Search

A new phosphorus-containing flame-retardant curing agent PPDTA was synthesized from phenylphosphonic dichloride (PPD) and 3-amino-1,2,4-triazole (TA) in tetrahydrofuran solvent to improve the flame retardancy of epoxy resin. The structure of the compound was analyzed and confirmed by infrared spectroscopy. The effects of reaction time, reaction temperature and ratio of reactants on yield were studied by using three-factor three-level orthogonal experiment. The results show that the yield of PPDTA can reach 86.4%, when the reaction time is 10h, reaction temperature is 70 °Cand the molar ratio of TA to PPD is 2.2:1.

Using 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10 oxide (DOPO) and N-methylol acrylamide as the main raw materials, the curing agent DOPO-NMA was synthesized. The flame retardant curing agent DOPO-NMA and E-51 epoxy resin (EP) were then cured to obtain epoxy resin E-51 system, and its flame retardancy, thermal stability and mechanical properties were studied. The results showed that the tensile, bending and impact strength of the cured system decreased with the increase of phosphorus mass fraction in the resin system, and the flame retardancy rating, limiting oxygen index (LOI) and char yield at 700°C increased with the increase of phosphorus mass fraction in the resin system.

By blending the different ratio of the low viscosity of bisphenol A type epoxy resin with low viscosity ammonia catalytic phenolic resin, the performance of the resin systems were investigated by the gel time, viscosity, mechanical properties, heat resistance, flame retardance. In addition, DSC was used to detect the thermal property, and FT-IR monitored the reactive process of phenolic-epoxy resin. When the phenolic resin was mixed with 5% epoxy resin, the results were as follow: the gel time of 121 s at 150°C, viscosity of 7760 mPa·s at 30°C, flexural strength of 83.3 MPa, impact strength of 6.9 kJ/m2, tensile strength of 20 MPa, heat deflection temperature of 148.5°C, oxygen index of 34.5% and the apparent cure activation energy of 94.2kJ/mol. The resin systems had higher service temperature, low viscosity, excellent mechanical properties and service characteristics, and it could meet the requirements of fast pultrusion process.

Two novel low viscosity polyamide curing agents are prepared, the viscosity of the polyamide-1 synthesized from adipic acid and tetraethylene pentamine is 12240mPa·s and that of the polyamide-2 synthesized from dimenthy tetrphthalate and tetraethylene pentamine is 11800mPa·s. The effect of synthetic polyamide content on the mechanical performance and thermal performance of the epoxy curing system is studied. The results show that overall performance of the curing system first increases and then decreases with the increase of synthetic polyamide content and reaches maximum with 33 wt% of polyamide. The tensile strength, flexural strength and impact strength of polyamide-1/CYD-128 are 32.41MPa, 81.55MPa and 19.6KJ/m2, respectively. While that of polyamide-2/CYD-128 are 37.88MPa, 104.60MPa and 16.5KJ/m2, respectively. This low viscosity curing system can be used as building adhesives due to its excellent mechanical properties.

In the title compound, C(14)H(16)N(4) (2+)·2C(7)H(5)O(6)S(-)·2H(2)O, the 3,3'-(p-phenyl-enedimethyl-ene)diimidazol-1-ium dication lies on a crystallographic inversion center. In the crystal structure, dications, anions and solvent water mol-ecules are linked via O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, and C-H⋯π inter-actions, forming a three-dimensional network containing R(2) (2)(4), R(2) (4)(12), R(4) (4)(22), R(8) (10)(32) and R(12) (14)(66) ring motifs.