Thin film compression

The 1% ethylene-carbon monoxide copolymer was also irradiated in the solid phase (thin film). Compression-molded films were fixed on plates which fitted into the Perkin Elmer 521 infrared spectrophotometer. An infrared spectrum of the polymer could thus be obtained after each period of photolysis without disturbing the film. For photolyses at room temperature and above the plates were mounted in a solid brass cell through which a stream of inert gas could be passed while the cell was being heated. 

Takei, A., Jin, L., Hutchinson, J.W. Ridge localizations and networks in thin films compressed by the incremental release of a large equi-biaxial pre-stretch in the substrate. Adv. Mater. 26,... 

Macrostrain is often observed in modified surfaces such as deposited thin films or corrosion layers. This results from compressive or tensile stress in the plane of the sample surface and causes shifts in diffraction peak positions. Such stresses can easily be analyzed by standard techniques if the surface layer is thick enough to detect a few diffraction peaks at high angles of incidence. If the film is too thin these techniques cannot be used and analysis can only be performed by assuming an un-... 

Plasma CVD tends to create undesirable compressive stresses in the deposit particularly at the lower frequencies. This may not be a problem in very thin films used in semiconductor applications, but in thicker films typical of metallurgical applications, the process is conducive to spalling and cracking. 

A volume of gas is enclosed in the space bounded by the rotor, the stator and the two vanes (see Fig. 1.6). The pump removes the gas by compressing it to a pressure slightly higher than the atmospheric pressure. This overpressure opens the spring-loaded outlet valve, and the gas escapes to the atmosphere. A thin film of oil makes the final seal therefore the ultimate pressure depends also on the oil vapour pressure. With one stage, the lowest attainable pressure is about 10 2torr and with two stages in series 10-3 torr. 

In the experiments on the Jt-A characteristics, it has been usually assumed that thermal equilibrium will be attained easily if the experiment is performed using a slow rate of compression of thin film at the interface. Measurements under thermal equilibrium are, of course, the necessary condition to obtain the physico-chemical properties of the individual "phase" of the lipid ensemble. 

Figure 6 shows the effects of compression rate on the ji-A curve for the PhDA2-8 thin film at air/water interface. Accompanied with the increase in the compression rate, the hump becomes more significant and the maximum surface pressure of the hump shifts toward the larger surface area. It is to be noted that the region with zero surface pressure appears only with appropriate compression rates of 3 - 7.5 (A2/molecule)/min as in (d), (e), and (f). 

As has been mentioned above, the 7t-A curves of the PhDA2-8 thin film show the existence of the zero pressure region after the formation of the overshoot hump. It is noteworthy that the remarkable overshoot hump and the subsequent zero surface pressure are observable only in a particular range of compression rates, suggesting that the inclusion of the effect of non-... 

Next, we discuss the mechanism of the characteristic features observed in the Jt-A curve. When the PhDA2-8 thin film is compressed with relatively high speed, there will be a non-negligible effect of the special inhomogeneity over the lipid film, i.e., the surface pressure in the region near the blade becomes larger than that in the other region. 

In the above subsection it was demonstrated that the inclusion of electrostatic interactions into the pressure-area-temperature equation of state provides a better fit to the observed equilibrium behavior than the model with two-dimensional neutral gas. Considering this fact, we would like to devote our attention now to the character of the lipid film under the dynamical, nonequilibrium conditions. In the following we shall describe the dynamical behavior of the phospholipid(l,2-dipalmitoyl-3-sn-phosphatidylethanolamines DPPE) thin films in the course of the compression and expansion cycles at air/water interface. 

Unlike the bulk morphology, block copolymer thin films are often characterized by thickness-dependent highly oriented domains, as a result of surface and interfacial energy minimization [115,116]. For example, in the simplest composition-symmetric (ID lamellae) coil-coil thin films, the overall trend when t>Lo is for the lamellae to be oriented parallel to the plane of the film [115]. Under symmetric boundary conditions, frustration cannot be avoided if t is not commensurate with L0 in a confined film and the lamellar period deviates from the bulk value by compressing the chain conformation [117]. Under asymmetric boundary conditions, an incomplete top layer composed of islands and holes of height Lo forms as in the incommensurate case [118]. However, it has also been observed that microdomains can reorient such that they are perpendicular to the surface [ 119], or they can take mixed orientations to relieve the constraint [66]. 

The thermal expansion coefficient of silicon is approximately seven times larger than that of Si02, as given in Table 2. When Si02 is deposited, typically at temperatures of several hundred degrees C, an in-plane compressive stress develops in the oxide layer as the Si wafer is cooled by AT to room temperature. For a uniform 2-dimensional thin film deposited on a substrate, the in-plane stress obtained from Equation 2 is ... 

Thin films of materials play an important role in modern electronics. Langmuir-Blodgett films (Mort, 1980) are prepared from surface-active molecules that adsorb at the surface of an aqueous solution. The surface is gently compressed to produce a close-packed monolayer, which can be coated on appropriate substrates by dipping at constant surface pressure. The layers so produced are of a precise thickness, and repeated dipping gives multilayers. For example, diacetylenes and other polymerizable... 

A number of peculiar properties are displayed, including rheology characterised by viscoelasticity. Viscosities are far higher than that of either bulk phase this is a result of the large amount of energy required to deform the network of thin films of the continuous phase. A yield stress is observed, below which HIPEs behave as elastic solids and will not flow. Resistance to flow occurs from the inability of compressed droplets to easily slip past each other. Above the... 

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