含马来酰亚胺结构的DOPO基反应型阻燃剂的合成及其对环氧树脂性能的影响

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和N-对羧基苯基马来酰亚胺(pCPMI)为主要原料合成了一种新型的反应型阻燃剂DOPO-pCPMI,利用傅里叶变换红外光谱(FT-IR),核磁共振谱(¹H-NMR、³¹P-NMR)对阻燃剂分子的结构及其组成进行了分析表征。随后将DOPO-pCPMI与环氧树脂预聚,再以4,4’-二氨基二苯基砜(DDS)为固化剂制备DOPO-pCPMI/EP复合材料。通过极限氧指数(LOI)、动态热机械分析(DTMA)、热失重分析研究了复合材料的阻燃性能和热性能。结果表明：当pCPMI的质量分数为6%时,DOPO-pCPMI/EP固化体系综合性能最佳,氧指数由24%提高至33.5%;玻璃化转变温度(T_g)为210℃;弯曲强度由90 MPa提升至127 MPa;在氮气气氛下不同组分树脂的浇铸体残炭率不断提高。对燃烧后炭层的红外分析和扫描电子显微镜(SEM)分析表明形成了含马来酰亚胺的刚性炭层,且炭层外部紧凑、完整,内部致密、多孔。     

新型磷硅改性双酚A型环氧树脂的制备及其固化反应动力学研究

采用羟基封端聚二甲基硅氧烷(HTPDMS)、9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与双酚A型环氧树脂合成了新型的含磷硅双酚A型环氧树脂,通过红外谱图以及核磁共振图确认了其结构,并简单讨论其反应机理;采用DSC分析方法研究其固化动力学,得到其与4,4’-二氨基二苯甲烷(DDM)固化的平均表观活化能Ea为40.74kJ/mol,反应级数n为0.90。     

DOPO与环氧树脂反应特性的研究

通过环氧值滴定和红外光谱研究了9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与环氧树脂E-20的反应特性,用红外谱图确认了DOPO与E-20进行反应的程度以及DOPO含磷阻燃环氧树脂的初步结构。采用DTA分析方法研究DOPO与E-20的反应动力学,测得DOPO与E-20反应的动力学参数lnA0为20.88,表观活化能E为96.42kJ/mol,反应级数n为0.74。实验结果表明,在120℃下添加15%催化剂,反应90min可获得最佳阻燃效果。     

Preparation and performance of waterborne polyurethane coatings based on the synergistic flame retardant of ferrocene,phosphorus and nitrogen

A synergistic reactive flame-retardant polyol (AFeDH) containing ferrocene, phosphorus, and nitrogen elements was synthesized from ferro-formaldehyde, 5-amino-1,3, 4-thiadiazole-2-mercaptan, 9,10-dihydro-9-oxa-10-phos-phaphenanthrene-10-oxide and hydroxyl terminated polybutadiene acrylonitrile, and then applied for flame retarding waterborne polyurethane (WPU). The chemical structures of intermediates and final products were well characterized to confirm the successful preparation of ternary P-N-Fe flame retardant. The effects of incorporated AFeDH on thermal stability, flame retardancy and mechanical properties of AFeDH/WPU films were systematically studied. The results indicated that LOI value increased with the increase amount of AFeDH, while the value then decreased as the loading content above 6 wt%. This increase in flame retardancy results from the competition between the catalytic degradation of iron and the catalytic carbonization. Benefiting from the good synergistic effects among each element of AFeDH, the WPU/AFeDH films perform the decreased heat release and smoke production. Moreover, the flame retardant films also show the enhanced tensile strength of 33.8 MPa and elongation at break of 763.3%. Therefore, this novel halogen-free flame retardant shows an excellent synergistic effect among P, N, and Fe elements, which has a great potential in the application of flame retardant WPU.     

Strengthen flame retardancy of epoxy thermoset by montmorillonite particles adhering phosphorus-containing fragments

Phosphaphenanthrene derivative tri-(3-DOPO-2-hydroxypropan-1-yl)-1,3,5-triazine-2,4,6-trione (TGD) and organo-modified montmorillonite (OMMT) were jointly introduced into the diglycidyl ether of bisphenol A cured by 4,4-diamino-diphenylmethane (EP) to investigate their flame retardant behaviors. With only addition of 0.5%OMMT and 2.5%TGD, epoxy thermoset achieved a limiting oxygen index value of 33.7% and passed UL 94 V-0 rating test. Compared with the combustion behaviors of 3%OMMT/EP and 3%TGD/EP, an obvious synergistic flame retardant effect between OMMT and TGD can be concluded in OMMT/TGD/EP. Meanwhile, the FTIR spectra of gas-phase and condensed-phase products further proved this synergistic effect working in a physical way. On one hand, the co-existence of hydroxyl-containing TGD enabled montmorillonite (MMT) particles to filtrate and adhere more smoke fragments. On the other hand, the co-action of MMT help the polar phosphorus-containing fragments from TGD better strengthened char layer, enhancing the barrier and protective effect of residue. The synergistic flame retardant effect from OMMT/TGD system endowed themselves with higher flame retardant efficiency, and epoxy thermoset with better flame retardant performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47500.     

DOPO衍生物的合成及其在阻燃PBT中的应用

以9,10–二氢–9–氧杂–10–磷杂菲–10–氧化物(DOPO)、顺丁烯二酸酐(MAH)和正丁醇(BA)为原料合成了新型DOPO衍生物2–(6–氧–6H–二苯并[c,e][1,2]氧杂磷菲–6–基)–丁二酸二丁酯(DOPOMB),利用红外光谱、核磁共振氢谱对合成产物的结构进行了表征。将其用作阻燃剂与聚对苯二甲酸丁二酯(PBT)熔融共混,对共混物的阻燃性、热性能和力学性能进行了研究。结果表明,DOPOMB的加入可以有效提高PBT树脂的阻燃性能,当DOPOMB的质量分数为15%时,共混物的阻燃性即可达到UL–94 V–0级。     

Preparation of DOPO-derived magnesium phosphate whisker and its synergistic effect with ammonium polyphosphate on the flame retardancy and mechanical property of epoxy resin

In this study, a magnesium phosphate whisker (DPM-H) was synthesized by the acid–base neutralization reaction between magnesium hydroxide and 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH) at 120°C. A new synergistic intumescent flame retardant (IFR) for epoxy resin (EP), which was composed of DPM-H and ammonium polyphosphate (APP) was thoroughly studied. When the IFR loading was 8%, with the DPM-H to APP weight ratio at 1:7, the prepared flame-retardant EP (EPDA-2) passed the vertical burning tests (UL-94) V-0 rating and obtained the limiting oxygen index (LOI) value of 29.3%. Microscale combustion calorimetry (MCC) results showed that the total heat release (THR) of EPDA-2 reduced by 32.1% compared with pure EP. Meanwhile, the addition of DPM-H can partially solve the problem of the decrease of the EP mechanical property caused by the addition of APP. Compared with the flame-retardant EP with the 8% loading of APP, the impact strength of EPDA-2 increased 152.3%.     

Flame-retardant epoxy resin with good smoke-suppression endowed by chitosan–cobalt/phosphorus complex

Chitosan-based flame-retardant CS–Co–DOPA (CCD) was synthesized by the neutralization reaction of 10-hydroxy-9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPA) with chitosan-cobalt complex and fully characterized by scanning electron microscopy (SEM), energy-dispersive spectrometer, x-ray diffraction, X-ray photoelectron spectroscopy (XPS), optical emission spectrometer, and Fourier transform infrared (FTIR) characterizations. The epoxy resin (EP) modified with CCD exhibited good flame retardancy. With the addition of 5 wt% CCD, the EP/CCD achieved UL-94 V-1 rating and possessed limiting oxygen index (LOI) value of 30%. Cone calorimetry (CC) test demonstrated that EP/CCD resulted in a remarkable reduction of peak smoke production rate (pSPR) and total smoke production (TSP) by 63% and 40%, respectively, showing an outstanding smoke suppression. The char residue obtained from the CC test was further characterized using SEM, FTIR, Raman, and XPS techniques. The results revealed that CCD facilitated the formation of a dense and compact char layer on EP during combustion, thereby impeding gas and heat transfer. In addition, TG-IR was employed to investigate the gas-phase flame-retardant effect of EP/CCD composites, which revealed that CCD promotes the release of water, CO_2, and other incombustible gases, altering the decomposition path of EP.     

A novel multifunctional phosphorous and nitrogenous reactive flame retardant toward epoxy resins by one-pot method

Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DB-DAD) was prepared by a facile “one-pot” method. Due to their synergistic gas-phase and solid-phase flame-retardant effects, DB-DAD modified EP composites (EP/DB-DAD composite) easily achieved UL-94 V-0 ratings, and an EP/DB-DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB-DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB-DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB-DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB-DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high-tech industries.     

The synthesis of biphenyl ether/vanillin-based flame retardants for enhancing both the flame retardant properties and mechanical performance of epoxy resin

Imparting good flame retardancy and mechanical properties to epoxy resin (EP), while pursuing the sustainable and safe application of EP, we synthesized a novel reactive phosphorus/nitrogen flame retardant for biomass through nucleophilic addition reaction, which contains flexible ether bonds and rigid aromatic ring structure (DVD). Owing to the cooperative effect of aryl ether diamine, phosphorus phenanthrene, and biomass vanillin, the DVD exhibited excellent flame retardancy. EP/DVD-1 (0.4 wt% phosphorus content) achieved UL-94 V-0 rating, with an improvement in limiting oxygen index value from 26.5% (pure EP) to 32.5%. In the CCT, the modified DVD EP showed a 44.5% reduction in peak peak of heat release rate (PHRR) and a 38.0% reduction in total heat release compared to pure EPs. And flame retardant epoxy resin (FREP) still had good transparency after the addition of DVD, which indicated the nice compatibility between DVD andEP. What was noteworthiness was that at high levels of addition, the mechanical properties of modified EP for DVD was still improved compared to pure EP. These results demonstrate that DVD is an excellent and multifunctional bio-based flame retardant with broad application prospects in the field of EP material modification.