Thermal, Mechanical and Micromechanical Analysis of PLA/PBAT/POE-g-GMA Extruded Ternary Blends

In order to toughen Poly(lactic) acid and binary blends with low PBAT content while maintaining a high biodegradability of the final material, poly(lactic) acid (PLA)/poly(butylene-adipate-co-terephthalate) (PBAT)/ polyolefin elastomer grafted with glycidyl methacrylate (POE-g-GMA) extruded ternary blends have been investigated in this work from a thermal, mechanical, and rheological point of view. The two elastomers have been added in different amounts as dispersed phases into the PLA matrix, paying attention to the final objective: the design of a 90% biodegradable formulation according to EN 13432. These ternary blends exhibited improved impact properties but still low elongation at break. Consequently, to the ternary composition with the best compromise of PLA quantity, biodegradability and thermo-mechanical properties (81 wt.% PLA, 9 wt.% PBAT, and 10 wt.% POE-g-GMA) a small quantity (10 wt.%) of a biobased plasticizer was added in order to further increase the impact properties in parallel with the tensile flexibility. Two types of plasticizers were investigated, one not reactive [Acetyl Tributyl Citrate (ATBC)], and one reactive [Glycidyl ether (EJ-400)]. A micromechanical study, in order to investigate the toughening mechanism of these systems, was carried out on the final formulations. They were also examined by dilatometric tests and elasto-plastic fracture mechanics correlating the data obtained to the morphology and to the rheological properties. In conclusion, the best compromise between impact, tensile properties and biodegradability content was achieved using the reactive plasticizer (EJ-400) whose interaction with the matrix is confirmed by the FT-IR analysis

analisi micro meccanica e processi di deformazione di poli (acido) lattico tenacizzati con elastomeri

Il presente lavoro di tesi si propone di migliorare la tenacità del PLA attraverso blending con due tipi di elastomero: PBAT e POE-g-GMA. è stata valutata inizialmente la processabilità attraverso l'estrusione in un bivite semiindustriale. test tensilie d'impatto sono stati effettuati su provini stampati a iniezione per caratterizzare micromeccanicamente i nuovi materiali. la caratterizzazione termica, al fine di valutare le transizioni, è stata condotta per mezzo di DSC; mentre l'analisi morfologica è stata valutata per mezzo di immagini SEM. infine prove dilatometriche con videoestensimetro sono state condotte per valutare le variazioni di volume di provini sottoposti a trazione e unmodello bastato sul concetto della separazione del carico su prove di flessione a tre punti è stato applicato per valutare l'energia assorbita al momento della propagazione della cricca