Immersion time

Spinbath concentration can be adjusted to obtain the desired microstmcture. Low spinbath concentration promotes rapid solvent extraction but this also produces a thick skin on each filament which ultimately reduces the rate of solvent extraction and may lead to the formation of macrovoids. High spinbath concentrations give a denser microstmcture, but solvent extraction is slow and filament fusion can occur. Other spinbath conditions that affect coagulation and microstmcture are dope soHds, spinbath temperature, jet stretch, and immersion time. 

Printed circuit boards manufacture is aided by the use of KMnO. Alkaline permanganate solution is used to remove resin smeared on the interior hole wall of multilayered printed circuit boards. Additionally the hole wall is etched, resulting in a surface with excellent adhesion characteristics, for electrodeless copper (250). The alkaline permanganate etchback system containing >60 g/L KMnO and 40-80 g/L NaOH at 70—80°C, is effective for difunctional, tetrafiinctional, and polyimide resin substrates, where the level of etchback is direcdy proportional to the immersion time (10—20 min) (251). 

Fig. 10. Low-frequency electrochemical impedance of an epoxy-coated FPL aluminum adherend as a function of immersion time in 50°C water. Adapted from Ref. [46].

A dipping solution consisting of 0.2% fast blue salt B in hydrochloric acid (c = 0.5 mol/1, immersion time 30 s) has been reported for the detection of resorcinol homologues [1]. 

Note The result of the analysis is extremely dependent on the acid concentration employed, the immersion time and the subsequent temperature and duration of heating. 

The conditions which affect the type of reaction are bath temperature and the composition of iron or steel which is being coated. At 480-520°C the reaction between iron and zinc can be linear with time so that the thickness of the alloy layers will increase in direct proportion to the immersion time and the reaction will continue to be relatively rapid. With some steels (e.g. some silicon-killed steels), the reaction can be linear at the normal galvanising temperature of about 450 C. 

The FTE SAMs have a good hydrophobic property. Ohio et al. [36] have compared the variation of contact angles with immersing time in a neat FTE and a 100 mM FTE solution. The contact angles of water and hexadecane increased to about 110° and 73° from the initial value 76° and 36°, respectively, after 24 h immersion. Their works also indicate that the adsorption rate in 100 mM FTE solution is slightly faster than that in neat FTE. 

From different solutions, Hu et al. [26,34] made SAMs over DLC films on magnetic heads. The samples were pulled out at different immersing times, cleared using an ultrasonic cleaner in octane solution, and then washed by DI water. After that, the samples dried by blowing nitrogen were annealed in a cleaning box for 30 min at a temperature of 120°C. 

Fig. 21—The thickness and water contact angle of FTE SAMs on the DLC surfaces as a function of the immersing time in a 10 mM FTE solution at temperature of 20°C (a) film thickness of FTE SAM, and (b) water contact angle.

The solution concentration also has an influence on the formation of the SAMs. The maps of X-ray photoelectron spectra show that the C(ls) peaks for the samples in 1 mM and 5 mM FTE solutions with 24 h immersing are similar to those in Fig. 20(a), which indicates that there was hardly any SAMs on the DLC surface. The thickness of FTE SAMs and the water contact angle value increased with the immersing time. Hu et al. [26,34] obtained FTE SAMs with a thickness of 1.2 nm and a water contact angle value of about 110° by immersing a sample in a 10 mM FTE solution for 35 hours as shown in Figs. 21 (a) and 21(b). 

In order to reduce the immersing time and to examine the influence of the chain length of the adsorbed molecules on the formation of SAMs, Hu et al. [26,34] has investigated the properties of the SAMs of FPTS, FOTS, and FDTS, which have a different molecular chain length as shown in Table 1. 

No. Reagent Chain Length Immersing Time Thickness (nm) Contact Angle (°) Roughness (nm) Description of SAMs... 

For the three sorts of molecules, the film thickness and the water contact angle value of the SAMs grow with increasing chain length. In the immersing time of 1 h, the film thickness obtained is 0.48 nm, 0.8 nm, 1.2 nm, corresponding to the molecules with the number of carbon of 3, 8, and 10, respectively, and the contact angle value is 94°, 107.6°, 110.4°. 

The variations of film thickness and the contact angle value of FDTS SAM are also closely related to the immersing time as shown in Fig. 22. The film thickness of FDTS SAM increases to about 20 A within 2 h, which is close to the molecular chain length of FDTS, and then the thickness in-... 

The property is hardly influenced by the molecular chain length, the film layers, and the surface roughness, but the uniformity of a FATS SAM was important considering that decreases when the immersing time was less than 50 min. 

Fig. 27—The value as functions of immersing time for a FATS SAM on the magnetic head.

An immersion time less than 1 min, the neutralization with ammonium hydroxide (it extracts the hydrogen from the sulfonic acid and leaves stabilized S03 NH4 ion pair), and the high concentration of the sulfuric acid (95 wt%) are essential to produce adequate effectiveness of the treatment. H2SO4 treatment increases the T-peel strength of treated TR or SBR-polyurethane adhesive joints (Figure 27.2). 

FIGURE 27.1 ATR-IR spectra of sulfuric acid-treated thermoplastic rubbers (TRs) with different styrene content. Immersion time = 0.5 min. (From Cepeda-Jimenez, C.M., Pastor-Bias, M.M., Ferrandiz-Gomez, T.P., and Martm-Martmez, J.M., Int. J. Adhes. Adhes., 21, 161, 2001.)... 

The objective of the immersion test is to determine the moisture content (percent weight gain) of a material as a function of its immersion time. To interpret immersion test data, moisture diffusion through the thickness of a test specimen can be described using a one-dimensional Fickian equation... 

Figure 18. Phase angle vs. frequency plots from mild steel at different immersion times in (a) natural oiffield-produced water and (b) the same water with added SRB nutrients. (Reprinted from Ref. 36 with permission from NACE International.)...

Sulfiir-anchored SAMs and thin films, mostly from organosulfiir precursors, have been discussed at length by a number of authors [10, 181]. SAMs of organosulfiir compounds (thiols, disulfides, sulfides) form on gold substrates by spontaneous adsorption from either the liquid or the vapor phase. A number of experimental factors can affect the formation and structure of SAMs such as choice of solvent, temperature, concentration, immersion time, purity of adsorbate, oxygen concentration in solution, cleanliness, and structure of the adsorbate. Interestingly, the... 

FIGURE 333 Potential PSD plots (a) and current PSD plots (b) for A526-70 carbon steel at different immersion times in 0.5 M NaHCOj + 0.5 M CU solution. (From Cheng et al., 2000, with permission of the Bulletin of Electrochemistry.)... 

Jin and Atrens (1987) have elucidated the structure of the passive film formed on stainless steels during immersion in 0.1 M NaCl solution for various immersion times, employing XPS and ion etching techniques. The measured spectra consist of composite peaks produced by electrons of slightly different energy if the element is in several different chemical states. Peak deconvolution (which is a non-trivial problem) has to be conducted, and these authors used a manual procedure based on the actual individual peaks shapes and peak positions as recorded by Wagner et al. (1978). The procedure is illustrated in Figure 2.8 for iron. 

The curves of Figure 2.9 exhibit the complex structure of the surface film. With increasing depth there is a peak of iron in the oxidized state at approximately 0.3 nm, and a peak of chromium in the oxidized state at about 1 nm irrespective of immersion time. The maximum concentration of oxidized iron decreases and the maximum concentration of oxidized chromium increases with increasing immersion time. 

There is a so-called dry mercerisation process [275] in which the fabric is padded with caustic soda liquor at 20-25 °C and then dried in a stenter at about 130 °C. An immersion time in the pad trough of 7-10 seconds is sufficient but the goods need a total saturation time in the alkaline liquor of 30-40 seconds, i.e. from the nip to entry into the drying zone. 

MCM-41 samples have been characterized by means of powder X-ray diffraction (X Pert Philips, CuKa radiation), nitrogen adsorption measurements at 77 K (Quantachrome Autosorbl) and Field Emission Scanning Electron Microscopy (Assing FESEM Supra 25) before soaking in SBF and after different immersion times. 

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