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Isotactic polypropylene (iPP) gives very extensive degradation when treated with peroxides above its melting temperature in mechanical mixers or extruders. This undesired reaction is very modestly affected by maleate molecules which on the contrary actively compete with side reactions of macroradicals in the case of ethylene polymers. In this work iPP was treated in a Brabender mixer at 180 °C with peroxide and different selected molecules capable of promptly reacting with the macroradical formed on iPP chain and converting it into a more stable free radical. Furan derivatives, successfully used for iPP cross-linking without any remarkable increase of MFR, were used as free radical removers and maleic anhydride as functionalizing monomer. The results indicate a detectable improvement with respect to the use of maleic monomers and peroxide only, allowing to us get a significant grafting of functional groups and only partial degradation. Moreover, furan derivatives bearing various reactive substituents were used as functionalizing molecules. The results are discussed in the frame of the general mechanism proposed for the free radical functionalization of polyolefin in the melt.

After a short survey devoted to revisit the exceptional properties of the various catalytic systems discovered by Giulio Natta and the many structures of the derived polyolefins, the present paper reports about the new processes, which also originate from the research activity of Natta, presently studied and applied for the production of innovative heterophasic materials. In these last polyolefins, with their versatile thermo-mechanical properties, continue to play a fundamental role.

Blends of styrene-butadiene-styrene triblock copolymer (SBS) with random styrene-maleic anhydride copolymers (PS-co-MA), having different MA content, were prepared in a Brabender Plastigraph mixer. The presence of polystyrene (PS) blocks in the SBS copolymer and the high styrene content (93 and 86 wt.-%, respectively) in the two kinds of used PS-co-MA samples afforded a good compatibility between the PS phases of the two polymers. On the other hand, the presence of polar anhydride groups allows a net improvement of the thermal properties of the polystyrene phase of the blends as shown by differential scanning calorimetry (DSC) analysis. In addition, the dynamic behavior of the blends, as highlighted by dynamic thermo-mechanical analysis (DMTA), shows in all cases a "stiffening" of the material in comparison to original SBS. Preliminary experiments aimed to convert, directly in the mixer, the anhydride groups into the corresponding zinc salt allowed only a partial neutralization. Both DSC and scanning electron microscopy (SEM) indicate that the reaction is not complete under the used experimental conditions.

Blending of styrene-b-(ethylene-co-1-butene)-b-styrene (SEBS) triblock copolymers with syndiotactic polystyrene (PSsyn) has been performed in a Brabender mixer above the higher glass transition temperature of the triblock copolymer but below the PSsyn melting point. The large excess of the triblock copolymer over the homopolymer as well as the significant amount of plasticized amorphous PSsyn phase allowed the easy processing under the used temperature conditions with good interface compatibility. The consequent interfacial adhesion between the amorphous PS phase and the unmelted PSsyn crystallites affects both the final morphology of the blend as well as its dynamic behaviour. Indeed, such solid particles act as reinforcing point of the overall blend structure, as evidenced by Scanning Electron Microscopy (SEM). Moreover, they contribute to a Tg increase of the blends and to an appreciable conservation of mechanical properties at temperatures higher than the Tg of the PS blocks of SEBS.

Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing sulfonated units were prepared by blending styrene-block-butadiene-block-styrene (SBS), with both sulfonated PS and sulfonated SEBS in a Brabender mixer. Such a procedure was performed as an alternative route to direct sulfonation of SBS which is actually not selective towards benzene rings because of the great reactivity of the double bonds in polybutadiene (PB) blocks to sulfonation agents. Thermal and dynamic-mechanic analysis, together with morphology characterization of the blends, is consistent with obtaining partially compatible blends characterized by higher Tg of the polystyrene domains and improved thermal stability.