Effect of ageing and annealing on the mechanical behaviour and biodegradability of a poIy(3-hydroxybutyrate) and poly(ethylene-co-methyl-acrylate-co-glycidyl-methacrylate) blend

摘要

Poly(3-hydroxybutyrate) (PHB) undergoes an ageing process that contributes to its remarkable fragility. Blending it with an elastomer is a possibility to increase toughness. In this work, the mechanical properties of a 70/30 wt% blend of PHB and poly(ethylene-co-methyl-acrylate-co-glycidyl-methacrylate) were studied over time. The phenomenon of ageing affected the blend, which lost its ductility and became fragile days after its processing. Differential scanning calorimetry and small angle X-ray scattering analyses showed that this drop in mechanical properties was due to changes in the crystalline structure of the matrix. Annealing reduced fragility, increased toughness and prevented a re-ageing of the blend. Biodegradation in soil was also more intense for annealed samples.