Miscibility and Mechanical Properties of Blends of (l)-Lactide Copolymers with Atactic Poly(3-hydroxybutyrate)

Abstract

Poly(l-lactide-co-glycolide) (PLLAGA) copolymers and poly(dl-lactide) (PDLLA) were synthesized using the low toxicity compound zirconium(IV) acetylacetonate. Blends with synthetic atactic poly(3-hydroxybutyrate) (a-PHB) were prepared in film form by solvent casting. The solid-state properties of the plain polymers and of the blends were investigated by thermogravimetric analysis coupled with mass spectrometry (TGA−MS), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and stress−strain measurements. The a-PHB/PDLLA blends are miscible over the whole composition range. On the other hand, blends of a-PHB with PLLAGA copolymers containing 5 and 16 mol % of GA units show partial miscibility. The solubility limit of a-PHB in PLLAGA is around 20 wt % in both cases. In the blends, the a-PHB in excess to this value segregates as a pure phase. The mechanical properties of blend films of either PDLLA or PLLAGA containing up to 50 wt % of a-PHB can be modulated by changing blend composition. The tenacity progressively increases by the addition of a-PHB not only in the miscible amorphous a-PHB/PDLLA system but also in the partially miscible a-PHB/PLLAGA blends.

Physical and mechanical properties of PLA, and their functions in widespread applications — A comprehensive review

“…At least five kinds of plasticizers with high Mw and being miscible to PLA without any compatibilizer have been reported so far, i.e. PEG [79,224,225], poly(propylene glycol) (PPG) [226], atactic poly(3-hydroxybutyrate) (a-PHB) [227], polyester diol (PED) as poly(diethylene adipate) (PDEA) [228], tributyl citrate-oligoester (TbC-oligoesters), diethyl bishydroxymethyl malonate oligoester (DBM-oligoester) and oligoesteramide (DBM-oligoesteramide) [223,229,230]. Despite the wide diversity, the choice of plasticizer used as a modifier for PLA is limited by the legislative or technical requirements of the application, and in this context, its selection becomes more difficult [223,230,231].…”

Tenacificação do poli(ácido lático) pela adição do terpolímero (etileno/acrilato de metila/metacrilato de glicidila)

“…A maneira mais prática e econômica de superar a fragilidade e rigidez do PLA é pela confecção de blendas por fusão [8] . Desta forma, blendas de PLA com diversos polímeros biodegradáveis e não biodegradáveis, têm sido confeccionadas para melhorar as propriedades do PLA [8][9][10][11][12][13][14] . Entretanto a maioria das blendas são imiscíveis apresentando propriedades que não são adequadas para aplicações industriais, ou seja, são incompatíveis [15] .…”

Forensic Engineering of Advanced Polymeric Materials. Part 1 – Degradation Studies of Polylactide Blends with Atactic Poly[(R,S)-3-hydroxybutyrate] in Paraffin

“…In blends, it is used to improve flexibility and impact resistance, while the isotactic one shows interesting processing properties, but it has a high melting point. 25,26 A synthetic analogue of aliphatic biopolyester, poly[(R)-3-hydroxybutyrate] -poly[(R,S)-3-hydroxybutyrate] ((R,S)-PHB) -has been recognised to be a suitable modifier for (bio)degradable polymers, such as the brittle polylactide or the highly crystalline polyhydroxyalkanoates (PHA)s of bacterial origin. 27,28 The ring-opening polymerisation of b-butyrolactone with various types of catalysts leads to poly(3-hydroxybutyrate)s of different tacticities, which mimic those polymers found in nature.…”