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.
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.
Introduction: Chronic kidney disease (CKD) is a general term for heterogeneous disorders that affect the structure and function of the kidney. Complications of CKD significantly limit exercise (Ex) tolerance by reducing functional capacity, endurance, and strength. However, the practice of regular Ex contributes to delaying the progression of CKD and stimulating improvements in health-related quality of life (HRQOL). Ex performed during the period of hemodialysis may be the best option when stimulating adherence and being under medical supervision. The purpose of the paper is to examine the effectiveness of intradialytic (iHD) Ex on health outcomes in patients with CKD by identifying the most appropriate component of Ex. Material and method: Systematic review, based on PRISMA guidelines, performing a structured search in Medline, SciELO and Cochrane Library Plus databases. Publications from the last 5 years relating iHD Ex and CKD up to 31 December 2019 were included. The methodological quality of the articles was evaluated using the McMaster critical review form. Results: We found 7 articles that described increases in endurance, upper and lower limb muscle strength, and HRQL of CKD patients providing emotional, social and psychological improvements. In addition, iHD Ex is able to control oxidative stress, inflammation, improve the lipid profile and stimulate endothelial progenitor cells, which together reduce the risk of mortality associated with multiple comorbidities in CKD patients, especially cardiovascular ones. Conclusions:Ex provides improvements in physical function and capacity, HRQL and biological markers. Aerobic Ex, muscle strength Ex and combined Ex programs are used.
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