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An experimental study on the influence of chain extender (CE) on the properties and foamability of two grades of polylactide (PLA) has been carried out. The influence of CE on the polymer crystallinity and viscoelastic properties that are critical during the foaming process was investigated. After addition of CE an increase in the viscosity and the cold crystallization temperature of PLA was observed. Selection of PLA grade has been correlated with a structure of the polymer. The cellular structure of PLA was obtained during extrusion process using the chemical blowing agent. The addition of 1.0 and 1.5 % CE caused fine cellular structure and low density (0.7 g/dm 3 ) of foamed PLA.

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In order to improve the properties of biodegradable polylactide (PLA), mixtures with polybutylene adipate-co-terephthalate (PBAT) were prepared. PLA is a bio-based and renewable biodegradable material, made from starch. PBAT is a biodegradable polyester for compostable film. In order to improve the composite properties, two types of additives were implemented via melt mixing, a chain extender (CE) and montmorillonite (MMT). CE was used as an interfacial modifier to enhance the adhesion between components. Montmorillonite is a widely studied clay added to polymer nanocomposites. Due to the lamellar structure, it improves the barrier properties of materials. PLA/PBAT films were oriented in the extrusion process and the amounts of filler introduced into the PLA/PBAT nanocomposites were 1.0, 3.0, and 5.0%. The improvement in the PLA barrier properties by the addition of PBAT and 5% of MMT was confirmed as the oxygen permeability decreased almost by a factor of 3. The addition of the biodegradable polymer, chain extender, montmorillonite, and the implemented orientation process resulted in a decrease in composite viscosity and an increase in the PLA crystallinity percentage (up to 25%), and the wettability tests confirmed the synergic behavior of the selected polymer blend.