Polymer reactions. IV. Thermal decomposition of polypropylene hydroperoxides

Abstract

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.

Surface studies of ultra-high molecular weight polyethylene irradiated with high-energy pulsed electron beams in air

“…It has been well documented that decomposition of hydroperoxides in polyethylene leads predominantly to oxidation, which is manifested in formation of carbonyl-containing structures within the polymer, such as ketone and carboxylic acid functionalities. 16,17 However, the results described above show clearly that the decomposition of hydroperoxides formed in the dose range of 2.5-20 Mrad (Fig. 2) did not result in formation of carbonyl groups (Fig.…”

Review on the thermo-oxidative degradation of polymers during processing and in service

“…The hydroperoxides formed in the propagation reaction decompose to form radicals, leading to an increase in the oxidation rate. The decomposition of hydroperoxides can be described by several mechanisms [35][36][37]. The unimolecular decomposition has a 5 rather high activation energy, which makes this reaction less likely at low temperatures.…”

“…In literature there is general agreement that peroxides in PP consist of a rapidly decomposing fraction and a slowly decomposing fraction, but there is no agreement on the origin of these fractions [35,36,37,109]. According to Zahradnickova et al, di-methyl-sulphide (DMS) reacts much faster with peracids than with other types of peroxides [109].…”

Pyrolysis and Oxidative Pyrolysis of Polypropylene

“…Oxidative Pyrolysis. Autoxidation of polypropylene below its melt ing point has been investigated quite thoroughly with our own laboratory among the most active ones (21,22,23,24). This is not the proper place to discuss that topic; a chapter written by one of us dealing with the subject can be found in this volume.…”