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441 results on '"McNally, Tony"'

7. Unveiling the Significance of Graphene Nanoplatelet (GNP) Localization in Tuning the Performance of PP/HDPE Blends.

Author

Salehiyan, Reza, El-Samak, Ali A., Kamkar, Milad, Erfanian, Elnaz, Hodge, Stephen A., Sundararaj, Uttandaraman, and McNally, Tony

Subjects
HIGH density polyethylene, POLYMER blends, ELASTIC modulus, X-ray diffraction, NANOPARTICLES
Abstract

High-density polyethylene (HDPE) and polypropylene (PP) blends are widely used in industries requiring mechanically durable materials, yet the impact of processing parameters on blend performance remains underexplored. This study investigates the influence of blending sequence and screw speed on the properties of blends of HDPE and PP filled with 1.25 wt.% graphene nanoplatelets (GNPs). Changes in crystallization behaviour, tensile strength, and viscoelastic responses with blending sequence are studied. The addition of GNP increases the crystallization temperature (Tc) of PP in the PE/PP blend by 4 °C when GNP is pre-mixed with PE to form (PE+GNP)/PP blends. In contrast, when GNP is pre-mixed with PP to create (PP+GNP)/PE blends, the Tc of PP rises by approximately 11 °C, from 124 °C for the neat PE/PP blend to 135 °C. On the other hand, the Tc of PE remains unchanged regardless of the blending sequence. XRD patterns reveal the impact of blending regime on crystallinity, with GNP alignment affecting peak intensities confirming the more efficient interaction of GNPs with PP when premixed before blending with PE, (PP+GNP)/PE. Tensile moduli are less sensitive to the changes in processing, e.g., screw speed and blending sequence. In contrast, elongation at break and tensile toughness show distinct variations. The elongation at the break of the (PP+GNP)/PE blend decreases by 30% on increasing screw speed from 50 to 200 rpm. Moreover, the elongation at the break of (PE+GNP)/PP prepared at 100 rpm is ~40% higher than that of the (PP+GNP)/PE. (PE+GNP)/PP displays a 'quasi-co-continuous' morphology linked to its higher elastic modulus G′ compared to that of the (PP+GNP)/PE blend. This study highlights the importance and correlation between processing and blend properties, offering insights into fine-tuning polymer composite formulation for optimal performance. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Polyelectrolyte Complexation of Chitosan and WS2 Nanotubes.

Author

Magee, Eimear, Xie, Fengwei, Farris, Stefano, Dsouza, Andrea, Constantinidou, Chrystala, Zak, Alla, Tenne, Reshef, and McNally, Tony

Subjects
CHITOSAN, NANOTUBES, PLASTICIZERS, YOUNG'S modulus, CHEMICAL properties, POLYELECTROLYTES, FOOD packaging, WATER vapor
Abstract

The inclusion of tungsten disulphide nanotubes (WS2 NTs) in chitosan, plasticized with glycerol, facilitates the formation of a polyelectrolyte complex. The glycerol interrupts the intramolecular hydrogen bonding between chitosan chains allowing positively charged protonated amines of chitosan to form a complex with negatively charged oxygen ions chemisorbed to the tungsten atoms in defects. These interactions, with the unique mechanical and chemical properties of WS2 NTs, result in a chitosan film with superior properties relative to unfilled chitosan. Even at low WS2 NT loadings (≤1 wt%), the Young's modulus (E) increases by 59%, tensile strength (σ) by 40% and tensile toughness by 74%, compared to neat chitosan, without sacrificing ductility. Addition of highly dispersed WS2 NTs significantly improves the gas barrier properties of chitosan, with a 50% reduction in oxygen permeability, while the addition of both glycerol and WS2 NTs to chitosan effectively reduces the carbon dioxide permeability by 80% and the water vapor transmission rate by 90%. The intrinsic antimicrobial efficacy of chitosan against both Gram‐positive and Gram‐negative bacteria is enhanced on inclusion of WS2 NTs. Polyelectrolyte complexation of WS2 NTs and glycerol‐plasticized chitosan provides a cost‐effective, sustainable route to biodegradable films with desirable mechanical, gas barrier properties, and antimicrobial efficacy suitable for food packaging applications. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Recent progress and outlook for the ECMWF Integrated Forecasting System

Author

Balsamo, Gianpaolo, primary, Rabier, Florence, additional, Balmaseda, Magdalena, additional, Bauer, Peter, additional, Brown, Andy, additional, Dueben, Peter, additional, English, Steve, additional, McNally, Tony, additional, Pappenberger, Florian, additional, Sandu, Irina, additional, Thepaut, Jean-Noël, additional, and Wedi, Nils, additional

Published
2023
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