Synthesis and characterization of high‐impact polystyrene using a multifunctional cyclic peroxide as the initiator

Abstract

This work deals with the synthesis of highimpact polystyrene (HIPS) using a novel cyclic multifunctional initiator, the diethyl ketone triperoxide (DEKTP), analyzing its effect on the prepolymerization step and its influence over the HIPS final properties. DEKTP showed a low selectivity toward grafting reactions at any of the concentrations of initiator and temperatures evaluated, and when it was used under a temperature ramp (120-130 C, heating rate ¼ 2 C/min), the synthesis of HIPS was possible with an adequate development of morphology and impact strength (i.e., 67 J/m) depending on DEKTP concentration.

Experimental and theoretical study of the use of multifunctional initiators in the high impact polystyrene bulk process

“…As regards grafting efficiencies at the PI point, it can be seen that cyclic initiators provide lower values than the linear initiator, indicating a lower selectivity toward grafting reactions with this type of initiators, as previously reported [22]. As expected, increasing initiator concentration increases the grafting efficiency.…”

“…For the cyclic peroxides DEKTP and PDP, it can be seen that at the PI point is very slightly dependent on initiator concentration. This has been experimentally verified in previous works and is related to the higher stability and lower decomposition rate of the cyclic initiators. In the case of L331, molecular weights decrease with increasing initiator concentration, due to the higher decomposition rate which generates a higher number of active sites.…”

“…It was observed that said initiators allow high productivity and high molecular weights, and can also have an effect on particle morphology . The cyclic trifunctional initiator diethyl ketone triperoxide (DEKTP) has also been experimentally studied in the production of HIPS , obtaining products with adequate particle morphology and a good physical properties. It has been observed that the sequential decomposition of the initiators leads to significant increases in the rate of polymerization, high molecular weights and may introduce branching in the chains leading to improvements in the rheological and processing properties .…”

Mathematical model for the bulk polymerization of styrene chemically initiated by sequential and total decomposition of the trifunctional initiator diethyl ketone triperoxide

“…There are a limited number of works dealing with the use of multifunctional initiators (i.e. initiators containing more than two labile groups per molecule) . Cerna et al studied the particular case of the bulk polymerization of St using a cyclic trifunctional peroxide initiator, the diethyl ketone triperoxide (DEKTP).…”

“…In this reaction, all peroxide groups decompose, generating three di‐radicals without undecomposed peroxide groups. The use of this trifunctional initiator in the synthesis of HIPS was experimentally studied by Acuña et al . Sheng et al studied the use of the cyclic trifunctional intiator 3,6,9‐triethyl‐3,6,9‐trimethyl‐1,4,7‐triperoxonane in the bulk polymerization of St.…”