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Polymers
Published in Bryan Ellis, Ray Smith, Polymers, 2008
General Information: Behaves as a thermoplastic rubber. It is rigid due to crystalline segments at room temp., but rubbery at elevated temps. when hard segments have melted. Pebax is a thermoplastic block copolymer of Nylon 12 and polytetramethylene glycol, with hard nylon and soft ether segments. The polymer has been studied by a thermally stimulated current method [1,2]
Advancements in running shoe technology and their effects on running economy and performance – a current concepts overview
Published in Sports Biomechanics, 2023
Kim Hébert-Losier, Milly Pamment
In 2016, the three medallists of the men’s Rio Olympic marathon road race were reportedly wearing a curved carbon fibre plate prototype shoe with a novel high-energy return Pebax® (polyester block amide) foam designed by Nike Inc. (Burfoot, 2020), as was the gold medallist of the women’s marathon (Hill, 2021). This prototype was a precursor to the commercially available Nike Vaporfly 4%. The emergence of super shoes is perhaps more widely associated with Eliud Kipchoge’s attempts to break 2 hours on the marathon distance. In 2017, Eliud Kipchoge wore a prototype of the Nike Vaporfly Elite during the Breaking2 event, which he completed in 2:00:25 (h:min:sec). In 2019 during the INEOS 1:59 Challenge, Eliud Kipchoge wore a prototype of the Nike Alphafly Next% and achieved his goal of running the marathon distance under 2 hours, completing the event in 1:59:40 (h:min:sec), a feat that some researchers predicted unlikely before the year 2100 (Weiss et al., 2016). In addition to the Vaporfly features, the prototype Alphafly contained cushioning Zoom Air pods in the forefoot region to increase energy return. The controversy surrounding the prototype used to break the 2-hour barrier led to World Athletics (2020b) modifying its footwear regulations to limit shoes used in competition to containing a single rigid plate or blade and a maximum thickness of 40 mm for non-spiked shoes. Nike Inc. has since released commercially available competition-legal versions of the Alphafly, including the Air Zoom Alphafly Next% (Nike Inc., 2022) that features on the World Athletics Shoe Compliance List (as of 14 January 2022).
Applying Pebax-1657/ZnO mixed matrix membranes for CO2/CH4 separation
Published in Petroleum Science and Technology, 2019
Zahra Farashi, Navid Azizi, Reza Homayoon
Pebax-1657 based MMMs with different contents of ZnO nanoparticles were prepared via a solution blending technique followed by the solution casting-solvent evaporation. The prepared membranes were characterized by FT-IR, XRD and FESEM analyses. The XRD and FT-IR results depicted the crystallinity reduction of MMMs compared to the neat membrane resulting from the rupture of the hydrogen bonding between the PA segments of Pebax due to the ZnO incorporation into the polymer matrix. FESEM images showed the membranes dense structures without significant defects and also a good dispersion of the ZnO nanoparticles even at the highest loading of ZnO (10.0 wt%). Permeation experiments showed that CO2 and CH4 permeability values were enhanced as the ZnO nanoparticles content increased in the polymer matrix due to the crystallinity reduction of the membranes. Furthermore, with strengthening the ZnO loading, ideal CO2/CH4 selectivity increased due to the combination of higher solubility of CO2 molecules in the membranes compared to CH4 molecules and higher diffusivity of CO2 molecules resulting from the formation of selective voids at the polymer-nanoparticles interface. The results also revealed that the Pebax/ZnO MMM loaded with 10.0 wt% of ZnO has the best performance for CO2/CH4 separation.
A new approach for hydrogen production in Claus sulfur recovery process
Published in Journal of Sulfur Chemistry, 2019
Ahmad Taghizadeh Damanabi, Fatemeh Bahadori
In this study, process simulation for separating H2 is performed by Aspen HYSYS 7.3. Lee-Kesler Plocker (LKP) equation of state is employed for predicting the thermodynamic properties of thermolysis reaction and its associated condenser. Peng-Robinson equation of state is used for determining thermodynamic properties of other unit operations in the process. After the thermolysis reactor, the hydrogen sulfide is separated from carbon dioxide by PEBAX membrane. Membranes were simulated by a membrane package of AspenTech. Co. coupled with Aspen HYSYS. The properties of PEBAX membrane for separation of sulfur compounds and carbon dioxide at operating temperature of 120–150°C and operating pressure of 1000–4000 kPa are shown in Table 2. The sulfur and carbon dioxide free stream are sent to the reforming reactor to convert the hydrocarbon contents of the stream, especially methane to hydrogen. Reforming reactions take place over the Ni-Based catalyst at the temperature of 260–1000°C, the pressure of 1700–2500 kPa, and CH4 to H2O ratio of 1:3.