Solid monomers

JD Affinito, ME Gross, PA Moumier, MK Shi, and GL Graff, Ultrahigh rate, wide area, plasma polymerized films from high molecular weight/low vapour pressure liquid or solid monomer precursors, J. Vac. Sci. Technol., A, 17 1974—1981, 1999. 

The liquid or low-melting solid monomers can be cured to the solid state by incorporating a curing catalyst and heating the mixtures below the decomposition temperature. Moreover, the cured solids are transparent and hard polymers formed of three-dimensional networks with moderate thermostability. 

A detailed study on the possibility of modifying polyethylene by mechanical method was performed by Protasov and Baramboim (26). In their investigation they used a low density polyethylene of Mv 35400 and several solid monomers... 

Table 5. Polymerization of solid monomers by vibromilling polyethylene. Composition and...

At lower temperatures a polymer (or solid monomer) was also de-poisted on the vessel wall, although it was not visible. This was verified by heating the vessel to 130°C. after termination of the reaction carried out at a low temperature. The brown coating became visible by heating. 

Accepting the conventional Flory-Huggins treatment, one deduces then the free energy of polymerization, A G1(S, of a liquid monomer into solid monomer to be... 

A quite different approach to chain-growth condensation polymerization is phase-transfer-catalyzed polycondensation of solid monomer dispersed in an... 

If a twin-screw extruder is stopped and opened, several zones can be clearly distinguished [9]. Depending on whether the extruder is fed with a solid or a liquid material, two different situations occur. In the case of a solid feed (a polymer or solid monomer), the channels near the feed hopper are more or less filled with solids. This material melts, resulting in a zone where the channels are only partly filled. At the end of the screw, close to the die, a zone exists where the channels are completely filled with polymer. If the extruder is fed with a liquid monomer, the first part does not necessarily need to be partly empty but, as will be explained later, for reasons of stability it is advisable to create a zone where the channels are not fully filled. In particular, the fully filled zone is very important for correct functioning of the extruder. In this zone the pressure is built up, the mixing and kneading mainly... 

The first, and perhaps most vivid, example is the effect of the structure of a monomer crystal on polymerization in the solid state. The fact that the configuration of the emerging polymer depends directly on the structure of the solid monomer is no longer doubted, having been proved for many cases. Thus, depending on its phase, acetaldehyde polymerizes... 

The fact that the structure of a solid monomer influences its polymerization substantially now seems obvious. It is not as clear whether structural phenomena can effect polymerization if the monomer is a liquid. It has long been known that ordered regions or clusters exist in liquids, and several years ago it was assumed that in some cases these regions in liquid monomers can influence the polymerization. One of the most vivid examples—namely, polymerization in the liquid-crystalline state—was accomplished by Krentzel and co-workers (I, 2, 3). The object of their study was p-methacrylylhydroxybenzoic acid, which forms conventional crystals in the pure state and does not polymerize in the solid state. However, when mixed with alkoxybenzoic acid, it forms liquid crystals of both smectic and nematic forms. Polymerization of p-meth-acryllylhydroxybenzoic acid in various forms of liquid crystals was compared with polymerization of the same substance dissolved in dioxane and dimethylformamide (DMF). 

Furfuryl alcohol, reacted with formaldehyde in the presence of acetic acid, is selective in yielding 2,5-bis(hydroxymethyl) furan. This crystalline solid monomer has been used in preparing polyesters and polyurethanes. Color stability has been a limitation in certain instances. Hydrogenation of 2,5-bis(hydroxy-methyl) furan to 2,5-bis(hyroxymethyl) tetrahydrofuran provides a water-white, stable, liquid diol that shows promise as a polyurethane/polyester component. In this instance, exceptionally color-stable products are produced (43). 

The largest production of acrylamide is in Japan the United States and Europe also have large production facilities. Some production is carried out in the Eastern Bloc countries, but details concerning quantities or processes are difficult to obtain. The principal producers in North America are The Dow Chemical Company, American Cyanamid Company, and Nalco Chemical Company (internal use) Dow sells only aqueous product and American Cyanamid sells both liquid and solid monomer. In Europe, Cliemisclie Fabrik Stockhausen Cie,. .Allied Colloids, The Dow Chemical Company, and Cyanamid BV are producers Dow and. American Cyanamid are the only suppliers to the merchant market, and crystalline monomer is available from. American Cyanamid. For Japan, producers are Alitsubislii Chemical Industries, Alitsui Toatsu, and Nitto Chemical Industries Company (captive market). Crystals and solutions are available from Alitsui Toatsu and Alitsubislii, whereas only solution monomer is available from Nitto. 

In a modification of this approach, monomer droplets (1-5 pm) are replaced by solid particles of monomer, which are then dispersed in the other monomer For example, N-phenylmaleamic acid is used as the solid monomer and triallylamine hydrochloride is the medium in which the solid particles are dispersed. Chlorobenzene is used as the third phase. However, the thermally regenerable capacity of this resin is not satisfactory. 

The polymerization of N-carboxy-a-amino acid anhydrides (Leuchs anhydrides) has also been achieved by water and by a variety of bases like amines, alkali metal hydroxides, alkali metal oxides, and organo-metallic compounds in bulk, inert solvents, or starting with the solid monomer (705). Despite a great interest in the polypeptides produced in these reactions, little attention has been paid to conditions which yield solid polymer. In case the solid was produced, no physical chemical analysis of the polymer was carried out. Pol5mierization of the crystalline monomer was already observed in 1940 705). 

We do not know how endothermic or exothermic the deoxygenated dinitroso reaction 33 is because the enthalpies of formation of nitrosobenzene (as solid monomer) and 1,3-dinitrosobenzene are not available. 

Solid monomers acrylamide and methacrylamide were recrystallized twice from methanol. Bulk monomers were polymerized in the manner described above, but in the solid state (no melting). Aqueous solutions of these monomers were handled as the liquid monomers. 

When solid monomers of acrylamide (AM) and methacrylamide (MAM) were subjected to plasma initiation, only trace amounts of insoluble polymers were obtained. Now if aqueous solutions of AM and MAM were used in the plasma initiated polymerization high conversions were again achievable upon post-polymerization. Polyacrylamide was found to be completely soluble, whereas polymethacrylamide forms a gel. It is of interest to note that no poljnner is formed with post-polymerization alone without plasma initiation... 

Gamma radiation is the most convenient type of high-energy radiation for initiating polymerization because its high penetrating power affords uniform irradiation of the system. Because gamma rays are absorbed to the same extent by solids as by liquids, solid monomers can be polymerized readily. This allows polymerization of many monomers at low temperatures. 

The 50% aqueous acrylamide is the preferred form because it eliminates the handling of solids and because its cost is lower. This is a result of the new manufacturing method put into effect in 1971. The aqueous form is applicable to nearly all the end uses of acrylamide when volume is taken into account. Aqueous acrylamide is shipped in tank trucks, rail cars, or dmms, but small samples can also be obtained. The solution should be kept in stainless steel or in tanks coated with plastic resin (phenolic, epoxy, or polypropylene). All containers, including tank trucks and rail cars, must be rinsed prior to disposal or return. When shipping costs are an important consideration, solid acrylamide may be the desired form. Acrylamide should be stored in a well ventilated area away from sunlight. The temperature should be under 30°C, and under these conditions no change of quality should be noticed for at least 3 months. Typical specifications for the 50% aqueous solution are shown in Table 5 and for the solid monomer in Table 6. 

The ease and efficiency of carrying out polymerization in the solid state and the polymerization of channel and layer inclusion compounds. Penetrating radiation, in particular y-radiation, ensures regular initiation throughout the bulk of the solid monomer. 

Polymerization rf this solid monomer (mp, 65 C) can be carried out by any one of the usual methods of radical type polymerimtimi, but it also can be. polymerized in the presence of ionic catalysts. The latter method can yield a polymer having a softening point of 210°C. 

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