有机硅改性松香基环氧树脂的制备及阻燃性能

制备了聚甲基苯基硅氧烷（PMPS）改性松香基乙二醇二缩水甘油醚AR-EGDE。红外光谱(IR)、核磁共振（¹³C NMR）和环氧值测试结果表明有机硅成功接枝至环氧树脂。同时,将PMPS与AR-EGDE充分混合得到物理改性树脂。通过力学性能和极限氧指数测试探讨了改性方法对改性树脂力学及阻燃性能的影响：化学改性优于物理改性及未改性的AR-EGDE。热失重、炭层分析表明,PMPS改性的树脂在受热和燃烧过程中,都能形成含硅炭层,该炭层可延缓内部材料热分解,同时阻止可燃裂解气体的释放和熔滴发生,从而提高材料的耐热和阻燃性能。物理改性松香基环氧,燃烧时无法形成有效富硅炭层覆盖于底部材料,从而使其阻燃性劣于化学改性。     

聚苯基甲氧基硅氧烷改性环氧树脂的阻燃性能研究

采用氧指数(LOI),UL-94,热失重(TGA)等手段考察了聚苯基甲氧基硅氧烷(PPMS)改性对环氧树脂(E-20)固化体系阻燃性能的影响.相比未改性环氧体系,当m(E-20)∶m(PPMS)=73∶时,改性环氧体系的LOI由纯E-20环氧树脂的17.5%上升到21.5%;水平火蔓延速率由36.23 mm/min降低到26.60 mm/min;质量损失为5%时的热分解温度由134.7℃上升到163.0℃,750℃时残炭量由0.21%增加到25.79%.此外,还通过红外光谱对燃烧后的残炭结构进行了分析,探讨了相关阻燃机理.     

Preparation of alginate flame retardant containing P and Si and its flame retardancy in epoxy resin

In the present paper, a novel biomass flame retardant based on alginic acid was synthesized through chemical combination with a reactive P–Si compound. Compared with alginates, the modified alginate showed obviously increased thermal stability and water resisting property, as well as better compatibility with epoxy resin, which can satisfy the requirements of a flame‐retardant additive in the polymer. The flame‐retardant properties were evaluated by vertical burning tests, limiting oxygen index, and microscale combustion calorimetry. Due to the self‐charring capacity of alginate combined with the charring catalyst from P and the charring reinforcer from Si, the modified alginate exhibited much better flame retardancy, taking advantage of the formation of a more continuous, denser, and strengthened char layer than either individual alginate or P–Si flame retardant. The corresponding flame‐retardant mechanisms were investigated and discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45552.     

Thermal degradation behaviors and flame retardancy of epoxy resins with novel silicon‐containing flame retardant

A novel macromolecular silicon‐containing intumescent flame retardants (Si‐IFR) was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus‐silicon characterized by IR. Epoxy resins (EP) were modified with Si‐IFR to get the flame retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI). Twenty percentage of weight of Si‐IFR was doped into EP to get 27.5% of LOI and UL 94 V‐0. The degradation behavior of the flame retardant EP was studied by thermogravimetry, differential thermogravimetry, scanning electron microscopy, and X‐ray photoelectron spectroscopy analysis. The experimental results exhibited that when EP/Si‐IFR was heated, the phosphorus‐containing groups firstly decompose to hydrate the char source‐containing groups to form a continuous and protective carbonaceous char, which changed into heat‐resistant swollen char by gaseous products from the nitrogen‐containing groups. Meanwhile, SiO₂ reacts with phosphate to yield silicophosphate, which stabilizes the swollen char. The barrier properties and thermal stability of the swollen char are most effective in resisting the transport of heat and mass to improve the flame retardancy and thermal stability of EP. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of novel biomass humate flame retardants and their flame retardancy in epoxy resin

Humic acid (HA), a biomass material with plentiful oxygen-containing functional groups, showed huge potential to be considered as a promising charring agent in flame retardancy. In this study, this HA was modified with four different metal ions like Fe²⁺, Mn²⁺, Al³⁺, and Cu²⁺ and finally, introduced into the epoxy resin (EP) to enhance the flame retardancy of the EP and the dispersion of these flame retardants into the EP matrix. When 10 wt% of HA-Fe and HA-Mn were incorporated into EP matrix, the limiting oxygen index (LOI) was increased from 21.2% for EP to 26.6 and 25.3% for the EP composites and the peak heat release rate (pHRR) was reduced by 36 and 35.5%, respectively. Such a significant improvement in flame retardancy was attributed to the catalytic charring of HA in the presence of metal ions, which ultimately increased the residual char formation and produced compact char layers during the combustion process to retard the transfer of heat and combustible gases between the EP composites and the flame zone. Finally, this kind of application provided a feasible way for the development of an environmentally friendly flame retardant with high efficiency, which improved the fire safety of EP matrix.     

新型含磷阻燃剂的制备及性能

以双三羟甲基丙烷为原料合成一种新型含磷阻燃剂,该阻燃剂分子量较大,具有稳定的环状结构,热稳定性高于常用阻燃剂,阻燃效果好。探讨了原料配比、反应温度、反应时间对产率的影响,考察了目标产物的热稳定性能及其对不同织物的阻燃效果,用傅里叶变换红外光谱仪表征了中间体及目标产物的结构。结果表明,当原料配比为1∶3时,磷化温度为50℃,磷化时间5h,胺化温度为75℃时,反应效果较好,收率可达90%以上。目标产物对于锦纶的阻燃效果比较明显,对涤纶、棉有一定的阻燃效果,对于混纺、腈纶阻燃效果不明显。     

Synergistic effects of phenethyl-bridged DOPO derivative with Al(OH)3 on flame retardancy for epoxy resins

ABSTRACT

Phenethyl-bridged DOPO derivative (DiDOPO) was combined with organo-modified aluminum hydroxide (OATH) in an epoxy resin (EP) to improve its flame retardancy. The results indicated that the introduction of only 10 wt% DiDOPO/60 wt% OATH in EP increased the limited oxygen index from 21.8% to 39.2%, thus the material met the UL 94 V-0 rating. Thermogravimetric analysis revealed that char yield increased in the presence of OATH to form thermally stable carbonaceous char. The evaluation of flame-retardant effect by cone calorimetry demonstrated that OATH improved the protective-barrier effect of the fire residue of EP/DiDOPO/OATH.     

Synthesis of bio-based reactive N/P flame retardant and its curing and flame retarding behavior in epoxy resins

In this study, a pioneering bio-based nitrogen–phosphorus flame retardant and curing accelerator named oxime-phosphazene hexakis [(4-(hydroxyimino) 2-methoxy) phenoxy] cyclotriphosphazene (HAPV) was successfully synthesized using hexachlorocyclotriphosphazene and vanillin. When 5 wt % HAPV was added into epoxy, the limiting oxygen index increased from 22% to 27% and passed UL-94 V-0 (UL is defined as Underwriters Laboratories) rating. Meanwhile, with the addition 5 wt% HAPV, the apparent activation energy (E_a) of HAPV/EP decreased from 20.22 to 67.15 kJ/mol, and the pHRR value was suppressed from 581.21 to 330.18 kW/m². It was due to that the HAPV quenched the combustion chain reaction through the gas phase and condensed phase, forming a dense char layer for blocking the heat transfer. Overall, the study provides an environmentally friendly epoxy flame retardant curing accelerator that shows great potential in epoxy flame retardant applications.     

Synthesis of a novel azaphosphorine flame retardant and its application in epoxy resins

A novel P? C? N bond containing azaphosphorine, 5‐(4‐hydroxy)anilinomethyl‐1,3‐di(4‐hydroxy)phenyl‐1,3,5‐diazaphosphorinane (ADDPP‐OH), which could be used as both a cocuring agent and a flame‐retarding agent for epoxy resins (EPs), was synthesized from tetrakis(hydroxymethyl)phosphonium sulfate and characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, ³¹P‐NMR, and so on. Compared with the pure EP, the ADDPP‐OH–EP composites showed increased decomposition temperatures and char yields. When the content of ADDPP‐OH was 10 wt %, the cured EP composite possessed a limiting oxygen index value of 33.7% and passed the V‐0 rating of the UL‐94 test. The mechanical properties of the ADDPP‐OH–EP composites was improved because of the increased crosslinking density. In addition, the morphology of the residual char indicated an intumescent and multiporous structure in the inner space and a compact and continual appearance in the outer layer; this was important in preventing the materials from burning further. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45721.     

Synthesis of a novel phosphonate flame retardant and its application in epoxy resins

A novel phosphonate flame retardant additive bis(2,6‐dimethyphenyl) phenylphosphonate (BDMPP) was synthesized from phenylphosphonic dichloride and 2,6‐dimethyl phenol, and its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H and ³¹P nuclear magnetic resonance. The prepared BDMPP and curing agent m‐phenylenediamine were blended into epoxy resins (EP) to prepare flame retardant EP thermosets. The effect of BDMPP on fire retardancy and thermal degradation behavior of EP/BDMPP thermosets was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter and thermalgravimetric analysis (TGA). The morphologies of char residues of the EP thermosets were investigated by scanning electron microscopy (SEM) and the water resistant properties of thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the cured EP/14 wt % BDMPP composites with the phosphorus content of 1.11 wt % successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.8%. The TGA results indicated that the introduction of BDMPP promoted EP matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield at high temperature. The incorporation of BDMPP enhanced the mechanical properties and reduced the moisture absorption of EP thermosets. The morphological structures of char residue revealed that BDMPP benefited to the formation of a more compact and homogeneous char layer on the materials surface during burning, which prevented the heat transmission and diffusion, limit the production of combustible gases and then lead to the reduction of the heat release rate. After water resistance tests, EP/BDMPP thermosets still remained excellent flame retardancy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42765.     

A facile approach to prepare cage-ladder-structure phosphorus-containing amino-functionalized POSS for enhancing flame retardancy of epoxy resins

The cage-ladder-structure phosphorus-containing amino-functionalized polyhedral oligomeric silsesquinoxanes (CLNH₂-POSS) have been synthesized through a facile catalyst-free hydrolytic condensation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-vinyltrimethoxysilane (DOPO-VTMS) with 3-aminopropyl trimethoxysilane (KH540). The successful preparation of CLNH₂-POSS has been proven by the characterization of Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (¹H-NMR, ²⁹Si-NMR), matrix-assisted laser desorption ionization time of flight (MALDI-TOF), and X-ray diffraction (XRD). Then flame retardant (FR) epoxy resins (EPs) were prepared by the addition of different content of CLNH₂-POSS into EPs with thermal curing technology. The CLNH₂-POSS showed good solubility in EP matrix. The well-dispersed CLNH₂-POSS contributed to thermal, mechanical, and FR properties of EP. Dynamic scanning calorimetry nonisothermal curing scans showed that CLNH₂-POSS had accelerating effect on the curing of EP. With the addition of only 3 wt% CLNH₂-POSS (0.30% phosphorus loading), the limiting oxygen index value of the EP composite increased from 25.5 of pure EP to 31.8, and vertical burning (UL-94) V-0 ratings was achieved. In addition, the EP composites showed improved thermal and mechanical properties. The investigations on char residue and pyrolysis volatiles of cured EP further revealed that CLNH₂-POSS exerted FR effects in condensed and gas phase simultaneously.     

Preparation and properties of halogen-free flame retardant epoxy resins with phosphorus-containing siloxanes

Novel epoxy resin modifiers, DOPO–TMDS and DOPO–DMDP were synthesized by addition reaction of divinylsiloxane with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Halogen-free flame retardant epoxy resins were obtained through modification of o-cresol novolac epoxy resin cured by phenol novolac resin using DOPO–TMDS and DOPO–DMDP which were characterized by ¹H NMR, ¹³C NMR, ³¹P NMR and FT-IR measurements. Effects of the phosphorus-containing siloxanes on thermal stabilities, mechanical properties and flame retardant properties of the epoxy resins were investigated. The cured epoxy resins exhibited better mechanical properties and greatly improved flame retardant properties due to the presence of phosphorus-containing siloxanes. The cured epoxy resins with phosphorus loading of 2.0 wt% showed LOI values of 32–33 and achieved UL94V-0 ratings.     

Synthesis and characterization of a functional polyhedral oligomeric silsesquioxane and its flame retardancy in epoxy resin

A functional polyhedral oligomeric silsesquioxane (NPOSS) with two epoxy ring groups was synthesized via the reaction between trisilanolisobutyl-POSS and triglycidyl isocyanurate, and then a halogen-free epoxy composite containing silicon/nitrogen was prepared. The results of microscale combustion calorimeter indicate that the presence of NPOSS (10% weight ratio) in epoxy resin (EP) can decrease its peak heat release rate by about 30%. The thermal oxidation and degradation behaviors of EP and EP/NPOSS composites were characterized by DSC, TG, FTIR-TG and dynamic FTIR. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the char residues of composites. The thermal degradation and flame retardant mechanism has been evaluated. NPOSS can retard the movement and scission of polymeric chains of EP and form a stable charred layer in the condensed phase to prevent the underlying materials from further combustion.     

Preparation and properties of polyhedral oligomeric silsesquioxane/epoxy hybrid resins

Octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) was synthesized using three‐step method and used to modify o‐cresol‐novolac epoxy resin (ECN) for printed circuit board. The influence of OAPS on the reactivity and the final properties of the hybrid networks were evaluated. The intercrosslinking reaction between ECN and OAPS was confirmed by Fourier transform infrared spectra. The ECN/OAPS hybrids have better impact strength, higher electrical resistivity and thermal stability, lower water absorption than the unmodified ECN. The volume resistivity and surface resistivity of the hybrids increase by an order of magnitude or more compared to the neat epoxy. The thermal stability of the hybrids improves by the incorporation of OAPS; the initial decomposition temperature and char yield show an increasing tendency up to 4 wt% loading of OAPS. The hybrids exhibit higher storage modulus and glass transition temperature (T_g) than the neat epoxy. The T_g of the hybrids greatly improves up to 153.3°C at 3 wt% content, much higher than 119.4°C of the neat epoxy. POLYM. COMPOS., 34:1753–1760, 2013. © 2013 Society of Plastics Engineers     

聚乳酸/苯基次膦酸铝复合材料的制备及其阻燃性能研究

采用共沉淀法制备了苯基次膦酸铝(AlP)并对其进行表征。在此基础上,通过熔融共混法制备了一系列聚乳酸/苯基次膦酸铝（PLA/AlP）复合材料,采用热重分析（TG）、极限氧指数测试（LOI）、UL 94垂直燃烧测试、微型量热测试研究AlP对复合材料热稳定性、阻燃性能、燃烧性能的影响。结果表明,AlP可以有效提高PLA/AlP复合材料的阻燃性能, 当AlP含量为30 %（质量分数,下同）时,PLA/AlP30的极限氧指数达到25.6 %,并达到UL 94 为V-0级;AlP可以提高PLA/AlP复合材料初始分解温度和成炭性; PLA/AlP复合材料的热释放速率峰值和总热释放随着AlP添加量增大呈现先增高再下降的趋势。     

Synthesis of modified graphene oxide and its improvement on flame retardancy of epoxy resin

In this work, the small molecule with double-phosphaphenanthrene structure was successfully grafted on the surface of graphene oxide (GO), which is called functionalized graphene oxide (FGO). The introduction of FGO improved the poor interfacial compatibility between graphene and epoxy matrix. And FGO could be used as the highly effective flame retardant. The thermogravimetric analysis results showed a significant improvement in the char yield of cured FGO/EP. When the content of FGO was 3 wt %, the limiting oxygen index value reached 30.4%. At the same time, the three-point bending and thermomechanical tests confirmed that the mechanical properties of the epoxy resin composites were improved. Based on the char analyses of SEM images and Raman spectroscopy, the flame retardant could promote the formation of a stable carbon layer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47710.     

Thermal degradation and flame retardance of epoxy resins containing a microencapsulated flame retardant

Two steps were used in the synthesis of a microencapsulated intumescent flame retardant (MIFR). First bis (1‐oxo‐2,6,7‐trioxa‐l‐phosphabicyclo[2.2.2]octane‐4‐methylol) phosphate melaminium salt (Melabis) was synthesized. Then the Melabis was encapsulated with melamine resin to obtain the MIFR. Its structure was characterized by XPS, SEM, and elemental analysis, and the factors affecting microencapsulation were identified and discussed. Epoxy resins (EP) were modified with the MIFR to prepare flame‐retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI) tests. The microcapsules (20% by weight) were added to EP in order to achieve an LOI of 29.5% and a UL 94 rating of V‐0. The thermal properties of epoxy resins containing the MIFR were investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). The FR decreased by weight loss, R_max (the maximum weight loss rate), and the thermal stability of EP while promoting the formation of an effective charring layer. The char structures were studied by SEM. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Inorganic–organic hybrid coating‐encapsulated ammonium polyphosphate and its flame retardancy and water resistance in epoxy resin

A novel encapsulated ammonium polyphosphate (APP) with an inorganic–organic hybrid coating (MAPP) was prepared by a sol–gel method using tetraethoxysilane and octyltriethoxysilane as precursors. The properties of MAPP were investigated by water solubility, hydrophobicity, and morphological determination. The structure of MAPP was characterized by X‐ray photoelectron spectroscopy. The flame retardancy of epoxy resin composite with MAPP was evaluated by limiting oxygen index, UL‐94 test, and cone calorimetry test. The results showed that both tetraethoxysilane and octyltriethoxysilane hydrolyze and condense to form a dense polysiloxane layer structure on the surface of APP. The water solubility of MAPP was reduced from 0.64 to 0.13 g/100 mL of water, and the water resistance of epoxy resin composites filled with MAPP was also greatly improved. The limiting oxygen index, UL‐94 test, and cone calorimeter results showed that the epoxy resin composites filled with MAPP had better flame retardancy, probably because of a synergistic effect between polysiloxane and APP. Copyright © 2013 John Wiley & Sons, Ltd.