It has been suggested that the radiation-induced solid-state polymerization of acrylamide is a heterogeneous reaction, that is, it goes by a two-phase mechanism [G. Adler, J. Chem. Phys. 31, 848 (1959) and B. Baysal, G. Adler, D. Ballantine, and P. Colombo, J. Polymer Sci. (to be published)]. According to this concept, the reaction procedes at definite sites within the crystal. After the first few reaction steps, it forms regions of pure or nearly pure polymer imbedded in pure monomer. Further reaction would take place at the interface between the two. The polymer and monomer regions would remain segregated until the crystal is completely polymerized. It has been shown previously that the reaction can take place without the crystal breaking up. The alternative to this scheme seems to be that the reaction takes place within the crystal lattice and is directed by it. This requires a more homogeneous reaction mechanism. It seems feasible, in principle to distinguish between the two mechanisms by x-ray diffraction. A single crystal technique that allows us to look at all the reflections simultaneously appeared to be most promising. It was therefore decided to run a series of rotation diagrams on a crystal in various stages of polymerization.
It has previously been shown that the polymer formed in solid state polymerization of acrylamide is amorphous in spite of the fact that the reaction takes place within a crystalline solid. The stage at which it becomes amorphous is not known
SynopsisThermogravimetric (TGA) and infrared (IR) analyses were used to determine the thermal stability of a polymer system consisting of styrene-acrylonitrile-acrylamide-trimethylolpropane trimethacrylate. This study indicates that increases in curing temperature and the use of two initiators with different activities decreases the percentages of unreacted monomers. This increases the thermal stability of the polymer. To prove this, dynamic and isothermal TGA were used. The change in typical functional groups found by IR spectra also confirms this observation.
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