Njira yosakanikirana ya poly-L-lactic acid ndi ethyl cellulose mu chloroform ndi njira yosakanikirana ya PLLA ndi methyl cellulose mu trifluoroacetic acid inakonzedwa, ndipo PLLA / cellulose ether blend inakonzedwa ndi kuponyera; Zophatikizika zomwe zidapezeka zidadziwika ndi mawonekedwe a masamba a infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) ndi X-ray diffraction (XRD). Pali chomangira cha haidrojeni pakati pa PLLA ndi cellulose ether, ndipo zigawo ziwirizi zimagwirizana pang'ono. Ndi kuwonjezeka kwa cellulose ether zomwe zili muzosakaniza, malo osungunuka, crystallinity ndi crystal umphumphu wa kusakaniza zonse zidzachepa. Pamene MC zili pamwamba kuposa 30%, pafupifupi zosakaniza amorphous angapezeke. Choncho, mapadi ether angagwiritsidwe ntchito kusintha poly-L-lactic asidi kukonzekera degradable polima zipangizo ndi katundu zosiyanasiyana.
Mawu osakira: poly-L-lactic acid, ethyl cellulose,methyl cellulose, kusakaniza, cellulose ether
Kupanga ndi kugwiritsa ntchito ma polima achilengedwe ndi zinthu zowonongeka za polima zithandizira kuthana ndi zovuta zachilengedwe komanso zovuta zomwe anthu amakumana nazo. M'zaka zaposachedwa, kafukufuku wokhudzana ndi kaphatikizidwe ka zinthu zapolima zomwe zimatha kuwonongeka pogwiritsa ntchito zinthu zongowonjezedwanso monga zida za polima zakopa chidwi chambiri. Polylactic acid ndi imodzi mwazinthu zofunikira zowonongeka za aliphatic polyesters. Lactic asidi akhoza kupangidwa ndi nayonso mphamvu ya mbewu (monga chimanga, mbatata, sucrose, etc.), komanso akhoza decomposed ndi tizilombo. Ndi gwero zongowonjezwdwa. Asidi a polylactic amakonzedwa kuchokera ku lactic acid ndi polycondensation mwachindunji kapena polima-kutsegula polima. Chotsalira chomaliza cha kuwonongeka kwake ndi lactic acid, yomwe siidzaipitsa chilengedwe. PIA ili ndi makina abwino kwambiri, osinthika, odekha komanso ogwirizana. Chifukwa chake, PLA sikuti ili ndi ntchito zambiri zokha pazamankhwala azachipatala, komanso ili ndi misika yayikulu yomwe ingatheke pamakampani opanga zokutira, mapulasitiki, ndi nsalu.
Mtengo wokwera wa poly-L-lactic acid ndi zolakwika zake monga hydrophobicity ndi brittleness zimachepetsa ntchito yake. Pofuna kuchepetsa mtengo wake komanso kupititsa patsogolo ntchito ya PLLA, kukonzekera, kugwirizanitsa, morphology, biodegradability, mechanical properties, hydrophilic / hydrophobic balance ndi minda yogwiritsira ntchito polylactic acid copolymers ndi zosakaniza zaphunziridwa mozama. Pakati pawo, PLLA imapanga kusakanikirana kogwirizana ndi poly DL-lactic acid, polyethylene oxide, polyvinyl acetate, polyethylene glycol, etc. mu chilengedwe. Zochokera ku cellulose ndi zida zoyambirira za polima zachilengedwe zopangidwa ndi anthu, zofunika kwambiri zomwe ndi ma cellulose ethers ndi cellulose esters. M. Nagata et al. adaphunzira dongosolo la PLLA / cellulose blend system ndipo adapeza kuti zigawo ziwirizo zinali zosagwirizana, koma crystallization ndi zowonongeka za PLLA zinakhudzidwa kwambiri ndi gawo la cellulose. N. Ogata et al adaphunzira momwe PLLA ndi cellulose acetate blend system imagwirira ntchito. Patent yaku Japan idaphunziranso za biodegradability ya PLLA ndi nitrocellulose blends. Y. Teramoto et al adaphunzira kukonzekera, kutentha komanso makina a PLLA ndi cellulose diacetate graft copolymers. Pakalipano, pali maphunziro ochepa kwambiri pa makina osakanikirana a polylactic acid ndi cellulose ether.
M'zaka zaposachedwa, gulu lathu lakhala likuchita nawo kafukufuku wokhudzana ndi kuphatikizika kwachindunji komanso kuphatikiza kusinthidwa kwa polylactic acid ndi ma polima ena. Kuti tiphatikize zinthu zabwino kwambiri za asidi wa polylactic ndi mtengo wotsika wa cellulose ndi zotumphukira zake kuti tikonzere zida za polima zomwe zimawonongeka, timasankha mapadi (ether) ngati gawo losinthidwa losinthira kusinthidwa. Ethyl cellulose ndi methyl cellulose ndi ma ether awiri ofunikira a cellulose. Ethyl cellulose ndi madzi osasungunuka omwe si a ionic cellulose alkyl ether, omwe angagwiritsidwe ntchito ngati zipangizo zachipatala, mapulasitiki, zomatira ndi kumaliza nsalu. Methyl cellulose ndi yosungunuka m'madzi, imakhala ndi madzi abwino kwambiri, ogwirizana, kusunga madzi ndi kupanga mafilimu, ndipo amagwiritsidwa ntchito kwambiri pazinthu zomangira, zokutira, zodzoladzola, mankhwala ndi mapepala. Pano, PLLA / EC ndi PLLA / MC zosakaniza zinakonzedwa ndi njira yothetsera njira yothetsera vutoli, ndipo kugwirizanitsa, katundu wotentha ndi crystallization katundu wa PLLA / cellulose ether blends anakambidwa.
1. Gawo loyesera
1.1 Zopangira
Ethyl mapadi (AR, Tianjin Huazhen Special Chemical Reagent Factory); methyl cellulose (MC450), sodium dihydrogen mankwala, disodium hydrogen mankwala, ethyl acetate, stannous isooctanoate, chloroform (pamwambapa zonse ndi zopangidwa Shanghai Chemical Reagent Co., Ltd., ndipo chiyero ndi AR kalasi); L-lactic acid (kalasi yamankhwala, kampani ya PURAC).
1.2 Kupanga zosakaniza
1.2.1 Kukonzekera kwa polylactic acid
Poly-L-lactic acid idakonzedwa ndi njira yolunjika ya polycondensation. Yesani L-lactic acid amadzimadzi njira ndi misa gawo la 90% ndi kuwonjezera pa botolo khosi atatu, dehydrated pa 150 ° C kwa maola 2 pansi pa kupanikizika wamba, ndiye kuchita kwa maola 2 pansi vacuum kuthamanga 13300Pa, ndipo potsiriza. chitani kwa maola 4 pansi pa vacuum ya 3900Pa kuti mupeze zinthu za prepolymer zopanda madzi. Kuchuluka kwa lactic acid yankho lamadzimadzi kuchotsera madzi otuluka ndi kuchuluka kwa prepolymer. Onjezerani stannous kolorayidi (kachigawo kakang'ono ndi 0,4%) ndi p-toluenesulfonic acid (chiŵerengero cha stannous kolorayidi ndi p-toluenesulfonic acid ndi 1/1 molar chiŵerengero) chothandizira dongosolo mu prepolymer analandira, ndi condensation Sieves maselo anaikidwa mu chubu. kuyamwa madzi pang'ono, ndipo kugwedeza kwa makina kunasungidwa. Dongosolo lonselo lidachitidwa pa vacuum ya 1300 Pa ndi kutentha kwa 150 ° C. kwa maola 16 kuti mupeze polima. Sungunulani polima yomwe mwapeza mu chloroform kuti mukonze yankho la 5%, fyuluta ndi kutentha ndi ether ya anhydrous kwa maola 24, sefa madziwo, ndikuyiyika mu uvuni wa vacuum -0.1MPa pa 60 ° C kwa maola 10 mpaka 20 kuti mupeze Koyera youma. PLLA polima. Kulemera kwa mamolekyulu a PLLA omwe adapezedwa adatsimikiziridwa kukhala 45000-58000 Daltons ndi high-performance liquid chromatography (GPC). Zitsanzo zinkasungidwa mu desiccator yokhala ndi phosphorous pentoxide.
1.2.2 Kukonzekera kwa polylactic acid-ethyl cellulose blend (PLLA-EC)
Yezerani kuchuluka kofunikira kwa poly-L-lactic acid ndi ethyl cellulose kuti mupange 1% chloroform yankho motsatana, ndiyeno konzani yankho la PLLA-EC losakanikirana. Chiyerekezo cha PLLA-EC mix solution ndi: 100/0, 80/20, 60/40, 40/60, 20/80, 0/l00, nambala yoyamba imaimira gawo lalikulu la PLLA, ndipo nambala yomaliza imaimira Mtengo wapatali wa magawo EC. Mayankho okonzedwawo amalimbikitsidwa ndi maginito oyambitsa maginito kwa maola 1-2, kenako amatsanulira mu mbale yagalasi kuti chloroform isungunuke mwachibadwa kuti ipange filimu. Filimuyo itapangidwa, idayikidwa mu uvuni wa vacuum kuti iume kutentha pang'ono kwa maola 10 kuti ichotseretu chloroform mufilimuyo. . Njira yothetsera vutoli ndi yopanda mtundu komanso yowonekera, ndipo filimu yosakanikirana imakhalanso yopanda mtundu komanso yowonekera. Msanganizowo unawumitsidwa ndikusungidwa mu desiccator kuti ugwiritse ntchito pambuyo pake.
1.2.3 Kukonzekera kwa polylactic acid-methylcellulose blend (PLLA-MC)
Yezerani kuchuluka kofunikira kwa poly-L-lactic acid ndi methyl cellulose kuti mupange 1% trifluoroacetic acid solution motsatana. Kanema wophatikiza wa PLLA-MC adakonzedwa ndi njira yofananira ndi filimu yophatikiza ya PLLA-EC. Msanganizowo unawumitsidwa ndikusungidwa mu desiccator kuti ugwiritse ntchito pambuyo pake.
1.3 Mayeso a magwiridwe antchito
MANMNA IR-550 infuraredi spectrometer (Nicolet.Corp) anayeza sipekitiramu infuraredi wa polima (KBr piritsi). DSC2901 differential scanning calorimeter (TA kampani) idagwiritsidwa ntchito kuyeza mayendedwe a DSC a chitsanzo, kutentha kwa kutentha kunali 5 ° C / min, ndi kutentha kwa galasi, malo osungunuka ndi crystallinity wa polima anayesedwa. Gwiritsani ntchito Rigaku. D-MAX/Rb diffractometer idagwiritsidwa ntchito kuyesa mawonekedwe a X-ray diffraction a polima kuti aphunzire za crystallization yachitsanzo.
2. Zotsatira ndi zokambirana
2.1 Kafukufuku wa infrared spectroscopy
Fourier transform infrared spectroscopy (FT-IR) imatha kuphunzira kuyanjana pakati pa zigawo za msakanizo kuchokera ku kawonedwe ka molekyulu. Ngati ma homopolymers awiriwa amagwirizana, kusinthasintha kwafupipafupi, kusintha kwamphamvu, komanso ngakhale mawonekedwe kapena kutha kwa nsonga zamaguluwo zitha kuwonedwa. Ngati ma homopolymer awiriwa sakugwirizana, kuchuluka kwa kuphatikizikako kumangokhala pamwamba pa ma homopolymer awiriwo. Mu mawonekedwe a PLLA, pali kugwedezeka kwapamwamba kwa C = 0 pa 1755cm-1, nsonga yofooka pa 2880cm-1 chifukwa cha C-H kutambasula kugwedezeka kwa gulu la methine, ndi gulu lalikulu pa 3500 cm-1 ndi. chifukwa cha ma terminal hydroxyl magulu. M'mawonekedwe a EC, nsonga yapamwamba pa 3483 cm-1 ndi chiwongolero cha OH chotambasula, kusonyeza kuti pali magulu a O-H otsalira pa unyolo wa molekyulu, pamene 2876-2978 cm-1 ndi C2H5 yotambasula kugwedezeka, ndi 1637 cm-1 ndi HOH Kupindika pachimake (chochitika chifukwa cha madzi omwe amamwa madzi). PLLA ikasakanizidwa ndi EC, mu IR sipekitiramu ya hydroxyl dera la PLLA-EC blend, nsonga ya O-H imasunthira ku nambala yotsika ya wavenumber ndi kuchuluka kwa EC zomwe zili, ndipo zimafika pochepera pomwe PLLA/Ec ndi 40/60 wavenumber, kenako ndikusunthira ku manambala apamwamba, zomwe zikuwonetsa kuti kuyanjana pakati pa PUA ndi 0-H ya EC ndizovuta. M'dera la C = O kugwedezeka kwa 1758cm-1, C = 0 nsonga ya PLLA-EC inasunthira pang'ono ku chiwerengero chochepa cha mafunde ndi kuwonjezeka kwa EC, zomwe zimasonyeza kuti kugwirizana pakati pa C = O ndi OH ya EC kunali kofooka.
Mu spectrogram ya methylcellulose, nsonga yapamwamba pa 3480cm-1 ndi O-H yotambasula kugwedezeka pachimake, ndiye kuti, pali magulu otsalira a O-H pa unyolo wa mamolekyulu a MC, ndipo chiwongolero cha kugwedezeka kwa HOH chili pa 1637cm-1, ndi MC chiŵerengero cha EC ndi hygroscopic kwambiri. Mofanana ndi PLLA-EC blend system, mu infrared spectra ya hydroxyl dera la PLLA-EC blend, chiwerengero cha O-H chimasintha ndi kuwonjezeka kwa MC, ndipo imakhala ndi chiwerengero chochepa cha mafunde pamene PLLA / MC ili. 70/30. M'dera la C = O (1758 cm-1), nsonga ya C = O imasunthira pang'ono ku mafunde otsika ndikuwonjezera kwa MC. Monga tanena kale, pali magulu ambiri mu PLLA omwe amatha kupanga mayanjano apadera ndi ma polima ena, ndipo zotsatira za mawonekedwe a infrared zitha kukhala zotsatira zophatikizana zambiri zomwe zingatheke mwapadera. Mu dongosolo lophatikizana la PLLA ndi cellulose ether, pakhoza kukhala mitundu yosiyanasiyana ya ma hydrogen bond pakati pa gulu la ester la PLLA, gulu la terminal la hydroxyl ndi gulu la ether la cellulose ether (EC kapena MG), ndi magulu otsala a hydroxyl. PLLA ndi EC kapena MCs zitha kukhala zogwirizana pang'ono. Zingakhale chifukwa cha kukhalapo ndi mphamvu za ma hydrogen bond angapo, kotero kusintha kwa dera la O-H ndikofunika kwambiri. Komabe, chifukwa cha kulepheretsa steric kwa gulu la cellulose, mgwirizano wa hydrogen pakati pa C = O gulu la PLLA ndi gulu la O-H la cellulose ether ndi lofooka.
2.2 Kafukufuku wa DSC
DSC ma curve a PLLA, EC ndi PLLA-EC ophatikiza. Kutentha kwa galasi Tg ya PLLA ndi 56.2 ° C, kutentha kwa crystal kusungunuka Tm ndi 174.3 ° C, ndi crystallinity ndi 55.7%. EC ndi polima amorphous ndi Tg ya 43 ° C ndipo palibe kutentha kosungunuka. Tg ya zigawo ziwiri za PLLA ndi EC zili pafupi kwambiri, ndipo zigawo ziwiri zosinthika zimagwirizanitsa ndipo sizingasiyanitsidwe, choncho n'zovuta kuzigwiritsira ntchito ngati njira yoyendetsera dongosolo. Ndi kuwonjezeka kwa EC, Tm ya PLLA-EC imagwirizanitsa pang'ono, ndipo crystallinity inachepa (crystallinity ya chitsanzo ndi PLLA / EC 20 / 80 inali 21.3%). Tm ya zophatikizika idatsika ndi kuchuluka kwa zomwe zili mu MC. Pamene PLLA / MC ndi yotsika kuposa 70/30, Tm yosakanikirana imakhala yovuta kuyeza, ndiko kuti, pafupifupi kusakanikirana kwa amorphous kungapezeke. Kutsika kwa malo osungunuka a kusakanikirana kwa ma polima a crystalline ndi ma polima amorphous nthawi zambiri amakhala chifukwa cha zifukwa ziwiri, chimodzi ndi kusungunuka kwa gawo la amorphous; chinacho chikhoza kukhala zotsatira zapangidwe monga kuchepetsa ungwiro wa crystallization kapena kukula kwa crystalline polima. Zotsatira za DSC zimasonyeza kuti mu dongosolo lophatikizana la PLLA ndi cellulose ether, zigawo ziwirizi zinali zogwirizana pang'ono, ndipo ndondomeko ya crystallization ya PLLA mu osakaniza inaletsedwa, zomwe zinachititsa kuchepa kwa Tm, crystallinity ndi kukula kwa crystal ya PLLA. Izi zikuwonetsa kuti kuyanjana kwa magawo awiri a dongosolo la PLLA-MC kungakhale bwinoko kuposa kachitidwe ka PLLA-EC.
2.3 X-ray diffraction
Mzere wa XRD wa PLLA uli ndi nsonga yamphamvu kwambiri pa 2θ ya 16.64 °, yomwe imagwirizana ndi ndege ya crystal 020, pamene nsonga za 2θ za 14.90 °, 19.21 ° ndi 22.45 ° zimagwirizana ndi 101, 023, ndi 121 motsatira. Pamwamba, ndiye kuti, PLLA ndi mawonekedwe a α-crystalline. Komabe, palibe nsonga yamtundu wa kristalo pamapindikira a EC, zomwe zikuwonetsa kuti ndi mawonekedwe aamorphous. PLLA itasakanizidwa ndi EC, nsonga ya 16.64 ° inakula pang'onopang'ono, mphamvu yake inafooka, ndipo inasunthira pang'ono kumunsi. Pamene EC zili ndi 60%, nsonga ya crystallization inali itabalalika. Mawonekedwe ocheperako a X-ray amawonetsa kuwala kwakukulu komanso kukula kwakukulu kwambewu. Kukula kwa nsonga ya diffraction, kumachepetsa kukula kwa njere. Kusintha kwa nsonga ya diffraction kupita ku ngodya yotsika kumasonyeza kuti kusiyana kwambewu kumawonjezeka, ndiko kuti, kukhulupirika kwa kristalo kumachepa. Pali mgwirizano wa haidrojeni pakati pa PLLA ndi Ec, ndi kukula kwa tirigu ndi crystallinity ya PLLA kuchepa, zomwe zingakhale chifukwa chakuti EC imagwirizana pang'ono ndi PLLA kupanga mapangidwe amorphous, potero kuchepetsa kukhulupirika kwa mawonekedwe a kristalo a osakaniza. Zotsatira za X-ray diffraction za PLLA-MC zimawonetsanso zotsatira zofanana. X-ray diffraction curve ikuwonetsa momwe chiŵerengero cha PLLA / cellulose ether chimapangidwira, ndipo zotsatira zake zimagwirizana kwathunthu ndi zotsatira za FT-IR ndi DSC.
3. Mapeto
Dongosolo losakanikirana la poly-L-lactic acid ndi cellulose ether (ethyl cellulose ndi methyl cellulose) adaphunziridwa apa. Kugwirizana kwa magawo awiriwa mu dongosolo lophatikizika kudaphunziridwa ndi FT-IR, XRD ndi DSC. Zotsatira zinasonyeza kuti kugwirizana kwa haidrojeni kunalipo pakati pa PLLA ndi cellulose ether, ndipo zigawo ziwiri za dongosololi zinali zogwirizana pang'ono. Kuchepa kwa chiŵerengero cha PLLA / cellulose ether kumabweretsa kuchepa kwa malo osungunuka, crystallinity, ndi crystal integrity ya PLLA muzosakaniza, zomwe zimapangitsa kukonzekera kusakanikirana kwa crystallinity yosiyana. Choncho, mapadi efa angagwiritsidwe ntchito kusintha poly-L-lactic asidi, amene adzaphatikiza ntchito kwambiri asidi polylactic ndi mtengo wotsika wa mapadi efa, amene amathandiza yokonza kwathunthu biodegradable polima zipangizo.
Nthawi yotumiza: Jan-13-2023