1.1. Synthesis method
Feem ntau, kev npaj ntawm polylactic acid (PLA) yog synthesized los ntawm lactic acid ua raw khoom. Tam sim no, muaj ntau txoj kev siv hluavtaws, qhov ntau mature yog txoj kev ncaj qha polycondensation ntawm lactic acid, thiab lwm yam yog los ua ke lactide los ntawm lactic acid ua ntej, thiab tom qab ntawd lub nplhaib-qhib polymerization nyob rau hauv qhov kev txiav txim ntawm lub catalyst. Kuj tseem muaj txoj hauv kev ua tau zoo-theem polymerization.
1. Lactic acid ncaj qha polymerization txoj kev
Txoj kev ncaj qha polymerization tau kawm thaum ntxov li xyoo 1930 thiab 1940s, tab sis txij li cov thev naus laus zis tseem ceeb ntsig txog kev tshem tawm cov dej hauv cov tshuaj tiv thaiv tsis tau daws tau zoo, cov khoom hnyav molecular ntawm cov khoom yog qis (tag nrho hauv qab 4000), muaj zog tsawg heev. , yooj yim rau decompose, tsis muaj practicality.
Nyiv Showa Polymer Co., Ltd. adopts txoj kev maj mam cua sov lactic acid nyob rau hauv inert gas thiab maj mam decompressing nws kom cov lactic acid yog ncaj qha lub cev qhuav dej thiab condensed, thiab cov reactant yog ntxiv polycondensed ntawm 220 ~ 260 degree C thiab 133 Pa rau. tau qhov hnyav molecular ntau dua 4000. Polylactic acid. Txawm li cas los xij, lub sij hawm cov tshuaj tiv thaiv ntawm txoj kev no yog ntev, thiab cov khoom yuav muaj hnub nyoog, decomposed, discolored, thiab tsis sib npaug ntawm qhov kub siab nyob rau theem tom ntej. Nyiv lub tuam txhab Mitsui Press Chemical siv cov tshuaj polymerization txoj kev ncaj qha polymerize lactic acid kom tau polylactic acid.
Lub ntsiab feature ntawm txoj kev ncaj qha yog hais tias cov synthesized polylactic acid tsis muaj ib tug catalyst, yog li thaum cov tshuaj tiv thaiv polycondensation nce mus rau ib tug tej yam, lub system yuav tshwm sim nyob rau hauv ib tug equilibrium lub xeev. Nws yuav tsum tau rhuab thiab pressurized los ua txhaum cov tshuaj tiv thaiv equilibrium, thiab cov tshuaj tiv thaiv tej yam kev mob kuj hnyav. Nyob rau hauv xyoo tas los no, los ntawm kev tsim kho tshiab thiab kev txhim kho thev naus laus zis, cov txheej txheem polymerization ncaj qha tau ua qee qhov kev vam meej, thiab nws yuav tsum tau siv rau kev lag luam loj loj nyob rau yav tom ntej vim tias cov thev naus laus zis tseem tab tom loj hlob.
2. Nplhaib-qhib polymerization txoj kev
Lub nplhaib-qhib polymerization yog txoj kev siv ntau tshaj plaws hauv ntiaj teb. Thaum ntxov li nruab nrab ntawm lub xyoo pua 20th, DuPont cov kws tshawb fawb tau txais qhov hnyav molecular polylactic acid los ntawm lub nplhaib-qhib polymerization. Nyob rau hauv xyoo tas los no, kev tshawb fawb txawv teb chaws ntawm kev sib txuas ntawm polylactic acid tau tsom mus rau lub nplhaib-qhib polymerization ntawm lactide.
Polylactic acid series cov khoom tsim los ntawm Boehringer Zngelhelm nyob rau hauv lub teb chaws Yelemees los ntawm txoj kev no tshwm sim nyob rau hauv lub lag luam nyob rau hauv lub lag luam npe; cov polylactic acid uas tsim los ntawm Cargill nyob rau hauv lub tebchaws United States yog ua tiav los ntawm yaj tshuab thiab spun bonding los tsim kho cov khoom uas tsis yog-woven; thiab tsuas muaj ib tug puv tes ntawm cov tuam txhab nyob rau hauv kuv lub teb chaws uas muaj peev xwm synthesize polymer polylactic acid, xws li lub koom haum ntawm Polymer tshawb fawb ntawm Sun Yat-Sen University. Nplhaib-qhib polymerization feem ntau siv stannous octoate ua tus pib, qhov hnyav molecular tuaj yeem ncav cuag ib lab, lub zog txhua yam yog siab, thiab polymerization thiab kev sib cais yog nqa tawm hauv ob kauj ruam:
3. Cov txheej txheem solid-state polymerization
Txoj kev no yog tau los ntawm polymerizing qhov tsawg molecular hnyav resin tau los ntawm ncaj qha polymerization nyob rau hauv cov kev mob ntawm txo lub siab thiab nqus tsev vacuum thiab kub ntawm Tg-Tm, thiaj li mus nce nws degree ntawm polymerization thiab nce nws molecular hnyav, yog li txhim kho cov khoom siv zog thiab processability. .
4. Nqa cov khoom
Plhaub cov qoob loo xws li pob kws yog crushed kom tshem tawm cov hmoov txhuv nplej siab, uas tom qab ntawd ua rau cov piam thaj tsis huv. Tam sim no ntau cov thev naus laus zis siab tau kov yeej cov txheej txheem ntawm kev sib tsoo thiab rho tawm cov ntaub ntawv raw ncaj qha los ntawm ntau cov qoob loo.
5. Fermentation
Glucose yog fermented zoo ib yam li kev tsim npias lossis cawv, uas dhau los ua lactic acid zoo ib yam li cov khoom noj ntxiv rau kev siv hauv tib neeg cov leeg nqaij.
6. Cov khoom nruab nrab
Cov lactic acid monomer hloov mus rau hauv cov khoom nruab nrab - dej-txo lactic acid, uas yog lactic, los ntawm cov txheej txheem tshwj xeeb.
7. Kev sib sau ua ke
Tom qab lub lactide monomer yog nqus purified, ib tug hnyav-dawb dissolution txheej txheem yog siv los ua kom tiav lub nplhaib-qhib kev txiav txim rau polymerize lub monomer.
8. Kev hloov kho polymer
Vim qhov sib txawv ntawm qhov hnyav molecular thiab crystallinity ntawm cov polymer, cov khoom siv tuaj yeem hloov pauv tau zoo, yog li PLA hloov pauv txawv rau kev siv sib txawv.