Thermolysis Kinetics of 1,1-Bis(t-butyldioxy)cycloalkanes and Their Utility for Styrene Polymerization

Abstract

ABSTRACT:Thermolysis kinetics of 1,1-bis(t-butyldioxy)cycloalkanes (cycloalkane perketals) with various alkyl substituents on the cycloalkane rings were investigated in cumene. Substitution at the 2-position on the ring greatly accelerated the peroxide decomposition; the accelerating effect of substituents is in the order H <n-Pr~ Me< iso-Pr. The bulk polymerization of styrene initiated by cycloalkane perketals proceeded via the two-step 0--0 decomposition and gave higher molecular weight polymers than polymerization by monofunctional initiators. It is shown that cycloalkane perketals act as unsymmetrical difunctional initiators.KEY WORDS Styrene / Radical Polymerization / Cycloalkane Perketal / Difunctional Initiator / Kinetics / Organic peroxides are used widely as polymerization initiators in the polymer industry and numerous organic peroxides have been developed so far: 1 For polymer makers, it is important to produce polymers having the desired molecular weight at high polymerization rate to reduce production cost. Organic peroxide initiators play an important role in controlling molecular weight and polymerization rate. Although thermally active initiators which decompose at relatively low temperature can increase polymerization rate effectively, the high polymerization rate causes lowering of molecular weight of the resulting polymer. This is because polymer molecular weight is inversely proportional to polymerization rate in sonventional free radical polymerization.production of desired polymers at high polymerization rate than conventional monofunctional peroxides. 2 -8 Among difunctional peroxides, particular attention has been paid to decomposition and initiation chemistries of gem-diperoxides (perketals). 9 -16 We reported several studies on the thermal decomposition of acyclic (1) 9 and cyclic perketals (2a) 10 and initiation mechanism for the polymerization of vinyl monomers with perketals. 11 -13 Recently, it was reported that difunctional peroxides which possess two 0--0 bonds in a molecule are more effective initiators for the * To whom all correspondence should be addressed. CH 3 It-Bu00-C-00Bu-t

Simulation of Free Radical Bulk/Solution Homopolymerization Using Mono- and Bi-functional Initiators

“…A systematic and detailed investigation on its thennolysis has been conducted by several workers (Suyama et al, 1994;Sugihara et al, 1992,). Sugihara et al (1992) (Villalobos, 1994).…”

“…Organic peroxides, existing in a large number, are widely used in polymerization industries. It has been demonstrated that peroxides play a major role in controlling molecular weights, polymer properties and rate of polymerization (Suyama et al, 1994). For economical and safety reasons, the selection of the right (initiator) peroxide is of great importance.…”

Mechanism for the Peroxide-Initiated Crosslinking of Polyethylene in the Presence of 2,4-Diphenyl-4-methyl-1-pentene

“…This result is consistent with the previous result obtained in the crosslinking of PE in the presence of MSD. 9 That is, when MSD was added, torque increased more mildly at 140°C (initial stage), but increased more rapidly and reached a higher maximum value at 180°C. Polym.…”

“…This is consistent with the previous result that scorch is effectively prevented by the presence of MSD for the crosslinking of PE. 9 …”

“…9 That is, MSD prevented scorch and also increased the crosslinking efficiency. This result is quite strange since prevention of scorch generally causes a decrease of the crosslinking efficiency if the action mechanism of MSD remains unchanged during the crosslinking.…”