Gelation in addition polymerization

Abstract

Recent investigations have shown that cyclization or intramolecular crosslinking plays a major part in the polymerization of diallyl phthalate, and an extension of the network theory of gelation to allow for this led to satisfactory agreement between actual and predicted degrees of conversion at gelation for this monomer. It became important, therefore, to find whether satisfactory agreement could be obtained for other systems, and a detailed examination of the polymerization of the diallyl esters of isophthalic, terephthalic, oxalic, and sebacic acids has now been made. In all of these cases gelation occurs at a conversion higher than the predicted value, the discrepancy being considerably greater than can be accounted for by experimental error. Complicating factors in the interpretation of the experimental results are shown to be absent and it is concluded that cyclization in the poly(diallyl esters) does not affect gelation in the manner expected from theory, and that the satisfactory correlation in the case of diallyl phthalate is fortuitous. It is shown, in the case of the isomeric phthalates which are considered strictly comparable, that all three systems gel at the same degree of conversion, although the ortho ester polymer has considerably fewer pendent allyl groups available for crosslinking and is also of a lower chain length than the other two polymers. This fact seems irreconcilable with the network theory of the gel point as it exists at present. The results are discussed in relation to Walling's diffusion control theory, and although the constancy of conversion at gelation is consistent with the predictions of this theory, supporting evidence regarding molecular complexity is lacking.

Bulk polymerization of diallyl benzene‐dicarboxylates. II. Effect of temperature on the gel point

“…This relationship between the critical double-bond conversion value and the temperature in the range 353 to 568 K can be described by the following empirical equations with the parameters estimated through a least-squares algorithm: ( 2 ) ( 3 ) where a, is the critical double-bond conversion in %; T , absolute temperature; and r , correlation coefficient.…”

Copolymerization of a multiallyl monomer with styrene

“…Residual unsaturation in the copolymers was determined by the bromide-bromate method as described by SIMPSON and HOLT [20]. lH NMR spectra (80 MHz and 60 MHz) were obtained by means of Tesla BS 487 C and Tesla BB 481 spectrometers, using tetramethylsilane as a standard.…”

Nonequilibrium stochastic theory of polymerization processes

“…(1 -p)-= ~fkwk + dp Equation 18 must be solved with the initial conditions w\ - 1 and Wk = 0, k > 1, for p = 0. The relationship between the mass and the functionality distributions is obtained from eqs 10 and 5: fe-l 7-T JA-Fi (18) , _ fknA _ fkwk r =m-p) (19) where N is the total number of molecules.…”

“…From eqs 19 and 29 we obtain a system for the functionality and mass average DP Xt = and Xw = Zkkwk, respectively, which is solved for the mass average…”