Browsing by Author "Wilkinson, Peter"

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    Future Sustainable Propellants
    (Cranfield University, 2018-11-15 10:26) Wilkinson, Peter
    Poster presented at the 2018 Defence and Security Doctoral Symposium.Traditionally propellants have been made from materials specifically manufactured for this purpose. This project seeks to find whether commercially available thermoplastic elastomers (TPEs) can be used to replace some or all of the existing propellants. Traditionally gun propellants used either nitrocellulose sourced from natural ingredients such as cotton or a synthetic binder such as hydroxyl terminated polybutadiene (HTPB), cross linked with an isocyanate. Two TPEs were selected and analysed for suitability as a propellant binder. Inert formulations were created by a new novel process. This involved coating the filler with TPE using a novel slurry coating process involving a Resonant Acoustic Mixer (RAM). The coated mixture was then hot pressed into a slab for mechanical testing. It is thought that TPEs may be able to match the excellent mechanical properties and good performance of traditional gun propellant binders, whilst having a much lower risk of obsolescence and being much easier to be decommissioned in a more environmentally sound manner.
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    Peter Wilkinson PhD
    (Cranfield University, 2018-09-13 09:13) Gill, Philip; Wilkinson, Peter
    Properties of Composite Propellants Containing New Elastomeric Binders Traditionally propellants have been made from materials specifically manufactured for this purpose. This project seeks to find whether commercially available thermoplastic elastomers (TPEs) can be used to replace some or all of the existing propellants. Traditionally composite propellants used an inert binder, usually hydroxyl terminated polybutadiene (HTPB), cross linked with an isocyanate and mixed with a powerful oxidiser, normally ammonium perchlorate (AP). It is thought that TPEs may be able to match the excellent mechanical properties and good performance of HTPB propellants, while being much easier to be decommissioned in a more environmentally sound manner. Two TPEs were selected and analysed for suitability as a propellant binder. Inert formulations were created by a new novel process. This involved coating the filler with TPE using a novel slurry coating process involving a Resonant Acoustic Mixer (RAM). The coated mixture was then hot pressed into a slab for mechanical testing.
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    Shaping the structure and properties of HyTemp using polyethylene glycol diglycidyl ether cross-linkers
    (Wiley, 2024-06-03) Dossi, Eleftheria; Mutele-Nkuna, Khuthadzo Lourate; Wilkinson, Peter; Kister, Guillaume; Patrick, Hugh; Khalili, Mohammad Hakim; Hawi, Sara
    Novel elastomers are made by reaction of hydroxyl-terminated polyacrylic ester (HyTemp) with polyethylene glycol (PEG, number of ethylene glycol units 1, 3, 6, 9) based cross-linkers. The influence of the cross-linker length, the HyTemp/cross-linker (w/w) ratio and the cross-linking accelerator trifluoromethanesulfonate scandium salt (ScTFMS) on the structure and the properties of the materials are studied. The cross-linker length has not influence on the glass transition (Tg) of the products because of the presence of the flexible PEG units that cancels out the cross-linking effect associated to a shift to higher Tg. A two-domain structure is seen by the presence of a dual Tg in samples cured with ScTFMS. Mathematical analysis of the modulated differential scanning calorimetry curves offers for the first time the possibility to identify/confirm structural differences in complex three-dimensional polymeric structures. Scanning electron microscopy and swelling experiments in ethyl acetate respectively reveal an increase in the pore size (1.13 to 5.48 nm) and in the absorption ability of the elastomers cured with different types and quantities of PEG cross-linker. The new elastomeric materials are exhibiting a rubbery state over a wide temperature range and absorptivity for the potential recovery of pollutants in soil and/or water.