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Blends of polypropylene, polystyrene (PS), polyethylene terephthalate (PET), and high‐, low‐ and linear low‐density polyethylene (LDPE and LLDPE) with different contents on polylactid acid (PLA) were prepared. Tensile and impact properties and melt flow rate (MFR) of the mixtures were determined. Morphology was analyzed through scanning electron microscopy (SEM) and interactions were studied by measuring glass transition temperatures (Tg) as well as applying a model to quantify the composition dependence of tensile strength. Results show that there are significant differences on structure and properties among the blends. Polyolefin based blends feature heterogeneous structures with big particle sizes, which translates to blend properties with high negative deviation from the rule of mixtures (ROM), especially for LDPE and LLDPE. Blends of PET and PS feature smaller dispersed particles, resulting in blends with mechanical properties close to those of ROM. Shifting in glass transition temperatures indicate interactions between these materials, which were quantitatively determined indicating the strongest interactions for the PS/PLA pair followed by the PET/PLA mixture.

Sheet molding compounds (SMCs) have considerable potential as lightweight alternative to traditional materials used in automotive components. However, despite their outstanding mechanical properties, their vibration damping characteristics are often relatively poor for several applications. Therefore, enhancing the vibration damping capability of SMCs represents a field with increasing interest. Application of viscoelastic layers to high stiffness materials, such as SMCs, represents an effective approach to add vibration damping functionalities to lightweight structural components. In this work, the incorporation of thermoplastic elastomers (TPEs) is studied as a novel strategy to enhance the structural vibration damping capability of SMCs. Several types of SMC and TPEs have been considered and the effect of TPE‐SMC thickness ratio on the damping and stiffness properties is investigated. The viscoelastic properties and vibration damping performance were evaluated by dynamic mechanical analysis. The effect of TPE addition on stiffness was studied by three‐point bending. Results reveal the potential of the incorporation of thin TPE layers as cost‐effective strategy to enlarge the vibration damping efficiency of SMCs while maintaining their overall high stiffness. It is expected that the bi‐material configurations presented in the current study will contribute to advance the development of new lightweight multi‐functional solutions for modern transport applications.

Over the years, our oceans have witnessed an enormous accumulation of marine plastic waste resulting from ocean-related economic activities. As plastic pollution adversely affects marine wildlife and habitat, our society requires urgent solutions to address this increasingly alarming dilemma. Here, we turn our attention to circular economy principles to reduce the amount of nonbiodegradable petroleum-based marine litter. We consider a production process based on 3D printing to fabricate products for the marine industry, which uses marine plastic waste as a source material. Additionally, the suitability of virgin bio-based polyamide (bio-PA), polylactic acid (PLA), and polyhydroxybutyrate (PHB) is explored. PHB is selected due to its extraordinary rapid biodegradation in aquatic environments. To quantify the environmental impacts of the proposed processes, a cradle-to-grave life cycle assessment (LCA) is applied according to ISO 14040:2006 and ISO 14044:2006 standards. Different endof-life alternatives are proposed, including landfill deposition, thermal degradation, and composting. LCA results reveal that the use of marine plastic waste is environmentally preferred in comparison with bio-PA, PLA, and PHB. Specifically, the global warming indicator, considered a prime driver toward sustainability, shows a 3.7-fold decrease in comparison with bio-PA. Importantly, the environmental impacts of PHB production through crude glycerol fermentation are quantified for the first time.Regarding the end-of-life options with a composting scenario, PLA and PHB are preferred as they yield biogenic carbon dioxide (CO 2 ), which can be used as a renewable energy source.

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