Cesare Lorenzetti

Fully biobased poly(propylene 2,5-furandicarboxylate) for packaging applications: excellent barrier properties as a function of crystallinity

High molecular weight, amorphous poly(propylene 2,5-furandicarboxylate) has been aged at 135 °C for different times. The crystal phase contributes to achieve exceptionally low oxygen transmission rates and also good impermeability to water vapors, making PPF one of the most interesting fully biobased polyesters for packaging applications.

Polyethylene like polymers. Aliphatic polyesters of dodecanedioic acid 1. Synthesis and properties

A series of aliphatic polyesters has been synthesized starting from 1,12-dodecanedioic acid and aliphatic diols, bearing from 2 to 12 carbon atoms. These polymers, which were fully characterized in terms of chemical structure, molecular weight and thermal behaviour, were obtained as crystalline materials with melting points ranging from 70 to 90 °C and with a relatively high molecular weight. All the monomers used can be obtained from biomasses, as a consequence these materials can be an interesting alternative to synthetic polymers produced from petrochemical processes based on nonrenewable resources.

Poly( m -xylylene adipamide)-based Copolyamides: Effect of the Chemical Structure on Oxygen Permeation Properties

Poly(m-xylylene adipamide) (MXD6) is a well-known polyamide, widely used in engineering applications for a favourable set of mechanical properties and in packaging materials manufacturing because of its excellent gas barrier properties. In this work new random copolymers based on MXD6 were prepared by melt polycondensation of different comonomers (diacids and diamines) together with m-xylylene diamine and adipic acid with the aim of studying the effect of various chemical structures on the final barrier properties and trying to improve barrier performances of MXD6 at high humidity level. The resulting copolyamides were characterized in order to investigate the structureproperty relationships. Attention has been focused on the changes in glass transition temperature, density, sub-Tg relaxations. Interesting correlations between structure and oxygen permeation properties have been found.

Synthesis and characterization of novel water-soluble polyamides with enhanced gas barrier properties

Poly(hexamethylene isophthalamide) (PA6I), an amorphous polymer characterized by high temperature resistance and significant oxygen barrier performances, has been chemically modified by using the 5-sulfoisophthalic acid sodium salt as a comonomer. Then, ionic groups have been randomly distributed along the polymeric chains. The new sulfonated PA6I samples were studied in order to understand structure–property relationships. It results that ionomeric PA6Is present an increment of Tg and, accordingly, a decrement of the oxygen transmission rate at 50% of relative humidity with the increment of the ionic content. Ionic groups, indeed, induce the formation of new interactions among the polymer chains, and then, a complex macromolecular network is realized. Interestingly, a molar amount of ionic groups equal to or higher than 10% makes sulfonated polyamides water-soluble. This characteristic, exploited to prepare new coatings on different polymers, opens a range of new applications for ionomeric PA6I.