The kinetics of two‐phase bulk polymerization. I. Monomer and initiator distribution

Abstract

SJnOpeifJRubber-reinforced thermoplastics are produced commercially by diseolvmg a rubber in the monomer of a glessy polymer and commencing polymerization with a free-radical initiator. Beyond a few per cent conversion, the incompatibility of the two polymers c a w a phase geparation, with each phase containing one nearly pure polymer. Subsequent polymerization o c c m in each phase. The heterogeneous nature of the reaction can influence both the kinetics of the reaction and the amount of grafting in the product. The fact that only monomer which polymerizes in the rubber phase can possibly graft establishes an upper limit to the amount of grafting and hence influences the mechanical properties of the product. It is shown theoretically how unequal partitioning of monomer and initiator between the phases can influence the extent of grafting, and can also explain the kinetic rate reductions which have been observed in such systems. The distributions of monomer and benzoyl peroxide and azobisisobutyronite initiators between the phases have been determined experimentally for 8 styrene-polystyrenepolybutadiene system. They cannot account for the rate reduction observed in such systems.

Partition of tert-dodecyl mercaptan in systems containing styrene, polystyrene, and polybutadiene. Its effect on the macromolecular characteristics of high-impact poly styrene

“…All the coefficients were close to 1. But while the initiators showed a slight preference for the PS-rich phase, the opposite was observed for St [10]. In addition, no significant variations were observed in the partition coefficients at the different analyzed temperatures, initiator concentrations, and emulated St conversions [10].…”

“…But while the initiators showed a slight preference for the PS-rich phase, the opposite was observed for St [10]. In addition, no significant variations were observed in the partition coefficients at the different analyzed temperatures, initiator concentrations, and emulated St conversions [10]. In a similar study, Bertin et al [11] determined the partition coefficients of commercial peroxides (3 percarbonates, a perester, and a perketal) in blends containing St, PS, and PB, and emulating the conditions of the HIPS process before the phase inversion.…”

“…Unauthenticated Download Date | 5/11/18 10:34 PM For the mentioned difficulties, the partitions of St and initiators have been investigated in blends that avoid the polymerization, and do not include the GC [9][10][11]. For simplicity, such distributions were described through partition coefficients ( i K ) defined as follows [9][10][11]:…”

“…For simplicity, such distributions were described through partition coefficients ( i K ) defined as follows [9][10][11]:…”

“…Ludwico and Rosen [10] measured the partitions of St, 2,2'-azobisisobutyronitrile (AIBN), and benzoyl peroxide (BPO) in blends containing 5% w/w of PB and several St/PS ratios. The experiments were carried out at 0 and 25 ºC, to avoid any thermal and/or chemical initiation.…”