Oxidation of polypropylene introduces hydroperoxide groups into the polymer. Infrared spectroscopy has determined that more than 90% of these groups are intramolecularly hydrogen bonded. The sequential lengths and sequence distributions of these neighboring hydroperoxides were estimated from the electronic spectra of the polyenes derived from the polypropylene hydroperoxide by two methods: (1) reduction, acetylation, and pyrolysis, and (2) reduction and dehydration. The results indicate that all the hydroperoxide groups are present in sequences of length two and greater. Intramolecular hydrogen abstraction during oxidation could account for the formation of these neighboring hydroperoxides.

The thermal decomposition of polypropylene hydroperoxide (PPH) consists of two consecutive reactions. The initial, faster reaction has rates up to 60 times that of the slower process. The former is largely suppressed by the addition of an excess of 2,6‐di‐tert‐butyl‐p‐cresol. The course of reaction is the same in either solid state or in solution. The results are consistent with an intramolecular radical‐induced mechanism for the initial reaction. This faster reaction consumes about 70–95% of the total hydroperoxides. The decomposition of PPH yields a maximum of about 1.8 radicals. Samples prepared from crystalline and amorphous polypropylenes have identical decomposition kinetics.

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For a series of menthol esters of increasing size and polarity, “mintyness” decreased rapidly as molecular weight increased. For molecular weights above about 700, the compounds were tasteless to a significant proportion of the taste panel. As polarity increased, the “sweet minty” taste of hydrophobic menthol esters became increasingly bitter, until water‐soluble menthol esters were strongly bitter. Bitterness was still apparent in quite high‐molecular‐weight water‐soluble esters; a different receptor may be involved for bitterness than for mint. An overall hypothesis relating flavor to molecular solubility parameters is proposed.