Compatibility stability incompatibility

A compatibility stability idiosyncrasy of diisodecyl adipate (DIDA) could pose a troublesome problem. A PVC plastisol formulated with DIDA and fused in an oven for 10 min at 175 C will exude but if the fusion period is lengthened to 0.5 h, it will not. One explanation is the dielectric constant of DIDA is below A it should be incompatible and therefore exude. However, upon extensive heating in air this oxidation-susceptible plasticizer builds up peroxides, undergoes chain scission and weight loss, and changes in compatibility. As shown in Table I, if the oxidation phenomenon is negated in per se DIDA by the presence of an antioxidant, bisphenol A, the plasticizer remains unchanged in dielectric constant and predictably would be incompatible (20). 

The compatibility of sorbitol in various solid [49,50] and solution [45-47] formulations has been investigated. In a study conducted using DSC as a stability screening tool, sorbitol was found to be incompatible with salbutanol sulfate [49] and cephalexin [50]. Sorbitol has been found to be... 

Nowadays it is well established that the interactions between different macromolecular ingredients (i.e., protein + protein, polysaccharide + polysaccharide, and protein + polysaccharide) are of great importance in determining the texture and shelf-life of multicomponent food colloids. These interactions affect the structure-forming properties of biopolymers in the bulk and at interfaces thermodynamic activity, self-assembly, sin-face loading, thermodynamic compatibility/incompatibility, phase separation, complexation and rheological behaviour. Therefore, one may infer that a knowledge of the key physico-chemical features of such biopolymer-biopolymer interactions, and their impact on stability properties of food colloids, is essential in order to be able to understand and predict the functional properties of mixed biopolymers in product formulations. 

Following are some properties of AECP explosion /emp(PA method) 305—10°(5 sec) impact test with 2kg wt—detonated at 12" bygroscopicity(% gain in wt at RT and 77% RH) 23% after 6 days and 22.3% after 13 days thermal stability—relatively stable at 85° for long periods of time but decomp extensively at 125° within a week tensile strength—decreases with increase in perchlorate content solubility—insol in common solvents, sometimes dissolved at elevated temps with decompn, swelled in some polar liquids dissociated to some extent in HaO compatibility with NC—incompatible... 

The choice of the proper stationary and mobile phases for the foregoing purpose would depend on several factors, such as the nature (polarity, stability in mobile phase) of the NOC analyzed and the availability/compatibility of the detector used. For example, if only a TEA is available as a detector, the use of an ion-exchange or a reversed-phase system is ruled out, because both require aqueous mobile phase for proper operation. Moisture in the mobile phase causes freeze-up of the cold traps in the TEA and also results in noisy response due to interference during chemiluminescence detection. Similarly, if one is using, as the detector the newly developed Hi-catalyzed denitrosation-TEA (62) or the photolytic cleavage-TEA (58), a reversed-phase system using aqueous mobile phase would be the method of choice. These detectors, however, have not been demonstrated to work in the normal-phase system. The use of an electrochemical detector will also be incompatible with an organic solvent as the mobile phase. 

The steric stabilization, which is imparted by polymer molecules grafted onto the colloidal particles, is extensively employed.3 Amphiphilic block copolymers are widely used as steric stabilizers. The solvent-incompatible moieties of the block copolymer provide anchors for the polymer molecules that are adsorbed onto the surface of the colloidal particles, and the solvent-compatible (buoy) moieties extend into the solvent phase. When two particles with block copolymers on their surface approach each other, a steric repulsion is generated bet ween the two particles as soon as the tips of the buoy moieties begin to contact, and this repulsion increases the stability of the colloidal system.4-6 Polymers can also induce aggregation due to either depletion 7-11 or bridging interactions.12 15... 

Suitable curatives for the polysulfide-epoxy reaction include liquid aliphatic amines, liquid aliphatic amine adducts, solid amine adducts, liquid cycloaliphatic amines, liquid amide-amines, liquid aromatic amines, polyamides, and tertiary amines. Primary and secondary amines are preferred for thermal stability and low-temperature performance. Not all amines are completely compatible with polysulfide resins. The incompatible amines may require a three-part adhesive system. The liquid polysulfides are generally added to the liquid epoxy resin component because of possible compatibility problems. Optimum elevated-temperature performance is obtained with either an elevated-temperature cure or a postcure. 

In choosing an epoxy and polymeric latex, it is important that they have compatibility. Incompatibility usually occurs when the pH of the epoxy resin dispersion alters the pH of the latex into a range where the ionically stabilized latex is broken, causing agglomeration of the latex polymer. The pH of the epoxy resin s emulsion may need to be adjusted before blending with the polymeric latex. 

In the methodology developed by us [24], the incompatibility of the two polymers was exploited in a positive way. The composites were obtained using a two-step method. In the first step, hydrophilic (hydrophobic) polymer latex particles were prepared using the concentrated emulsion method. The monomer-precursor of the continuous phase of the composite or water, when that monomer was hydrophilic, was selected as the continuous phase of the emulsion. In the second step, the emulsion whose dispersed phase was polymerized was dispersed in the continuous-phase monomer of the composite or its solution in water when the monomer was hydrophilic, after a suitable initiator was introduced in the continuous phase. The submicrometer size hydrophilic (hydrophobic) latexes were thus dispersed in the hydrophobic (hydrophilic) continuous phase without the addition of a dispersant. The experimental observations indicated that the above colloidal dispersions remained stable. The stability is due to both the dispersant introduced in the first step and the presence of the films of the continuous phase of the concentrated emulsion around the latex particles. These films consist of either the monomer-precursor of the continuous phase of the composite or water when the monomer-precursor is hydrophilic. This ensured the compatibility of the particles with the continuous phase. The preparation of poly(styrenesulfonic acid) salt latexes dispersed in cross-linked polystyrene matrices as well as of polystyrene latexes dispersed in crosslinked polyacrylamide matrices is described below. The two-step method is compared to the single-step ones based on concentrated emulsions or microemulsions. 

The stability and stoichiometry of the complex between polymers containing nucleic add bases are affected by the compatibility of the different base-base distances in the polymers, and also by the mutual penetration ability between the main chains. In the polyMAOA-polyMAOT system, for example, intramolecular base-base distances in each polymer are compatible and these polymers are able to penetrate each other38, Poly-L-lysine derivatives and vinyl polymers are apparently incompatible. This situation alone would lead to unstable complex formation where the overall stoichiometry would not be simple and thus could not reflect the stoichiometry on the binding site. 

The experimental details of dispersion polymerization with various polymeric dispersants and macromonomers are fairly well established. A basic expression for particle size control has also been derived for the formation of clear-cut core-shell particles based on highly incompatible core-shells such as polystyrene-PVP and polystyrene-PEO. However, results deviate considerably from theory in compatible polymers such as PMMA with PEO macromonomer. The detailed structures of the hairy shells need to be discovered in order to better understand the exact mechanism of their formation and stabilizing function. 

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