Swelling data

A solubihty parameter of 24.5-24.7 MPa / [12.0-12.1 (cal/cm ) ] has been calculated for PVF using room temperature swelling data (69). The polymer lost solvent to evaporation more rapidly than free solvent alone when exposed to air. This was ascribed to reestabUshment of favorable dipole—dipole interactions within the polymer. Infrared spectral shifts for poly(methyl methacrylate) in PVF have been interpreted as evidence of favorable acid—base interactions involving the H from CHF units (70). This is consistent with the greater absorption of pyridine than methyl acetate despite a closer solubihty parameter match with methyl acetate. 

Returning to the evaluation of the SAH network parameters, it should be noted that the crosslinking densities obtained from the modulus and swelling data agree satisfactorily with each other [22]. Analysis of the data from Refs. [18,90] confirms this conclusion. 

Kraus equation and Kraus plots based on swelling data are largely used to explore the rubber-filler interaction in conventional composites [62]. Bandyopadhyay et al. [38] have employed the same equation for understanding the reinforcement behavior in ACM-silica and ENR-silica hybrid... 

Swelling data and stress-strain results in SBS have shown that Me is approximately the molecular weight between entanglements. Choudhury and Bhowmick [201] have shown in the case of different NR-based TPEs the following relation ... 

B was also obtained from equilibrium-swelling data of selected block copolymers the results showed excellent agreement with the other methods (Equations 7.1 and 7.2)7... 

FIG. 12 Swelling data, (a) Variation of swelling ratio with % C. (Reprinted with permission from Ref. 168, Copyright 1990, American Chemical Society.) (b) Variation of swelling ratio with % T. (Reprinted with permission from Ref. 28, Copyright 1994, American Chemical Society.)... 

FIG. 14 Swelling data as function of % C. (Reprinted with permission from Ref. 313, Copyright 1971, Nature.)... 

Equilibrium swelling measurements have been done on B2 and on But 21-27 in benzene. No swelling data is reported for the PCP2 system for the reasons stated later in this paper. 

The data on isocyanate crosslinked polybutadiene (B2) is given in Table II, and for this the molecular weight (Mc) was calculated using eqn. (2) (Mc=l0,1OOF3). The expected value of Mc as obtained from GPC on uncrosslinked polymer should be somewhere in the range of Mn (5100) to Mw (7400). Comparison of GPC and swelling data yields that F3 is in the range of 0.51-0.73, which in turn determines the extent up to which the chains deform non-affinely. 

Figure 1. Molecular weight between cross-links obtained from swelling data as a function of DCP...

Correctness of the sixth parameter equation (7) and its simplified forms for the generalization of the swelling data was proved for other coals including the Donbas coal [32] at the parameters B and VM- If to apply the equation (7) to the coal extraction data, then the factor of molar volume VM is insignificant, and the connection between quantities of extracted substance (in g/mole of the solvent) and physical-chemical characteristics can be satisfactorily described by fifth parameter equation (6) or by its simplified forms in this case possible acid-base interaction is the decisive factor, that is factor B [33 - 35], This confirmation is in good agreement with the above-said bigger molecules harder introduce... 

The swelling data in Table IV can be used to calculate x parameters for the extract and O-methylated extract using Equation 1. The results are shown in Table V. The x parameters for both extracts are observed to be positive and independent of pressure or concentration of benzene. The magnitude of the parameters are much larger than that determined for the O-octylated extract (0.65) which is consistent with their lower solubilities in liquid benzene. The X parameters are much larger than those determined by Larsen el al. for the pyridine-extracted Illinois No. 6 coal, which was near 0.3.(6) The reason for this are not clear. However, we note that benzene is a very poor solvent for these pyridine-extracts so large x parameters are expected. 

Question 4. Why is the preliquefied insoluble product so easily liquefied The most probable answer. The preliquefaction product with the reduced carboxyl groups content is more easily liquefied than the parent coal. Based on the product distribution, solvent swelling data and the model simulation, this improvement results from a reduction in the CO2 associated crosslinks and from the bond breaking which produces the chloroform solubles. Both effects reduce the total number of bonds linking the network so that the coal can become fluid. If the chloroform soluble fraction is removed after preliquefaction and the residue liquefied, the drastic improvement in the liquefaction is not observed. The model simulation confirms that the residue alone will liquefy slightly better than the parent coal, but not nearly as well as the mixture. 

Swelling data indicate that crosslink density in the continuous phase of the 70 30 and 60 A0 networks is high. Crosslink densities were estimated from the data in Table III by the method of Hill and Kozlowski ( ). Results were for 80 20, "Vg = 10" moles of elastically effective network chains/cm for 70 30, Vg = 2.5 x lO" chains/cm for 60 AO, Vg = A.3 x 10" chains/cm. These estimates suggest that the crosslink densities are within the range reported for conventional, highly crosslinked acrylic HMMM and polyester HMMM enamels (19,20). 

Fig. 5. Equilibrium swelling data for copolymers of P(HEMA-co-MAA) containing 10 mol% HEM A (O), 60 mol% HEMA ( ), and 80 mol% HEM A (O) as a function of the pH of the swelling medium along with predictions of that swelling behavior using Eq. (38)...

Poly(4-vinylpyridine) resins 6 cross-linked with 9.6 % divinylbenzene and 68-82 % alkylated also have been tested as catalysts for reaction of 1-bromooctane with cyanide ion 81). The catalytic activities depended on the organic solvent in the order benzene > toluene > o-dichlorobenzene. No swelling data were reported, so it is not known if the activities correlate with the swollen volumes of the catalysts. 

Swelling tests and determination of tensile properties. The procedure for estimating cross-link density from equilibrium swelling data is described in detail in a previous paper (6). The tensile properties of the PU films were carried out at 23°C and 60% relative humidity. The crosshead speed and distance were 10 mm/min and 30 mm, respectively. A more detailed description of the tensile tests is given elsewhere (6). 

Crosslink density of PU films. The PU films were subjected to swelling tests in dimethylformamide. The crosslink densities of the films were thereafter estimated from equilibrium swelling data using a modified version of the Flory-Rehner equation. The swelling tests as well as the calculation of crosslink density are described in detail in a previous paper (6). 

For the determination of sorption data, gravimetric methods are usually used the most difficult task is to take into account the buoyancy effect. This effect is negligible at low pressures, but becomes important at SCF densities. Accurate equations of state for pure fluids are used to calculate gas densities, and swelling data are needed to calculate the volume of the polymeric phase. Generally, the amount of dissolved gas increases with increasing pressure until a saturation value is reached. 

More elaborate treatments of the swelling data were attempted50 without great success, since besides the two constants A and B a third parameter, x> is not known precisely. One may assume that x remains nearly the same, whether the polymer is... 

Fig, 6. Least squares fit of the modified theory of Marchetti et al. to swelling data for gels of different polymer types. Values of fit parameters are given in Table 3. Reprinted with permission from [53], Copyright [1993] American Chemical Society... 

Fig. 12.13 Extrudate swelling data for polystyrene melts , broad molecular weight sample O, , A, narrow distribution sample data at various temperatures. [Reprinted by permission from W. W. Graessley, S. D. Glasscock, and R. L. Crawley, Die Swell in Molten Polymers, Trans. Soc. Rheol., 14, 519 (1970).]...

Mechanical properties of crosslinked elastomers are influenced not only by the volume-average crosslink density but also by network heterogeneity. The influence of structural defects (such as residual sol, dangling chains, chain loops and the heterogeneity of the junction distribution) on the viscoelastic properties and the equilibrium swelling data is still under discussion. Local methods which probe molecular properties are very suitable for the determination of the degree of network heterogeneity [11]. 

To evaluate the swelling behavior and the crosslinked parameters of coal networks, swelling data were obtained for seven American coals supplied in fine particles by the Pennsylvania State University coal bank. To eliminate experimental artifacts, several separations and purifications were performed prior to swelling, according to the general experimental protocol reported in earlier communications (1,12). 

The data listed in Table 1 also confirm the observation made in the comparison of swelling data reported for polymers made in Staudinger s [1] and Boyer s [39] laboratories under ostensibly the same conditions, namely that the ratio of DVB mole fraction in the monomer charge (y) to the mole fraction of DVB in the resulting polymer (x) varies significantly from one laboratory to another, which presumably reflects small differences in experimental conditions, such as the electrophilicity of the initiating free radical(s) or the time profile of their concentration (or design of the equipment, such as the surface to volume ratios). 

Swelling data for Sty-co-DVB polymers that have very-narrow-range molecular weight distributions for the poly(styrene) segments between poly(DVB) nodules have been reported by Rempp [141-143] and his coworkers. The size of these nodules and the number of polystyrene segments covalently bonded to a given... 

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