Polylactic acid (PLA), raws li ib tug neeg sawv cev ntawm bio-raws li biodegradable plastics, yuav tsum tau ib tug systematic kev txiav txim siab- ua cov txheej txheem uas txiav txim siab yam xws li raw cov ntaub ntawv, molecular qauv, kev ua tau zoo indicators, As kev ua, thiab kawg - siv scenarios, es tsis yog ib tug txheej txheem. Cov ntaub ntawv sib txawv thiab cov qauv tsim ncaj qha cuam tshuam rau kev ua haujlwm, kev coj tus cwj pwm degradation, thiab cov txiaj ntsig ib puag ncig ntawm cov khoom. Yog li ntawd, yuav tsum tau tsim ib qho kev ntsuam xyuas kev tshawb fawb nyob rau hauv lub sij hawm xaiv cov khoom.
Ua ntej, qhov sib txawv ntawm cov khoom siv raw thiab cov txheej txheem synthesis txiav txim siab qhov kev ua tau zoo ntawm lub hauv paus cob. PLA tuaj yeem ua polymerized los ntawm L-lactic acid thiab D-lactic acid hauv qhov sib txawv. Homopolymer PLA nrog siab L- hom cov ntsiab lus muaj crystallinity siab, zoo thaum tshav kub kub tsis kam, thiab zoo rigidity, ua rau nws tsim nyog rau cov ntaub ntawv pov tseg, tshav kub- resistant ntim, thiab lwm yam kev siv uas yuav tsum tau zoo tu thiab luv luv - lub sij hawm siab - kub siv. Copolymer PLA (xws li PLLA-co-PDLA los yog random copolymer PLA), vim txo cov saw hlau molecular tsis tu ncua, qis crystallinity thiab melting point, thiab txhim kho yooj thiab pob tshab, yog qhov tsim nyog rau cov yeeb yaj kiab, ntim tau yooj yim, thiab cov khoom siv fiber ntau. Yog tias lactic acid tau los ntawm fermentation ntawm cov qoob loo ua liaj ua teb siv, qhov cuam tshuam ntawm cov khoom siv raw purity thiab residues ntawm kev ruaj ntseg thiab cov khoom xim yuav tsum raug txiav txim siab.
Qhov thib ob, qhov hnyav molecular thiab nws qhov kev faib tawm yog qhov ntsuas tseem ceeb rau kev xaiv cov khoom siv. Qhov hnyav molecular PLA muaj ntau dua txhua yam lub zog thiab kev cuam tshuam tsis kam, tab sis nws cov viscosity yaj nce raws li, xav tau cov cuab yeej ua haujlwm ntau dua thiab tsis muaj. Tsawg molecular yuag PLA muaj kev ua haujlwm zoo tab sis tuaj yeem cuam tshuam rau cov khoom siv kho tshuab thiab kav ntev. Resins nrog qhov nqaim molecular hnyav faib ua kom pom kev zoo sib xws thiab thermal stability thaum ua, txo cov khoom tsis xws luag. Yog li ntawd, thaum xaiv cov ntaub ntawv, qhov hnyav molecular thiab kev faib tawm yuav tsum sib npaug raws li cov khoom phab ntsa thickness, cov txheej txheem complexity, thiab cov txheej txheem tom ntej.
Thib peb, kev taw qhia txog kev hloov kho cov qauv nthuav dav daim ntawv thov ciam teb ntawm PLA. Ntshiab PLA muaj qhov tsis zoo hauv kev cuam tshuam, tiv thaiv tshav kub, thiab hydrolysis tsis kam, uas feem ntau tau them nyiaj los ntawm kev hloov kho: kev sib xyaw nrog polycaprolactone (PCL) tuaj yeem txhim kho qis dua -kub toughness; ntxiv natural fibers los yog inorganic fillers tuaj yeem txhim kho rigidity thiab seem stability; thiab kev sib xyaw nrog biodegradable elastomers tuaj yeem ua kom lub zog tsim kua muag thiab ductility. Tsis tas li ntawd, rau kev sib cuag zaub mov lossis kev siv kho mob, cov khoom siv ntxiv uas ua raws li cov kev cai cuam tshuam (xws li cov tshuaj nucleating, cov khoom siv hluav taws xob, thiab cov roj nplua nyeem) yuav tsum tau ua tib zoo xaiv kom tsis txhob muaj kev tsiv teb tsaws ntawm cov tshuaj phem.
Kev tswj hwm kev ua haujlwm degradation kuj yog qhov tseem ceeb hauv kev xaiv cov khoom siv. Tus nqi degradation ntawm PLA cuam tshuam los ntawm crystallinity, molecular hnyav, khoom morphology, thiab ib puag ncig tej yam kev mob. Cov khoom uas muaj crystalline ntau degrade qeeb dua nyob rau hauv ib puag ncig composting, thaum nyias -cov phab ntsa los yog ntxeem tau decompose sai dua. Yog tias daim ntawv thov ib puag ncig tsis muaj qhov kub thiab txias, cov av noo siab, thiab cov kab mob microbial, qhov ntev - yuav tsum tau ntsuas qhov kev pheej hmoo ntawm qhov seem. Yog tias tsim nyog, cov khoom siv nrog qeeb degradation los yog cov khoom sib xyaw nrog lwm cov biodegradable polymers yuav tsum raug xaiv kom sib npaug ntawm kev pab cuam lub neej thiab kev phooj ywg ib puag ncig.
Thaum kawg, tus nqi thiab cov saw hlau ruaj khov tsis tuaj yeem tsis quav ntsej. Cov khoom sib txawv ntawm cov khoom siv raw thiab cov txheej txheem synthesis cuam tshuam rau tus nqi lag luam thiab cov khoom txuas ntxiv ntawm PLA. Thaum xaiv cov ntaub ntawv, cov phiaj xwm peev nyiaj thiab kev npaj peev xwm yuav tsum raug txiav txim siab, ua ntej cov qhab nia nrog kev ua haujlwm siab - rau - tus nqi piv, thiab tsim kom muaj ib qho kev ntsuam xyuas batch rau cov ntaub ntawv raw kom zoo ib yam. Hauv cov ntsiab lus, kev xaiv cov ntaub ntawv PLA yuav tsum muaj qhov sib npaug ntawm kev ua haujlwm, kev ua haujlwm, kev degradation, kev cai, thiab kev lag luam. Los ntawm kev qhia meej txog daim ntawv thov, txheeb xyuas cov yam ntxwv ntawm cov resin thiab kev hloov kho, thiab ntxiv nrog rau kev soj ntsuam xyuas thiab kev ntsuam xyuas lub neej, cov khoom siv uas haum rau qhov tseeb scenario tuaj yeem xaiv, yog li kev siv tag nrho cov txiaj ntsig ntawm PLA hauv cov khoom siv ruaj khov.