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dc.contributor.authorShmelin, George
dc.date.accessioned2014-07-03T20:26:27Z
dc.date.available2014-07-03T20:26:27Z
dc.date.issued2012-05-17
dc.identifier.urihttp://hdl.handle.net/2299/13901
dc.description.abstractThe research described in this thesis originated from an idea to develop new body protection for the sport of fencing. The ultimate goal is to develop body armour which would be flexible, wearable, washable, light and breathable, offer protection from injuries and cover the entire body of a sportsman. A new material which exhibits shear thickening behaviour has been specially developed for this purpose in the process of this investigation. The material was designed and synthesised as a soft polymeric system which is flexible, chemically stable and able to increase the value of its modulus of elasticity upon impact at a high strain rate, while remaining in its soft gel-like elastomeric state when low strain rate deformation is applied. The polymeric system that has been developed is based on interpenetrating polymeric networks (IPN) of immiscible polyurethane/urea-ester/ether and poly(boron)n(dimethylsiloxane)m (where on average m ≈ 16 n). In addition, as the polydimethylsilane (PDMS) based polymeric system strongly tends to phase separation, the siloxane polymeric network was chemically cross-linked to the polyurethane polymeric network through polyurethane chemical cross-link-bridges. In order to introduce polyurethane cross-links to a siloxane-based polymeric network, some of the attached methyl groups in the PDMS polymeric backbone were substituted by ε-pentanol groups. The resulting polymeric system combines properties of an alternating copolymer with IPN. The actual substitution of the methyl groups of PDMS into alternating ε-pentanol groups was performed by Grignard reaction of trifunctional chlorosilane monomers, magnesium and 1,5-dibromopentane. Chemical analytical techniques like FT-IR, 13C NMR and 1H NMR spectroscopy were used to reveal the chemical structure of the synthesised polymeric network. The mechanical and dynamical properties of the obtained polymeric system were analysed by dynamic mechanical analysis (DMA). This part of the investigation indicated that the novel polymeric system exhibited shear thickening behaviour, but only at a narrow diapason of deformations (i.e., deformations between 2 to 3 % of the length of the sample). At this limited diapason of deformation an effective increase of the modulus of elasticity from 6 MPa (at lower frequencies, i.e., up to ≤6 Hz of the applied oscillating stress) to 65 MPa (at frequencies between 12.5 to 25 Hz) was obtained. However, no increase in the modulus of elasticity was recorded at deformations below 1.5 % or above 3.5 % of length of the sample at the same frequencies (0 to 25Hz) of the applied oscillating stress.en_US
dc.language.isoenen_US
dc.publisherUniversity of Hertfordshireen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectPolymeren_US
dc.subjectrheologyen_US
dc.subjectsiliconeen_US
dc.subjectsiloxaneen_US
dc.subjecthetero-siloxaneen_US
dc.subjectpolyurethaneen_US
dc.subjectpolyurea-urethaneen_US
dc.subjectpolyurethane-siloxane co-polymeren_US
dc.subjectpolymeric synthesisen_US
dc.subjectDMA polymer analysisen_US
dc.subjectFT-IR and HNMR/CNMR spectroscopy polymer analysisen_US
dc.subjectIPNen_US
dc.subjectscarcely cross-linked IPNen_US
dc.subjectone side Grignard reaction of short αω-di halo olefinsen_US
dc.titleA New Rheological Polymer Based on Boron Siloxane Cross-Linked by Isocyanate Groupsen_US
dc.typeinfo:eu-repo/semantics/doctoralThesisen_US
dc.type.qualificationlevelDoctoralen_US
dc.type.qualificationnamePhDen_US
herts.preservation.rarelyaccessedtrue


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