR50, thiab TR70. TR10 cuam tshuam rau qhov kub thiab txias; TR70 cuam tshuam rau qhov deformation mus tas li ntawm cov qauv hauv qhov kub thiab txias compression; thiab qhov sib txawv ntawm TR10 thiab TR70 yog siv los ntsuas crystallization ntawm cov qauv (qhov ntau dua qhov sib txawv, qhov ntau dua qhov nyiam crystallize).
6. Low Temperature Compressive Stress Relaxation (CSR)
Kev xeem CSR tuaj yeem siv los ua kev kwv yees txog kev ua tau zoo thiab lub neej ntawm cov khoom sib khi. Thaum ib qho elastomeric compound tau muab ib qho deformation tas li, ib qho kev sib xyaw ua ke yog tsim, thiab lub peev xwm ntawm cov khoom siv los tswj cov quab yuam no nyob rau hauv ib puag ncig ib puag ncig ntsuas nws lub peev xwm kaw. Ob qho tib si lub cev thiab tshuaj lom neeg ua rau muaj kev ntxhov siab, raws li lub sijhawm thiab qhov kub thiab txias, ib qho tseem ceeb yuav muaj zog, kev so ntawm lub cev yog pom ntawm qhov kub thiab txias, sai li sai tau tom qab kev ntxhov siab, uas ua rau cov saw rov qab thiab hloov pauv ntawm cov roj hmab-filler thiab muab tub lim-filler, thiab kev so ntawm lub zog tshem tawm kev ntxhov siab yog thim rov qab. Nyob rau ntawm qhov kub thiab txias, cov tshuaj muaj pes tsawg leeg txiav txim siab tus nqi ntawm kev so, thaum cov txheej txheem ntawm lub cev twb me me thiab cov tshuaj lom neeg so yog irreversible, ua rau cov saw breakage thiab cross-linking reactions. Kev caij tsheb kauj vab kub los yog qhov kub nce sai tuaj yeem cuam tshuam rau kev ntxhov siab hauv elastomers. Thaum kuaj CSR, cov qauv kuaj tau muab tso rau
Thaum lub sij hawm kuaj CSR, kev ntxhov siab yog nce ntxiv thaum cov qauv kuaj tau raug kub siab. Yog tias kev ntxhov siab tshwm sim thaum ntxov ntawm qhov kev xeem, tus nqi ntawm kev so ntxiv nce ntxiv ua ntej thiab muaj qhov siab tshaj plaws thaum thawj lub voj voog. Nyob rau hauv ib tug tensile loj xeem piece los tsim gasket kuaj (19 hli txheej kab, puab txoj kab uas hla ntawm 15 hli), nrog ib tug elastic fixture yuav compressed rau cov qauv mus rau lawv chav tsev kub thickness ntawm 25%, thiab ntawm 25 ℃ mus rau hauv ib puag ncig kuaj chamber, qhov kub ntawm 25 ℃ los tswj 24h, thiab ces cia li mus rau -20 ~ 4 ℃ tom ntej no, tswj qhov kub ntawm -20 ~ 4 ℃. 110 ℃ lub voj voog ntawm 24h, tag nrho lub sijhawm kuaj ntawm qhov ntsuas kub, qhov ntsuas kub, kev txiav txim siab tsis tu ncua. Kev ntsuas quab yuam yog ua tsis tu ncua thoob plaws lub sijhawm ntsuas ntawm qhov ntsuas kub.
7. Cov ntsiab lus ntawm Ethylene
7.1 Cov ntsiab lus Ethylene muaj qhov cuam tshuam loj tshaj plaws ntawm kev ua haujlwm kub ntawm EPDM polymers. Polymers nrog Ethylene cov ntsiab lus xws li 48% mus rau 72% raug soj ntsuam nyob rau hauv cov txheej txheem sealing zoo. Txhua lub hom phiaj los txo qhov kev hloov pauv hauv lub hli viscosity los ntawm kev qhia ENB hauv cov polymers sib txawv.
EPDM roj hmab yog amorphous yog tias qhov sib piv ntawm ethylene / propylene sib npaug thiab kev faib tawm ntawm ob lub monomers hauv cov saw hlau polymer yog random. EPDM nrog 48% thiab 54% ethylene cov ntsiab lus tsis crystallize ntawm lossis siab dua chav tsev kub. Thaum cov ethylene cov ntsiab lus nce mus txog 65%, cov ethylene sequences pib nce tus naj npawb thiab ntev thiab tuaj yeem tsim cov muaju, uas tau pom nyob rau hauv crystallization peaks ntawm DSC nkhaus nyob ib ncig ntawm 40 ° C. Qhov loj dua ntawm DSC peaks, qhov loj dua cov muaju uas tsim.
7.2 Ntxiv nrog rau cov txiaj ntsig ntawm ethylene cov ntsiab lus ntawm cov khoom kub tsis tshua muaj kev sib tham tom qab, crystallite loj cuam tshuam qhov yooj yim ntawm kev sib xyaw thiab ua cov khoom sib xyaw uas muaj cov muaju. Qhov loj ntawm crystallite loj, qhov kub thiab txias ua hauj lwm yuav tsum tau nyob rau hauv lub mixing theem kom tag nrho cov polymer nrog rau lwm yam. Cov roj hmab raw lub zog ntawm EPDM tebchaw nce nrog nce ethylene cov ntsiab lus. Hauv kev sib khi cov qauv uas ntsuas cov txiaj ntsig ntawm cov ntsiab lus ethylene, qhov nce ntawm ethylene cov ntsiab lus los ntawm 50% mus rau 68% ua rau tsawg kawg plaub npaug ntawm lub zog ntawm cov roj hmab. Chav-kub hardness kuj nce nrog nce cov ntsiab lus ethylene. Lub Ntug A hardness ntawm amorphous polymer nplaum yog 63 °, whereas Shore A hardness ntawm polymer nrog cov ntsiab lus ethylene siab tshaj plaws yog 79 °. Qhov no yog vim qhov nce hauv cov ethylene ib ntus, qhov nce hauv crystallization hauv cov nplaum, thiab qhov sib txuas ntxiv hauv cov thermoplastic polymers.
7.3 Thaum lub hardness yog ntsuas ntawm qhov kub thiab txias, sib piv rau cov polymers nrog siab ethylene cov ntsiab lus, cov amorphous polymers qhia tsis tshua muaj kev hloov nyob rau hauv hardness, whereas qhov kev hloov nyob rau hauv hardness ntawm lub siab dua ethylene cov ntsiab lus tsis qhia ib tug linear qauv thiab lub hardness tseem nyob rau hauv chav tsev kub, yog li ntawd cov polymers uas muaj cov ntsiab lus ntawm ethylene hardness tseem nyob rau hauv qhov kub thiab txias.
7.4 Compression set feem ntau nyob ntawm qhov ntsuas kub. Yog tias kuaj ntawm 175 ° C, tsis muaj qhov sib txawv ntawm compression teeb ntawm ib qho ntawm cov polymers (teev yog cuam tshuam los ntawm kev tsim cov khoom sib xyaw thiab kev xaiv ntawm vulcanization system). Tom qab melting ntawm ethylene crystals, lub polymer muaj ib tug amorphous daim ntawv, thiab thiaj li yuav soj ntsuam cov nyhuv ntawm cov ntsiab lus ethylene, kev ntsuam xyuas tau ua nyob rau ntawm 23 ° C. Polymers uas muaj cov ntsiab lus ethylene siab dua kom meej meej muaj ntau dua deformation (ntau dua ob zaug ntau dua), thiab cov txiaj ntsig ntawm cov ntsiab lus ethylene tseem loj dua thaum kuaj ntawm -20 ° C thiab -40 ° C. Polymers uas muaj ntau tshaj 60% ethylene cov ntsiab lus muaj siab deformation mus tas li (> 80%); ntawm -40 ° C, tsuas yog tag nrho cov amorphous polymers muaj tsawg deformation (17%).
7.5 Qhov cuam tshuam ntawm Ethylene Cov ntsiab lus ntawm qhov kub thiab txias hardening los ntawm Gehman Tests. Muab qhov kub thiab txias, lub kaum sab xis siab dua, qhov qis dua qhov nce hauv qhov tawv nqaij (los yog nce hauv modulus). Thaum qhov kub tsis tshua muaj, qhov kev sib tw khov kho nce ntxiv nrog cov ntsiab lus ethylene. Rau amorphous polymers, T2 yog -47 ° C, thaum lub siab tshaj plaws ethylene cov ntsiab lus polymer muaj T2 ntawm -16 ° C.
7.6TR Kev ntsuas lub ntsws rov qab ntawm cov qauv tom qab txuas ntxiv khov, cov ntsiab lus ethylene muaj qhov cuam tshuam loj rau txoj kev sim, uas zoo ib yam li Gehman xeem.
Qhov no zoo ib yam li Gehman xeem. Lub shrinkage (%) ntawm ntau yam polymers sib txawv raws li kev ua haujlwm ntawm qhov kub thiab txias, nrog rau cov amorphous polymers muaj qhov siab tshaj plaws shrinkage rov qab los ntawm qhov kub thiab txias; Txawm li cas los xij, raws li kev kwv yees, qhov kev rov qab los tsis zoo li cov ntsiab lus ethylene nce ntawm qhov kub thiab txias.
rov qab deteriorates. Tus nqi ntawm TR10 txawv ntawm -53 ° C rau amorphous polymers rau -28 ° C rau polymers nrog cov ntsiab lus ethylene siab.
7.7 Compressive stress relaxation (CSR) cycle
Lub voj voog. Muab cov sib xyaw ua ke, tso cai rau lawv so ntawm 25 ° C rau 24 teev, thiab tom qab ntawd muab tso rau hauv lub voj voog ntawm qhov kub ntawm -20 ° C mus rau 110 ° C tsis tu ncua rau 24 teev. Thaum compressed thawj zaug, tom qab lub sij hawm sib npaug, cov crystalline polymer E muaj kev ntxhov siab ntau dua li cov amorphous polymer, thiab thaum txo qis rau -20 ° C lub sealing quab yuam ntawm ob lub polymers txo qis, thaum lub amorphous polymer A muaj kev ruaj ntseg siab (siab dua F / F0). Thaum tshav kub kub cov khoom sib tov rau 110 ° C rov qab los ntawm nws cov sealing quab yuam, thiab thaum coj rov qab mus rau -20 ° C, qhov seem sealing quab yuam ntawm crystalline polymer yog tsawg dua 20% ntawm nws cov nqi, uas feem ntau suav hais tias qis heev rau cov ntawv thov feem ntau, nrog rau cov amorphous polymer khaws ntau dua 50% ntawm nws cov sealing quab yuam, thiab cov amorphous polymer dua muaj cov crystalline rov qab. Lub voj voog tom ntej tau muab cov lus xaus zoo sib xws. Nws yog qhov tseeb tias amorphous polymers yog qhov zoo tshaj rau kev sib khi daim ntaub ntawv uas yuav tsum tau ua haujlwm siab thiab qis.
8. Cov nyhuv ntawm Diolefin Cov ntsiab lus
Txhawm rau muab cov ntsiab lus tsis txaus ntseeg uas xav tau rau vulcanization, tsis yog-conjugated diolefins zoo li ENB, HX thiab DCPD yog ntxiv rau ethylene propylene polymers. Ib ob daim ntawv cog lus reacts nyob rau hauv lub polymer matrix, thaum lub thib ob ua raws li ib tug ntxiv rau lub polymerized molecular saw thiab muab lub vulcanization point rau sulfur yellow vulcanization. Cov nyhuv ntawm ENB raug soj ntsuam nyob rau hauv lub qhov rais (los nag) bar profiles. Polymers uas muaj 2%, 6% thiab 8% ENB tau muab piv.Qhov sib ntxiv ntawm ENB tau muaj txiaj ntsig zoo rau cov yam ntxwv ntawm vulcanization thiab crosslink ceev. Modulus nce thaum elongation txo qis. Lub hardness nce thiab compression teeb tau zoo dua thaum kub nce. Raws li ENB cov ntsiab lus nce, lub sij hawm charring yuav luv dua.
ENB yog cov khoom siv amorphous, thiab thaum ntxiv rau hauv cov pob txha polymer, nws cuam tshuam cov crystallization ntawm ethylene ib feem ntawm cov polymer, kom cov polymers nrog tib cov ntsiab lus ethylene tuaj yeem tau txais, thiab cov ntsiab lus siab dua ntawm ENB txhim kho cov khoom qis. Nyob rau hauv chav tsev kub, qhov siab dua ENB cov ntsiab lus me ntsis txhim kho cov txheej txheem compression vim kev txhim kho crosslink ceev. Txawm li cas los xij, ntawm qhov kub thiab txias, cov txheej txheem compression ntawm cov polymers nrog cov ntsiab lus ENB siab dua yog qhov zoo dua li cov polymers nrog 2% ENB cov ntsiab lus. Cov nyhuv ntawm ENB cov ntsiab lus ntawm brittleness kub, qhov kub thiab txias retraction, thiab Gehman qhov kev ntsuam xyuas tsis tau qhia ib qho tseem ceeb sib txawv ntawm brittleness kub ntawm polymers feem ntau, thiab rau Gehman qhov kev xeem thiab TR xeem, txhua lub polymer qhia ib qho kev txhim kho nyob rau hauv qis-temperature zog nrog nce ENB cov ntsiab lus.
9. Cov nyhuv ntawm mooney viscosity ntawm cov khoom kub qis
Nws paub zoo tias lub hli viscosity (molecular mass) muaj txiaj ntsig zoo rau kev ua haujlwm ntawm elastomers. Nyob rau hauv extrusion thiab molding daim ntaub ntawv Nyob rau hauv extrusion thiab molding daim ntaub ntawv, nws yog ib qho tseem ceeb rau xaiv ib tug compound nrog ib tug haum Mooney viscosity nqi. Siv tib lub formulation uas tau siv los soj ntsuam cov txiaj ntsig ntawm peb lub monomer, ENB, ntawm cov khoom kub qis los tshuaj xyuas Mooney viscosity, polymers nrog Mooney viscosities ntawm 30, 60, thiab 80 tau muab piv, thiab Mooney viscosity ntawm cov tebchaw tau nce raws li Mooney viscosity ntawm cov polymers siv tau nce. Lub zog tensile, modulus, thiab cov roj hmab nyoos muaj zog ntxiv nrog nce Mooney viscosity. Cov nyhuv ntawm Mooney viscosity ntawm qhov kub thiab txias ntawm EPDM tsis tseem ceeb. Txawm li cas los xij, compression mus tas li deformation ntawm chav tsev kub, -20 ° C thiab -40 ° C nce nrog nce molecular loj. Txawm li cas los xij, qhov compression teem nyob rau hauv chav tsev kub, -20 ° C thiab -40 ° C tsis hloov pauv nrog nce molecular mass, whereas lub compression teem rau siab kub (175 ° C) pom ib co kev hloov rau lub siab dua mooney viscosities ntawm EPDM adhesives.
10. Cov lus xaus
Cov ntsiab lus ethylene thiab diolefin muaj qhov cuam tshuam loj rau kev ua haujlwm ntawm EPDM elastomers hauv cov ntawv thov kub tsawg, nrog cov polymers uas tsis tshua muaj ethylene cov ntsiab lus ua tau zoo thiab cov polymers nrog cov ntsiab lus diolefin siab txhim kho vim cuam tshuam crystallization ntawm ethylene feem ntawm cov polymer. Tsawg ethylene cov ntsiab lus polymers yuav tsum tau siv thaum qhov kub thiab txias ua haujlwm yog qhov txwv.
