Synthesis and Characterization of New Aliphatic Biodegradable Polyesters for Packaging Applications

Abstract

Until now, petrochemical-based plastics have been extensively used as packaging materials thanks to their low cost and excellent physic-mechanical properties. Unfortunately, as it is well-known, these materials are not readily degraded in the environments where they are disposed once their function has ended. As a consequence, thousands of tons of plastic packaging are disposed in landfills every year, causing a continuous pollution increment. In this view, replacing non-degradable plastics based on fossil oil with sustainable bio-based, biodegradable materials for short time applications is of great environmental importance. Among biobased and biodegradable plastic packaging materials, one of the most economically competitive polymer class is represented by aliphatic polyesters, that have attracted considerable attention in last decades as they combine the afore mentioned features with interesting physical and chemical properties. In this framework, the present research work focused on the modification of some interesting aliphatic polyesters, in order to prepare new materials, which guarantee full compostability and offer suitable characteristics, especially in terms of mechanical and barrier properties to be used in food packaging applications. Simple, ecofriendly, cost-effective synthetic strategies have been employed to obtain the designed materials. All the synthesized polymers have been deeply characterized by the molecular, thermal and mechanical point of view. Moreover, their barrier properties have been studied to prove their suitability for packaging applications. Lastly, lab-scale composting experiments have been carried out, in order to check their potential compostability. Solid-state properties and biodegradation rate can be tailored acting on chemical structure, copolymer composition and polymer architecture: in particular, the introduction of different amounts of ether- or thio-ether linkages or short ramifications along macromolecular backbone of parent homopolymer, or simply acting on soft/hard ratio in block structures permitted to modulate mechanical behaviour and biodegradation rate of the parent homopolymer itself, without compromising the good properties.