Maria Beatrice Coltelli

Recyclability of PET/WPI/PE Multilayer Films by Removal of Whey Protein Isolate-Based Coatings with Enzymatic Detergents

Multilayer plastic films provide a range of properties, which cannot be obtained from monolayer films but, at present, their recyclability is an open issue and should be improved. Research to date has shown the possibility of using whey protein as a layer material with the property of acting as an excellent barrier against oxygen and moisture, replacing petrochemical non-recyclable materials. The innovative approach of the present research was to achieve the recyclability of the substrate films by separating them, with a simple process compatible with industrial procedures, in order to promote recycling processes leading to obtain high value products that will beneficially impact the packaging and food industries. Hence, polyethyleneterephthalate (PET)/polyethylene (PE) multi-layer film was prepared based on PET coated with a whey protein layer, and then the previous structure was laminated with PE. Whey proteins, constituting the coating, can be degraded by enzymes so that the coating films can be washed off from the plastic substrate layer. Enzyme types, dosage, time, and temperature optima, which are compatible with procedures adopted in industrial waste recycling, were determined for a highly-efficient process. The washing of samples based on PET/whey and PET/whey/PE were efficient when performed with enzymatic detergent containing protease enzymes, as an alternative to conventional detergents used in recycling facilities. Different types of enzymatic detergents tested presented positive results in removing the protein layer from the PET substrate and from the PET/whey/PE multilayer films at room temperature. These results attested to the possibility of organizing the pre-treatment of the whey-based multilayer film by washing with different available commercial enzymatic detergents in order to separate PET and PE, thus allowing a better recycling of the two different polymers. Mechanical properties of the plastic substrate, such as stress at yield, stress and elongation at break, evaluated by tensile testing on films before and after cleaning, were are not significantly affected by washing with enzymatic detergents.

Alternative synthetic routes for the preparation of PLA/montmorillonite nanocomposites

Although the improvement of tensile Modulus and thermal stability due to the addition of innovative organoclays to PLA were negligible, our investigation allowed to evidence that the preliminary preparation of an inorganic rich composite through in situ polymerization of lactyde gave a final morphology improved with respect to that achieved by simply melt dispersing organoclay powder. Anyway the former preparation method should be further investigated in order to control PLA structural features resulting from the ring opening polymerization synthesis.

Effect of different nucleating agent on crystallinity and properties of polylactic acid

Polylactide (PLA) is a promising biobased, compostable polymer suitable for replacing petro-derived polymer not just in single use applications but also for durable equipment requiring more demanding technical performances, in particular in terms of mechanical properties and stability. Consequently a better knowledge of the crystallization behavior of PLA and its effects on the mechanical properties is crucial in order to extend its industrial applications, and even for optimization of polymeric matrices to be further used for biocomposite or active packaging production. In the present study, different nucleating agents have been added to PLA during processing by extrusion and injection molding, to tune the percentage of crystallinity, and modulate the mechanical properties. Boron Nitride and nano fillers (Talc, Calcium Carbonate) have been tested as nucleating agents in variable amount. All the additives investigated evidenced a positive effect on increasing in the degree of crystallinity of PLA and, consequently an improvement of its mechanical properties and widening of potential performance.Polylactide (PLA) is a promising biobased, compostable polymer suitable for replacing petro-derived polymer not just in single use applications but also for durable equipment requiring more demanding technical performances, in particular in terms of mechanical properties and stability. Consequently a better knowledge of the crystallization behavior of PLA and its effects on the mechanical properties is crucial in order to extend its industrial applications, and even for optimization of polymeric matrices to be further used for biocomposite or active packaging production. In the present study, different nucleating agents have been added to PLA during processing by extrusion and injection molding, to tune the percentage of crystallinity, and modulate the mechanical properties. Boron Nitride and nano fillers (Talc, Calcium Carbonate) have been tested as nucleating agents in variable amount. All the additives investigated evidenced a positive effect on increasing in the degree of crystallinity of PLA and, con...