Homo (Co) Polymerization of Styrene Initiated by a New Tetrafunctional Peroxide
|Keywords||Tetrafunctional peroxide Styrene Polymerization kinetics Graft Phase transition|
Tetrafunctional peroxide initiator is a new kind of a radical polymerization initiator, containing four peroxy bond in its molecule, so that the polymerization process becomes complicated. This study the tetrafunctional peroxide is of four carbonate, 4-tert-butyl ester (JWEB50) oxide. Thesis on the activity assumptions bulk polymerization of styrene (St) JWEB50 triggered discussed JWEB50 decomposition kinetics characteristics and the St polymerization process kinetics and molecular weight characteristics trigger system; Second, based on the establishment of the dynamic model and calculate Finally, the polymerization kinetics of the process; kinetics process JWEB50 prepared high impact polystyrene (HIPS), molecular weight, viscosity, phase transition characteristics of the process and graft efficiency, and application for such initiator to HIPS industrial production to provide theoretical guidance. The study JWEB50 initiator ST bulk polymerization through the oxidation of 2 - ethyl hexyl tert-butyl carbonate (TBEC) initiator as controls, a similar structure, the half-life temperature similar monofunctional found under the same temperature and the peroxide concentration, the two initiator curve completely overlap, the polymerization kinetics of the system described in the concentration of free radicals in the two systems in the polymerization process substantially consistent; DSC measured JWEB50 initiator obtained polystyrene (PS) present in the molecule is starting a peroxy bond, different conversion rates under the PS in the decomposition temperature of the peroxy bond at 165 ℃ around, and the concentration of the peroxide bond with the conversion rate decreases with an increase. Therefore, JWEB50 the decomposition kinetics characteristics with traditional monofunctional initiator agent (TBEC) Based on the above results, during the polymerization reaction of reactive groups and other active assumptions JWEB50 initiator. Studied initiator ST bulk polymerization in the polymerization rate and polymer molecular JWEB50 characterized. Compared monofunctional TBEC, at the same temperature, initiator the concentration, JWEB50 initiator to the polymerization rate of the system is much larger than TBEC, but lead to the molecular weight of the polymer obtained by the system is less than TBEC JWEB50; at the same temperature, peroxy key concentrations initiator system with the same polymerization rate, while JWEB50 initiator system obtained PS molecular weight greater than TBEC, this increase in molecular weight the effect will be more apparent as the temperature rises, the temperature on the tetrafunctional initiator the system synthetic polymer molecular weight smaller Dilatometer microscopic dynamics triggered St bulk polymerization polymerization rate impact study on the factors of JWEB50. Drawn: the temperature rises to 10 ° C, the polymerization rate increases to 2-2.5 times. Proportional to 1/2 power of the polymerization rate and the concentration of peroxy bond. Assumptions based JWEB50 active group activity, the assumption of long-chain initiation efficiency equivalent assumption, established JWEB50 triggered St bulk polymerization kinetics model. Microscopic dynamics method of measuring the rate of polymerization initiator efficiency f. Polymerization kinetics of model calculations with the experimental data very well. JWEB50 initiator Synthetic HIPS, the monofunctional peroxides TBEC as control. Rate of polymerization and molecular weight characteristics of the ST bulk polymerization initiator the polymerization rate and the molecular weight characteristics and JWEB50 completely consistent. Under the same temperature, the concentration of the peroxide bond, both the same as the rate of polymerization initiator prepared HIPS, but JWEB50 the raised high, i.e. the molecular weight of the preparation of HIPS with JWEB50 without changing the reactor residence time, a relatively high molecular weight of the HIPS resin; high temperatures effect is more obvious, JWEB50 increased initiator to obtain the molecular weight of the HIPS resin. HAAKE RS6000 rheometer under the polymerization conditions used to record changes to the viscosity of the polymerization process, the viscosity curves of the two initiator system completely overlap side also illustrates two initiator to improve the rate of polymerization of the system. Whereby will be applied to the process of industrial production HIPS JWEB50 may, without changing the polymerization apparatus, polymerization process, under the premise of the rate and capacity, etc. of the polymerization can be obtained a high molecular weight polymer. Determination of the grafting efficiency of the preparation of HIPS. At the same temperature, initiator concentration, comparison the TBEC, JWEB50 initiator system which can effectively improve the grafting efficiency. The phase transition region, when the amount of rubber initially added during the synthesis of the HIPS, the phase transition occurs in between 15-26% of the monomer conversion is determined by the the online viscosity method and the TEM method. Finally, the observation of the TEM method of particle size and morphology in the system after the phase transition with the conversion rate changes found Synthesis of HIPS JWEB50 initiator after the phase transition of the particle size and shape of the system is substantially constant, relatively stable.