About the lab
To find out more about the Polymer & Composite Engineering (PaCE) Group please see: http://www.materialstoday.com/lab-profile-alexander-bismarck-pace/
Featured research (16)
The long-term drag reduction capability of poly(ethylene oxide) with a nominal molar weight of 𝑀𝑤=4×10^6 g/mol dissolved in water was investigated in a pilot-scale pipe flow device (inner diameter of test section 26 mm) at a Reynolds number of 10^5. A total loss of the initially high (75%) drag reduction capability was observed over a flow distance of several ∼10 km while the molar weight of the polymer was still 𝑀𝑤∼5×10^5 g/mol. Mechanical degradation in the turbulent flow as well as ageing of the polymer dissolved in water caused this loss in drag reduction capability. A simple ansatz of two independent, statistical polymer chain scission mechanisms was used to describe the polymer degradation empirically using a modified Brostow model. This empirical description was applied successfully and suggested that the polymer exhibited at least 15 cleavage points for mechanical degradation.
Hydrophobically modified associating polymers could be effective drag-reducing agents containing weak "links" which after degradation can reform, protecting the polymer backbone from fast scission. Previous studies using hydrophobically modified polymers in drag reduction applications used polymers with M w ≥ 1000 kg/mol. Homopolymers of this high M w already show significant drag reduction (DR), and the contribution of macromolecular associations on DR remained unclear. We synthesized associating poly(acrylamide-co-styrene) copolymers with M w ≤ 1000 kg/mol and various hydrophobic moiety content. Their DR effectiveness in turbulent flow was studied using a pilot-scale pipe flow facility and a rotating "disc" apparatus. We show that hydrophobically modified copolymers with M w ≈ 1000 kg/mol increase DR in pipe flow by a factor of ∼2 compared to the unmodified polyacrylamide of similar M w albeit at low DR level. Moreover, we discuss challenges encountered when using hydrophobically modified polymers synthesized via micellar polymerization.
Continuous liquid-liquid extraction and separation of 4-aminoacetophenone, a product of the hydrogenation of 4-nitroacetophenone, was performed within emulsion templated macroporous polymer (polyHIPE) extraction units using a miniaturized gravity-based settler. PolyHIPEs with interconnected and tailorable macroporous structures are effective micromixers allowing to mix fluids in both axial and radial directions. We fabricated extraction units by combining hydrophilic and hydrophobic polyHIPEs, which improved the extraction efficiency by inverting the liquid/liquid dispersion type from oil/water to water/oil (or vice versa) during the extraction, which is governed by the wettability of the porous medium. The extraction efficiency of our combined polyHIPE micromixer reached 98%, while that of control experiments performed using a blank tube or commercial Kenics® static mixer was 78%. The overall volumetric mass transfer coefficient kLa in polyHIPE micromixer-settlers was significantly higher 0.011 s⁻¹ reaching interfacial areas a of 17900 m²/m³, much larger compared to a blank tube (kLa = 0.0035 s⁻¹ and a = 5700 m²/m³) and static mixer (kLa = 0.0041 s⁻¹ and a = 6800 m²/m³). PolyHIPE micromixer-settlers could be potentially useful to intensify continuous L-L extractions.
Immediate and widespread changes in energy generation and use are critical to safeguard our future on this planet. However, while the necessity of renewable electricity generation is clear, the aviation, transport and mobility, chemical and material sectors are challenging to fully electrify. The age-old Fischer-Tropsch process and natural gas industry could be the bridging solution needed to accelerate the energy revolution in these sectors – temporarily powering obsolete vehicles, acting as renewable energy’s battery, supporting expansion of hydrogen fuel cell technologies and the agricultural and waste sectors as they struggle to keep up with a full switch to biofuels. Natural gas can be converted into hydrogen, synthetic natural gas, or heat during periods of low electricity demand and converted back to electricity again when needed. Moving methane through existing networks and converting it to hydrogen on-site at tanking stations also overcomes hydrogen distribution, storage problems and infrastructure deficiencies. Useful co-products include carbon nanotubes, a valuable engineering material, that offset emissions in the carbon nanotube and black industries. Finally, excess carbon can be converted back into syngas if desired. This flexibility and the compatibility of natural gas with both existing and future technologies provides a unique opportunity to rapidly decarbonise sectors struggling with complex requirements.
Uncured solid bisphenol-A epoxy resins containing up to 20 wt% carbon nanotubes (CNTs) were prepared using melt blending in a high shear mixer. The extrudate was ground to produce fine nanocomposite (NC) powders. This simple method produced well-dispersed NC, with CNT agglomerate sizes below 1 μm. Consolidated NCs displayed improved tensile moduli and strengths up to 3.3 GPa (+32%) and 78 MPa (+19%), respectively at 15 wt% CNT, compared to the pure cured epoxy matrix. The relatively high Tg of 39 °C for the uncured NC powders simplified the manufacture of composite prepregs using wet powder impregnation. The prepregs were laminated into hierarchical carbon fibre reinforced composites with improved through-thickness properties. Interlaminar shear strength improved for intermediate CNT loadings in the matrix up to 65 MPa (10 wt% CNT, +19%) but decreased at higher concentrations. Compression moduli remained constant irrespectively of CNT loading but compression strength increased with a CNT loading of 2.5 wt% to 772 MPa (+31%). The mechanical properties of the hierarchical composites reflect good consolidation (void content <3%) and excellent fibre alignment (<±0.8°). In addition to the improved mechanical properties, incorporation of CNTs improved the through-thickness electrical conductivity up to 115 S/m.
- Materials Chemistry and Research
About Alexander Bismarck
- To find out more about the Polymer & Composite Engineering (PaCE) Group please see: http://www.materialstoday.com/lab-profile-alexander-bismarck-pace/