Cloud point comparison

Table IV shows a comparison of some aqueous solution properties of nonionics having the same total number (ten) of carbon atoms in the hydrophobe and a comparable POE chain length, but different hydrophobe structure. It can be seen that multi-chain hydrophobes bring about a striking decrease in the cloud point and in the surface tension at the cmc, and an increase in the cmc, while cyclic fixation of the alkyl chain causes a large increase in the cloud point, the cmc and in the surface tension at the cmc.

Thus, an estimation can be made of the hydrophilicity of the crown ring. The acetal-type crown ring obtained from hexaethyl-ene glycol and a higher aliphatic aldehyde is estimated to be e-quivalent to about four OE units in an alkyl POE monoether, from our study of the cloud point (11). Moroi et al. concluded, from a comparison of the cmc, that a diaza-18-crown-6 is equivalent to 20 OE units in the usual type of nonionic (12). Okahara s group evaluated the effective HLB based on the cloud point, phenol index and phase-inversion-temperature in emulsion of oil/water system and they concluded that 18-crown-6 and monoaza-18-crown-6 rings with dodecyl group are approximately equivalent to 4.0 and 4.5 units, respectively, of OE chains with the same alkyl chain (17). 

Figure 7.1. Comparison of the cloud-point curves of poly(ethyl acrylate) (PEA), poly(butyl acrylate) (PBA), poly(ethylhexyl acrylate) (PEHA), and poly(octadecyl acrylate) (PODA) in C02. The overall polymer concentration is 5 wt % for each curve and the Mw of the polymer is given on each curve (Kirby and McHugh, 1999). The demarcations L + L and FLUID denote a two-phase and a one-phase region, respectively.

CjiEOj is present as a W+L dispersion between 0 and about 30 °C (it does not exhibit a cloud point), and undergoes a transition to a W+L2 system above 30 °C. A comparison of the detergency performance of the lamellar phases of C12E03 and C,2E04 can be made at 30 °C. At 48 °C, the performance of the very hydrophobic phase can be compared with that of the La phase of C12E04 and the Ll phase of C12E03. 

Table 2 presents cloud and pour points of biodiesel prepared by our supercritical alcohol method at 350°C. For comparison, the results of the commercial biodiesel fuels are also shown. These results demonstrate that the cloud point of ethyl esters was 3°C lower than that of methyl esters, while that of butyl esters was even lower. The cloud point of methyl ester was similar to that of commercial biodiesel fuels. 

Pour point, viscosity, cloud point, wetting power and foam properties, being important advantages of SAE, are presented here in comparison with other commercial products derived from primary alcohols (Ziegler and Oxo) or nonylphenol (branched chain). 

Also reported for comparison are the curves relative to two non polymerizable salts, sodium acetate and sodium chloride which cause a salting out of the surfactant. The role of electrolytes in the stabilization of the polymerized systems will be discussed below. The cloud point shift values, for the surfactant blend, measured after addition of a unimolal electrolyte solution are listed in Table II. 

Pandit, N.K. Caronia, J. Comparison of the cloud point behavior of triton x-100 in H2O and D2O. Journal of Colloid and Interface Science 1988, 122, 100-103. 

Three different isothermal crystallization experiments were performed in this work classical static (i.e., quiescent) crystallization in the DSC apparatus, dynamic crystallization with the apparatus described above, and dynamic-static crystallization. Dynamic isothermal crystallization consisted in completely solidifying cocoa butter under a shear in the Couette apparatus. Comparison of shear effect with results from literature was done using the average shear rate y. This experiment did not allow direct measurement of the solid content in the sample. However, characteristic times of crystallization were estimated. The corresponded visually to the cloud point and to an increase of the cocoa butter temperature 1 t) due to latent heat release. The finish time, was evaluated from the temperature evolution in cocoa butter. At tp the temperature Tit) suddenly increases sharply because of the apparition of a coherent crystalline structure in cocoa butter. This induces a loss of contact with the outer wall and a sharp decrease in the heat extraction. 

FIGURE 16.11 LLE of polypropylene (PP)-propane at three temperatures in a pressure-weight fraction plot. (PP M =290 kg/mol, MJM, = AA). Comparison of experimental cloud points to PC-SAFT calculations (k y = 0.0242). The polymer was modeled using three pseudo-components. (From Tumakaka, F. et al., Fluid Phase Equilibria, 541, 194—197, 2002. With permission.)... 

FIGURE 16.12 Cloud-point curve of polypropylene (PP)-n-pentane-C02 for various COj contents. Initial polymer weight fraction Wpp= 0.03 (before the addition of COj). Comparison of experimental cloud points to PC-SAFT calculations (PP-n-pentane 0.0137, PP-CO2 0.177, -pentane-C02 kij= 0.143). (From... 

Figure 5.10 Comparison of calculated (lines) and experimental cloud point data (symbols) of the poly(ethylene-co-methyl acrylate) (69 mol%/ 31 mol%)-acetone-propane system (Hasch et al., 1993). The polymer concentration is fixed at 5wt%. The calculations are performed with the Sanchez-Lacombe EOS with kij and 17,y set equal to zero for the EMAt9/3i-acetone pair, kij = 0.030 and rj/y = 0.000 for the propane-acetone pair, and kij = 0.023 and 77,/ = -0.002 for the EMA soi-propane pair. The weight average and number average molecular weights of EMA69/31 are 58,900 and 31,000, respectively.

Equation 8.39 involves the use of the cloud point temperature. Its value depends on the standard method adopted for its determination principally designed for comparison purposes. The conditions at the interface are unlikely to match those used in the empirical standard method so that may not be the true temeprature at the assumed liquid/solid interface. 

Figure 16.5 Comparison between the self-consistently solved coexistence line and the cloud points (filled triangle) of iPP/EPDM and the melting points (filled circles). The solidus and liquidus lines are virtually overlapped (dots), but the existence of both fines is manifested by the kink in the LCST coexistence line. The phase diagram was calculated using the material parameters, AHufp = 2110calmol , = 162.5°C, rj>p = 1800, repoM = 1000, and = 0.8 at T. ...

Figure 2 gives the comparison among the cloud point data for blends of... 

LOS LoStracco, M.A., Lee, S.-H., and McHugh, M.A., Comparison of the effect of density and hydrogen bonding on the cloud point behavior of poly(ethylene-co-methyl acrylate)-propane-cosolvent mixtures. Polymer, 35, 3272, 1994. 

Figure 9.24 Comparison of experimental and calculated phase diagram. The circles are from experimental cloud point measurements. Lines were calculated for the system with 0 = 0.27, = 600, = 1200, T = 600 K at a...

Figure 10.13 Comparison between experimental and calculated cloud-point pressures [38] for the system ethylene -f poly(ethylene-co-methyl acrylate), where the polymer weight fraction is 0.05.

Fig. 10.38 Qualitative comparison between the theory and the experimental phase diagram (cloud points) for the PVA/PMMA polymer blend without fillers (filled diamonds) and with 10 wt% fumed silica (open squares). The two curves correspond to the spinodals calculated using equations. It is assumed that both PVA and PMMA had degrees of polymerization (N) 1,000 and that (pN) a + bT, with (a)-lO.O, (b) 0.026374. Finally, assumed that (F) 0.65. For the filled system, we took nanoparticle loading of 14 vol%, with the dimensionless particle radius (R) 20 (corresponding to the real- particle radius of 10 run) (Ginzburg 2005)...

Comparison between the theoretical calculation of the coexistence curve and the experimental cloud-point curve is made in Figure 2.17(a). The experimental data (dotted lines) are wider than the theoretical binodals, but the shape of the curves, including the molecular weight dependence, is well reproduced. 

Fig. 2.17 (a) Comparison of the experimental cloud-point curves (symbols) and theoretical coexistence... 

Figure 1 depicts the experimental cloud points and the nematic-isotropic transition temperatures in comparison with the theoretical phase diagram of the PMMA-OH/E7 PDLC system. The phase diagram calculation was carried out based on the combined Flory-Huggins (FH) and Maier-Saupe (MS) free energies using r = 2.25 and a = -4.0. The b value was estimated from the critic temperature using x = a + (Xc-a)Tc /T. 

Figure 1. The predicted "tea-pot" phase diagram in comparison with the experimental cloud points ( ) by LS and nematic-isotropic transition temperatures ( ) by DSC. Line ABC represents the peritectic line. The solid and dotted lines represent the binodal and spinodal, respectively.

---