Polyacrylate volume

We also studied the effect of initiator on the dispersion polymerization of styrene in alcohol-water media by using a shaking reactor system [89]. We used AIBN and polyacrylic acid as the initiator and the stabilizer, respectively. Three different homogenous dispersion media including 90% alcohol and 10% water (by volume) were prepared by using isopropanol, 1-butanol, and 2-... 

Several solid surfaces, such as filter paper, sodium acetate, and silica gel chromatoplates with a polyacrylate binder, have been used in solid-surface luminescence work (1,2). Experimentally it is relatively easy to prepare samples for analysis. With filter paper, for example, a small volume of sample solution is spotted onto the surface, the filter paper is dried, and then the measurement is made. In many cases, an inert gas is passed over the surface during the measurement step to enhance the RTF signal. For powdered samples, the sample preparation procedure is somewhat more involved. Commercial instruments can be readily used to measure the luminescence signals, and a variety of research instruments have been developed to obtain the solid-surface luminescence data (1,2). 

A series of slurries of high solids, dispersed ground calcium carbonate were prepared. Firstly, a sample of Carrara marble was ground without dispersant to a mean size of 0.5 fim. This was then filtered to a solids level of 76% (volume fraction 46%), before being thoroughly mixed with the required dose of sodium polyacrylate dispersant and adjusted to a constant solids level of 70%. Doses ranged from zero to 25mgg (2.5%) of calcium carbonate. Samples were then left for two days to reach a steady-state adsorption level. After this they were sheared and their viscosity (Brookfield RV, 100 rpm, spindle 3) was measured. 

The temperature position of the secondary fi relaxation (about 290 K 1 Hz), generally attributed to partial rotations of the side chains COOR, is only slightly affected by the polarity and volume of the substituent R but decreases markedly (by 120 K) on removal of the a-methyl group on the main chain. The experimental data obtained contradict the assumption that there is a certain relationship between this temperature and the glass transition temperature. Nevertheless, we can infer that the pertinent molecular mechanism in polymethacrylates differs from that in polyacrylates, probably due to the different participation of the main chains. The values of the individual contributions to the activation energy were estimated by employing a procedure similar to that used in the y relaxation process, and their sum was found to agree approximately with the experimental values. 

The effect of temperature and volume on the order parameter, s, in polyacrylic acid. The order increases with pressure and decreases with temperature. The straight lines indicate the validity of Equation 16.4. Data from J. R. McColl and C. S. Shih, Phys. Rev. Letters 29 (1972) 85. 

By what fraction would the specific volume of polyacrylic acid have to change keep the same degree of order, s, as a change of temperature from 140 to 145 °C ... 

The reactor was composed of a 312-mL total volume jacketed polyacrylic (192 x 46 mm) vessel. The reactor was sterilized using 30% (v/v) ethanol solution for 48-72 h, after which it was drained and washed thoroughly with sterilized deionized water. Brick pieces (4 to 5 mm, total weight of 220 g) were washed with deionized water several times followed by sterilization in an oven at 250°C for 2 h. The particles were then cooled in an anaerobic chamber to room temperature. The void volume inside the reactor was 186 mL. The reactor was packed aseptically with the sterilized brick particles. After the reactor was packed, oxygen-free N2 was passed through the column overnight. This was done to ensure that anaerobic conditions were attained inside the column and inside the particles. 

When hydrolyzed in water, the resulting diacid exhibits two pKs ( 3 and 8) the half ester as expected has one pKa typical of polycarboxylic acids. A cross-linked version of this polymer, referred to as Stabileze, thickens a variety of formulations by expanding its hydrodynamic volume when neutralized. Because of the low pKa of the vicinal diacids, Stabileze acquires a negative charge at lower pH than competitive cross-linked polyacrylic acids (carbomers). This allows for efficient thickening at lower pHs similar to that found on moist skin, which in turn allows products to perform at optimum pH as desired by skin-care product formulators (63). 

Study on the rapid transport of a polymer in dextran solutions, first observed by Preston et al., is extended into two directions. They arc (1) enhancement effect on the transport rate of polyvinylpyrrolidone (PVP) by the addition of a simple salt, and (2) extension to the transport of linear polyelectrolytes. The enhancement effect was observed on the structured flow as well as on the transport rate. The enhancement effect was correlated with the densities of the solutions in the lower compartment of the diffusion cell. The correlation was improved when the rate was corrected for the differences in viscosities. We have found that effects of charges on the polymers favor the rapid transport of polyacrylates (PA) and sodium hyaluronate. Counterion condensation was manifested in the transport rate of PA. Transport rates of several salts of PA in the absence of added salt increased linearly with their partial specific volumes in water. 

MgAl,04 Darvan 821 A, derivative of polyacrylic acid volume fraction... 

Some polymers can be used as accelerators of nucleic acid hybridization. They sometimes produce background staining and are only recommended when the hybridization rate is low (small amounts of probe or target). Dextran sulfate is often used as an accelerator but polyethylene glycol (PEG 6000) and sodium polyacrylate have been shown to be valuable alternatives. These polymers probably act by exclusion of probe molecules from the volume occupied by the hydrated polymer which results in an effective increase in the probe concentration (Wetmur, 1975). The optimal probe concentration in membrane hybridization is considered to be about 10 cpm of probe/ml (1-10 ng/ml), but Amasino (1986) found a 2- to 10-fold reduction in the probe concentration to be optimal when 10% PEG was included (note that these effects may depend on the specific activity of the probe). These polymers do not act in a similar way and have their own characteristics. 

As a result of the increase in the number of laboratories carrying out environmental analysis and the corresponding increase in the volumes that are used primarily for extraction and have to be disposed of, there has been increasing use of solid-phase extraction (SPE) methods including solid-phase microextraction (SPME) procedures using fiber-coated poly(dimethylsilox-ane), methyl silicone, or polyacrylate. These procedures are discussed in Sections 2.2.4 and 2.2.7. 

Table I. Volume Changes for the Binding of Silver Ion by Polyacrylic Acid (PAA-2) as a Function of the Degree of Neutralization...

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