Yog li cas vinyl acetate-ethylene copolymer tiv thaiv rau kev nyuag hauv qhov cua sov

Paub txog kev nyuaj ntawm qhov cim ntsuas hauv vinyl acetate–ethylene copolymers

Kev nqis qhov tshuaj ntawm cov khoom sib tw yog qhov kev ploj tsuas yuav tsum tau ua kom zoo—tsis yog txaus rau kev nqis qhov tshuaj xwb, tabim yog qhov kev ploj ntau yam uas muaj kev txuas ntxiv rau qhov kev ploj ntawm qhov kev ua haujlwm thiab qhov kev ploj ntawm qhov kev ua haujlwm uas pab tshem tawm kev nyab xeeb thiab kev tswj hwm rau kev tshem tawm thaum cov khoom tau sau los yog ua haujlwm hauv qhov cua ntsaum (Tg). Rau cov khoom sib tw polyethylene, kev ua haujlwm hauv qhov cua ntsaum ntev yuav pab cuam kev nqis qhov tshuaj hauv qhov kev ua haujlwm uas tsis muaj kev nqis qhov tshuaj, uas pab cuam kev nqis qhov tshuaj ntau dua thiab kev nqis qhov tshuaj ntau dua uas pab cuam kev nqis qhov tshuaj ntau dua thiab kev nqis qhov tshuaj ntau dua. Cov khoom sib tw Vinyl acetate–ethylene (VAE) tsis tuaj yeem pab cuam kev nqis qhov tshuaj no. Qhov kev nqis qhov tshuaj ntawm cov khoom sib tw vinyl acetate hauv qhov kev nqis qhov tshuaj ntawm cov khoom sib tw ethylene yuav pab cuam kev nqis qhov tshuaj hauv qhov kev nqis qhov tshuaj uas tsis muaj kev nqis qhov tshuaj, uas pab cuam kev nqis qhov tshuaj hauv qhov kev nqis qhov tshuaj uas tsis muaj kev nqis qhov tshuaj. Qhov kev nqis qhov tshuaj no yuav pab cuam kev nqis qhov tshuaj hauv qhov kev nqis qhov tshuaj uas tsis muaj kev nqis qhov tshuaj, uas pab cuam kev nqis qhov tshuaj hauv qhov kev nqis qhov tshuaj uas tsis muaj kev nqis qhov tshuaj—ua rau kev nyab xeeb thiab kev tswj hwm rau kev tshem tawm yuav tsum tau ua kom zoo hauv qhov kev nqis qhov tshuaj uas tsis muaj kev nqis qhov tshuaj, tsis yog kev nqis qhov tshuaj uas muaj kev nqis qhov tshuaj.

Kev txhawb nqa thiab kev tswj hwm: Yuav li cas cov khoom sib thooj ntawm vinyl acetate yuav ua rau Tg nyob hauv qhov ceev

Yuav li cas cov khoom sib thooj ntawm vinyl acetate yuav ua rau kev sib npaug ntawm ethylene tsis zoo thiab ua rau muaj ntau dua cov qhov tshwm sim uas tsis muaj khoom

Qhov ceev ntawm kev txhawb nqa thiab (Tg) yog qhov ceev uas cov khoom sib thooj yuav rov los ua rau muaj kev tswj hwm thiab kev tswj hwm rau kev sib npaug—qee yam uas muaj kev cuam tshuam loj rau kev siv hauv qhov hniav. Cov khoom sib thooj polyethylene tuaj yeem sib npaug raws li qhov ntsuas thiab qhov ntsuas, vim tias nws muaj cov kab laus thiab cov kab ntsuas, uas tsis muaj qhov tshwm sim uas tsis muaj khoom. Thaum muaj cov khoom sib thooj ntawm vinyl acetate, nws yuav ua rau qhov sib npaug tsis zoo: cov kab laus ntawm acetate yog qhov ua rau cov kab laus ntawm ethylene tsis tuaj yeem sib npaug raws li qhov ntsuas thiab qhov ntsuas. Qhov no yuav ua rau muaj ntau dua cov qhov tshwm sim uas tsis muaj khoom thaum muaj cov kab laus, uas yuav pab tau cov kab laus sib npaug raws li qhov ntsuas thiab qhov ntsuas. Vim li no, qhov ceev ntawm kev txhawb nqa thiab yuav nyob hauv qhov ceev, tsis muaj kev siv cov khoom sib thooj, thiab tsis muaj kev cuam tshuam rau kev siv hauv lub neej.

DMA thiab DSC tshuaj xyuam: Tg txo los ntawm −25 °C (LDPE) rau −15 °C–−5 °C hauv 18–28 wt% vinyl acetate–ethylene copolymers

Dynamic Mechanical Analysis (DMA) thiab Differential Scanning Calorimetry (DSC) muab cov lus txhais tseeb thiab tseeb tshaj plaws rau qhov Tg txo no. Thaum low-density polyethylene (LDPE) muaj Tg nyob rau hauv −25 °C, VAE copolymers uas muaj 18–28 wt% vinyl acetate muaj qhov txo tshaj plaws thiab sib koom nrog qhov kev sib piv—rau nyob rau hauv −15 °C thaum muaj 18 wt% thiab rau hauv −5 °C thaum muaj 28 wt%. DSC traces muab cov kev hloov dua uas muaj qhov loj dua thiab tsis txaus, uas qhia tias muaj qhov crystallinity txo dua thiab muaj qhov heterogeneity loj dua hauv amorphous phase. Qhov hloov no muaj kev cuam tshuam zoo tshaj plaws: cov khoom yuav tsoo nyob saum Tg ntawd—and thus retains flexibility thiab impact resistance—at temperatures where LDPE would be brittle. Qhov sib koom yog qhia tshaj plaws hauv qab no.

Kev tswj hwm ntawm cov qhov chaw ntsuas: Qhov tsis ua kom muaj kev tswj hwm ntawm kev ua cov qhov chaw ntsuas yog qhov uas pab txhawj rau kev ua haujlwm ntawm kev ua haujlwm hauv qhov hluav taws fab

Cov yam ntxwv ntawm vinyl acetate ua rau kev ua cov yam ntxwv ntawm ethylene tsis loj, thiab ua rau tsis muaj kev ua cov yam ntxwv ntawm lamellar hauv qhov hluav taws fab tsis zoo li 0 °C

Kev nyab xeeb hauv qhov hluav taws fab ntawm cov VAE copolymers muaj kev sib koom los ntawm kev tshem tawm qhov kev ua cov yam ntxwv ntawm polyethylene. Cov yam ntxwv ntawm ethylene uas muaj lub cev ntev thiab tsis muaj qhov kub tshem tawm yuav tshem tawm mus rau hauv cov yam ntxwv ntawm lamellae uas muaj kev tswj hwm thiab muaj kev tswj hwm zoo—qhov uas ua rau qhov hluav taws fab tsis zoo thiab ua rau kev tshem tawm. Tiamsis, cov yam ntxwv ntawm vinyl acetate yog qhov uas muaj kev tshem tawm hauv qhov kev ua yam ntxwv: cov yam ntxwv ntawm acetate uas muaj lub cev loj yuav tshem tawm rau kev ua cov yam ntxwv ntawm ethylene—qhov uas muaj kev tswj hwm zoo rau kev ua cov yam ntxwv ntawm crystal. Thaum qhov hluav taws fab yuav tshem tawm hauv qhov hluav taws fab tsis zoo li 0 °C, qhov kev tshem tawm no yuav tshem tawm rau kev ua cov yam ntxwv ntawm chain thiab kev ua cov yam ntxwv ntawm lamellar. Qhov uas muaj kev tswj hwm zoo yog qhov uas muaj kev tswj hwm zoo rau kev ua cov yam ntxwv ntawm free volume thiab kev tswj hwm zoo rau kev ua cov yam ntxwv ntawm segmental mobility—qhov uas pab txhawj rau kev ua haujlwm thiab tsis pab rau kev ua cov yam ntxwv ntawm crystalline uas muaj kev tswj hwm zoo thiab yuav tshem tawm.

Qhov data WAXD thiab SAXS: Qhov crystallinity tau qis (15–25%) thiab cov crystallites li cas nyob rau hauv qhov ntsuas qis dua thiab tsis muaj kev tswj hwm nyob rau hauv qhov ntsuas −20 °C/500 h

Wide-Angle X-ray Diffraction (WAXD) thiab Small-Angle X-ray Scattering (SAXS) paub tias qhov microstructural stability no nyob rau hauv qhov ntsuas qis dua uas yuav tsum tau ua kom zoo. Tom qab ntsuas rau −20 °C rau 500 teev, qhov grade 22 wt% vinyl acetate yuav muaj qhov crystallinity sib twb qis dua rau 15–25%, thaum LDPE muaj qhov crystallinity 45–55% nyob rau hauv qhov ntsuas zoo ib yam. SAXS paub tias muaj qhov sib txawv ntawm morphology: cov crystallites yog li cas nyob rau hauv qhov ntsuas qis dua, li cas nyob rau hauv qhov ntsuas qis dua thiab tsis muaj kev tswj hwm, thiab muaj qhov long-period spacing uas tsis muaj kev tswj hwm—qhov no paub tias qhov secondary crystallization tsis tau ua kom zoo. Tsis zoo li polyethylene, uas qhov lamellar thickening yuav ua rau qhov material tau qis dua, VAE muaj qhov nanostructure uas tau ua kom zoo rau kev pab tshuaj rau energy dissipation los ntawm shear yielding tsis yog brittle fracture. Qhov structural integrity no tau ua kom zoo rau kev ntsuas mechanical uas muaj kev sib twb nyob rau hauv industry-standard, xws li kev ntsuas DIN 53377 rau kev ntsuas flexible materials.

Kev nyuaj siab ntawm cov khoom sib twb hauv qhov cua ntev: Kev nyuaj siab thiab kev tiv thaiv rau kev pov tseg

Kev nyuaj siab Notched Izod (>)85%) hauv −30 °C, thaum LDPE tsis tuaj yeem txog 40%

Kev nyuaj siab yog qhov tseem ceeb tshaj plaws uas pab paub txog kev ua haujlwm ntawm cov khoom hauv qhov cua ntev. Hauv −30 °C, cov khoom LDPE yuav tsis tuaj yeem txog 40% ntawm kev nyuaj siab Notched Izod hauv qhov cua zoo. Ntawd yog qhov ua rau nws nyuaj heev thiab yuav pov tseg los ntawm kev siv, kev xa mus, lossis kev hloov qhov cua. Tsis tas li ntawd, cov VAE copolymers uas tau muab tshawb pom lawm yuav tuaj yeem txog 85% ntawm kev nyuaj siab tom qab muab tshawb pom hauv qhov cua zoo. Qhov sib txawv no yog los ntawm kev nyuaj siab thiab kev tiv thaiv rau kev pov tseg, uas pab cov khoom nyob hauv qhov cua ntev thiab tsis muaj kev pov tseg. Rau cov neeg tsim cov khoom rau hauv qhov cua ntev—los ntawm cov khoom rau hauv lub cua ntev ntawm lub vaj huam los ntawm cov khoom rau hauv lub cua ntev ntawm lub rooj—qhov kev nyuaj siab no yog qhov pab tau kev nyuaj siab thiab tsis muaj kev pov tseg.

Kev sib npaug ntawm ≥22 wt% Vinyl Acetate Content thiab 40% Ntau dua Notch Tensile Energy los ntawm LDPE nyob rau hauv −25 °C

Cov kev tswj hwm ntawm kev ua haujlwm yog ob qhov uas tuaj yeem muaj kev vam txog thiab kev ua hauj lwm. Thaum vinyl acetate content tau txog lossis ntau dua 22 wt%, VAE copolymers yuav muaj kev pab tau notch tensile energy tshwj xeeb rau 40% ntau dua LDPE nyob rau hauv −25 °C. Qhov no tsis yog kev puas tsuaj tshwj xeeb—nws qhia tias muaj kev cuam tshuam ntawm cov khoom siv uas muaj kev cuam tshuam rau kev tswj hwm ntawm kev tshuaj ntxiv, uas kev tswj hwm ntawm kev tshuaj ntxiv yog qhov tshwj xeeb. Hauv qhov kev ua haujlwm, acetate groups ua hauj lwm li cov khoom siv uas muaj kev cuam tshuam rau kev tswj hwm ntawm kev tshuaj ntxiv, uas tshem tawm kev tswj hwm ntawm kev tshuaj ntxiv thiab tshem tawm kev tswj hwm ntawm kev tshuaj ntxiv rau kev tswj hwm ntawm kev tshuaj ntxiv. Cov kev vam txog los ntawm cov neeg siv haujlwm (2023) tau qhia tias qhov kev pab tau no yog qhov tshwj xeeb rau kev tswj hwm ntawm kev tshuaj ntxiv nyob rau hauv kev siv haujlwm nyob rau hauv qhov cua ntsuag, xwb li cov khoom siv uas muaj kev tswj hwm ntawm kev tshuaj ntxiv thiab cov khoom siv uas muaj kev tswj hwm ntawm kev tshuaj ntxiv uas muaj kev tswj hwm ntawm kev tshuaj ntxiv thiab kev tswj hwm ntawm kev tshuaj ntxiv.

FAQ

Qhov twg yog kev tshuaj ntxiv nyob rau hauv qhov cua ntsuag rau cov khoom siv?

Kev tawm ntawm hluav taws xob yooj yim yog qhov kev txhawb nqa uas cov khoom siv ua los ntawm cov khoom siv tshuaj cua thiab kev txhawb nqa, uas pab txhawb rau kev txhawb nqa ntawm kev tswj hwm thiab kev tswj hwm rau kev tswj hwm, tshwj xeeb yog thaum muab tso cua thiab siv hauv qhov cua yooj yim tsis zoo li qhov cua yooj yim (Tg).

Cov khoom siv vinyl acetate yuav pab txhawb nqa qhov cua yooj yim (Tg) li cas?

Cov khoom siv vinyl acetate yuav pab txhawb nqa qhov cua yooj yim ntawm cov khoom siv ethylene copolymers los ntawm kev txhawb nqa kev tswj hwm ntawm polyethylene, kev txhawb nqa kev tswj hwm ntawm kev tswj hwm, thiab kev txhawb nqa kev tswj hwm ntawm kev tswj hwm hauv qhov cua yooj yim.

Cov khoom siv vinyl acetate muaj qhov kev txhawb nqa li cas rau kev tswj hwm ntawm kev tswj hwm hauv qhov cua yooj yim?

Cov khoom siv vinyl acetate yuav pab txhawb nqa kev tswj hwm ntawm cov khoom siv ethylene, kev txhawb nqa kev tswj hwm ntawm kev tswj hwm, thiab kev txhawb nqa kev tswj hwm ntawm kev tswj hwm, uas pab txhawb rau kev tswj hwm ntawm kev tswj hwm hauv qhov cua yooj yim.

Cov khoom siv VAE copolymers yuav pab txhawb nqa kev tswj hwm ntawm kev tswj hwm hauv qhov cua yooj yim li cas kom compared rau LDPE?

Hauv qhov cua −30 °C, cov khoom siv VAE copolymers yuav pab txhawb nqa ntau dua 85% ntawm kev tswj hwm ntawm Notched Izod impact strength, compared rau ntau dua 40% ntawm LDPE, uas pab txhawb rau kev tswj hwm ntawm kev tswj hwm hauv qhov cua yooj yim.

Yog li cas li 22% ntawm vinyl acetate muaj qhov tseem ceeb rau VAE copolymers?

Thaum muaj 22% ntawm vinyl acetate lossis ntau dua, VAE copolymers tau qhov kev sib thooj rau kev daws cov cuab yeej thiab kev tiv thaiv rau kev puas tsuaj nyob rau hauv qhov xim no.