Press, polymerization

A well-known high conversion reactor is the so-called polymerization press, a modified plate-and-frame filter press where polystyrene is polymerized in frames alternating between cooling platens through which water (or steam) can be circulated. Other versions of the high conversion reactor have been utilized, e.g., the early "can process of Dow, where styrene monomer was placed in sealed cans in water baths and the metal stripped off at the end of the polymerization 2). 

Access to Practice. Publications and patents on the batch mass process are limited. Bishop s book CD contains the most detailed description of the polymerization press and mass-suspension processes for PS and HIPS. Fong (16) presents an economic analysis of the press process based on Bishop s description. Patent references are few for the batch-mass process the 1939 Bakelite patent on transfer of prepoly syrup to chambers or containers is of historical interest (17). 

Partially polymerized resins of urea are used by the textile industry to impart permanent-press properties to fabrics (see also Textiles, finishing). 

J. Green, in M. Lewin, S. M. Adas, and E. M. Pierce, eds., Flame-Retardant Polymeric Materials, Vol. 3, Plenum Press, New York, 1982, Chapt. 1. 

An ink is considered dry when a print does not stick or transfer to another surface pressed into contact with it. Drying is accompHshed by one or more of the following physical or chemical mechanisms absorption, evaporation, precipitation, oxidation, polymerization, cold setting, gelation, and radiation curing. 

During the press operation, which is actually a form of compression mol ding, the resin-treated laminate pHes are heated under pressure and the resins cured. The initial heating phases cause the resin to melt and flow into voids in the reinforcing ply and bond the individual pHes together. The appHed heat simultaneously causes the resin to polymerize and eventually to cross-link or gel. Therefore, resin viscosity reaches a minimum during the press cycle. This is the point at which the curing process becomes dominant over the melt flow process. Dynamic mechanical and dielectric analyses (11) are excellent tools for study of this behavior. 

D. H. Napper, Polymeric Stabilisation of Colloidal Dispersions, Academic Press, London, 1983. 

D. R. Paul and Y. P. Yampol skii, eds.. Polymeric Gas Separation Membranes, CRC Press, Boca Raton, Fla., 1994. 

Metal-Matrix Composites. A metal-matrix composite (MMC) is comprised of a metal ahoy, less than 50% by volume that is reinforced by one or more constituents with a significantly higher elastic modulus. Reinforcement materials include carbides, oxides, graphite, borides, intermetahics or even polymeric products. These materials can be used in the form of whiskers, continuous or discontinuous fibers, or particles. Matrices can be made from metal ahoys of Mg, Al, Ti, Cu, Ni or Fe. In addition, intermetahic compounds such as titanium and nickel aluminides, Ti Al and Ni Al, respectively, are also used as a matrix material (58,59). P/M MMC can be formed by a variety of full-density hot consolidation processes, including hot pressing, hot isostatic pressing, extmsion, or forging. 

E. Tuti, ed.. Thermal Characterisation of Polymeric Materials, Academic Press, Inc., New York, 1981. 

Blends of wool and cotton (80 20) are being used more and more. For durable-press properties, resins, catalysts, and polymeric additives in finishing systems must be adjusted (186). 

G. M. Jenkins and K. Kawamura, Polymeric Carbons—Carbon Fiber, Glass, and Char., Cambridge University Press, New York, 1976, 178 pp. 

Benzene-1,2-dithiol [17534-15-5] M 142.2, m 24-25 , 27-28 , b 110-112 , pKEst(i) -6.0, p K s,(2) 9.4. Likely impurities are the oxidation products, the disulfides which could be polymeric. Dissolve in aq NaOH until the soln is alkaline. Extract with Et20 and discard the extract. Acidify with cold HCl (diluted 1 1 by vol with H2O) to Congo Red paper under N2 and extract three times with Et20. Dry the Et20 with Na2S04, filter, evaporate and distil residue under reduced press in an atmosphere of N2. The distillate solidifies on cooling. [UV J Chem Soc 3076 7 955 J Am Chem Soc 81 4939 7957 Org Synth Coll Vol V 419 1973.]... 

The book scries Electron Spectroscopy Theory, Techniques, and Applications, edited by C. R. Brundle and A D. Baker, published by Academic Press has a number of chapters in its 5 volumes which are useful for those wanting to learn about the analytical use of XPS In Volume 1, An Introduction to Electron Spectroscopy (Baker and Brundle) in Volume 2, Basic Concepts of XPS (Fadley) in Volume 3, Analytical. plications of XPS (Briggs) and in Volume 4, XPSfor the Investigation of Polymeric Materials (Dilks). 

BAIRD, M. E., Electrical Properties of Polymeric Materials, The Plastics Institute, London (1973) BLYTHE, A. R., Electrieal Properties of Polymers, Cambridge University Press, Cambridge (1979) FROMMER, J. E. and CHANCE, R. R., Chapter in Encyclopedia of Polymer Science and Teehnology, 2nd Edn, Vol. 5, p. 462, Wiley, New York (1986)... 

Jenkins, G.M. and Kawamura, K., Polymeric Carbons Carbon t ibre. Class, and Char, Cambridge University Press, Cambridge, 1976. 

Walls, J.M., Methods of Surface Analysis. Cambridge University Press, Cambridge, 1989. Wightman, J.P. In Akovali, G. (Ed.), The Intcrfacia Interactions in Polymeric Conti>os-ites. Kluwer Academic, Dordrecht, 1993, p. 125. 

Even though UF adducts are known to be present in OSB, formaldehyde emissions are not elevated over those expected of an unmodified PF. There are three reasons for this. First, the molar ratio of formaldehyde-to-urea in these situations is very low. It is at least an order of magnitude lower than practical molar ratios for curable UF resin binders. Second, UF adducts are quite stable under the alkaline conditions that prevail in PF-bonded OSB. Finally, the urea only reacts with the formaldehyde that was left behind during polymerization and would have been largely emitted in pressing and cool-down. Urea additions have been shown to reduce PF formaldehyde emissions from hot pressing [121 ]. 

Luck, R.M. and Sadhir, R.K., Shrinkage in conventional monomers during polymerization. In Sadhir, R.K. and Luck, R.M. (Eds.), Expanding Monomers, Synthesis. Characterization and Applications. CRC Press, Boca Raton, FL, 1992, p. 5. 

Dunky, M., Urea-formaldehyde glue resins. In Salamone, J.C. (Ed.), Polymeric Materials Encyclopedia, Vol. 11. CRC Press, Boca Raton, FL, 1996. 

F. Oozawa, S. Asakura. Thermodynamics in the Polymerization of Proteins. New York Academic Press, 1975. 

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