Cov teebmeem ntawm cov qauv sib txawv ntawm cov khoom ntawm Polyurethane Elastomers
Muaj ntau ntau yam khoom siv raw ntawm polyurethane elastomers, muaj pes tsawg leeg thiab kev npaj ntawm pab pawg nyob rau hauv cov qauv macromolecular yog complex, thiab cov txheej txheem synthesis thiab ua cov txheej txheem ntawm polyurethane elastomers muaj ntau yam, uas constitutes lub complexity ntawm cov tshuaj qauv ntawm polyurethane elastomers thiab lub pom tseeb lub cev conformation. qhov sib txawv, ua rau muaj kev hloov pauv hauv cov khoom ntawm polyurethane elastomers.
Polyurethane elastomer yog siv rau hauv lub xeev ruaj khov, thiab nws lub zog txhua yam nyob rau hauv ntau lub zog sab nraud yog qhov tseem ceeb tshaj plaws ntawm nws qhov kev ua tau zoo. Feem ntau, polyurethane elastomers yog tib yam li lwm cov polymers, thiab lawv cov khoom muaj feem xyuam rau qhov hnyav molecular, intermolecular rog, ntu toughness, crystallization nyiam, branching thiab crosslinking, raws li zoo raws li txoj hauj lwm, polarity thiab loj ntawm substituents. Txawm li cas los xij, polyurethane elastomers txawv ntawm hydrocarbon-based (PP, PE, thiab lwm yam) polymers, thiab lawv cov qauv molecular yog tsim los ntawm cov mos mos (oligomer polyols) thiab ntu tawv (polyisocyanates, saw txuas ntxiv, thiab lwm yam). cross-linking agent, thiab lwm yam) blocks, lub zog electrostatic muaj zog heev ntawm nws cov macromolecules, tshwj xeeb tshaj yog nyob nruab nrab ntawm cov ntu nyuaj, thiab feem ntau ntawm cov hydrogen bonds feem ntau tsim. Qhov no muaj zog electrostatic quab yuam, ntxiv rau ncaj qha Ntxiv rau qhov cuam tshuam rau cov khoom siv kho tshuab, nws tseem tuaj yeem txhawb kev sib sau ua ke ntawm cov ntu nyuaj, tsim microphase sib cais, thiab txhim kho cov khoom siv kho tshuab thiab cov khoom kub thiab tsis kub ntawm elastomers.
1. Kev sib raug zoo ntawm cov khoom siv tshuab thiab cov qauv
Cov khoom siv ntawm polyurethane elastomer nyob ntawm seb qhov crystallization nyiam ntawm polyurethane elastomer, tshwj xeeb tshaj yog crystallization nyiam ntawm cov mos mos. Txawm li cas los xij, polyurethane elastomer yog siv nyob rau hauv lub siab elasticity, thiab crystallization tsis xav tau. Yog li ntawd, nws yog ib qho tsim nyog kom dhau cov qauv tsim thiab cov txheej txheem tsim pom qhov sib npaug ntawm elasticity thiab lub zog, kom cov polyurethane elastomer npaj tsis crystallize ntawm qhov kub thiab txias, muaj elasticity zoo, thiab muaj peev xwm crystallize sai heev thaum nws yog heev stretched, thiab Lub melting kub ntawm no crystallization yog nyob ib ncig ntawm chav tsev kub, thaum lub sab nraud quab yuam raug tshem tawm, lub crystal melts sai sai, thiab lub reversible siv lead ua qauv no zoo heev los txhim kho lub zog txhua yam ntawm polyurethane elastomer.
Txawm hais tias polyurethane elastomer tuaj yeem muaj qhov rov qab crystallization feem ntau yog nyob ntawm polarity, molecular hnyav, intermolecular quab yuam thiab tsis tu ncua ntawm cov qauv ntawm cov mos mos. Lub molecular polarity thiab intermolecular quab yuam ntawm polyester yog ntau dua li ntawm polyether, yog li lub zog txhua yam ntawm polyester polyurethane elastomer yog ntau dua li ntawm polyether polyurethane elastomer; cov pab pawg sab hauv cov ntu mos yuav txo cov crystallinity, uas yuav txo cov khoom ua haujlwm. Mechanical cwj pwm.
Cov qauv ntawm polyurethane nyuaj ntu kuj muaj qhov cuam tshuam ncaj qha thiab tsis ncaj rau cov khoom siv ntawm polyurethane elastomer. Feem ntau, cov tshuaj tsw qab diisocyanates (xws li MDI, TDI) loj dua ester diisocyanates (xws li HDI); diisocyanates nrog cov qauv symmetrical (xws li MDI) tuaj yeem muab polyurethane elastomer siab dua hardness, tensile zog thiab tsim kua muag; Cov nyhuv ntawm cov saw txuas ntxiv crosslinking tus neeg sawv cev qauv ntawm cov khoom siv ntawm lub elastomer zoo ib yam li cov diisocyanate.
2. Kev sib raug zoo ntawm cov cua sov thiab cov qauv
The thermal stability of polymers can be measured by softening temperature and thermal decomposition temperature. In general, the thermal decomposition temperature of polyurethane elastomers is lower than the softening temperature. Generally speaking, polyester polyurethane elastomers have better heat resistance than polyether polyurethane elastomers; for aromatic diisocyanates, the heat resistance sequence is PPDI>NDI>MDI>TDI.
3. Kev sib raug zoo ntawm kev ua haujlwm kub thiab cov qauv
Qhov kub tsis tshua muaj elasticity ntawm cov polymers feem ntau yog ntsuas los ntawm iav hloov qhov kub thiab txias coefficient (los yog embrittlement kub). Feem ntau, qhov kub tsis tshua muaj kev hloov pauv ntawm polyether polyurethane elastomer zoo dua li ntawm polyester.
4. Kev sib raug zoo ntawm cov dej tsis kam thiab cov qauv
Cov nyhuv dej ntawm polyurethane elastomers: dej plasticization (dej nqus dej) thiab dej degradation. Thaum tus txheeb ze av noo yog 100 feem pua: cov dej nqus tus nqi ntawm polyester polyurethane elastomer yog hais txog 1.1 feem pua, thiab cov kev kawm poob yog li ntawm 10 feem pua; Cov dej nqus dej ntawm polyether polyurethane elastomer yog li 1.4 feem pua, thiab kev ua haujlwm poob yog li 20 feem pua; Txawm li cas los xij, kev ruaj ntseg hydrolytic ntawm polyether polyurethane elastomers yog ntau dua li ntawm polyester polyurethane elastomers.
5. Kev sib raug zoo ntawm cov roj kuj thiab tshuaj lom neeg thiab cov qauv
Polyurethane elastomers muaj kev tiv thaiv zoo rau cov roj thiab cov kuab tshuaj tsis muaj polar. Feem ntau, polyester polyurethane elastomers muaj kev ua tau zoo dua hauv cov roj ua haujlwm dua li polyether polyurethane elastomers; siab dua qhov hardness ntawm polyurethane elastomer, qhov zoo dua cov roj kuj; Cov tshuaj tiv thaiv ntawm polycaprolactone polyurethane elastomers (xws li sulfuric acid, nitric acid, thiab lwm yam) kev ua tau zoo dua li lwm hom polyurethane. Lub zuag qhia tag nrho alkali tsis kam ntawm polyurethane elasticity thiab tsis kam mus rau lub zog polar solvents (xws li cyclohexanone, dej Tianna, thiab lwm yam) tsis zoo.
