Different effects of tri(acryloyloxyethyl) phosphate on the thermal degradation of photopolymerized epoxy acrylate and polyurethane acrylate films

Tri(acryloyloxyethyl) phosphate (TAEP) was blended in different ratios with epoxy acrylate EB600 and polyurethane acrylate EB270 to obtain a series of UV curable flame retardant resins. The thermal degradation mechanisms of their cured films in air were studied by thermogravimetric analysis, in situ Fourier‐transform infrared spectroscopy, and direct pyrolysis/mass spectrometry measurements. The results showed that the phosphate group in TAEP first degraded to form poly(phosphoric acid) before the degradation of EB600. Then, the formed poly(phosphoric acid) effectively promoted the conversion of EB600 to form char, which prevented the sample from further burning. However, urethane group in EB270 degraded simultaneously with phosphate group in TAEP, leading to not effectively increase the conversion of EB270 to char during the thermal degradation. It was thus found that the addition of TAEP more effectively improved the thermal stability, flame retardance, and the char yield during combustion of EB600 than those of EB270. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3130–3137, 2006     

防火涂料的防火性能及其测量

本文依据有关国家标准对饰面型防火涂料和钢结构防火涂料的防火性能及其检测方法作了简要介绍。     

Thermal degradation behaviors of polypropylene with novel silicon‐containing intumescent flame retardant

The N‐[3‐(dimethoxy‐methyl‐silanyl)‐propyl]‐N′‐ (9‐methyl‐3,9‐dioxo‐2,4,8,10‐tetraoxa‐3,9‐diphospha‐spiro[5.5]undec‐3‐yl)‐ethane‐1,2‐diamine/dimethoxy dimethyl silane copolymer (PSiN II), which simultaneously contains silicon, phosphorus, and nitrogen, is synthesized and incorporated into polypropylene (PP). The flame retardancy is evaluated by the limiting oxygen index value, which is enhanced to 29.5 from 17.4 with 20% total loading of PSiN II. The thermal degradation behavior of PP/PSiN II is investigated by thermogravimetric analysis under N₂ and air. The PP/PSiN II sample degrades at 400°C for different amounts of time, and the process of degradation is studied by Fourier transform IR. The morphology of the char formed at 400°C for 10 min is investigated by scanning electron microscopy. The swollen inner structure, close, and smooth outer surface provide a much better barrier for the transfer of heat and mass during fire and good flame retardancy. The thermal stability of PP is improved by incorporation of PSiN II. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2487–2492, 2005     

阻燃硅橡胶的研制

通过测定硅橡胶试片的离火熄灭时间及燃烧速率来判定热硫化硅橡胶的阻燃性。结果表明，氢氧化铝对热硫化硅橡胶具有良好的阻燃效果；随着氢氧化铝用量的增加，硅橡胶的物理机械性能下降。通过对氢氧化铝进行表面处理，并与氯铂酸等阻燃剂配合，可制得符合美国UL-94V-0阻燃标准的硅橡胶制品。在本实验条件下的最佳配比为：100份混炼硅橡胶，45份氢氧化铝，50份氯铂酸(以铂质量计／10^-6)，2份乙炔炭黑及铁锡复合氧化物，制品拉伸强度大于5MPa。     

聚酰胺66的复配阻燃研究

采用35％磷-溴-锑复配阻燃体系对聚酰胺66进行阻燃，极限氧指数可提高到33．6％，达到UL94-V0级(1．6mm)，且无熔融滴落。阻燃体系的添加会导致聚酰胺66力学性能的下降，但与无机阻燃体系相比较，磷-溴-锑复配阻燃体系对聚酰胺66的力学性能影响较小。采用扫描电镜观察阻燃剂在聚酰胺66中的分散效果，发现分散均匀的体系，在水中或者在110℃的析出实验条件下，阻燃剂的析出量很小，可以维持较长时间的阻燃效果。     

钢结构防火涂料的研究和应用

作者结合工作实践,综述了国内外钢结构防火涂料的研究及应用情况,展望了钢结构防火涂料的发展前景。     

Synthesis,characterization, and thermal properties of phosphorus‐containing,wholly aromatic thermotropic copolyesters

A series of phosphorus‐containing, wholly aromatic thermotropic copolyesters from acetylated 2‐(6‐oxide‐6H‐dibenz〈c,e〉〈1,2〉oxa phosphorin‐6‐yl)‐1,4‐dihydroxy phenylene, p‐acetoxybenzoic acid, terephthalic acid, and isophthalic acid were prepared by melting polycondensation. The structure and basic properties of the polymers, such as the glass‐transition temperature (T_g), melting temperature (T_m), thermal stability, crystallinity, and liquid crystallinity, were investigated with Fourier transform infrared, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray diffraction, and hot‐stage polarizing optical microscopy. The copolyesters had relatively high T_g values ranging from 183 to 192°C. The T_m values obtained from DSC curves for samples P‐20 and P‐25 were 290 and 287°C, respectively (where the number in the sample name indicates the molar fraction of the phosphorus‐containing monomer in the reactants). The initial flow temperatures of other samples observed with hot‐stage polarizing microscopy were 271–290°C. The 5% degradation temperatures in nitrogen ranged from 431 to 462°C, and the char yields at 640°C were 41–52%. All the copolyesters, except P‐40, were thermotropic and nematic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1278–1284, 2002     

Synthesis and characterization of new flame‐retardant poly(amide‐imide)s containing phosphine oxide and hydantoin moieties in the main chain

Six new flame‐retardant poly(amide‐imide)s (PAIs) 9a–f with high inherent viscosities containing phosphine oxide and hydantoin moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7 with six hydantoin derivatives 8a–f by two different methods such as solution and microwave assisted polycondensation. Results showed that the microwave assisted polycondensation, by using a domestic microwave oven, proceeded rapidly, compared with solution polycondensation, and was completed in about 7–9 min. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties and flame retardant behavior of the PAIs 9a–f were investigated using thermal gravimetric analysis (TGA and DTG) and limited Oxygen index (LOI). Data obtained by thermal analysis (TGA and DTG) revealed that these polymers showed good thermal stability. Furthermore, high char yields in TGA and good LOI values indicated that these polymers are capable of exhibiting good flame retardant properties. These polymers can be potentially utilized in flame retardant thermoplastic materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5062–5071, 2006     

Evaluation and characterization of ammoniumpolyphosphate–pentaerythritol‐based systems for intumescent coatings

Intumescent coatings are increasingly used as a method of passive fire protection on steel constructions. By forming a carbon network and releasing a blowing agent, the thin intumescent film swells 100‐fold at elevated temperatures. The highly insulating foam effectively prevents the load bearing steel from reaching its critical temperature at which it looses its mechanical properties and collapses. The role of the carbon donor in intumescent coatings has been studied. Comparison in temperature development, foaming ratios, and rheological behavior has been performed between formulations containing pentaerythritol (penta), di–penta, and tri–penta. A simulated fire test, in which the temperature development during intumescence was studied, showed that the formulations containing penta were considerably more efficient in keeping a low temperature throughout the process. A more rapid temperature development was displayed when using di–penta and tri–penta as the carbon donor. Rheometer tests indicate that penta formulations enter the intumescent process at a lower temperature and stays in it for a longer time than di–penta and tri–penta formulations. Furthermore, the crossover temperature and maximum phase angle are shifted towards higher temperatures by replacing penta with di–penta and with tri–penta in the formulations, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 748–753, 2007     

Heat-release mechanism in ammonium dinitramide flame

To verify the adequacy of various models of heat release in ammonium dinitramide flame to real processes, chemical processes in products of thermal decomposition at a pressure of 10 torr and in ammonium dinitramide [ADN; NH₄N(NO₂)₂] flame at a pressure of 0.4 to 60 atm are numerically simulated. The calculations are performed on the basis of a detailed kinetic mechanism and boundary conditions correlated with experimental data, thermodynamic properties, and chemical composition of ADN. The kinetic mechanism includes submechanisms that describe high-temperature chemical processes in NH₃/N₂O/NO/NO₂/HNO₂/HNO₃ and NH₃/HN(NO₂)₂ mixtures, and the global stages of aerosol decomposition. Based on calculated and experimental data, the role of dinitraminic acid HN(NO₂)₂, aerosols, and ADN vapor in heat release in the ADN flame zone adjacent to the burning surface is estimated. The calculations predict that the main source of heat release in the cold flame zone at p ≥ 3 atm is dinitraminic acid incoming through the channel of dissociative evaporation ADN_liq → NH₃ + HN(NO₂)₂ from the burning surface. In the high-temperature flame zone, heat release is caused by the reaction that occurs in the NH₃/N₂O/NO/NO₂/HNO₂/HNO₃ mixture. At moderate pressures, the high-temperature and low-temperature zones are separated by an induction zone. The stage governing production of the OH radical, which plays an important role in combustion, in the induction zone is the reaction HNO₃ + M → OH + NO₂ + M. Because of a high activation energy of the stage, small temperature perturbations in the induction zone at low pressures lead to a finite change in the stand-off distance between the high-temperature flame zone and the burning surface. Therefore, small temperature perturbations in the induction zone, which are caused by admixtures in the sample or by heat transfer between the reacting gas and the ambient medium, may be responsible for disagreement between various experimental data and between experimental and calculated data on the stand-off distance between the high-temperature flame zone and the burning surface. In numerical calculations, the position of the high-temperature zone is effectively controlled by varying rate constants of elementary stages within admissible limits. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 64–76, September–October, 2007.