Effect of hexaphenoxycyclotriphosphazene combined with octapropylglycidylether polyhedral oligomeric silsesquioxane on thermal stability and flame retardancy of epoxy resin

Abstract

A novel phosphazene-based compound called hexaphenoxycyclotriphosphazene (HPCTP) was synthesized and characterized by Fourier transform infrared spectroscopy as well as proton and phosphorus nuclear magnetic resonance spectroscopies. Epoxy (EP) resin composites containing HPCTP and octapropylglycidylether polyhedral oligomeric silsesquioxane (OGPOSS) were prepared using 4,4 0 -diamino diphenylmethane as curing agent. Differential scanning calorimetry, thermogravimetric analysis, UL 94 vertical burning test, and cone calorimetry test were used to assess thermal stability and flame retardancy of the composites. Evaluation of thermal properties demonstrated that the resulting composites achieved less thermal stability compared with control EP resin but possessed high char yields at high temperatures. It indicated that both HPCTP and OGPOSS could induce the formation of intumescent char layer that retarded the degradation and combustion process of EP resin. The peak heat release rate of EP resin composite containing 15 wt% HPCTP was 61% less than that of control EP resin. Meanwhile, other flame-retardant parameters were also improved. Results of scanning electron microscopy and energy-dispersive x-ray spectroscopy of residual chars confirmed that both HPCTP and OGPOSS can enhance thermal stability and flame retardancy of EP resin.

The effect of 10-(2,5-dihydroxyphenyl)-9, 10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide on liquid oxygen compatibility and cryogenic mechanical properties of epoxy resins

“…From these phenomena, it can be concluded that the phosphorus groups also thermally decompose in company with the degradation of the ODOPB-modified EPs at relatively lower temperature, forming an insulating phosphorous-rich char layer, which covers over the surface of the specimen to prevent further oxidation and decomposition by raising the decomposition temperature and consequently results in higher char residues. [27][28][29][30] As verified in Table 2, EP/DDM and EP/DDS possess char residues of 4.6% and 1.6% at 600 C, respectively, almost decomposing completely. Nevertheless, char residues of all the modified resins show significantly higher values between 13.2% and 19.8%.…”

Improved thermal properties of epoxy resin modified with polymethyl methacrylate-microencapsulated phosphorus-nitrogen-containing flame retardant

“…Interestingly, the samples blended with the microcapsules containing 2.25, 2.5, and 2.75 g HPCTP achieved increasing T g values as HPCTP increased, especially the 1 wt% blend of P(2.75H) microcapsule with a T g value of 179.9 C. The result differs from those of HPCTP/EP sample and previous references that showed distinct decreases when phosphazene ame retardants were added to EPs. 4,6,9 By contrast, with high size uniformity among the microcapsules incorporated into the system, the particles can easily disperse evenly through the gaps of EP networks without regional agglomeration of HPCTP or PMMA. As a result, the cross-linking density of EP composites is improved.…”

“…25 However, for the other samples with P(H) microcapsules blended, this deterioration was not as distinct as those in the other studies shown. 4,26,27 Aer PMMA polymers were used to cover the HPCTP particle surfaces, the additives were improved in thermal stability through the chemical polymeric long chains, which can protect the inner P-O-C structures from decomposing at high temperature. Besides, the T 5 wt% , T 10 wt% , and T 50 wt% values in the P(H)/EP composites were observed to slightly rise with increasing HPCTP content in P(H) microcapsules.…”

“…For example, in our previous works, a cyclic phosphazene named as hexaphenoxycyclotriphosphazene (HPCTP) that contains phenoxyl groups was successfully synthesized and added to modied EPs separately 9 or along with other ame-retardant additives. 4,6 However, the T g of the EP composites deteriorated distinctly. The search for an effective mean to use additive phosphazenes in manufacturing ame-retardant EP composites with guaranteed thermal resistance is highly worth studying.…”

Preparation of halogen‐free flame‐retardant expandable polystyrene foam by suspension polymerization

“…In our research process, hexaphenoxycyclotriphosphazene (HPCTP) is proposed as a flame retardant for suspension polymerization; it is one of the early developments of cyclotriphosphazene derivatives . Cyclotriphosphazene derivative is a kind of compound containing a PN structure in the molecule obtained by nucleophilic substitution of hexachlorocyclotriphosphazene, which has good thermo‐oxidative stability and flame retardancy. It is rich in nitrogen and phosphorus and has high synergistic flame‐retardant efficiency .…”