Packaging sector generates 40% of the plastics consumption in Europe. Among the most consumed plastics, polyethylene terephthalate (PET) is still the material that undoubtedly continues to grow in the packaging sector. Hence, there is a concern related to the recycling process, which today is only around 56%. Therefore, the objective of this work focuses on the use of this recycled material as a source of raw material for pultrusion processes. This work studies and compares the processability of final composite pultruded parts by using three different pre-impregnated recycled materials different in their viscosity and stream. Those composites were characterized by mechanical testing and microscopy analysis. The obtained results were compared with those of another pultruded thermoplastic (polypropylene) composite. From this study, it was possible to transform a waste into a product with high added value, reducing the carbon footprint.

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The use of recycled PET (rPET) in long-term applications, such as composites, may provide an environmentally friendly solution for PET wastes. Main problem to overcome to use rPET in composites is its high viscosity which compromises the impregnation with the fibers during the consolidation process. As it is well known, PET undergoes thermo-mechanical and hydrolytic degradation during its mechanical recycling decreasing its viscosity and causing a loss of mechanical properties. For this reason, this paper takes into consideration a rheological modification during mechanical recycling to achieve the necessary fluidity for composites while maintaining the mechanical properties. Rheological modification was carried out by physical and chemical methods. Physical method was realized through blending with virgin PET (vPET) of low melt viscosity. Chemical method was performed on rPET, vPET and its blends by reactive extrusion. The effect of rheological modifications on the final thermal and mechanical properties was studied. Main results showed that both methods are able to decrease the viscosity without compromising mechanical properties. In addition, the chemical method during the reactive extrusion provided higher Elastic Modulus values.

Poly(lactic acid) (PLA) nanocomposite ternary blends based on unmodified sepiolite were prepared by melt blending using a corotating twin-screw extruder. Two grafted polymers were used as compatibilizer agents, in an effort to increase the PLA tensile toughness. The influence of incorporating a low-cost commodity low-density polyethylene, as dispersed phase to the composites on thermal degradation, and rheological and tensile properties was studied. The morphology of the blends and composites was determined through transmission and scanning electron microscopy techniques. Results showed that the compatibilized blends prepared without clay have higher thermal degradation susceptibility and tensile toughness than those prepared with sepiolite and significant changes in complex viscosity and melt elasticity values were observed between them. The nanocomposite blends exhibited similar thermal degradation, lower tensile strength, and Young's modulus values and increased elongation at break and tensile toughness, complex viscosity, and storage modulus compared with those of the nanocomposite of PLA. These results are related to the clay dispersion, to the type of morphology of the different blends, to the localization of the sepiolite in the different phases, the thermomechanical degradation of the PLA matrix phase during melt blending and the grafting degree of the compatibilizers used. POLYM. ENG. SCI., 52:988-

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The use of bio‐based plastics as polymeric matrices to produce technical composites has become an important topic in material science. In this sense, bio‐based polyamides represent an interesting alternative to their petroleum‐based counterparts because of their good thermal and mechanical properties, their low specific weight, and their ability to be used in complex parts by injection molding. In the present study, bio‐based polyamide 11/sepiolite nanocomposites were prepared using the two most feasible techniques from the industrial point of view: melt compounding and in situ polymerization. The effect of the preparation approach and the amount of nanoclay were evaluated to check their influence on thermal, morphological, and mechanical behavior of the final nanocomposites. Regardless of the preparation approach, all nanocomposites showed improvements in thermo‐mechanical properties with increasing contents of sepiolite. However, the nanocomposites obtained by in situ polymerization presented higher values of Young's modulus, tensile strength, and heat distortion temperature due to a greater dispersion of the nanoclay in the final composites. For in situ polymerization, the dispersion of sepiolite nanoparticles is carried out when polymer chains are growing and the viscosity of the system is low. POLYM. COMPOS., 40:E704–E713, 2019. © 2018 Society of Plastics Engineers

a b s t r a c tIn an effort to understand the influence of the shape and area of the nanoclay type used in the in situ polymerization process, two different types of clays (fibrillar and laminar) were employed to obtain nanocomposites. The preliminary results demonstrated that a needlelike shaped clay promotes higher molar mass and better mechanical properties compared with laminar clay. The ultra-high molecular weight of sepiolite/nanocomposites introduces significant problems with processability. Therefore, a new method of polymerization was designed to include two significant changes. The first change was related to the use of a non-isothermal temperature profile and the second to the addition of an additional amount of non-anchored co-catalyst leading to materials with higher fluidity.

Additive manufacturing provides an opportunity to redefine sustainability for plastic products, as polyolefins, which dominate traditional plastics manufacturing, are generally unsuitable for 3D printing. One of the most widely used 3D printing technologies is fused filament fabrication (FFF), where a thermoplastic filament is melted and extruded to build the object layer-by-layer. The printing performance can be quantified in terms of mechanical properties and dimensional accuracy of the part. Here we demonstrate the ability to print high-quality parts via FFF using a biorenewable polyamide-11 (PA-11). The PA-11 monomer, 11-aminoundecanoic acid, is derived directly from castor beans by hydrolysis, methylation, and heat treatment of its oils. The elastic modulus and dimensional accuracy can be further improved by the incorporation of a natural nanofiller, sepiolite. The role of print orientation and filler content are systematically investigated, with elastic moduli greater than 1.1 GPa obtained for the optimal printing conditions. The addition of sepiolite tends to improve both the dimensional accuracy of the printed part and the elastic modulus. The mechanical properties are dependent on the print orientation, with a flat (XY) orientation leading to the highest moduli as well as ductile failure, while the elastic modulus when printed in the end-on (YZ) orientation is decreased by 10−30% with greater decrease as the sepiolite content increases. Moreover, the samples with an YZ orientation exhibit brittle failure, which is attributed to the deposition direction being perpendicular to the applied tensile load. These results demonstrate the potential of sustainable nanocomposites for additive manufacturing via FFF.