Interlayer volume fraction

PS-PEO diblocks adsorbed on glass plates. Adsorption from toluene led to preferential adsorption of PEO however, due to the very high asymmetry of the copolymers studied, and the favourable adsorption energy, PS was also adsorbed. On the approach of a second coated plate, the PS volume fraction increased near the interface, indicative of strong interlayer repulsion (Cosgrove et al. 1994). 

T can be calculated (7). Therefore, it is possible to carry out relaxation time measurements in such a way as to obtain xfa, the volume fraction of the solvent bouijid to the contour surface of the tactoid. Indeed, in that case T. appears as a linear function of the content in solid (Figure 2) because x x l. If the interlayer water were taking part in the exchange (that s, if T T ) the slope (xfa + x.) of the linear relationship would be larger than that observed. On th other hand, if x was changing with the solid content, then T would not be linear with respect to the concentration in solid. 

Jinnai et aL [18] measured by neutron-scattering the interlayer separation between the butylammonium vermic-ulite platelets as a function of the poly(vinyl methyl ether) (PVME) volume fraction in an aqueous butylammonium chloride solution. The n-butylammonium vermiculite swelled in the n-butylammonium chloride solution, and the interlayer separation of the platelets increased from 2 to 12 nm at 8<7 <20 °C. When the PVME was added to this... 

Fig. 16. The interlayer separation of n-butylammonium vermiculite against the volume fraction of PVME. The experimental data are from Fig. 4 of Ref. [18]. The values of the parameters employed in the calculation were T= 8 C C, the salt concentration is 0.1 M, <3=1.88 nm, the Hamaker constant between the plates h=1x10-19 J, the Hamaker constant between the segments and plates =1 x 10—20 J, c=—0.035 C/m2, v=300 A3, =83.

Given the volume fraction of the polymer inside the gel, we are now able to propose a quantitative model of bridging flocculation. Because Crawford et al. [4] studied the contraction of the interlayer spacing as a function of uniaxial stress for the same system without any added polymer, we are able to convert the observed d-values to effective uniaxial pressures caused by the bridging polymers. If we assume that we have one polymer bridge when the end-to-end polymer distance l (calculated according to Equation 12.1) exactly matches the d-value with the... 

The ordering occurs up to an oil volume fraction, , of ca. 0.18 (as measured for segments 5-8) for a soap.water weight fraction of 0.6. It is interesting to notice that this value corresponds closely with a value of 0.175 for <)> where the curve of interlayer spacing against calculated for nonpenetration crosses the experimental curve (Moucharafieh at al 1979) for the same sample composition. 

In the absence of interlayer slip, addition of a second phase leads to an increase of viscosity. The simplest way to treat the system is to consider that the relative viscosity as a function of the solids volume fraction, particle aspect ratio and orientation. There is no difference between the flow of suspensions in Newtonian liquids and that of polymeric composites, when the focus is on the Newtonian behavior. The non-Newtonian behavior of suspensions originates either from the non-Newtonian behavior of the medium or from the presence of filler particles. The problems associated with this behavior can originate in inter-particle interactions (viz. yield stress), and orientation in flow [Leonov, 1990 Mutel and Kamal, 1991 Vincent and Agassant, 1991 Shi-kata and Pearson, 1994]. 

The main purpose of middle layers is to provide additional (thermal) insulation. Nowadays, these layers are often made of fleece materials with good air entrapment properties. Their thermal conductivity (typically 0.03-0.04 W/mK) is near from air (0.026 W/mK). The thermal resistance of such layers is directly correlated with their thickness, provided that no air movement occurs within the fabric. Thermal conductivity and air permeability also are generally dependent on the fabric density (Yip and Ng, 2008). Conduction has been shown to be the main heat transfer mechanism through textile layers as long as the fibre volume fraction is higher than 9% (Woo et al., 1994). However, materials with very low density (like spacer materials) allow radiant and convective heat transfer. This was demonstrated by Das et al. (2012) who compared a spacer fabric middle layer with two non-woven middle layers and showed that the contribution of this spacer fabric to the overall insulation was higher than the two other samples in a non-convective mode, while it was the lowest in a forced convective mode. The positive effect of metallised interlayers with low emissivity on the reduction of... 

In the absence of interlayer slip, addition of a second phase leads to an increase of viscosity. The simplest way to treat the system is to consider the relative viscosity as a function volume fraction of the solids, < ), particle aspect ratio and orientation. 

In eq. (4.1) a number of proportionality constants [such as the monomeric volume fractions of polymer and surfactant in the interlayer, the surface area per surfactant, and the gallery height (h = dooi — 0.97 nm) of the intercalated structure] are omitted. ReadCTs interested in the detailed calculation of A/f are referred to the theoretical papers [17, 18]. 

Figure 9.5. Interlayer spacing shifts as a function of the volume fraction of added solute and surfactant chain. Comparison is shown with the predicted theories of penetration , with r/, constant, and swelling , with the area per molecule, a, constant. (Reprinted with permission from ref. (30), copyright 1998, the American Chemical Society.) ( ) decane, (O) dodecanol, ( ) m-xylene, ( ) SH244...

At a low volume fraction of functionalized polymers, these chains form an interlayer that the nonfunctionalized polymer can readily penetrate. As the fraction of the functionalized chains is increased, the polymers are driven to coat the substrates and consequently, the surfaces are pushed apart by the adsorbing chains. Note that increasing the fraction of functionalized chains beyond 30% has little effect on... 

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