Synthesis of new flame‐retarding epoxy resin based on 3′, 5′, 3″, 5″‐tetrabromophenolphthalein

Abstract

SynopsisNew flame-retarding epoxy is synthesized by reacting 3',5',3",5"-tetrabromophenolphthalein (TBPP) with epichlorohydrin and characterized in comparison with commercially available tetrabromobisphenol-A(TBBA) epoxy on their flame retardancy and thermostability. TBPP epoxy show better results in promoting flame resistance than TBBA epoxy. However, TBPP epoxy exhibits a greater effect on thermal decomposition temperature. The order of char yield at 800°C under nitrogen for the cured products is TBPP epoxy > phenolphthalein (PP) epoxy > TBBA epoxy. Meanwhile, there is a linear relationship between oxygen index and char yield for cured products of TBPP-PP epoxy and TBBA-BA epoxy systems. INTRODUCTIONEpoxy resins have been used in many applications such as surface coating, electronic insulation, composites, adhesive, and etc.'t2 Because of the recent requirement for flame-retarding materials, the study of flame-retardant epoxys has become of great importance now. Thermostability of epoxys can be achieved by introducing a high aromaticity structure to the chain backbone of the epoxy.3 Kovosshak et aL4 have discussed the effect of different structures on thermal stability. Fire-retardant epoxys can be obtained by incorporation of phosphorous ~o m p o u n d s~-~ or halide compoundss-l0 into the backbone structure of epoxys, or into the structure of the curing agent. Epoxys based on phenolphthalein or 4,5,6,7-tetrabromophenolphthalei11~~~ l2 have been synthesized, and higher flame retardancy is found in these phthalide-containing resins. Van Krevelen13 concludes that excellent flame resistance always existed with higher char yield which depends on the structure and substituents on the chain backbone of molecules.13* l4 There is linear relationship3. l5 between char yield and oxygen index (01) for epoxys based on high aromaticity.In this study, new flame-retarding epoxy based on 3',5',3",5"-tetrabromophenolphthalein is synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectra, and differential scanning calorimetry (DSC) is used to observe its curing behaviors. The relationship between 01 and char yield for this epoxy is also studied by thermal gravimetric analysis (TGA) and 01 analysis, and the effect of bromine content on polymer decomposition temperature was studied. EXPERIMENTAL MaterialsPhenolphthalein (PP) and bromine were obtained from WAKO Chemical Co., and epichlorohydrin was from Hayashi Co. TBBA epoxy was supplied by Kokudo Co. and commercially used BA epoxy was adopted.Polyoxypropylenediamine, amine equivalent = 217, was used as curing agent and was supplied by Pasico Chemical Co. without further purification. InstrumentationJasco IRA-2 spectrometer was used to detect IR spectra, and NMR spectra were recorded by JEOL, JEN FX-9OQ H'NMR spectrometer. Thermogravametric analysis (TGA) and differential scanning calorimetric analysis (DSC) were carried out by Du Pont 1090 thermal analyzer. Oxygen index (01) was measured by Suga ON-1 meter. Synthetic MethodSynthesis of 3',5',3',...

Comparative Study of Different Methods of Synthesis and Their Effect on the Thermomechanical Properties of a Halogenated Epoxy-Based Flame-Retardant Resin

“…The resin synthesized by the conventional method consists of macromolecules with linear structures, and their packing density can be higher. However, the viscosity value of the resin synthesized by the nonconventional method is lower, indicating the less ordered structure of the resin …”

“…However, the viscosity value of the resin synthesized by the nonconventional method is lower, indicating the less ordered structure of the resin. 53 …”

“…However, the viscosity value of the resin synthesized by the nonconventional method is lower, indicating the less ordered structure of the resin. 53 Furthermore, the resin synthesized by the conventional method exhibits a non-Newtonian behavior and the resins synthesized by the nonconventional methods exhibit a Newtonian behavior. The change in the behavior of the resins may be due to their different molecular weights.…”

“…Its environment-friendly properties make TBBPA a suitable material because it has been extensively reported that TBBPA has almost no effect on flora or fauna. 51,52 The synthesis of TBBPA is reported in the literature by a conventional method using nitrogen, 53 but the process is complicated and time-consuming. With the advent of technology, novel and efficient methods such as sonication and microwave irradiation have gained popularity due to the advantages of being environment-friendly, less time-consuming, and cost-effective.…”