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Recovery of l-lactic acid from poly(l-lactic acid) under hydrothermal conditions of dilute aqueous sodium hydroxide solution / Masaru Yagihashi in Industrial & engineering chemistry research, Vol. 49 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 1247–1251 Titre : Recovery of l-lactic acid from poly(l-lactic acid) under hydrothermal conditions of dilute aqueous sodium hydroxide solution Type de document : texte imprimé Auteurs : Masaru Yagihashi, Auteur ; Toshitaka Funazukuri, Auteur Année de publication : 2010 Article en page(s) : pp. 1247–1251 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Recovery--l-Lactic--Acid  from  Poly(l-lactic  acid)--under  Hydrothermal--Conditions--Dilute  Aqueous--Sodium--Hydroxide  Solution Résumé : Poly(l-lactic acid) (PLLA) pellets were degraded in a batch reactor under hydrothermal conditions of aqueous sodium hydroxide solution, from 343 to 453 K, compared to water in the absence of NaOH. Over an entire range of conversion, components solubilized from PLLA mainly consisted of l-lactic acid (LLA) in the presence of NaOH. For instance, PLLA was nearly completely converted into LLA at 433 K for 60 min or 453 K for 20 min with 0.6 M aqueous NaOH solution, where d-lactic acid was not observed. The degradation reaction with/without NaOH proceeded in the induction stage followed by the major degradation stage, as has been seen for polyesters reported in our previous studies. In the major degradation stage the overall reaction rate for PLLA was represented by 2/3-order reaction kinetics with respect to the amount of unreacted polymer, suggesting that the reaction occurred on the polymer surface. The NaOH concentrations above 0.6 M at 343 K hardly affected the reaction rates, but did affect the induction time remarkably. It can be considered that the degradation reaction is controlled by not chemical reaction but dissolution of products on the pellet surface. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008925 [article] Recovery of l-lactic acid from poly(l-lactic acid) under hydrothermal conditions of dilute aqueous sodium hydroxide solution [texte imprimé] / Masaru Yagihashi, Auteur ; Toshitaka Funazukuri, Auteur . - 2010 . - pp. 1247–1251. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 1247–1251 Mots-clés : Recovery--l-Lactic--Acid  from  Poly(l-lactic  acid)--under  Hydrothermal--Conditions--Dilute  Aqueous--Sodium--Hydroxide  Solution Résumé : Poly(l-lactic acid) (PLLA) pellets were degraded in a batch reactor under hydrothermal conditions of aqueous sodium hydroxide solution, from 343 to 453 K, compared to water in the absence of NaOH. Over an entire range of conversion, components solubilized from PLLA mainly consisted of l-lactic acid (LLA) in the presence of NaOH. For instance, PLLA was nearly completely converted into LLA at 433 K for 60 min or 453 K for 20 min with 0.6 M aqueous NaOH solution, where d-lactic acid was not observed. The degradation reaction with/without NaOH proceeded in the induction stage followed by the major degradation stage, as has been seen for polyesters reported in our previous studies. In the major degradation stage the overall reaction rate for PLLA was represented by 2/3-order reaction kinetics with respect to the amount of unreacted polymer, suggesting that the reaction occurred on the polymer surface. The NaOH concentrations above 0.6 M at 343 K hardly affected the reaction rates, but did affect the induction time remarkably. It can be considered that the degradation reaction is controlled by not chemical reaction but dissolution of products on the pellet surface. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008925

Recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate) under hydrothermal conditions of aqueous trimethylamine solution / Natsumi Wakabayashi in Industrial & engineering chemistry research, Vol. 51 N° 16 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5699-5704 Titre : Recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate) under hydrothermal conditions of aqueous trimethylamine solution Type de document : texte imprimé Auteurs : Natsumi Wakabayashi, Auteur ; Tomoharu Kojima, Auteur ; Toshitaka Funazukuri, Auteur Année de publication : 2012 Article en page(s) : pp. 5699-5704 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrothermal  condition Résumé : Poly(ethylene terephthalate) pellets were subjected to various amine solutions under hydrothermal conditions in a semibatch reactor. Methylamine, ethylamine, dimethylamine, trimethylamine, ammonia, and sodium hydroxide were examined at 473 K and 10 MPa at concentrations of 0.6 mol/kg. The effects of the amine species on reaction rates and monomer yields were compared. For all solvents examined in the present study, the reactions were expressed by a surface reaction model, i.e., the 2/3rd-order reaction kinetics with respect to unreacted polymer mass. The reaction rates with the four amines were not very different and were similar to that with NaOH at the same concentration; but, they were faster than the rate with ammonia. When the reaction was conducted with trimethylamine, the yields of monomers and total yields of terephthalic acid and ethylene glycol were very close to the theoretical values. However, those with dimethylamine, ethylamine, and methylamine were slightly lower with intermediate products found in the product solutions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834483 [article] Recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate) under hydrothermal conditions of aqueous trimethylamine solution [texte imprimé] / Natsumi Wakabayashi, Auteur ; Tomoharu Kojima, Auteur ; Toshitaka Funazukuri, Auteur . - 2012 . - pp. 5699-5704. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5699-5704 Mots-clés : Hydrothermal  condition Résumé : Poly(ethylene terephthalate) pellets were subjected to various amine solutions under hydrothermal conditions in a semibatch reactor. Methylamine, ethylamine, dimethylamine, trimethylamine, ammonia, and sodium hydroxide were examined at 473 K and 10 MPa at concentrations of 0.6 mol/kg. The effects of the amine species on reaction rates and monomer yields were compared. For all solvents examined in the present study, the reactions were expressed by a surface reaction model, i.e., the 2/3rd-order reaction kinetics with respect to unreacted polymer mass. The reaction rates with the four amines were not very different and were similar to that with NaOH at the same concentration; but, they were faster than the rate with ammonia. When the reaction was conducted with trimethylamine, the yields of monomers and total yields of terephthalic acid and ethylene glycol were very close to the theoretical values. However, those with dimethylamine, ethylamine, and methylamine were slightly lower with intermediate products found in the product solutions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834483