The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high molecular weight polyethylene (UHMWPE)-based nanocomposites. First, CNTs have been subjected to sonication for different time intervals and the performed spectroscopic and morphological analyses reveal that a dramatic decrease of the CNT’s original length occurs with increased sonication time. The reduction of the initial length of CNTs strongly affects the nanocomposite rheological behaviour, which progressively changes from solid-like to liquid-like as the CNT sonication time increases. The study of the thermo-oxidative behaviour of the investigated nanocomposites reveals that the CNT sonication has a detrimental effect on the thermo-oxidative stability of nanocomposites, especially for long exposure times. The worsening of the thermo-oxidative resistance of sonicated CNT-containing nanocomposites could be attributed to the lower thermal conductivity of low-aspect-ratio CNTs, which causes the increase of the local temperature at the polymer/nanofillers interphase, with the consequent acceleration of the degradative phenomena.

In this work, biocomposite blown films based on poly(butylene adipate-co-terephthalate) (PBAT) as biopolymeric matrix and biochar (BC) as filler were successfully fabricated. The materials were subjected to a film-blowing process after being compounded in a twin-screw extruder. The preliminary investigations conducted on melt-mixed PBAT/BC composites allowed PBAT/BC 5% and PBAT/BC 10% to be identified as the most appropriate formulations to be processed via film blowing. The blown films exhibited mechanical performances adequate for possible application as film for packaging, agricultural, and compost bags. The addition of BC led to an improvement of the elastic modulus, still maintaining high values of deformation. Water contact angle measurements revealed an increase in the hydrophobic behavior of the biocomposite films compared to PBAT. Additionally, accelerated degradative tests monitored by tensile tests and spectroscopic analysis revealed that the filler induced a photo-oxidative resistance on PBAT by delaying the degradation phenomena.

Increasing environmental awareness has led to a great research effort towards the formulation of increasingly sustainable pavements, mainly by developing bituminous mixtures incorporating waste materials. Furthermore, some waste materials have been proved to be useful for enhancing the performance of road bitumen and bituminous products, so their use is a potential solution for ensuring environmental, economic, and also technical benefits. Amongst the different wastes to be used for bitumen modification, a possible one is that obtained via the pyrolysis of biomass, named biochar. In the research reported here, a selected biochar was added to bitumen to verify the possibility of improving bitumen performance in terms of photo-oxidation resistance, which is a major problem in urban areas where black flexible pavements contribute to the urban heat island effect. Different biochar amounts were selected, and two different aging methods were performed: short-term aging and UVB aging resistance; they were monitored using rheological and spectroscopic analysis. The structural changes in bitumen in terms of carbonyl and hydroxyl accumulation were observed at various UV irradiation times. All the experimental data indicate that the use of biochar can have a positive effect on the UV resistance of bitumen, lowering its photo-oxidation tendency. This may lead to reductions in use of natural, non-renewable materials, since intervention maintenance may be scheduled at longer terms.

To obtain road bitumen with improved temperature and fatigue resistance, polymers and/or rubbers could be added to it. A particularly suitable polymer for bitumen modification is styrene-butadiene-styrene (SBS) copolymer but limited information is available about the ageing behaviour of modified binders. In this work, two neat bitumens, with different penetration grades, and two SBS-modified bitumens, containing different SBS amounts, were selected, and their short-term and UVB ageing behaviour were investigated considering dynamic shear rheometry and Attenuated Total Reflectance-Fourier Transformation InfraRed spectroscopy (ATR-FTIR). Short-time ageing behaviour was investigated performing the rolling thin film oven test (RTFOT), while artificial UV ageing was examined/investigated using UVB lamps. The structural changes in bitumen were monitored at different UV exposure times. All the results suggest that the bitumen having higher penetration grade is more stable than the one with a lower penetration grade in the RTFOT ageing condition, and SBS addition exerts a beneficial effect on thermal stability during processing. Further, SBS addition also has a beneficial effect on the UV ageing resistance of bitumen, reducing its oxidation tendency.

Finding an appropriate technical solution for reusing waste plastics is crucial for creating a circular plastic economy. Although mechanical recycling is the best option for recycling post-consumer plastics, some heterogeneous mixed plastics cannot be recycled to produce secondary material due to their very low properties. In this case, alternative routes should be considered in order to limit their disposal as much as possible. Therefore, in order to solve the environmental problems in the landfills of plastic waste recycling, and to improve the mechanical performance of bitumen for road pavement, the reuse of these post-consumer plastic wastes are preliminarily evaluated for the modification of bitumen for road use. The field of polymers used so far and widely studied concerns virgin materials, or highly homogeneous materials, in case of recycled plastics. In this work, a highly heterogeneous mixed plastic—Plasmix—from the separate collection in Italy, is used as a bitumen modifier for road construction. The research focused on the dry (into the mixture) and wet (into the binder) addition of different content of the Plasmix compound, with the aim of assessing the feasibility of the modification itself. Results of the mechanical tests carried out prove an increase in performance and that there is a potential of the addition of the Plasmix compound both for binder and mixture modifications.

In this work, naturally occurring compounds, such as Vitamin E (VE) and Ferulic Acid (FA), at high concentrations, have been considered as pro-degradant agents for Low Density Polyethylene (PE). However, all obtained results using the naturally occurring molecules as pro-oxidant agents for PE have been compared with the results achieved using a classical pro-oxidant agent, such as calcium stearate (Ca stearate) and with neat PE. The preliminary characterization, through rheological, mechanical and thermal analysis, of the PE-based systems highlights that the used naturally occurring molecules are able to exert a slight plasticizing action on PE and subsequently the PE rigidity and crystallinity slightly decrease, while the ductility increases. To assess the pro-degradant activity of the considered naturally occurring compounds, thin films of neat PE and PE-based systems containing 2 and 3 wt.% Ca stearate, VE and FA have been produced and subjected to accelerated weathering upon UVB light exposure. All obtained results point out that the VE and FA, at these high concentrations, exert a clear pro-oxidant activity in PE and this pro-oxidant activity is very similar to that exerted by Ca stearate. Moreover, the VE and FA at high concentrations can be considered as suitable eco-friendly pro-degradant additives for PE, also in order to control the polyolefin degradation times.