Kuhambana na ti thermoplastics, ti elastomers hi ntolovelo titirhisiwa eka mahiselo yohambana hambana naswona tile henhla swinene ka mahiselo ya tona ya glass transition (TG). Swipfuno swa ti elastomers eka ti thermoplastics i vuswikoti bya tona byo hola kwalomu ka hinkwaswo kusuka eka xiyimo xa tensile (ku olova ka le henhla), xikan’we na ku olova ka tona loku andlariweke, ku tiya ka le hansi na swivumbeko swa modulus yale hansi. Loko ti elastomers titirhisiwa ehansi ka mahiselo ya kamara, ti kombisa ku tlakuka ka ku tiya, ku tlakuka ka modulus, na kuhunguteka ka elasticity. Loko ti elastomers titirhisiwa ehansi ka mahiselo ya kamara, kuna ntolovelo wa ku tiya ku tlakuka, modulus ku tlakuka, elasticity ku hunguteka (low tensile) na compression set ku tlakuka. Kuya hi xiphiqo xa elastomer, swiendlakalo swimbirhi swinga humelela hi nkarhi wun’we - glass hardening na partial crystallization - CR, EPDM, NR i swikombiso swin’wana swa ti elastomers leti kombisaka crystallization.
1. Nkatsakanyo wa ku kamberiwa ka mahiselo ya le hansi .
Brittleness, compression permanent deformation, retraction, hardening na cryogenic hardening switirhisiwile kuringana malembe yotala leswaku kuta hlawuriwa swivumbeko swa polymer eka mahiselo yale hansi. Ku olovisiwa ka ntshikelelo wa ntshikelelo i swintshwa swinene naswona swi kongomisa eka ku kumisisa matimba yo pfalela ya nchumu eka nkarhi wo karhi ehansi ka swiyimo swo hambana swa mbango.
2. Ku hisa ka brittleness .
ASTM D 2137 yi hlamusela mahiselo ya brittleness tani hi mahiselo yale hansi swinene lawa rhaba ya vulcanized yingata kombisa ku tshoveka kumbe ku phatluka ehansi ka swiyimo swa nkucetelo lowu boxiweke. Ntlhanu wa swikombiso swa rhaba swa xivumbeko lexi vekiweke ka ha ri emahlweni swi lulamisiwa, swi vekiwa eka kamara kumbe mati ya le xikarhi, leswi endliwaka eka mahiselo lama vekiweke ku ringana 3±0.5min, ivi swi nyikiwa rivilo ra ku khumbeka ra 2.0±0.2m/s. Swikombiso swi susiwa kutani swi endliwa xikambelo xa ku khumbeka kumbe ku phatluka. Xikombiso xa susiwa kutani xi kamberiwa kuva xiva na nkucetelo kumbe ku tshoveka, hinkwaswo swinga onhakanga. Xikambelo lexi xi phindhiwile kuya fika eka mahiselo ya brittleness - mahiselo yale hansi swinene lawa kungari na ku tshoveka loku aku kumeka aya ri ekusuhi swinene na 1°C.
3. Seti ya ntshikelelo wa mahiselo ya le hansi na ku nonoka ka mahiselo ya le hansi .
Endlelo ro kambela ra low-temperature compression set ri le kusuhi swinene na leri ra standard compression set, handle ka leswaku mahiselo ya lawuriwa hi ndlela yin’wana ya eneji, kufana na ayisi yo oma, nitrogen ya mati, kumbe tindlela ta michini, naswona ntikelo wu le ndzeni ka ± 1°C ya mahiselo lawa ya vekiweke ka ha ri emahlweni. Endzhaku ka ku vuyiseriwa eka xitirhisiwa xo khoma, xikombiso xitlhela xivekiwa eka mahiselo yale hansi lawa ya vekiweke naswona xivumbiwile kuya eka diameter ya 29 mm xikan’we na vukulu bya 12.5 mm. Low-temperature compression set i ndlela yo ka yi nga kongomanga yo pfalela switirhisiwa swa nkatsakanyo lowu ku vulavuriwaka ha wona. Compressive stress relaxation i ndlela yo kongoma naswona yi ta xopaxopiwa endzhaku. Ku tiya ka mahiselo yale hansi switlhela switala ku kumiwa hiku tirhisa xivumbeko xa vulcanized compression set (29mm x 12.5mm), kambe swikamberiwile nakambe eka vulawuri bya mahiselo yale hansi, leswi fanaka na leswiya swa compression set, kutani nakambe eka mahiselo lawa ya fanaka na mahiselo lawa ya vekiweke. Ku nonoka na ku tshikileriwa ka mahiselo yale hansi swi khumbeka hiku kongoma hiku kufumela, kambe na hi mboyamelo wa polymer kuva yi crystallize, laha mpimo wa crystallization wu titshegeke hi mahiselo, xikombiso, CR yi crystallizes hiku hatlisa swinene kwalomu ka -10°C, kutani yihunguteka eka mahiselo yale hansi, ngopfu ngopfu hikokwalaho ka ku nga fambi ka swiphemu swa polymer chain (the molecular chains freeze before rearrangement).
4. Gehman Ku tiya ka mahiselo ya le hansi .
ASTM D 1053 yi hlamusela ndlela ya ku nonoka ka mahiselo ya le hansi hi ndlela leyi landzelaka: nxaxamelo wa swikombiso swa polymer leswi olovaka swi namarhetiwa hi ndlela leyi nga cinciki eka waya lowu nga na torsional constant leyi tivekaka, naswona makumu man’wana ya waya ya khomanisiwile na nhloko ya torsion leyi kotaka ku pfumelela waya ku soholotiwa. Ti specimens ti nyuperisiwa eka heat transfer medium eka mahiselo yokarhi yale hansi ka ntolovelo, hi nkarhi walowo nhloko ya torsion yi soholotiwile hi 180°, kutani swikombiso swi soholotiwile hi nhlayo (ehansi ka 180°) leyi titshegeke hi inverse ya specimen’s flexibility na stiffness. Kutani tirhisa nhlayo ya goniometer ku kumisisa nhlayo ya specimen twist, angle ya twist na ku tiya ka nchumu wa rhaba. Mahiselo ya sisiteme ya tlakusiwa hakatsongotsongo eka ndzhawu leyi, naswona plot ya angle ya twist eka mahiselo ya kumeka. Mahiselo lawa eka wona modulus yifikaka eka T2, T10, na T100 hi ntolovelo ya rhekhodiwa tani hi leyi ringanaka na nhlayo ya modulus eka mahiselo ya kamara.
5. Ku tlheriseriwa endzhaku ka mahiselo ya le hansi (Xikambelo xa TR) .
Xikambelo xa TR xi tirhisiwa ku kambela vuswikoti bya xikombiso eka xiyimo xa tensile loko compressive permanent deformation na compressive stress relaxation leswi kumiwaka hi ntshikelelo wa ntshikelelo swi tirhisiwa ku kumisisa switandzhaku swa mahiselo ya le hansi. Tani hileswi swinga funengetiwa khale, ti polymers totala tofana na NR na PVC tita crystallize eka mahiselo yale hansi, kambe ku ololoka swinga tlhela swi crystallize, leswinga endla leswaku kuva na swilo swo engetelela loko ku langutiwa swivumbeko swa mahiselo yale hansi. Eka swikombelo swa nkambisiso swofana na exhaust suspension, TR ehansi ka tension yifaneleka swinene naswona yitirhisiwa ngopfu. Eka xikambelo lexi, xikombiso xi lehe (hakanyingi hi 50% kumbe 100%) naswona xi titimela eka xiyimo xo leha. Xikombiso xa humesiwa, hi nkarhi walowo mahiselo ya tlakusiwa hi mpimo lowu vekiweke kuva ku pimiwa ku vuyiseriwa ka xikombiso, ku leha ka kuhunguteka ku pimiwa naswona ku leha ka yona ku rhekhodiwa. Mahiselo lawa xikombiso xihungutekaka eka wona hi 10%, 30%, 50%, na 70% hi ntolovelo ya xiyiwa tani hi TR10, TR30, TR50, na TR70. TR10 yi fambelana na mahiselo ya brittleness; TR70 yi fambelana na ku onhaka ka nkarhi hinkwawo ka xikombiso eka ntshikelelo wa mahiselo ya le hansi; naswona ku hambana exikarhi ka TR10 na TR70 ku tirhisiwa ku pima crystallization ya xikombiso (loko ku hambana ku ri kukulu, mboyamelo wa crystallize wu va wukulu).
6 . Ku olovisiwa ka ntshikelelo wa ntshikelelo wa mahiselo ya le hansi (CSR) .
Xikambelo xa CSR xinga tirhisiwa ku endla vuprofeta mayelana na matirhelo na vutomi bya switirhisiwa swo pfalela. Loko nkatsakanyo wa elastomeric wu nyikiwa ku onhaka loku nga cincekiki, matimba lama hlanganisiweke ya tumbuluxiwa, naswona vuswikoti bya swilo swo hlayisa matimba lawa endzeni ka mpimo wo karhi wa mbango byi pima vuswikoti bya yona byo pfalela. Havumbirhi bya tindlela ta nyama na ti khemikhali ti hoxa xandla eka ku olovisiwa ka ntshikelelo, hi ku ya hi nkarhi na mahiselo, nchumu wun’we wu ta lawula, ku olovisiwa ka miri ku voniwa eka mahiselo ya le hansi, hi ku hatlisa endzhaku ka ntshikilelo lowu nyikiweke, leswi yisaka eka ku lulamisiwa nakambe ka tikheteni na ku cinca eka swiphemu swa rhaba-filler na filler-filler, naswona ku wisa ka sisiteme yo susa ntshikelelo swa tlhelela endzhaku. Eka mahiselo yale henhla, xivumbeko xa ti khemikhali xi boha mpimo wa ku wisa, loko maendlelo ya physical se yari matsongo naswona ku olovisiwa ka ti khemikhali swinga hundzuki, leswi yisaka eka ku tshoveka ka ti chain xikan’we naku cross-linking reactions. Ku rhendzeleka ka mahiselo kumbe ku tlakuka ka mahiselo hi xitshuketa swinga va na mbuyelo eka ku olovisiwa ka ntshikelelo eka ti elastomers. Hi nkarhi wa xikambelo xa CSR, xikombiso xa xikambelo xi vekiwa .
Hi nkarhi wa ku kamberiwa ka CSR, ku olovisiwa ka ntshikelelo ku engeteleka loko xikombiso xa xikambelo xi endliwa eka mahiselo lama tlakukeke. Loko ku olovisiwa ka ntshikelelo ku humelela eku sunguleni ka xikambelo, nhlayo ya ku wisa loku engetelekeke yi tlakuka ku sungula naswona yi na ntikelo lowukulu hi nkarhi wa xirhendzevutana xo sungula. Eka xiphemu lexikulu xa xikambelo xa ten. -20 ~ 110 °C cycle ya 24h, nkarhi hinkwawo wa xikambelo eka mahiselo ya xikambelo, mahiselo ya xikambelo, ku kumiwa ka matimba loku yaka emahlweni. Ku pima ka matimba ku endliwa hi ku ya emahlweni eka nkarhi hinkwawo wa xikambelo eka mahiselo ya xikambelo.
7. Vuyelo bya nhlayo ya ethylene .
7.1 Nhlayo ya ethylene yina nkucetelo lowukulu eka matirhelo ya mahiselo yale hansi ya ti polymers ta EPDM. Ti polymers letingana nhlayo ya ethylene kusuka eka 48% kuya eka 72% ti kamberiwile ehansi ka swivumbeko swa khwalithi yale henhla swa ku pfalela. Hinkwaswo swi kongomisa eka ku hunguta ku hambana ka mooney viscosity hiku nghenisa ENB eka ti polymers leti to hambana.
EPDM rubber yina amorphous loko ethylene/propylene ratio yiringana naswona ku hangalaka ka ti monomers timbirhi eka polymer chain swiri random. EPDM leyingana 48% na 54% wa ethylene a yi crystallize eka kumbe ehenhla ka mahiselo ya kamara. Loko nhlayo ya ethylene yifika eka 65%, ntlhandlamano wa ethylene wusungula ku tlakuka ka nhlayo na ku leha naswona swinga endla ti crystals, leswi voniwaka eka tinhlohlorhi ta crystallization eka ti curve ta DSC kwalomu ka 40°C. Loko DSC yi ri yikulu, yi va yikulu, tikristale leti vumbekaka ti va tikulu.
7.2 Ku engetela eka mbuyelo wa nhlayo ya ethylene eka swivumbeko swa mahiselo ya le hansi leswi ku buriweke ha swona endzhaku, vukulu bya crystallite byi khumba ku olova ka ku hlanganisiwa na ku lulamisiwa ka swihlanganisi leswi nga na tikristale. Loko sayizi ya crystallite yiri yikulu, ntirho wotala wa ku hisa na shear wulaveka eka xiteji xa mixing kuva wu hlanganisa polymer hiku hetiseka na swiphemu swin’wana. Matimba ya rhaba yoka yanga swekiwanga ya ti compounds ta EPDM ya tlakuka loko ku tlakuka nhlayo ya ethylene. Eka swivumbeko swa ku pfalela laha mbuyelo wa nhlayo ya ethylene wu pimiweke, ku tlakuka ka nhlayo ya ethylene kusuka eka 50% kuya eka 68% swiendle leswaku kuva na ku tlakuka ka mune wa mune eka matimba ya rhaba. Ku tiya ka room-temperature switlhela swikula loko ku tlakuka ka ethylene content. Ribuwa ra ku tiya ka amorphous polymer adhesive i 63°, kasi ku tiya ka ribuwa ra polymer leri nga na nhlayo ya le henhla ya ethylene i 79°. Leswi swivangiwa hiku tlakuka ka ntlhandlamano wa ethylene, ku tlakuka ka crystallization eka adhesive, xikan’we naku tlakuka loku fambelanaka na ti thermoplastic polymers.
7.3 Loko ku tiya ku pimiwa eka mahiselo yale hansi, kuhambanana na ti polymers letingana nhlayo yale henhla ya ethylene, ti amorphous polymers ti kombisa ku cinca kutsongo eka ku tiya, laha ku cinca ka ku tiya ka nhlayo yale henhla ya ethylene aswi kombisi xivumbeko xa linear naswona ku tiya ka le henhla switshama swiri e henhla eka mahiselo yale hansi.
7.4 Seti ya ntshikelelo yi titshege ngopfu hi mahiselo ya xikambelo. Loko swikamberiwa eka 175°C, akuri na ku hambana eka compression set exikarhi ka yin’wana na yin’wana ya ti polymers (set yikuceteriwa hi dizayini ya compound xikan’we naku hlawuriwa ka vulcanization system). Endzhaku ka ku n’oka ka ti ethylene crystals, polymer yi kombisa xivumbeko xa amorphous, naswona leswaku kuta kamberiwa mbuyelo wa nhlayo ya ethylene, swikambelo swi endliwile eka 23°C. Ti polymers letingana nhlayo yale henhla ya ethylene swile rivaleni leswaku tina deformation yale henhla ya nkarhi hinkwawo (ku tlula kambirhi), naswona mbuyelo wa nhlayo ya ethylene wukulu swinene loko wu kamberiwa eka -20°C na -40°C. Ti polymers letingana kutlula 60% wa ethylene tina deformation yale henhla ya permanent (>80%); Eka -40°C, i ti polymers ntsena leti nga na amorphous ntsena leti nga na deformation ya le hansi ya nkarhi hinkwawo (17%).
7.5 Vuyelo bya nhlayo ya ethylene eka ku nonoka ka mahiselo yale hansi kusuka eka swikambelo swa Gehman. Loko ku nyikiwa mahiselo, loko khoneni yiri e henhla, ku tlakuka ka ku tiya ka le hansi (kumbe ku tlakuka ka modulus). Eka mahiselo yale hansi, modulus ya stiffness yi tlakuka swinene loko ku tlakuka ka ethylene content. Eka ti amorphous polymers, T2 i -47°C, kasi nhlayo yale henhla ya ethylene polymer yina T2 ya -16°C ntsena.
7.6TR Ku pima ku vuyiseriwa ka ku hunguteka ka swikombiso Endzhaku ka ku titimela ka ku andzisiwa, nhlayo ya ethylene yi na vuyelo lebyikulu eka ndlela ya xikambelo, leyi nakambe yi fanaka na xikambelo xa Gehman.
Leswi swi fana na xikambelo xa Gehman. Ku hunguteka (%) ka ti polymers to hambana hambana ta hambana tani hi ntirho wa mahiselo, laha ti amorphous polymers tingana ku vuyelela ka le henhla ka ku hunguteka eka mahiselo yale hansi; Hambiswiritano, tani hileswi swinga languteriwaka, ku vuyelela ku hohloka loko nhlayo ya ethylene yi tlakuka eka mahiselo lawa ya nyikiweke.
Ku hola ku hohloka. Nhlayo ya TR10 yihambana kusuka eka -53°C eka ti amorphous polymers kuya eka -28°C eka ti polymers letingana nhlayo yale henhla ya ethylene.
7.7 Xirhendzevutani xa Ntshikelelo wa Ntshikelelo wa Ntshikelelo (CSR) .
Ndzendzeleko. Cinca cinca ti compounds, ti pfumelela ku wisa eka 25°C kuringana 24 h, kutani u ti veka eka xirhendzevutani xa mahiselo lawa ya sukaka eka -20°C kuya eka 110°C hiku tsekatseka kuringana 24 h. Loko yi tshikileriwa rosungula, endzhaku ka nkarhi wa equilibration, crystalline polymer E yina ku lahlekeriwa lokukulu ka ntshikelelo kutlula polymer ya amorphous, naswona loko yi ehlisiwile kuya eka -20°C matimba yo pfalela ya ti polymers letimbirhi ya hunguteka, kasi polymer ya amorphous A yina ku khomiwa lokukulu ka ntshikelelo (higher F/F0). Ku hisa nkatsakanyo kuya eka 110°C swi vuyisele matimba ya yona yo pfalela, naswona loko yi vuyisiwile ehansi eka -20°C, matimba yo pfalela lawa ya saleke ya crystalline polymer a yari ehansi ka 20% wa nkoka wa yona, lowu hi ntolovelo wu tekiwaka wuri ehansi swinene eka switirhisiwa swotala, laha polymer ya amorphous yi hlayisaka ku tlula 50% wa matimba ya yona yo pfalela, naswona polymer ya amorphous nakambe yiri na polymer ya crystalline. Xirhendzevutana lexi landzelaka xi humese makumu lama fanaka. Swile rivaleni leswaku ti amorphous polymers ti tlakukile eka switirhisiwa swo pfalela laha ku lavekaka matirhelo yale henhla na mahiselo yale hansi.
8. Vuyelo bya nhundzu ya diolefin .
Ku nyika ndzhawu leyinga saturated leyi lavekaka eka vulcanization, ti non-conjugated diolefins tofana na ENB, HX na DCPD ti cheriwa eka ti ethylene propylene polymers. Bond yin’we ya double yi endla reacts eka polymer matrix, kasi ya vumbirhi yi tirha tani hi complement eka polymerized molecular chain naswona yi nyika vulcanization point ya sulphur yellow vulcanization. Mbuyelo wa ENB wu kamberiwile eka ti windshield (rain) bar profiles. Ti polymers letingana 2%, 6% na 8% ENB ti pimanisiwile.Ku engeteriwa ka ENB akuri na mbuyelo lowukulu eka swihlawulekisi swa vulcanization xikan’we na crosslink density. Modulus yi tlakukile loko elongation yihunguteka swinene. Ku tiya ku tlakukile naswona set ya compression yi antswile hi nkarhi wa ku tlakuka ka mahiselo. Loko nhlayo ya ENB yi ya yi andza, nkarhi wo charring wu ya wu koma.
ENB i nchumu wa amorphous, naswona loko yi cheriwa eka backbone ya polymer, yi kavanyeta ku crystallization ka xiphemu xa ethylene xa polymer, leswaku ti polymers letingana ethylene leti fanaka tinga kumiwa, naswona nhlayo yale henhla ya ENB yi antswisa swivumbeko swa mahiselo yale hansi. Eka mahiselo ya kamara, nhlayo yale henhla ya ENB yi antswisa nyana ntshikelelo lowu vekiweke hikokwalaho ka ku antswisiwa ka crosslink density. Kambe eka mahiselo yale hansi, compression set ya ti polymers letingana ENB yale henhla yi antswa swinene kutlula ya ti polymers letingana 2% ENB content. Vuyelo bya nhlayo ya ENB eka mahiselo ya brittleness, ku tlheriseriwa endzhaku ka mahiselo, na xikambelo xa Gehman a swi kombisanga ku hambana lokukulu eka mahiselo ya brittleness exikarhi ka ti polymers hi ku angarhela, naswona eka xikambelo xa Gehman na xikambelo xa TR, polymer yin’wana na yin’wana yi kombisile ku antswisiwa eka swivumbeko swa mahiselo ya le hansi na nhlayo ya ENB leyi engetelekaka.
9. Vuyelo bya Mooney Viscosity eka swivumbeko swa mahiselo ya le hansi .
Switiveka kahle leswaku Mooney viscosity (molecular mass) yina mbuyelo lowukulu eka mahanyelo ya processing ya ti elastomers. Eka switirhisiwa swa extrusion na molding eka switirhisiwa swa extrusion na molding, swina nkoka ku hlawula compound leyingana mooney viscosity value leyi faneleke. Hiku tirhisa xivumbeko lexi fanaka lexi tirhisiweke ku lavisisa mbuyelo wa monomer ya vunharhu, ENB, eka swivumbeko swa mahiselo yale hansi ku kambela ku tsindziyela ka mooney, ti polymers letingana mooney viscosities ta 30, 60, na 80 ti pimanisiwile, naswona mooney viscosity ya ti compounds yi andzile loko mooney viscosity ya ti polymers leti tirhisiweke leti tirhisiweke. Matimba ya tensile, modulus, na matimba ya rhaba yoka yanga swekiwanga ya tlakukile loko ku engeteleriwa mooney viscosity. Vuyelo bya mooney viscosity eka swivumbeko swa mahiselo yale hansi ya EPDM aswiri swa nkoka. Hambiswiritano, compression permanent deformation eka mahiselo ya kamara, -20°C na -40°C yi tlakuka loko ku tlakuka molecular mass. Hambiswiritano, ku tshikileriwa loku vekiweke eka mahiselo ya kamara, -20°C na -40°C a swi cincanga ngopfu loko ku tlakuka ka molecular mass, kasi compression leyi vekiweke eka mahiselo yale henhla (175°C) yi kombisile ku cinca kun’wana eka ti viscosities tale henhla ta mooney ta swinamarheti swa EPDM.
10. Mahetelelo .
Nhlayo ya ethylene na diolefin yina mbuyelo lowukulu eka matirhelo ya EPDM elastomers eka switirhisiwa swa mahiselo yale hansi, laha ti polymers letingana low ethylene ti tirhaka kahle na ti polymers letingana nhlayo yale henhla ya diolefin leyi antswisaka hikokwalaho ka ku kavanyetiwa ka crystallization ya xiphemu xa ethylene xa polymer. Ti polymers tale hansi ta ethylene tifanele kutirhisiwa loko matirhelo ya mahiselo yale hansi yari xipimelo.
