No abstract

Volatile decomposition products of ultraviolet‐irradiated polyethylene, nylon, Mylar, and Acrilan have been analyzed. The principal decomposition products of polyethylene are hydrogen and methane. Besides hydrogen and methane, carbon monoxide occurs in considerable amounts in the decomposition products of the other polymers. There is a considerable difference in the relative abundances of methane and hydrogen in the decomposition products, depending on whether irradiation was performed in a vacuum or in nitrogen. Decomposition products of ultraviolet‐irradiated nylon include all of the primary amines from methyl through hexyl. Mechanisms consistent with the observed results of photolysis are proposed.

The microwave spectrum of pyridine has been studied in the region from 20 000 to 40 000 Mc. Twelve low-J R-branch lines have been identified. Analysis of the spectrum requires that the dipole moment lie in the a axis, and leads to the following values of rotational constants: a=6039.436 Mc, b=5804.997 Mc, c=2959.210 Mc, and κ=+0.847781. The dipole moment of pyridine vapor was found to be 2.15±0.05 D from quantitative Stark effect studies.

Ultraviolet irradiation of polyethylen, nylon, Mylar, and Acrilan produces higher scission‐to‐crosslinking ratios when irradiation is performed in a nitrogen atmosphere than it does when irradiation is in a vacuum. Irradiation of polyethylene in nitrogen causes a sharp decrease in molecular weight while irradiation of Acrilan in vacuum causes an equally notable increase in molecular weight.

The rotational spectrum of the slightly asymmetric top, vinyl cyanide, has been investigated in a microwave spectrograph employing Stark effect modulation and in a direct absorption cell. The rotational constants a=49 076.2 Mc/sec, b=4971.33, and c=4514.05 were computed from the observed frequencies of the J = 2-->3 transitions. From measurements of the Stark effect, the components of the dipole moment were found to be I'a=3.68D, I'b= 1.25, 1'=3.89. Partial resolution of the hyperfine structure of certain lines gave the value -3.0 Mc/sec for the X.a component of quadrupole coupling.