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We report a study of the structure and mechanical properties of copolymers of syndiotactic polypropylene (sPP) with different comonomers, as ethylene, butene, hexene, octene etc., up to long branched -olefins. All these copolymers show elastomeric properties even though they present non negligible level of crystallinity at low comonomeric units concentration. The effect of the presence of short or long branches on the crystallization behaviour and elastomeric properties has been analyzed. Incorporation of long branched comonomers, as 1-octadecene and 1-eicosene, allows fast decrease of the glass transition temperature that, associated with the elastic properties, makes these copolymers interesting rubbers. The relationships between structure, crystal morphology and stress-induced phase transformations and mechanical properties have been clarified. In samples with low comonomer content the elastic properties are associated with a reversible polymorphic transition between different polymorphic forms of sPP characterized by chains in trans-planar and helical conformations that occurs upon stretching and releasing the tension. These phase transformations provide an enthalpic contribution to the elasticity. Samples with higher comonomer concentrations show very low crystallinity and a typical thermoplastic elastomeric behavior with a classic entropic elasticity. The study of the crystal morphology shows the presence of small bundles of rod-like lamellar crystals in all copolymers whose size decreases with increasing content and size of comonomeric units. The small needle-like crystals act as knots of an elastomeric lattice, accounting for the development of classic entropic elastic properties. Young modulus and strength of these elastomeric materials can be easily tuned by suitable modification of type and concentration of the comonomeric unit to be copolymerized with propylene that, indeed, affect the degree of crystallinity and the level of entropic and enthalpic contributions to the elasticity. These copolymers represent a new class of elastomeric materials, defined “crystalline elastomers” where the crystallinity plays a fundamental role.

Cardoon seeds oil (Cynara Cardunculus CCO) has been attracting an increasing interest in Italy for the bio-plastic industry. Cardoon is a wild robust perennial plant, native from the Mediterranean basin. The aim of this work is the preparation of biodegradable and non-toxic plasticizers by epoxidation reaction (ECO) of CCO and the study of their potential plasticizing effect in environmentally friendly polymers like poly(lactic acid) (PLA), whose drawbacks are its brittleness and lower impact resistance. The morphological analysis evidenced a well embedding of epoxidized oil inside the polymeric matrix, thus suggesting a good compatibility; the bulk analysis of the systems, by means of DSC and TGA highlighted the decrease of Tg, due to the physical interactions between the polar residues of the polymer and oils in the amorphous region of PLA and higher thermal stability of the polymer in presence of the oils; finally mechanical properties evidenced the enhancement of polymer ductility, particularly in PLA_ECO system.

Thymol can be easily derived from plants (thyme and oregano) and is a FDA approved food additive commercially available at low price. It has been recognized to have antibacterial and antioxidant properties, and is registered in the list of flavourings that do not present risks to the health of the consumers. This interesting properties can in principle be exploited also to prepare functional coatings, which in turn can be applied to packaging materials to obtain antibacterial and antifungi packagings. This study is devoted to investigate the possibility to prepare thymol-doped antibacterial coatings. For this purpose, thymol has been dissolved in different amounts into a liquid photo-crosslinkable diacrylic resin and the antibacterial activity has been evaluated against gram-positive and gram-negative bacterias by qualitative modified agar diffusion assays. The rate of diffusion of thymol from the doped-resins have been performed with different liquid simulating fat (n-hexane), acqueous (water) and intermediate polarity (MeOH, Ethyl Acetate and EtOH) media.

Organic-inorganic hybrid coatings can be used to improve the barrier of plastic films against oxygen diffusion. This work aims at investigating by means of solid-state multinuclear NMR (29Si, 13C, 1H) the molecular structural and dynamic properties of hybrid coatings obtained by the sol-gel method by reacting tetraethoxysilane with trialkoxysilane terminated polyethylene-b-poly(ethylene glycol) copolymer and poly(4-hydroxystyrene). Attention has been directed to the attempt of clarifying the role of hydroxystyrene and in particular its capability to form hydrogen bonds with either the organic or the inorganic components, as well as to highlight possible structural and dynamic differences in both the inorganic and organic domains among samples with different compositions. Correlations between molecular properties and oxygen barrier performances have been hypothesized on the basis of the solid-state NMR results.

Gli ibridi organici-inorganici rappresentano un nuovo tipo di materiali in cui la componente organica ed inorganica si trovano intimamente connesse in una scala dimensionale che può essere nanometrica o sub-micrometrica. Il processo sol-gel si sta attualmente imponendo come uno dei metodi più interessanti nella preparazione di materiali ibridi organici-inorganici nanostrutturati. In questo testo, vengono presentati quelli che sono i principi generali del processo sol-gel e le principali modalità di preparazione di materiali ibridi O/I (organici-inorganici). Sono inoltre brevemente illustrate le proprietà di questi nuovi materiali anche in funzione della diversa modalità di sintesi e struttura, in esame i vantaggi e le problematiche legate all’utilizzo di ibridi O/I come coating protettivi e funzionali per substrati polimerici.

In this work a hybrid organic-inorganic coating, obtained with a sol-gel process from tetraethoxysilane and a polyethylene-polyethlenglycol block copolymer, was prepared in three different compositions and applied by spin coating to untreated and plasma treated LDPE films. The adhesion between coating and LDPE was characterized by fragmentation tests: an increase in coating strength, elongation at break and in adhesion with increasing organic fraction is observed along with the beneficial effect of surface plasma treatment.

Silver-doped organic–inorganic hybrid materials, prepared by a sol–gel process, have been recently proposed as antibacterial coatings. The antibacterial activity of the coated materials is related to the diffusion capability of Ag+ ions within the coating and can be affected by several parameters, and in principle controlled to some extent by controlling the composition of the coating and the sol-gel process conditions. The effect of the organic-inorganic ratio and type of catalysis on the release of Ag+ from the organic-inorganic hybrid coatings in physiological saline solution at 37 °C, up to 240 h, was examined.