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| 2. |
- Koyi, Hemin, et al.
(författare)
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The effect of basement faulting on diapirism
- 1993
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Ingår i: Journal of Petroleum Geology. - : Wiley. - 0141-6421 .- 1747-5457. ; 16:3, s. 285-312
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and natural examples illustrate the influence of sub-salt horizon basement faults on diapirism. In a series of experimental models, viscous diapirs were observed to form above or close to basement faults. In all the models, basement faults initiated a half-graben, where thicker overburden units enhanced differential loading on an underlying buoyant layer. The buoyant material flowed updip to the low-pressure zones in the uplifted block, and updip along the tilted upper boundary of the hanging-wall. Basement faulting extended the overburden, and provided the space through which the buoyant layer could rise. Subsidence and faulting of overburden layers allowed diapirism along the faulted zones. In all cases, the deformation in the overburden was accommodated within a wider zone of faulting than the discrete basement fault which initiated the deformation. Differential compaction enhances differential loading and accumulation of thicker overburden on the downthrown sides of basement faults. Seismic profiles from the Danish Basin, Dutch Central Graben, Gulf of Mexico and North Sea show that diapirs are spatially associated with basement faults. However, model results show that diapirs triggered by basement faults are not necessarily located directly above the faults. Basement faults extend the cover sequences. If detached from the cover by a ductile layer, thick-skinned extension is accompanied by thin-skinned extension and decoupling of the cover. The influence of basement faults on diapirs depends on: the thickness and effective viscosity of the ductile layer (e.g. rock salt); the thickness ratio between the buoyant layer and the overburden; the mechanical properties of the brittle cover in the case of clastic sediments; the rate of sedimentation; the displacement rate throw and the dip of the basement faults.
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| 4. |
- Petersen, G., et al.
(författare)
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A Raman study of ion-polymer and ion-ion interactions in low molecular weight polyether - LiCF3SO3 complexes
- 1992
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 37:9, s. 1495-1497
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Tidskriftsartikel (refereegranskat)abstract
- We report Raman scattering investigations of the stability of various ion—polymer interactions from studies of LiCF3SO3—polyethers. New results for endcapped polyethers of different molecular weights in the range of one to eight repeat units are compared with previous data from OH-terminated polyether salt complexes. We conclude that anions coordinated to OH-endgroups are more stable than cations forming crosslinks between oxygens of adjacent polymer chains which in turn are more stable than cations coordinated to single oxygens. It is the weak oxygen—cation bond which is causing the dramatic increase in ion—ion association as tempearature increases. OH—anion bonds are little affected by temperature.
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| 6. |
- Torell, Lena M., et al.
(författare)
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A Raman study of ion solvation and association in polymer electrolytes
- 1993
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Ingår i: Polymers for Advanced Technologies. - : John Wiley & Sons. - 1042-7147 .- 1099-1581. ; 4:2-3, s. 152-163
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Tidskriftsartikel (refereegranskat)abstract
- Ion–polymer and ion–ion interactions in polymer electrolytes have been investigated at different temperatures and pressures, and for different polymer molecular weights. Salt–polymer complexes of various triflate salts, M(CF3SO3)x (M = Li+, Na+, Ca2+, Cu2+ and Nd3+), in low molecular weight polyethers (PEO and PPO) have been studied using Raman and Brillouin scattering. It is found that anions coordinated to the OH end groups of the polyethers are more stable than cations forming crosslinks between oxygens of adjacent chains, which in turn are more stable than cations coordinated to single chains. We have observed that the number of ion pairs increases as the polymer molecular weight increases. Furthermore, the ion–ion interaction is strongly temperature-dependent and shows widely different behavior in different systems. In the case of Li+-, Na+- and Ca2+-containing polyether complexes the ion association increases with increasing T. It is constant in Cu2+–triflate complexes, while it decreases for complexes containing trivalent Nd3+ cations. Pressure observations in LiCF3SO3–PPO complexes reveal increasing solubility and fewer ion pairs as pressure increases. It is shown that theories which consider volume changes in the salt dissociation process can qualitatively explain the effects of molecular weight, temperature and pressure using entropy considerations. The entropy effect includes contributions due to free-volume dissimilarities between the solvated ions and the macromolecules, structural ordering induced via cationic crosslinking of adjacent chains and electrostriction. Comparing the spectroscopic data with conductivity data, it is found that differences in the “free” solvated ion concentration can account for differences in conductivity.
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| 7. |
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| 8. |
- Torell, Lena M., et al.
(författare)
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The importance of ion-polymer crosslinks in polymer electrolytes
- 1992
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Ingår i: Solid State Ionics. - Amsterdam : Elsevier. - 0167-2738 .- 1872-7689. ; 53-56:Part 2, s. 1037-1043
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Tidskriftsartikel (refereegranskat)abstract
- Raman-, Brillouin-and photon correlation spectroscopy have been used to study LiCF3SO3 and NaCF3SO3 containing polyethers (PEO and PPO). At focus are factors controlling the ion-polymer interactions, the formation of transient ionic crosslinks and their effect on the local flexibility. Brillouin and photon correlation spectroscopy show that the structural relaxation time is independent of the polymeric chain length for chains longer than n≈20 repeat units. For shorter chains OH bridging slightly stiffens the dynamics whereas for CH3 end-capped chains the local chain flexibility increases dramatically as n decreases. The crossover at ∼20 monomer indicates the number of monomers involved in the cooperative segmental rearrangements needed for structural relaxations in high Mw complexes, and thus also for an ionic displacement to occur in these systems. It is found that transient crosslinks are established for n > 4 and they considerably slow down the local dynamics. The density of crosslinks is found to be strongly temperature dependent and this is the reason for departure from Tg scaled dynamics in the complexes.
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