One potential way to overcome the poor toughness and low ductility of poly(lactic acid), PLA, is to blend it with more ductile components that may or may not be biobased and biodegradable. Our lab has developed a mild and efficient biotechnological route to convert fatty acids such as tetradecanoic acid to ?-hydroxytetradecanoic acid. This monomer is then chemically converted by conventional condensation polymerizations to prepare poly(?-hydroxytetradecanoic acid) (PC14). This new-to-the-world bioplastic has an elongation at break of 700% and true tensile strength of 50 MPa resembling some properties of medium density polyethylene (PE).In this presentation we describe a reactive processing method that results in compatibilized PLA/PC14 blends that offer attractive properties. Processing parameters such as residence time in the extruder, reaction temperature and screw speed were investigated, and it was found that a reaction time of 15 min, screw speed of 150 RPM, temperature of 200 �C in the presence of 200 pm of Ti(OBu)4 gave optimal results in terms of mechanical properties and control of depolymerization. With just 5 % PC14 (95% PLA) the blend elongation at break relative to pure PLA increased from 3 % to 150 % with a small decrease in the tensile modulus (3200 MPa to 2900 MPa). Without catalyst, a typical morphology showed pullout which is typical of immiscible polymer blends. However, with the addition of catalyst, an increased compatibility between the two phases was achieved as shown in figure 1.

Reactive extrusion compatibilization of PLA with poly(?-hydroxytetradecanoic) results in important improvements in PLA properties

248th National Meeting (2014)

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