The kinetics of photosensitized polymerization of methyl methacrylate with benzoin was investigated. The rate of polymerization was proportional to the square root of the concentration of benzoin and the first power of the monomer. The equation Rp=K1 ([M]‐α1) ([B]0.5+α2) was proposed, and K1 α1 and α2 were evaluated as 0.999×10−4, 0.181 and 1.11×10−2, respectively. The rate of polymerization was also proportional to the square root of light intensity in accordance with the equation Rp=5.65×10−12 I0.5. Carbon tetrachloride and chloroform markedly decreased the average degree of polymerization. The chain transfer coefficients were evaluated as 2.44 × 10−3 and 1.90 × 10−3 for carbon tetrachloride and chloroform respectively.

The polymerization of methyl methacrylate with Ni (II) benzoyl trifluoroacetonate was investigated. The rate of polymerization was proportional to the square root of the initiator concentration and 1.5 power of the monomer concentration. The activation energy for the overall polymerization was 13.4 Kcal/mole, which yields 17.6 Kcal/mole for the activation energy and 9.58 × 105 sec−1 for the collision frequency factor for the initiation.

Aniline markedly accelerated polymerization .of methyl methacrylate initiated by metal chelates of ,6-diketones. The kinetic studies of the polymerizaion of methyl methacrylate initiated by Ni (II) acetyl acetonate in the presence of aniline yielded Rp=[IJM~(A)o.611 (MJ1.3 7• The polymerization was of free radical in character. The accelerating effect of aniline was attributed to its reduction activation of the chelate, The activation energy for the overall polymerization was 21.3Kcal/moZe, which yielded 33.4Kcal/mole for the activation energy for the initiation.

The kintetic studies of polymerization of methyl methacrylate initiated with nickel ethyl acetoacetate gave the following . Some aromatic amines such as aniline markedly accelerated the polymerization, while pyridine had no such effe:::t. The activation energy of initiation was 24.8 kcalfmot in the absence of aniline, and 8.8 kcal/mol in the presence of aniline. Both the kinetic data and the infrared spectra of the polymer indicated that the polymerization was radical in nature. The reaction order against monomer varied, as the temperature differed. The spectrophotometric investigation indicated formation of a complex between the chelate and the monomer, or amines. It also showed that the formation of a complex was not a factor which controlled the rate of initiation. A scheme of initiation mechanism was .presented on the basis of the above experimental evidence. InboducHonPolymerization of vinyl compounds initiated by metal chelates of l3-diketones has been studied by a few wcrker.P"? TJ1e function of the chelates has been considered a ttribu ta ble to the formation 145