Formulation et caractérisation des matériaux biodégradables à base de l’acide polylactique-Plastifiants

Type : Thèse de doctorat
Auteur(s) :  MAIZA Mounira
Directeurs du mémoire/thèse :  -
Année :  2016
Domaine : Chimie
Etablissement :  Université Ferhat Abbas - Sétif 1
Résumé en PDF :  (résumé en pdf)
Fulltext en PDF :  (.pdf)
Mots clés :  Polylactic acid (PLA), plasticizing, Triethyl Citrate (TEC), Acetyl Tributyl Citrate (ATBC)

Résumé :

In this study, the characterization of plasticized PLA with TEC and ATBC by melt blending method wasreported. The value of the melt flow index (MFI) observed for all samples are higher than those of neat PLA.The evaluation of the influence of the type and plasticizer content on the viscoelastic properties of PLA withDMA indicates a decrease in the storage modulus for plasticized PLA, indicating the flexibility and mobility ofthe amorphous phase of PLA caused by TEC and ATBC. UV-Visible spectroscopy shows that the twoplasticizers: TEC and ATBC have no effect on the color change of the films. The opacity values of the PLAfilms plasticized with TEC and ATBC were slightly lower than the value of the treated PLA film. X-raydiffraction shows the appearance of a strong diffraction at 16.7° assigned to the crystalline phase α, whichconfirms that the PLA has no crystalline polymorph transition. FTIR spectra indicate that there are somemolecular interactions by intermolecular hydrogen bonds between PLA and citrate ester. The thermal propertiesof plasticized PLA shows that TEC and ATBC are effective in lowering the glass transition temperature (Tg), themelting temperature (Tm) and the cold crystallization temperature (Tcc) of the PLA. In addition, its crystallinityincreases with increasing content of plasticizer. The TGA results indicated that the TEC and ATBC promote adecrease in thermal stability of the PLA. The weight loss plasticizer with heating time and at 100 °C is lesserthan at 135 °C. Leaching of TEC and ATBC results in cracks and changed color of material. The tensile testshowed that the formulations of the plasticized PLA with citrate ester (TEC and ATBC) give better mechanicalproperties by providing treated PLA. The observation by SEM confirmed there is miscibility between the PLAand plasticizer. Finally it can be said that the higher molecular weight of citrate exhibited a greater plasticizingeffect.