Effect of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide on liquid oxygen compatibility of bisphenol a epoxy resin

Abstract

In this study, bisphenol A epoxy resin (DGEBA) was chemically modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and the molecular structure of the modified epoxy resin was characterized by Fourier transform infrared spectra. The effects of DOPO on liquid oxygen compatibility of DGEBA were calculated using mechanical impact method. The results indicated that epoxy resin (EP-P1)/4,4-diaminobisphenol sulfone (DDS) was compatible with liquid oxygen. When compared with EP/DDS, differential scanning calorimetry and thermogravimetry analyses showed that EP-P1/DDS and EP-P2/DDS had much higher glass transition temperatures and char yield. X-ray photoelectron spectroscopic analysis suggested that phosphorus atoms on the surface of EP-P1/DDS and EP-P2/DDS could act in the solid phase to restrain the incompatible reaction, which was in accordance with the flame-retardant mechanism of phosphorus-containing compounds. The compatibility mechanism of EP-P1/DDS was further proposed.

Paving the way for a wider use of composites in railway industry

“…On the other hand, DOPO prereacted epoxy FR presented in addition to the characteristic vibrations of epoxy, P=O (1237 cm -1 ) and P-O-Ar (751 cm -1 ) stretching vibrations. Additionally, the presence of a small peak attributed to P-H stretching (2362 cm -1 ) and P-H bending (907 cm -1 ) suggested the presence of adducts of unreacted DOPO [27]. Finally, in PMP spectrum the characteristic P=O stretching band (1239 cm -1 ), O-Ar stretching in P-O-Ar (1118 cm -1 ), P-O stretching in P-O-Ar (972 cm -1 ), P-CH 3 rock (895 cm -1 ) and P-C stretching (690 cm -1 ) vibrations [21] were observed.…”

“…On the other hand, the incorporation of DOPO pre-reacted epoxy reflected a decrease in DH c and T g comparing EP_34DP and EP_64DP to EP_REF, which is usual when introducing DOPO in epoxy formulations [30,31]. This effect was attributed to the higher epoxy equivalent mass of the pre-reacted epoxy (370 g Eq -1 in Polyphlox Ò 3742 compared to 202.02 g Eq -1 of Araldite Ò LY 5150) which resulted in lower crosslinking [27,32], being more pronounced with increasing DOPO content [22]. Additionally, the steric hindrance affected the temperature of maximum curing rate, T peak , which was shifted toward slightly higher values (10°C higher comparing EP_REF with EP_34DP and EP_64DP) in the presence of DOPO.…”

“…In regard to the effect of introducing DOPO in the epoxy formulation (EP_34DP and EP_64DP), a decrease in the T onset by 15 and 11°C was registered, suggesting that the presence of phosphorus could have catalyzed the thermal degradation of the epoxy network, without altering its degradation mechanism [38,39]. Notwithstanding, this decrease was also attributed to the lower crosslink density of the material [27]. On the other hand, the T d1 was delayed 12°C with respect to EP_REF probably due to the volatilization of the phosphorus-derived compounds.…”

Study of the epoxy/amine equivalent ratio on thermal properties, cryogenic mechanical properties, and liquid oxygen compatibility of the bisphenol A epoxy resin containing phosphorus

“…First, a DOPO-containing bisphenol A epoxy resin (Figure 1) was prepared by the reaction between P–H bond of DOPO and epoxide group of epoxy resins. 19 E51 (135.0 g, 0.69 mol) and DOPO (15.0 g, 0.069 mol) were added to a 250-ml three-necked flask, stirred, and slowly heated to 160°C, which was equipped with a condenser. The reaction was kept for 6 h and then was cooled to 90°C.…”

Liquid crystalline hyperbranched polyesters with phosphorus functional groups

“…For instance, the incorporation of DOPO groups into the structure of bi-functional monomers results in polymers with good solubility, improved thermal stability, flame retardant properties, good adhesion and decreased birefringence. [35][36][37][38][39][40][41][42][43][44][45][46][47] To date, several papers described the preparation of phosphorus-containing hyperbranched polymers appealing for flame retardancy applications. [48][49][50][51][52] As a rule, a high content of phosphorus in a polymer brings better fire performances, thus, current work aimed to prepare hyperbranched polyesters derived from A 2 and B 3 monomers, as a facile route to novel phosphorus-containing hyperbranched polyesters.…”