PLA polylactic acid yog dab tsi?

Polylactic acid (PLA) yog cov khoom siv polymer tsim los ntawm polymerization ntawm lactic acid li raw khoom, uas muaj cov yam ntxwv ntawm non-toxic, siab zog, ua tau yooj yim thiab zoo heev biocompatibility, thiab yuav txo tau tag nrho tom qab PLA npaj. Vim tias nws yooj yim heev rau degrade nyob rau hauv L ua haujlwm, cov khoom siv kho tshuab raug txo qis, thiab nws yuav tsum tau hloov kho los ntawm kev siv lub cev los nthuav nws daim ntawv thov.
1. Cov qauv thiab cov khoom ntawm PLA
Nyob rau hauv 1780, Sweden chemist Scheele rho tawm cov organic acid los ntawm qaub mis nyuj, hu ua lactic acid. Lactic acid yog cov khoom lag luam ntawm cov piam thaj hauv cov metabolism hauv lub cev, uas yog raws li cov hmoov txhuv nplej siab muab rho tawm los ntawm qee cov nroj tsuag ua cov khoom siv thawj zaug, thiab cov piam thaj tau txais los ntawm enzyme decomposition, thiab tom qab ntawd tau los ntawm fermentation ntawm cov kab mob mis. Cov lactic acid molecule muaj chiral carbon atom, uas yuav muab faib ua L-lactic acid thiab txoj cai-tes D-lactic acid raws li nws cov kev ua ub no, thiab cov mis mos molecular yog C3H6O3.
Cov sib txawv monomer muaj pes tsawg leeg thiab kev faib ua ntu zus hauv PLA molecular saw muab cov khoom sib txawv. Polylactic acid muaj peb stereoisomers: polyracemic lactic acid PDLLA (polyDL-lacticacid), polyL-lactic acid (PLLA), thiab polyD-lactic acid (PDLA). Ntawm lawv, PDLA thiab PLLA yog crystalline, thaum PDLLA yog amorphous. PDLLA thiab PLLA feem ntau siv. Rau polylactic acid, PLLA thiab PDLA yog degraded rau hauv lactic acid los ntawm hydrolysis nyob rau hauv cov kab mob nyob, nkag mus rau lub tricarboxylic acid voj voog, thiab tag nrho absorbed los ntawm cov kab mob tsis muaj tshuaj lom. Lactic acid, cov khoom siv tseem ceeb ntawm polylactic acid, yog ib qho ntawm cov khoom siv hauv lub cev ntawm tib neeg lub cev, uas tsis muaj tshuaj lom thiab tsis muaj mob rau tib neeg lub cev. Tsis tas li ntawd, polylactic acid muaj cov khoom siv zoo thiab lub cev, thiab tsim nyog rau ntau txoj hauv kev xws li tshuab moulding thiab thermoplastic, thiab yooj yim rau kev khiav lag luam. Nws tuaj yeem siv los ua ntau yam khoom yas, ntim khoom noj, ntim khoom noj ceev ceev thiab cov ntaub ntawv rau kev lag luam thiab kev siv pej xeem. Polylactic acid muaj cov dej noo-pov thawj, roj-pov thawj thiab airtightness, ruaj khov kev ua haujlwm ntawm chav tsev kub, tab sis yuav cia li decompose nyob rau hauv qhov kev txiav txim ntawm kub siab tshaj 55 degree los yog oxygen-nplua nuj thiab microorganisms, thiab yuav degraded tag nrho los ntawm microorganisms nyob rau hauv cov xwm. siv, thiab thaum kawg tsim carbon dioxide thiab dej, uas tsis ua phem rau ib puag ncig.
Polylactic acid muaj biocompatibility zoo, absorbability, mechanical zog thiab durability, tuaj yeem tiv taus ntau yam tshuaj tua kab mob, thiab muaj cov khoom ua haujlwm zoo, yog li nws tau siv dav, feem ntau hauv ob qho kev tiv thaiv ib puag ncig thiab tshuaj. Tam sim no, cov txheej txheem tag nrho biodegradable hnab ua los ntawm PLA + PBAT tau ua tiav.