A review is given of the synthesis, physical properties, and decomposition kinetics of organic peroxycarbamates. The activity of these compounds in initiating free‐radical vinyl polymerization is discussed. The decomposition of hexamethylene N,N′‐bis‐(α‐cumyl peroxycarbamate) has been measured in different solvents between 65 and 95°C and found to be a first‐order reaction governed by the specific rate constant kd = 2.21 × 1016 exp {−34 100/RT}. The initiator exhibits normal free‐radical polymerization kinetics and in polymerization of styrene at 80°C shows an initiating efficiency of 0.53. Cobalt naphthenate can act as both accelerator and retarder of styrene polymerization, depending upon its concentration and the temperature of the polymerization.
SynopsisBlock copolymers having the basic structure of PMMA-PE-PMMA were prepared by the reaction of diisocyanate-terminated polyesters with hydroxyl-terminated poly(methy1 methacrylate). The molecular weights of these copolymers varied from 7,500 to 47,000. The formation of block copolymers by this method was confirmed by infrared and molecular weight analyses as well as by the physical behavior of these materials. Block copolymers of molecular weight lea than 21,000 were extremely brittle in nature. The stronger copolymers of molecular weight greater than 29,000 were examined as to their dynamic modulus and stress-strain behavior. This included the effect of added homopolymer on the strea-strain behavior of such materials. To better understand their physical properties, the micelle theory of Inoue et al. was applied to these copolymers to help elucidate their morphologies.
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