Swelling, combined polymerization

Hou et al. [42] studied the effect of AA in pressure-sensitive adhesives composed of a terpolymer of 2-ethylhexyl acrylate, VAc and AA. Like Gajria et al. they noticed a dependence of latex swelling with polymerization procedure. Hou et al. noted that batch polymerized latexes produced greater viscosity responses with pH adjustments. They demonstrated that addition of sodium chloride effectively reduced the pH-thickening response curve. Hnally, Kries and Sheiman [43] studied the influence of polymerizing various fimctional monomers on the wet adhesion of VAc/B A latexes. A number of monomer types were studied, such as polymoizable monomers containing amines, amides and acetoacetates, alone and in combination with each other. The ureido functional monomras exhibited supoior wet adhesion. 

Model networks can be considered as a new class of tridimensional polymeric material, with elastic chains of known and rather constant length, and branch points of almost constant functionality, with few defects, and of very satisfactory homogeneity. By combination of structural determinations and of swelling and deformation measurements it was shown that the existing theories of rubber elasticity are applicable, even though some ambiguity still exists as to what concerns the value and the meaning of the memory term. 

Dickinson and Walt (119) recently reported the synthesis and characterization of a small four-member model hbrary L20 using two monomers in different relative amounts. The composition of L20 is represented in Fig. 11.27. The library individuals were polymerized at the end of a fiber-optic sensor, and a solvatochromic dye was entrapped in the matrix during the polymerization. The exposure of such a sensor to vapors causes the swelling of the four polymers, depending on their nature and composition, and a spectral shift of the polarity-sensitive dye. The two effects combined lead to a sensing region-specific temporal change in the fluorescence emission... 

By combining thermodynamically-based monomer partitioning relationships for saturation [170] and partial swelling [172] with mass balance equations, Noel et al. [174] proposed a model for saturation and a model for partial swelling that could predict the mole fraction of a specific monomer i in the polymer particles. They showed that the batch emulsion copolymerization behavior predicted by the models presented in this article agreed adequately with experimental results for MA-VAc and MA-Inden (Ind) systems. Karlsson et al. [176] studied the monomer swelling kinetics at 80 °C in Interval III of the seeded emulsion polymerization of isoprene with carboxylated PSt latex particles as the seeds. The authors measured the variation of the isoprene sorption rate into the seed polymer particles with the volume fraction of polymer in the latex particles, and discussed the sorption process of isoprene into the seed polymer particles in Interval III in detail from a thermodynamic point of view. 

J.U. Keller, H. Rave, R. Staudt Measurement of gas absorption in a swelling polymeric material by a combined gravimetric-dynamic method. Macromo/. Cfiem. Phys. 200 (1999) 2269-2275. 

There are at least four general types of combinations of crosslinked (x) and linear (1) polymers in a two-component system both components crosslinked (xx), one or the other component crosslinked (lx or xl), and both components linear (11). Where at least one of the components has been polymerized in the presence of the other, the xx forms have often been called interpenetrating polymer networks (IPN), the lx and the xl forms termed "semi-IPNs", and the last, linear or in situ blends. There are also a number of ways in which the components can be formed and assembled into a multicomponent system. Sequential IPNs are prepared by swelling one network polymer with the precursors of the second and polymerizing. Simultaneous IPNs are formed from a mixture of the precursors of both components polymerization to form each component by independent reactions is carried out in the presence of the other precursors or products. Usually, the simultaneous IPNs that have been reported are extremes in the component formation sequence the first component is formed before the second polymerization is begun. Sequential IPNs and simultaneous IPNs of the same composition do not necessarily have the same morphology and properties. 

Virtually all polymeric materials, not just those designed to function in an aqueous environment, will be exposed to environmental water at some stage of their service lives, and water imbibition can have adverse effects on their physical and mechanical properties.Although the polymer itself may be able to tolerate such degradation, if water is absorbed at the interfaces of high moduli materials, substantial swelling pressures and the generation of unwanted stresses can be anticipated. Combined STRAFI and MRM studies of some commercial thermoset adhesives used in the construction industry have... 

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