Effect of a novel phosphorous-nitrogen containing intumescent flame retardant on the fire retardancy and the thermal behaviour of poly(butylene terephthalate)

A novel phosphorus-nitrogen containing intumescent flame retardant (P-N IFR) was prepared via the reaction of a caged bicyclic phosphorus (PEPA) compound and 4,4′-diamino diphenyl methane (DDM) in two steps. The product was added to poly(butylene terephthalate) (PBT) to obtain halogen-free flame retarded polyester. UL-94 test, thermogravimetry and in situ infrared spectroscopy were used to characterize the flammability, thermal degradation properties and the char-forming process. It was shown that the phosphorus-nitrogen containing compound could improve both the flame retardancy and thermal stability more effectively than other P-N flame retardants. Furthermore, it was a good char-forming agent incorporated with the co-addition of polyurethane (PU) when the combustion occurred. The formation of P-N structure was incorporated in the char layer.     

Study on flame-retardant mechanism of polycarbonate containing sulfonate-silsesquioxane-fluoro retardants by TGA and FTIR

The flame retardancy of bisphenol A polycarbonate (PC) containing potassium diphenylsulfone sulfonate (KSS), poly(aminopropyl/phenylsilsesquioxane) (PAPSQ) and poly(vinylidenefluoride) (PVDF) was measured by limited oxygen index (LOI) and examined according to UL94. A high LOI and UL94 V-0 rating for 1.6 mm thickness samples were obtained by a combined use of equivalent KSS, PAPSQ and PVDF at 0.1-0.3 wt% loading, respectively. The improvement in flame retardancy of PC compositions arose from the synergistic interaction of three additives. Thermogravimetric analysis (TGA) indicated that the combination decreased the activation energy (E) of PC degradation and elevated the thermal degradation rate of PC to ensure the formation of an insulating carbon layer. FTIR analysis showed that the LOI char of PC containing the three additives took on a highly cross-linking aromatic ester and ether structure.     

Study of hydromagnesite and magnesium hydroxide based fire retardant systems for ethylene-vinyl acetate containing organo-modified montmorillonite

A new flame retardant (FR) system for ethylene-vinyl acetate, mainly based on the combination of hydromagnesite (HM, obtained from an industrial by-product) and organo-modified montmorillonite (oMMT) has been compared with a magnesium hydroxide (MDH) and oMMT flame retardant system. The presence of oMMT in association with both hydrated minerals gave a strong decrease of heat release rate in cone calorimeter tests. Moreover, the HM/oMMT combination leads to a better improvement of resistance to ignition and self-extinguishability in comparison with the MDH/oMMT one. The study of residues formed during thermal decomposition revealed the formation of forsterite (Mg₂SiO₄) when either MDH or HM was used in combination with oMMT. SEM observations of residues showed sintering of the mineral particles at high temperature particularly in the case of HM/oMMT composition.     

阻燃及可瓷化硅橡胶成炭结构的研究进展

简单介绍了硅橡胶的阻燃和瓷化机理。依据阻燃剂、填料及炭层结构的不同,将硅橡胶分为阻燃和可瓷化两大类.综述了阻燃硅橡胶和可瓷化硅橡胶的阻燃性能和成炭结构的研究进展。分析表明:添加物理或化学膨胀型阻燃剂的硅橡胶,燃烧过程中形成的炭层疏松多孔,阻燃隔热性能优异,但炭层强度差;添加非膨胀型阻燃剂的硅橡胶,炭层结构相对密实,但表面不平整,存在孔洞和裂缝,阻燃效果不好;添加可瓷化填料的硅橡胶燃烧形成的陶瓷炭层坚硬而致密,具有优异的耐火持久性,但在隔绝热量方面不如膨胀炭层。炭层的疏松隔热与坚固耐久兼顾是阻燃硅橡胶未来可能的发展方向。     

Novel bismaleimide containing cyclic phosphine oxide and an epoxy unit: Synthesis, characterization, thermal and flame properties

A new type of bismaleimide resin (EPBMI), containing epoxy unit and phosphorus in the main chain, was synthesized. The structure of the new resin was confirmed by infrared spectroscopy (IR), ¹H NMR and ¹³C NMR spectroscopies. In addition, the compositions of the new synthesized bismaleimide with two reactants, 4,4′-diaminodiphenylsulfone (DDS) and 4,4′-diaminodiphenylether (DDE), was used to compare its reactivity and thermal properties with conventional bismaleimide (EBMI). Reactivity was measured by differential scanning calorimetry. Thermogravimetric analysis revealed that the polymers, obtained through the reactions between bismaleimides and diamine agents, also demonstrated excellent thermal properties and high char yield.     

Calcium-based hydrated minerals: Promising halogen-free flame retardant and fire resistant additives for polyethylene and ethylene vinyl acetate copolymers

In this study, we evaluated the potential flame retardant effect of calcium-based hydrated minerals, such as hydrated lime, partially and completely hydrated dolomitic limes in polyethylene (MDPE) and ethylene vinyl acetate copolymers (EVA) and compared to that obtained with magnesium di-hydroxide (MDH). The most significant flame retardant effects, observed using the mass loss calorimeter test, indicated that Ca-based MDPE composites showed similar peak Heat Release Rate (pHRR) level to that obtained with MDH composite while the pHRR was lower for Ca-based fillers in EVA compositions. X-ray Diffraction (XRD) data, combined with thermal analysis results, indicated that the calcium di-hydroxide plays a role in the formation of an intumescent cohesive residue during the combustion. Indeed, Ca(OH)₂ reacts with CO₂ formed during the thermal degradation of the polymer to generate CaCO₃ (calcium carbonate) that contributes to the enhancement of the mechanical resistance of the residue.     

Thermal degradation and flame retardance in copolymers of methyl methacrylate with diethyl(methacryloyloxymethyl)phosphonate

Methyl methacrylate (MMA) has been free radically copolymerized, both in bulk and in solution, with diethyl(methacryloyloxymethyl)phosphonate (DEMMP), to give polymers which are significantly flame retarded when compared with PMMA, as indicated by the results of limiting oxygen index (LOI) measurements, UL 94 tests, and the results of cone calorimetric experiments. The physical and mechanical properties of the copolymers are similar to those of PMMA, except that the bulk copolymers are slightly crosslinked, and are better than those of PMMA flame retarded to a similar extent by some phosphate and phosphonate additives. Examination of the some of the gaseous products of pyrolysis and combustion, and of chars produced on burning, show that flame retardation occurs in the copolymers by both a condensed-phase and a vapour-phase mechanism. The condensed-phase mechanism is shown to involve generation of phosphorus acid species followed by reaction of these with MMA units giving rise to methacrylic acid units. The methacrylic acid units subsequently form anhydride links, which probably impede depolymerization of the remaining MMA sequences, resulting in evolution of less MMA (the major fuel when MMA-based polymers burn). By undergoing decarboxylation, leading to interchain cyclisation and, eventually, to aromaticisation, the anhydride units are probably also the principal precursors to char.     

Characterization of high heating rate chars of biomass fuels

Data on biomass chars obtained under conditions similar to those of practical applications (high heating rate and low residence time) are required for co-combustion and gasification plants. A methodological procedure is developed and applied to two biomass fuels (cacao shells and olive cake) for producing high heating rate chars and characterizing their reactivity and morphology after the first steps of devolatilization. Different chars are produced in a drop tube reactor (rapid pyrolysis) by varying the nominal temperature and the residence time. Oxidation in air is performed to compare typical temperatures and kinetic parameters and evaluate the effect of the operating conditions on char reactivity. A detailed SEM analysis allows to assess the structural variations during the pyrolysis and detect the main phenomena (softening, swelling, melting, formation of bubbles). A quantitative morphological study is also performed to provide size and shape (important for biomasses) distributions of the parent fuel and the chars. These data are more significant than average values in advanced model to correctly simulate the fluid dynamic behaviour of each dimensional class of particles in large scale furnaces and gasifiers and predict a more reliable residence time of the particles.     

不同气氛下煤焦吸附NO的量子化学计算

本文应用密度泛函理论B3LYP方法,分别研究了空白气氛、O2气氛、CO气氛对煤焦吸附NO的影响。建立了由6个苯环组成的煤焦模型,计算得到了在不同气氛、不同吸附位置的吸附能。在O2气氛下,吸附效果最好的方式依然为平行吸附,但吸附能绝对值较空白气氛减小,O2氛围抑制了煤焦对NO的吸附;在CO气氛下,吸附效果最好的方式为平行吸附且吸附能绝对值较空白气氛有所增加,CO氛围促进了煤焦对NO的吸附。     

杉木炭磺酸对4-甲基香豆素的催化合成研究

将杉木粉热解、再用发烟硫酸磺化为杉木炭磺酸,FT-IR、XPS等分析表明,磺化反应成功地将磺酸基团键合到杉木炭骨架上。杉木炭磺酸对乙酰乙酸乙酯和取代酚的Pechmann缩合反应表现了较好的催化活性,催化合成了取代4-甲基香豆素。考察了催化剂的用量等反应条件对Pechmann缩合反应收率的影响,并比较研究了杉木炭磺酸与其...