Dynamic water absorption

ECCO MP-170-CONC is a solvent soluble mildewproofing agent containing 16.3% G-4 together with added wax components which contribute substantially to water repellency and improved dynamic water absorption properties. 

Fig. 16. Water penetration into a w/c = 0.4 sample as a function of soaking time, reaching a peak after 24 h of soaking - the water reservoir was on the right side. The insert shows the decrease in intensity after 7 and 9 days of soaking, indicating the establishment of a dynamic equilibrium within the sample between water absorption from the reservoir on the right and evaporation on the left.

Thus, knowledge of the transition moment direction of a phenol band could help in interpreting the fluorescence spectrum of a tyrosine chromophore in a protein in terms of orientation and dynamics. The absorption spectrnm of the first excited state of phenol was observed around 275 nm with a fluorescence peak aronnd 298 nm in water. The tyrosine absorption was reported at 277 nm and the finorescence near 303 nm. Fluorescent efficiency is about 0.21 for both molecules. The fluorescent shift of phenol between protic and aprotic solvents is small, compared to indole, a model for tryptophan-based protein, due to the larger gap between its first and second excited states, which resnlts in negligible coupling . ... 

The mass of a 50 m dynamic rope must be low (typically 3.5 kg) to enable it to be carried. The rope must be affordable and it must survive several years of use. Television series, showing expert climbers falling while attempting extreme routes, illustrate the required rope properties— tensile strength, low weight, easy bending to be clipped through belays, durability, low water absorption. 

Figure 12.12 DMT A tan d spectra of a cured, untoughened Fibredux 924 base epoxy resin showing the reduction of Tg with water absorption and the development of secondary peaks (Tg2, Tgs) on moisture absorption (a) isothermally and (b) dynamically in the presence of thermal excursions to 100, 140 and 200 °C [4],...

The interference of water absorption is eliminated when the physicochemical and dynamic approaches are used for measuring the spectra, since a water response to a perturbation differs from that of a protein (vide supra). As an alternative, the spectrum can be rendered practically free from background absorption with a polarization modulation technique. To illustrate. Fig. 7.54 shows the spectrum from PM-IRRAS of an acetylcholinesterase (AChE) (enzyme) monolayer at the air-water interface at different surface pressures [838]. The spectra were... 

Textiles have different properties, depending on their structure. Waip knitted structures are used when hig elastic deformation is required. This type of mechanical deformation must be concerned for implants that are designed for the reinforcement of an organ, subjected to continuously dynamic stress, for example vascular grafts. Nonwovens have similar fibre structures to natural connective tissue and are well known, and used in tissue engineering because of their mazy structure and good water absorptivity. 

A wide variety of research work is being conducted worldwide with sometimes conflicting ideas. Focus usually lies on physical, especially water absorption and degradation, and mechanical properties of hybrid composites. The research on electrical, thermal, acoustic and dynamic mechanical properties of hybrid vegetable/glass thermoplastic composites, however, is more restrict. 

The aim of this research was to obtain new clarifications regarding the preponderant reactions responsible for the PU consolidation process and to study the evolution of the PUs mechanical performance during the post cure process in correlation with the dynamics of different diffusion processes like water absorption and CO2 desorption. 

Fluorine substitution generally substantially reduced the dielectric constant in cases with symmetric substitution. It was estimated that around 50% of the observed decreasing trend in the dielectric constant versus the percentage of fluorene can be attributed to a reduction in absorbed moisture as the result of an increase in hydrophobicity. The remaining 50% can be apportioned, on average, between the increased free volume (approximately 25%) and reduced total polarizability (approximately 25%). Little effect of fluorene substitution on dynamic thermal or thermo-oxidative stability was observed for a series of fluorinated polyimides [48]. Low dielectric constant polyimides and low water absorption polyimides were reported by several researchers [49-51]. The correlation between a high free volume and dielectric constant in polyimides has been previously reported in the literature [52]. 

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