Reaction Kinetics of Photoinduced Bulk Polymerization of 4-Acrylamido-2,2,6,6-Tetramethyl-Piperidine in Melting State

doi:10.7517/j.issn.1674-0475.2004.04.277

Abstract

Abstract: 4-acrylamido-2,2,6,6-tetramethyl-piperidine(AATP),a water soluble r-HALS,is synthesized and the structure and composition of AATP is characterized by FT-IR,¹H-NMR and elemental analysis.The reaction kinetics of photoinduced bulk polymerization of AATP in melting state is studied by using photo-DSC (DPC) technique.The results show that the conversion and the rate of AATP photopolymerization are obviously affected by the reaction condition such as temperature,incident light intensity and concentration of photoinitiator etc.Darocur 1173 is the available initiator and the optimum mass fraction of Darocur 1173 is 0.5—1.0 %.The rate of AATP photopolymerization is proportional to the square root of photoinitiator concentration c_PI^0.5 and incident light intensity I₀^0.5 respectively under given condition.The kinetic parameters of photoinduced bulk polymerization for AATP were measured at the steady and non-steady state.The rate constants for termination k_t is much larger than that for propagation k_p(k_p/k_t=3.43—33.57).k_t and k_t is increased with the conversion increasing in the reaction system.k_p and k_t is 2.22—7.96×10² and 0.08—2.67×10⁴(L/mol·s) corresponding to a conversion from 4.00% to 15.68%,respectively.These values are within the range of corresponding parameters typical for a free radical polymerization.The induction period of the reaction system is decreased with the increment of photoinitiator concentration and incident light intensity respectively.Because of apparent activation energy of the reaction system is negative[E_p-E_t/2 is from -7.70 to -13.36 kJ/mol] and A_p/A_t^0.5 is from 0.076 to 0.333(L/mol·s)^0.5,the rate of AATP photopolymerization is decreased with increment of the temperature from 110 ℃ to 150 ℃ and the irradiating time of that is prolonged.

Key words: 4-acrylamido-2,2,6,6-tetramethyl-piperidine, photopolymerization, photo-DSC (DPC) technique, reaction kinetics

CLC Number:

LIU Xiao-xuan, DENG Xiang-hua, GUO Xu, REN Ya’e, WU Guang-guo. Reaction Kinetics of Photoinduced Bulk Polymerization of 4-Acrylamido-2,2,6,6-Tetramethyl-Piperidine in Melting State[J]. Imaging Science and Photochemistry, 2004, 22(4): 277-286.

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