Viscoelastic Properties of Polyvinyl-i-Butyl Ethers at High Frequencies

Abstract

The Ariel 3 satellite (orbital inclination 80°, mean altitude 550 km) was launched from Vandenberg, California on 5 May 1967. One of the five experiments carried by the spacecraft was a synoptic study of v.1.f. phenomena above the ionosphere using a v.1.f. receiver with loop aerial. The peak, mean and minimum signals at 3.2, 9.6 and 16 kHz are measured in each 28 second period around the orbit. At 16 kHz wide (Af= 1 kHz) and narrow (hf = 100 Hz) band channels are used to distinguish C.W. transmissions from GBR (Rugby) from natural noise-like signals such as hiss. The measurements are stored on the satellite tape recorder and telemetered to ground at an appropriate Stadan station. The factors governing the choice of receiver parameters are discussed. The equipment and technical problems encountered are described.

Transfusion independence in patients with myelodysplastic syndromes

“…However, because the long‐time mechanisms are unavailable for the bulk response, this behavior cannot be observed for the bulk. Consistent with our interpretation is the early finding of Kono and Hoshizaki5 that the bulk modulus is also independent of molecular weight.…”

“…This conclusion is in agreement with the other two works, by Bero and Plazek10 and by Meng and Simon,12 in which retardation spectra for the bulk and shear responses were compared. Although the conclusion is inconsistent with Leaderman's suggestion1 that bulk and shear responses arise from different underlying molecular mechanisms, it is consistent with the majority of the literature,2, 4–6, 10, 12 as pointed out in the introduction: the bulk response is generally found to be narrower than the shear response and to occur at shorter times scales (i.e., the midpoint of the bulk and shear dispersions are shifted in time), similar to our results here. However, without comparison of the retardation spectra, these observations were often previously interpreted, incorrectly we argue, to indicate differences in the molecular origin of the two responses.…”

“…Leaderman1 initially hypothesized that the bulk modulus arises from intramolecular relaxations and that the shear modulus arises from intermolecular or intersegmental relaxations. This idea, that the bulk and shear responses have different molecular origins, is backed up by several experimental observations, namely, that the bulk relaxation response occurs at shorter time scales or higher temperatures than the shear response,2–4 has a narrower relaxation time distribution than the shear response,2, 5 and is independent of molecular weight 5. Calculations by Tschoegl6 show similar differences in time scale and spectral width.…”

Bulk and shear rheology of silica/polystyrene nanocomposite: Reinforcement and dynamics

“…Leaderman's hypothesis has been backed up by experimental evidence. For example, the bulk relaxation occurs at higher temperatures or frequencies, has a higher apparent activation energy, and a narrower breadth of the relaxation time distribution than the respective shear response. Similar differences in time scale were also observed in calculations by Yee and Takemori and by Tschoegl .…”