acrylate) is shown to consist of two components: a continuous Planck component (the thermal one) and a line
component in the form of three separate lines. It is suggested that the lines of the line component should be
regarded as a fragment of the spectral series that emerges due to radiative deactivation of three adjacent vibra-
tionally excited levels of the macromolecule. Two processes can contribute to the line component: chemilumi-
nescence and phase radiation. Chemiluminescence may be due to the exothermal reaction of methyl methacryl-
ate polymerization on the cooling fracture surface when its temperature falls below 197°C, which is the ceiling
temperature for poly(methyl methacrylate). Phase radiation may be due to orientational crystallization of syn-
diotactic PMMA blocks in the layer of the oriented polymer adjacent to the fracture surface. Orientational crys-
tallization must be accompanied by generation of the upper harmonics of phase radiation. Experimentally
recorded spectral lines at wavelengths of 8.28, 6.2, and 4.96
m are found to correspond to the third, fourth, and fifth harmonics, respectively. The energy of the first harmonic (4.816 kJ/mol) coincides with the average
energy (4.812 kJ/mol) of hole formation (termination) calculated by Wunderlich according to the experimental
value of the heat capacity jump
(Tg) for poly(methyl methacrylate). The temperature of the freshly formed fracture surface in the range of its lifetimes 5–100
s remains invariable and equal to 113–140°C.