Cov ntu hauv qab no piav qhia txog kev hloov pauv viscoelastic ntawm polyurethane ua npuas ncauj theem los ntawm theem, kev sib txuas cov txheej txheem tshuaj tiv thaiv, cov xwm txheej pom tau, thiab kev txiav txim siab tsim khoom.

1. Cov Ntsiab Lus Tseem Ceeb

1. Qhov nplaum

Qhov viscosity sawv cev rau qhov tsis kam ntawm cov khoom siv kom ntws thiab qhia txog nws tus cwj pwm viscous. Qhov viscosity siab dua txhais tau tias qhov ntws tsis zoo.

2. Kev ywj pheej

Elasticity txhais tau hais tias cov khoom siv muaj peev xwm rov qab tau nws cov duab qub tom qab deformation. Elasticity ntau dua ua rau muaj kev tiv thaiv zoo dua rau kev deformation thiab kev tawg ua npuas ncauj.

3. Gel Point

Lub ntsiab lus gel yog qhov kev hloov pauv tseem ceeb uas lub kaw lus hloov pauv ntawm cov kua dej ntws mus rau cov khoom khov uas tsis ntws. Nws yog qhov chaw faib tseem ceeb tshaj plaws hauv cov txheej txheem ua npuas dej.

4. Qhov Sib Txawv Tag Nrho

Thaum lub sijhawm ua npuas dej, qhov viscosity txuas ntxiv nce ntxiv, thaum elasticity maj mam txhim kho los ntawm qhov tsis muaj zog heev mus rau qhov tseem ceeb. Tom qab gelation, elasticity dhau los ua tus yam ntxwv tswj hwm ntawm lub kaw lus.

2. Kev Hloov Pauv Viscoelastic los ntawm Theem Ua Npuas Ncauj

Theem 1: Theem Sib Tov Pib (Lub Sijhawm Pib Ua Ntej Lub Sijhawm Ua Kom Qab Zib)

Xeev

Cov Polyol, isocyanate, thiab cov khoom ntxiv tau sib xyaw ua ke lawm. Cov tshuaj lom neeg ua haujlwm qeeb qeeb, cov pa roj tsawg heev, thiab lub kaw lus tseem yog cov kua dej sib xyaw.

Cov yam ntxwv ntawm viscoelastic

• Cov viscosity qis thiab flowability zoo heev.
• Yuav luag tsis muaj elasticity.
• Nyob rau hauv lub zog sab nraud, cov khoom ntws tau yooj yim thiab deformation tsis tuaj yeem rov qab tau.

Ua rau muaj kev hloov pauv

Cov saw hlau molecular tseem tsis tau tsim cov kev sib txuas tseem ceeb. Qhov nrawm ntawm NCO-OH tseem qis, thiab tsis muaj lub network polymer tau tsim.

Kev Soj Ntsuam Txog Kev Tsim Khoom

Cov khoom sib tov zoo li pob tshab los yog tsuas yog me ntsis mis nyuj thiab ntws tau yooj yim.

Theem 2: Theem Qab Zib (Kev Pib Ua Npuas Ncauj)

Xeev

Cov kev sib xyaw ua ke sai dua. Dej sib xyaw nrog isocyanate los tsim cov CO₂ ntau heev. Lub kaw lus hloov mus ua dawb, cov npuas me me tshwm sim, thiab kev nthuav dav pib.

Cov yam ntxwv ntawm viscoelastic

• Viscosity nce sai sai thaum oligomers thiab cov saw hlau ntev dua tsim.
• Qhov elasticity tsis muaj zog pib tshwm sim vim yog kev tsim cov kev sib koom ua ke ua ntej.
• Lub kaw lus tseem nyob ruaj khov thiab txuas ntxiv ntws thiab ncab.

Qhov Tseem Ceeb

Cov npuas dej pheej tsim thiab loj hlob tuaj. Lub kaw lus no feem ntau siv nws cov viscosity los qhwv cov npuas roj thiab tiv thaiv cov roj tawm.

Theem 3: Theem Sawv (Lub Sijhawm Ua Npuas Ncauj Ua Ntej Gelation)

Xeev

Cov kev ua haujlwm nrawm nrawm mus txog qhov siab tshaj plaws. Cov pa roj ntau heev raug tsim tawm, cov npuas dej nthuav dav sai sai, thiab cov hlwb loj hlob sai. Qhov no yog theem tseem ceeb tshaj plaws rau kev tsim npuas dej.

Cov yam ntxwv ntawm viscoelastic

• Viscosity tseem pheej nce ntxiv.
• Kev ntws dej txo qis heev.
• Cov kev sib txuas ua ke ua rau muaj zog, ua rau elasticity nce sai.
• Tus cwj pwm viscoelastic ua rau pom tseeb dua, maj mam hloov mus rau elastic dominance.
• Cov khoom siv tsim lub zog tensile thiab tiv taus kev tawg.

Thaum ncab, cov ua npuas dej yuav hloov pauv tab sis rov zoo li qub ib nrab thaum lub zog raug tshem tawm. Cov npuas dej uas loj hlob tseem ruaj khov hauv lub matrix.

Cov Txheej Txheem Cuam Tshuam

• Yog tias elasticity tsis txaus thiab viscosity dominates, cov npuas yuav tawg, sib koom ua ke, lossis vau.
• Yog tias qhov elasticity tsim tawm ntxov dhau los yog muaj zog dhau, kev nthuav dav ntawm ua npuas ncauj raug txwv, ua rau qhov ceev kawg siab dua.

Theem 4: Gel Point (Theem Hloov Pauv Tseem Ceeb)

Xeev

Ib lub network txuas peb sab tau tsim tsa lawm. Kev ua npuas thiab gelation mus txog qhov sib npaug, ua rau qhov no yog qhov tseem ceeb tshaj plaws hauv tag nrho cov txheej txheem.

Kev Hloov Pauv Viscoelastic

• Lub kaw lus poob nws lub peev xwm los ntws.
• Qhov viscosity pom tseeb mus txog infinity.
• Elasticity ua lub ntsiab tseem ceeb.
• Kev deformation feem ntau yog elastic, nrog rau kev rov zoo sai tom qab compression lossis stretching.
• Cov qauv ntawm lub cell yuav ruaj khov mus tas li thaum cov phab ntsa ntawm lub cell khov kho.

Qhov Tseem Ceeb ntawm Kev Tsim Khoom

• Kev ua kom gelation thaum ntxov dhau tuaj yeem ua rau tsis nthuav dav thiab ua npuas dej ntau.
• Kev ua gelation uas tshwm sim lig dhau tuaj yeem ua rau poob roj, ua npuas ncauj ntsws, thiab tawg.

Theem 5: Kev Kho thiab Kev Loj Hlob (Tom Qab Gelation)

Xeev

Cov pab pawg tshuaj uas tseem tshuav tseem txuas ntxiv ua rau muaj zog ntxiv rau qhov sib txuas ntawm cov network. Kev nthuav dav ntawm cov ua npuas ncauj tsis ua haujlwm lawm, thiab cov khoom siv maj mam tawv.

Cov yam ntxwv ntawm viscoelastic

• Qhov ceev ntawm crosslink txuas ntxiv mus ntxiv.
• Kev ruaj khov maj mam nce siab.
• Elasticity stabilizes.

Rau cov ua npuas ncauj mos mos:

• Kev ywj pheej siab tseem khaws cia.
• Kev ua kom muaj zog thiab kev tawv tawv zoo raug tswj hwm.

Rau cov ua npuas ncauj khov kho:

• Kev ywj pheej txo qis.
• Cov khoom siv hloov mus rau qhov khov kho.
• Kev deformation ua ntau dua yas dua li elastic.

Thaum xub thawj, cov kev ntxhov siab sab hauv seem tab sis maj mam tso tawm thaum lub sijhawm kho, ua rau cov khoom viscoelastic ruaj khov.

Cov Kev Hloov Tom Qab

Tom qab kho kom zoo ntawm qhov chaw ib puag ncig, kev sib txuas ua tiav tag nrho, thiab cov khoom siv kho tshuab thiab viscoelastic tseem ruaj khov.

3. Cov Yam Tseem Ceeb Uas Cuam Tshuam Rau Kev Coj Tus cwj pwm Viscoelastic

1. Cov Catalysts (Qhov Tseem Ceeb Tshaj Plaws ntawm Kev Tswj Xyuas)

Cov Catalysts Tshuab

• Ua kom cov roj tsim sai dua.
• Txhawb kev txhim kho viscosity ua ntej.
• Ua kom cov npuas dej nthuav dav sai dua.

Cov tshuaj gel catalysts

• Ua kom cov tshuaj tiv thaiv crosslinking sai dua.
• Tsim kom muaj lub network elastic sai dua.
• Ua kom lub sijhawm luv dua ntawm cov gel.

Kev Tsis Sib Npaug ntawm Catalyst

Qhov sib npaug tsis zoo ntawm cov tshuaj blowing thiab gel catalysts cuam tshuam qhov kev sib phim foaming-gelation, distorts qhov viscoelastic profile, thiab tej zaum yuav ua rau ua npuas dej tawg, shrinkage, lossis cov qauv cell coarse.

2. Cov Khoom Siv Raw Kub

Kub dua

• Ua kom cov nqi tshuaj tiv thaiv tag nrho sai dua.
• Ua rau cov nqi ntawm viscosity thiab elasticity nce ntxiv.
• Ua rau muaj gelation ua ntej.

Kub qis dua

• Ua rau cov tshuaj tiv thaiv qeeb.
• Ua rau muaj kev nce ntxiv ntawm cov khoom viscoelastic.
• Ua rau qeeb qhov gelation thiab ua rau muaj kev pheej hmoo ntawm kev poob roj.

3. NCO Index (Isocyanate Index)

Cov NCO Index Siab

• Txhawb kom muaj zog dua crosslinking.
• Ua rau elasticity thiab rigidity sai dua.
• Tsim cov ua npuas ncauj uas tawg yooj yim dua.

Cov NCO Index Qis

• Ua rau muaj kev sib txuas tsis txaus.
• Ua rau cov elasticity tsis zoo thiab cov viscosity ntau dua.
• Tsim cov ua npuas ncauj mos dua nrog kev hloov pauv ntau dua thiab kev rov zoo tsis zoo.

4. Cov tshuaj Surfactants thiab Fillers

Cov tshuaj silicone surfactants

• Txhim kho kev tswj kev nruj ntawm cov interfacial.
• Txhawb kom muaj kev faib tawm viscoelastic thoob plaws hauv lub ua npuas ncauj.
• Tiv thaiv cov qauv cell tsis sib npaug uas tshwm sim los ntawm qhov sib txawv ntawm qhov viscosity lossis elasticity.

Cov khoom siv tsis muaj organic

• Ua kom qhov viscosity ntawm lub kaw lus pib nce ntxiv.
• Txo qhov elasticity.
• Ua kom cov qauv ua npuas ncauj ruaj khov dua tag nrho.

5. Cov Qauv Polyol

Cov Polyols Ua Haujlwm Siab

• Tsim cov tes hauj lwm sib txuas ua ke yooj yim dua.
• Ua kom elasticity thiab rigidity sai sai.

Cov Polyols Uas Muaj Molecular Hnyav, Cov Saw Ntev

• Tsim kom muaj cov txheej txheem sib txuas qeeb dua.
• Tsim kom muaj tus cwj pwm mos mos dua.
• Tswj cov viscosity rau lub sijhawm ntev dua.
• Yog cov yam ntxwv ntawm cov qauv ua npuas ncauj uas yoog tau.

4. Cov Lus Qhia Tseem Ceeb: Tag Nrho Cov Qauv Viscoelastic Thoob Plaws Foaming

Hauv qhov tseem ceeb, tag nrho cov txheej txheem ua npuas ncauj yog qhov kev hloov pauv rheological uas lub kaw lus hloov pauv los ntawm ib qhokua nplaum nplaum xwbmus rau hauv ib qhopeb-seem crosslinked elastomeric network.

Qhov sib npaug ntawmua npuas ncauj nthuav dav thiab gelation, raws li tau pom los ntawm kev hloov pauv ntawm cov khoom viscoelastic ntawm lub kaw lus, ncaj qha txiav txim siab qhov kawg ua npuas ncauj qauv, qhov ruaj khov ntawm qhov ntev, thiab tag nrho cov khoom zoo.