Disintegration under composting conditions of PLA/PHB plasticized films

IGLESIAS MONTES, MAGDALENA L.; D'AMICO DAVID ALBERTO; LUZI, FRANCESCA ; D. PUGLIA; CYRAS, VIVIANA P.; MANFREDI, L.B.

Mar del Plata

Simposio; Simposio Latinoamericano de Polímeros; 2018

The concerns on the environmental impact of food packaging materials after use are currently increasing by their high consumption and short shelf-life1. In this sense, polymers from renewable resources have attracted an increasing amount of attention.The aim of this work was to prepare polylactic acid / poly(3-hydroxybutyrate) (PLA/PHB) blends plasticized with tributyrin (TB) for food packaging applications, as a sustainable alternative to current non-natural and non-biodegradable materials. In particular, we focus the investigation on the biodegradability of materials. During disintegration under composting conditions it was observed that films samples changed their colour and became more opaque after 7 days. The opacity is due to changes in the refractive index which can be attributed to the water absorption and to the formation of low molecular weight compounds produced by the hydrolytic degradation2.The kinetic of disintegration (Fig. 1) is mainly ruled by the amorphous phase3, thus PLA undergoes the most rapid disintegration; after 14 days was almost pulverized. Instead, the rate was longer for PHB, because the high crystalline index of it; few changes were noticed until 21 days of incubation. PLA/PHB blends presented a similar behaviour to PLA due to the higher content of this polymer in them, showing a slightly longer disintegration rate. Regarding plasticized samples, it was observed that disintegration was higher in TB incorporated films. After 21 days all the blend samples were practically pulverized.The disintegrability under composting conditions revealed that while PLA and TB facilitated the hydrolysis process, PHB delays the disintegration of PLA matrix. The rate of disintegration was longer for PLA/PHB blends with respect to PLA counterparts due to the increased crystalline phase and the surface water resistant. However, all formulations resulted fully disintegrated under composting in times compatible with the regular composting time