Effect of the addition of a natural compatibilizer on mechanical, thermal and barrier properties of polylactic acid/ poly(3hydroxybutyrate) blends

IGLESIAS MONTES, MAGDALENA L.; D'AMICO DAVID ALBERTO; V. P. CYRAS; L. B. MANFREDI

Sevilla

Simposio; Frontiers in Polymer Science 2017; 2017

Biodegradable and biosource polymers have been extensively studied as alternatives to nondegradablepolymers currently used in the food packaging industry. Two of the most promisingbiopolymers studied for this purpose are: polylactic acid (PLA) and poly (3hydroxybutyrate)(PHB), both biodegradable and biocompatible polyesters which can be fully obtained fromrenewable resources. However, PLA and PHB present some disadvantages over oilbasedplasticssuch as fragility and difficult processing as well as limited applications. In this context, blendingtechniques are an extremely promising approach which can improve polymer?s original properties.Blends provide numerous suitable properties which are the result of a combination of those of thepristine components. Most polymer pairs are immiscible but can be made compatible by adding athird component named as compatibilizer.In a previous work, blends with different ratio PLA (Nature Works)/PHB (PHB Industrial),compatibilized with 20 wt% of glyceryl tributyrate (TB) (Fluka) were obtained in a Haake mixer(185ºC and 50 rpm). Two ratios PLA/PHB: 70/30 and 60/40, resulted in materials with interestingmechanical properties. In this work, to further study the behaviour of the blends, thecompatibilizer content was varied (10, 15 and 20 wt%) in these formulations to obtain a superiormaterial. Mechanical, thermal and barrier properties were investigated by means of differentialscanning calorimetry analysis, thermogravimetric analysis, Xraydiffraction, water vaporpermeation tests, opacity and uniaxial tensile tests.Elongation at break slightly changed by decreasing from 20 to 15% the TB content, but the elasticmodulus and the ultimate stress both increased. A new material, PLA70/PHB30TB15%,withimproved mechanical properties respect to the pristine components was obtained, withoutdeterioration in the vapor barrier properties.