It is well known that the free radical bulk polymerization of lower n-alkyl methacrylates is characterized by autoacceleration after definite conversions of the monomers. The conversion vs.time curves of polymerization have a typical 'S' shape. There are several characteristic points in these curves: the onset
of autoacceleration (point M), the maximum in the polymerization rate (point S) and the end of the polymerization (point K).
We have observed points P and R (maximum and minimum of autoacceleration) as inflection points in the derived polymerization
rate vs. time curve.
In this work, the free radical bulk polymerizations of methyl, ethyl and butyl methacrylates were investigated by differential
scanning calorimetry. The effects of the polymerization temperature and the alkyl group length in the esters on the monomer
conversions at the points M, P, S, R and K were studied. By regression analysis of the experimental results, relations were
developed with which it is possible to predict the positions of the characteristic points, depending on the polymerization
temperature and the alkyl group length.