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The effect of reprocessing Polyamide 6 (PA6) has been studied in this paper. To simulate recycled PA, we reprocessed virgin PA through 5 cycles. The PA 6 has undergone mechanical, thermal and rheological characterization after the various cycles of reprocessing in order to evaluate the corresponding properties and correlate them with the number of cycles undergone.In order to widen our injection simulation analysis by computer (CAE: Computer Aided Engineering) of these new materials, it was necessary to determine the viscosity using a mathematical model; in this case the Cross-WLF, to determine the relevant parameters.Our results show that tensile strength, elongation at break and hardness remain practically constant, while the charpy impact decreases as the number of reprocessing cycles increases.The effects of reprocessing on the material may decrease the rheological properties; specifically the viscosity of the material decreases with increasing processing cycles. The thermal properties are also influenced with the reprocessed material. The crystallinity increases and the degradation reaction will be advanced to increase the reprocessing cycle.

The present work develops an accurate prediction model of the COVID-19 pandemic, capable not only of fitting data with a high regression coefficient but also to predict the overall infections and the infection peak day as well. The model is based on the Verhulst equation, which has been used to fit the data of the COVID-19 spread in China, Italy, and Spain. This model has been used to predict both the infection peak day, and the total infected people in Italy and Spain. With this prediction model, the overall infections, the infection peak, and date can accurately be predicted one week before they occur. According to the study, the infection peak took place on 23 March in Italy, and on 29 March in Spain. Moreover, the influence of the total and partial lockdowns has been studied, without finding any meaningful difference in the disease spread. However, the infected population, and the rate of new infections at the start of the lockdown, seem to play an important role in the infection spread. The developed model is not only an important tool to predict the disease spread, but also gives some significant clues about the main factors that affect to the COVID-19 spread, and quantifies the effects of partial and total lockdowns as well.

Recovery of recycled acrylonitrile-butadiene-styrene (ABS) through mixing with styrene-ethylene/butylene-styrene (SEBS) has been studied in this paper. To simulate recycled ABS, virgin ABS was processed through 5 cycles, at extreme processing temperatures, 220 ºC and 260 ºC. The virgin ABS, the virgin SEBS, the recycled ABS and the mixtures were mechanically, thermally and rheologically characterized after the various cycles of reprocessing in order to evaluate their corresponding properties and correlate them with the number of cycles undergone. With these data and using CAE (Computer Aided Engineering) the injection process was simulated by obtaining the optimal injection process parameters. Mixtures were injected at two temperatures in a sensorised mold correlating the shrinkage of the parts with temperature.The results show that tensile strength of ABS remains practically constant as the number of reprocessing cycles increases, while in the material injected with SEBS the tensile strength decreases. Concerning the Charpy notched impact strength; the values of the ABS reprocessed at 220 ºC remain more or less unchanged, while the values for 260 ºC show a significant decrease. The adhesion of the SEBS causes, in both cases, an increase in impact strength. DSC techniques enabled us to observe how the glass transition temperature (T g ) remains more or less constant regardless of the number of cycles or the temperature, whereas the crosslinking is much greater in the samples reprocessed at 260 ºC.Finally, the viscosity decreases with each cycle and this decrease becomes even more noticeable with the addition of SEBS, and also that the parts molded at lower temperatures have less shrinkage.

This work reports on the use of dibutyl itaconate (DBI) as an environmentally friendly plasticizer for polylactide (PLA) with different proportions of DBI in the 2.5–20 wt% (weight content) range. A co‐rotating twin‐screw extrusion process followed by injection molding is employed for the manufacturing of the samples. The results show that the plasticized PLA formulation with 10 wt% DBI offers the most balanced overall properties, with a noticeable increase in the elongation at break from 4.6% (neat PLA) up to 322%, with a tensile modulus of 1572 MPa, and a tensile strength of 23.8 MPa. In the case of 15 and 20 wt% DBI formulations, PLA reaches the saturation point with no more increase in the elongation at break and a clear decrease in the tensile modulus. DBI also decreases the glass transition temperature (Tg) from 61.3 °C (neat PLA) down to 23.4 °C for plasticized PLA formulation containing 20 wt% DBI, thus showing the high plasticization efficiency of DBI.

The effect of reprocessing two mixtures: recycled high impact polystyrene (HIPS) with polybutadiene (PB); and HIPS with styrene-ethylene-butylenestyrene (SEBS) have been studied in this article. To simulate recycled HIPS, we reprocessed virgin HIPS through five cycles. The virgin HIPS, the recycled HIPS, and the mixtures have been mechanically and rheologically characterized after the various cycles of reprocessing to evaluate their corresponding properties and correlate them with the number of cycles undergone. To widen our injection simulation analysis by computer (CAE: Computer Aided Engineering) of these new materials with additives, it was necessary to determine the viscosity using a mathematical model, in this case the Cross-WLF, to determine the relevant parameters. Our results show that tensile strength increases, while the lengthening and viscosity decrease, as the number of reprocessing cycles increases. If we mix PB or SEBS with degraded HIPS, the mechanical properties of the virgin material are recovered and the rheological behavior maintains the viscosity values for the mixture with PB but these diminish notably for the mixture with SEBS. The results on mechanical properties show that the mixture with SEBS behaves better than the mixture with PB as the number of cycles increases. The viscosity of the mixture with SEBS diminishes more than the viscosity of the mixture with PB as the number of reprocessing cycles increases.

In this study, an analysis of the possible causes of the failure in-service of a section of a plastic modular belt was conducted. The study begins with a reproduction of the service conditions in a traction gear. An analysis of the fracture surfaces revealed the existence of defects in the interior of the parts. With the aim of determining the origin of the imperfections and their influence on the failure, an exhaustive mechanical and rheological characterization of the material was carried out. The development of an FE Analysis established that the reduction of the tensile strength of the part due to internal defects was around 70%. Tests also showed that the most stressed area was the area where the most defects appeared. A simulation of the injection process showed that the defects are caused by the geometry of the part, leading to the conclusion that its failure was caused by bad dimensioning of thicknesses.

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