Search results for "Cycling"
showing 10 items of 516 documents
The role of crystalline, mobile amorphous and rigid amorphous fractions in the performance of recycled poly (ethylene terephthalate) (PET)
2012
[EN] The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation of -OH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percen…
Recycling of a starch-based biodegradable polymer
2002
A new starch-based polymeric system, ZI1OU from Novamont, mainly composed of starch and polycaprolactone, was reprocessed several times in an extruder to investigate the recyclability of this biodegradable polymer. A previous investigation of the thermomechanical degradation in a mixer has been also done. The degradation is mostly due to the thermal stress but the presence of the mechanical stress strongly increases the degradation kinetic. During melt processing two concurrent processes take place: the first is the degradation, i.e. the breaking and shortening of polymeric chains, mostly occurring in the PCL phase; the second is the formation of some crosslinked structure in the starch pha…
Influence of process parameters on the product integrity in friction stir extrusion of magnesium alloys
2016
Friction Stir Extrusion is an innovative direct-recycling technology for metal machining chips. During the process a specifically designed rotating tool is plunged into a cylindrical matrix containing the scraps to be recycled. The stirring action of the tool prompts solid bonding related phenomena allowing the back extrusion of a full dense rod. This process results to be particularly relevant because allows the reuse of the scrap without any previous treatment. Experiments have been carried out in order to investigate the influence of the process parameters on the extrudes quality and a numerical model has been developed in order to simulate the evolution of the material flow.
Applications of fast field cycling NMR relaxometry
2021
Abstract Fast field cycling (FFC) NMR relaxometry is emerging as a powerful tool to investigate physical chemistry properties of many systems in a number of different scientific fields. As an example, it is used to investigate environmental issues such as soil erosion, water, and nutrient dynamics in environmentally relevant porous systems, to discriminate among different kinds of foodstuff in order to understand possible source of adulteration and fraud, to evaluate the properties of new materials, and much more. In the present study, an overview about the possible applications of FFC NMR relaxometry is given. The paper is not intended to be exhaustive. Rather, it is thought to provide an …
Friction stir consolidation of aluminum machining chips
2017
Friction stir consolidation (FSC) is a solid-phase manufacturing process that consolidates metal powder, chips, or scraps into solid blocks via severe plastic deformation and solid state welding. It has the potential to be a more economical and âgreenâ process to recycle metal waste. In this study, solid discs were made from AA6061 aluminum alloy machining chips by FSC. The progression of the process was revealed by analyzing the motion of the tool, consolidating force, power history, and macro/microstructure of discs produced from a series of partial consolidation experiments. A bowl-shaped recrystallized zone in the vertical cross-sections of the disc products was observed and conside…
Multi-material based functionally graded billets manufacturing through friction stir consolidation of aluminium alloys chips
2022
New deal of Friction Stir Consolidation (FSC) is its evolution from Recycling technique towards Upcycling. In this paper, the potential of FSC to manufacture Functionally Graded billets is proved. Processing chips of two different aluminium alloys (AA7075, AA2011-T3), graded hardness distributions were obtained along the longitudinal direction of the manufactured billet. Material flow was analysed by EDX analyses and numerical simulations; mechanical properties were assessed through hardness measurements. The influence of material's position, mass fraction of each material and process parameters was considered. Results reveal that FSC offers a proper control in the design of billets with gr…
'Not as safe as I believed': Differences in perceived and self-reported cycling behavior between riders and non-riders
2021
Cycling behavior remains a key issue for explaining several traffic causalities occurring every day. However, recent studies have shown how the assessment of the own safety-related behaviors on the road may substantially differ from how third parties assess them. Thus, the aim of this study was to evaluate the differences between cyclists’ self-reported behavior and the proxy-reported behavior that other (non-cyclist) road users perceive from bike riders. For this purpose, this study used data from two samples: (i) 1064 cyclists (M = 32.83 years) answering the Cycling Behavior Questionnaire—CBQ, and (ii) 1070 non-cyclists (M = 30.83 years) answering an adapted version of the CBQ for externa…
The composition of fluids stored in the central Mexican lithospheric mantle: Inferences from noble gases and CO2 in mantle xenoliths
2021
We present the first isotopic (noble gases and CO2) characterization of fluid inclusions coupled to Raman microspectroscopy analyses in mantle xenoliths from Central Mexico, a geodynamically complex area where the Basin and Range extension was superimposed on the Farallon subduction (terminated at 28 Ma). To characterize the isotopic signature of the Central Mexican lithospheric mantle, we focus on fluid inclusions entrapped in mantle xenoliths found in deposits of the Joya Honda maar (JH), a Quaternary monogenetic volcano belonging to the Ventura Espiritu Santo Volcanic Field (VESVF) in the state of San Luis Potosí (central Mexico). Thirteen ultramafic plagioclase-free xenoliths were selec…
Importance of denitrifiers lacking the genes encoding the nitrous oxide reductase for N2O emissions from soil
2010
Analyses of the complete genomes of sequenced denitrifying bacteria revealed that approximately 1/3 have a truncated denitrification pathway, lacking the nosZ gene encoding the nitrous oxide reductase. We investigated whether the number of denitrifiers lacking the genetic ability to synthesize the nitrous oxide reductase in soils is important for the proportion of N2O emitted by denitrification. Serial dilutions of the denitrifying strain Agrobacterium tumefaciens C58 lacking the nosZ gene were inoculated into three different soils to modify the proportion of denitrifiers having the nitrous oxide reductase genes. The potential denitrification and N2O emissions increased when the size of ino…
Forgeability characterization of multi-material based functionally graded materials manufactured through friction stir consolidation
2022
Solid state recycling allows direct recycling of metal chips into semi-finished products. This process category proved to lower the environmental impact of metals recycling. Friction stir consolidation (FSC) is a new solid-state technique taking advantage of friction heat generation and severe plastic deformation to consolidate chips into billets. The new frontier of FSC process could be its evolution from recycling techniques towards the concept of upcycling technique: reuse (discarded objects or material) in such a way as to create a product of higher quality or value than the original. The authors have recently successfully applied FSC for producing multi-material based functionally grad…