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Title: Amphiphilic polyethylene block copolymers and their application as wax crystal modifiers in middle-distillate fuels
Author: Goring, Paul Derek
ISNI:       0000 0004 7223 9838
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2017
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Chapter 1 Reviews the synthesis of polyolefin block copolymers, focussing on strategies involving catalytic coordination polymerisation to produce end-functionalised polyolefins followed by the growth of a second block from the reactive end group using living/controlled techniques. The advantages and disadvantages of the various literature methods are discussed. Chapter 2 Discusses the utilisation of the Catalytic Hydride Insertion Polymerisation (CHIP) mechanism for the synthesis of low molecular weight polyethylene macromonomers by manipulating the relative concentrations of dihydrogen and ethylene in the reactions. The application of the mechanism is investigated further with the introduction of two non-styrenic comonomers 5-vinyl-2-norbornene and 5-ethylidene-2-norbornene. Observations made when we studied the effects of comonomer concentration and dihydrogen partial pressure on the products are discussed and some mechanistic insights for the copolymerisation between ethylene and norbornene derivatives in the presence of dihydrogen are proposed. Chapter 3 Focusses on the investigation of the mechanism for the copolymerisation between the PE-i-DIB macromonomer and n-butyl acrylate using a small-scale batch process and a larger scale starved feed semi-batch process. Observations are found to be consistent with a reversible cross-propagation mechanism between PE-i-DIB and the propagating P(n-BA) chain in which the continued availability of monomer is key to the lifetime of the process, as demonstrated by the difference in the evolution of molecular weight in the batch and semi-batch processes. The semi-batch process also provides superior control over the copolymerisation compared to the batch process. Chapter 4 Investigates the versatility of the PE-i-DIB macromonomer in copolymerisations with several other types of polar monomer. Copolymer products with vinyl esters, methacrylates and styrenes are synthesised and the challenges provided by the new monomer types are discussed. The products discussed here and in Chapter 3 are characterised by NMR, GPC, DLS and DSC and the evidence is found to be consistent with the presence of block copolymers. Chapter 5 Describes the testing of some of the block copolymers synthesised in Chapters 3 and 4 for their wax crystal modification properties in one type of diesel fuel. The block copolymers were tested as neat additives and in formulation with commercial nucleators and growth arrestors in the Cold Filter Plugging Point (CFPP) test to assess performance and to indicate mode of action. The mode of action was then investigated further by observing the effect of the additives on the crystallisation events using DSC. The performance in CFPP and the observations in DSC are consistent with the block copolymers generally acting as nucleating agents, though some also display single-shot activity. There is an observable trend in performance with the varying size of the polar block as well as varying the polar block itself. Chapter 6 Details the experimental procedures used to carry out the work in this thesis.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TP Chemical technology