L. Quiles-Carrillo

Manufacturing and Characterization of Toughened Poly(lactic acid) (PLA) Formulations by Ternary Blends with Biopolyesters

Ternary blends with a constant poly(lactic acid) (PLA) content (60 wt %) and varying amounts of poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) were manufactured by one step melt blending process followed by injection moulding, with the main aim of improving the low intrinsic toughness of PLA. Mechanical properties were obtained from tensile and Charpy impact tests. The miscibility and morphology of the system was studied by thermal analysis and field emission scanning electron microscopy (FESEM). The obtained results showed a clear phase separation, thus indicating poor miscibility between these three biopolyesters, i.e., PLA, the continuous component with dispersed PHB and PCL domains in the form of different sphere size. Nevertheless, the high fragility of PLA was remarkably reduced, as detected by the Charpy impact test. In accordance with the decrease in brittleness, a remarkable increase in elongation at break is achieved, with increasing PCL load due to its flexibility; in addition, increasing PCL load provides thermal stability at high temperatures. Thus, tailored materials can be manufactured by melt blending PLA, PHB, and PCL in different percentages to offer a wide range of biodegradable polymer blends.

Environmentally Friendly Compatibilizers from Soybean Oil for Ternary Blends of Poly(lactic acid)-PLA, Poly(ε-caprolactone)-PCL and Poly(3-hydroxybutyrate)-PHB

Ternary blends of poly(lactic acid) (PLA), poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) with a constant weight percentage of 60%, 10% and 30% respectively were compatibilized with soybean oil derivatives epoxidized soybean oil (ESO), maleinized soybean oil (MSO) and acrylated epoxidized soybean oil (AESO). The potential compatibilization effects of the soybean oil-derivatives was characterized in terms of mechanical, thermal and thermomechanical properties. The effects on morphology were studied by field emission scanning electron microscopy (FESEM). All three soybean oil-based compatibilizers led to a noticeable increase in toughness with a remarkable improvement in elongation at break. On the other hand, both the tensile modulus and strength decreased, but in a lower extent to a typical plasticization effect. Although phase separation occurred, all three soybean oil derivatives led somewhat to compatibilization through reaction between terminal hydroxyl groups in all three biopolyesters (PLA, PHB and PCL) and the readily reactive groups in the soybean oil derivatives, that is, epoxy, maleic anhydride and acrylic/epoxy functionalities. In particular, the addition of 5 parts per hundred parts of the blend (phr) of ESO gave the maximum elongation at break while the same amount of MSO and AESO gave the maximum toughness, measured through Charpy’s impact tests. In general, the herein-developed materials widen the potential of ternary PLA formulations by a cost effective blending method with PHB and PCL and compatibilization with vegetable oil-based additives.

Manufacturing and Characterization of Composite Fibreboards with Posidonia oceanica Wastes with an Environmentally-Friendly Binder from Epoxy Resin

Highly environmentally-friendly fibreboards were manufactured by hot-press moulding using Posidonia ocaeanica wastes and a partially biobased epoxy resin as binder. Fibreboards with a constant fibre content of 70 wt % were successfully manufactured by thermo-compression. The effects of a conventional alkali treatment were compared to the synergistic effects that additional silanization with two silanes (amino and glycidyl) can exert on the mechanical and thermo-mechanical properties of fibreboards. The results revealed a remarkable improvement of the mechanical properties with the combination of the alkali treatment followed by the silanization. Scanning electron microscopy also revealed increased resin-fibre interactions due to the synergistic effect of both amino- and glycidyl-silanes. These fibreboards represent a formaldehyde-free solution and can positively contribute to sustainable development as the lignocellulosic component is a waste and the binder resin is partially biobased.

High toughness poly(lactic acid) (PLA) formulations obtained by ternary blends with poly(3-hydroxybutyrate) (PHB) and flexible polyesters from succinic acid

This work reports the development of poly(lactic acid) (PLA) formulations with improved toughness by ternary blends with poly(3-hydroxybutyrate) (PHB) and two different flexible polyesters derived from succinic acid, namely poly(butylene succinate) (PBS) and a copolymer, poly(butylene succinate-co-adipate) (PBSA). The main aim of this work is to increase the low intrinsic toughness of PLA without compromising the thermal properties by manufacturing ternary blends using epoxidized vegetable oils as compatibilizer agents. The ternary blends were manufactured by reactive extrusion in a co-rotating extruder and were subjected to mechanical, thermal, thermos-mechanical and morphology characterization. The obtained results confirm that these two succinic acid-derived polymers, i.e., PBS and PBSA, positively contribute to increase ductile properties in ternary blends with PLA and PHB with a subsequent improvement on impact toughness. In addition, both epoxidized vegetable oils, ELO and ESBO, are responsible for somewhat compatibilization between all three polyesters in blends which gives improved ductile properties with regard to uncompatibilized ternary blends. In addition, the temperature range in which these materials can be used is broader than ternary blends with other flexible polyester such as poly(e-caprolactone), as both PBS and PBSA melt at about 100xa0°C. These PLA-based materials with improved impact properties offer interesting applications in the packaging industry.