Preparation And Heat Performance Of Hyperbranched Epoxy Resins With N-P Skeleton By Thiol-ene Click Reaction

Controllable synthesis of hyperbranched epoxy resin is still a challenge, which hinders their exploration and application. Thiol-ene click reaction has been a principal synthetic method for the preparation of macromolecule compounds in recent years due to its advantageous features, such as mild reaction conditions, fast reaction rate, facile operation, high yield, high selectivity and reliability. In this work, we have successfully fabricated hyperbranched epoxy resin with controllable degree of branching(DB) via thiol-ene click reaction, and studied its thermal properties, curing kinetics and thermal decomposition kinetics. These important results will supply foundation for researching relationship between molecular structure and performance. The main contents of the paper are shown as follows.(1) The degree of branching controllable preparation and characterization of nitrogen-phosphor skeleton hyperbranched epoxy resin(NPHEP). The desired NPHEP materials are prepared via thiol-ene click reaction, using diphenylphosphinyl chloride(DPPC), glycidyl methacrylate(GMA), thiohydracrylic acid and trimethylolpropane tris(3-mercaptopropionate) as main materials. The chemical composition and structure of NPHEP are characterized by means of NMR and FT-IR technologies. Calculated from the results of NMR spectra, the DB of NPHEP-n(n=0, 0.33, 0.50, 0.67 ? 1)samples are 0, 0.334, 0.509, 0.667 and 1.00, respectively, which are closed with the designed values.(2) Effect of DB and content of NPHEP on performance of cured NPHEP/DGEBA composite using diethylenetriamine-acrylonitrile as curing agent was studied in detail. The results show that, the glass transition temperature(Tg) of the composite increases with the increase of DB, increased from 113.3? to 122.4?indicating a maximum Tg at the DB of 1. However, the Tg of the composite decreases gradually as the content of NPHEP-1 increases. Moreover, the initial decomposition temperature of the composite(Td, weight loss of 5%) has been reduced with the content and DB of NPHEP increases. According to the thermolysis curves of NPHEP-1/DGEBA in N2 and air atmosphere, with respect to the nitrogen atmosphere, at air atmosphere the Td of the composite increases about 18.7?, exhibiting two maximum weight loss rates at 344.0? and 538.3?, respectively. The thermolysis data indicate that the thermal decomposition rate of the composite should be lower in air, suggesting the potential flame-retardance of the composite.(3) Curing and thermal degradation kinetics of NPHEP/DGEBAE composites. With the increase of the DB of NPHEP, curing reaction living energy increases first and then decrease, reaches a maximum value at the DB of 0.667. Meanwhile, the apparent activation energy shows a reverse trend and reaches a minimum value at the DB of 0.667. With the increase NPHEP-1 content in the composites, exothermic energy increases of the composite materials, and thus the apparent activation energy of decreases. Moreover, the activation energies of thermal decomposition in both low and high temperature region have been reduced with the increase of the DB and content of NPHEP.