Compared with the conventional monofunctional initiators

the multifunctional initiators can increase the polymerization rate and polymer molecular weight simultaneously．As a novel initiator

the decomposition rate constant

initiator effciency and chain transfer constant to the initiator are its basic parameters．However

these basic parameters have rarely been determined

and the mechanism and the kinetics have not been studied．In the present paper

a new kind radical initiator

2

5-dimethyl-2

5-di(2-ethylhexanoylperoxy)hexane (DMDEHPH)

has been utilized to initiate styrene polymerization in the temperature range of 55～80℃ and DMDEHPH concentration range of 0.01～0.10 mol／L．The effects of initiator concentration

monomer concentration and reaction temperature on the polymerization rate were investigated in details．The increase of monomer concentration

initiator concentration and reaction temperature all can increase the polymerization rate．The relationship of polymerization rate and the corresponding concentration shows that the orders of polymerization rate to active group of initiator concentration and monomer concentration are 0.5 and 1.0

respectively

which validates the correctness of kinetic model presented from the mechanism of polymerization. The activity energy obtained from the polymerization rate constants at various temperatures is 92.0 kJ／mol．The initiator efficiency is in the range of 0.55±0.03 under the experiment conditions

and the initiator efficiency decreases with the increase of initiator concentration．Considering the decomposition degree of O—O bonds during the polymerization

the chain transfer constants to DMDEHPH and monomer are 0.037 and 0.59×10-4 at 60℃

and 0.048 and 0.75×10-4 at 70℃

respectively．