用热分析法研究木材阻燃剂FRW的阻燃机理

采用热重(TG)、微商热重(DTG)和差热(DTA)分析法，对木材阻燃剂FRW及其主要组分硼酸和磷酸脒基脲(GUP)、硼酸处理紫椴木材(BZ)、GUP处理紫椴木材(GZ)、FRW处理紫椴木材(FZ)以及未处理紫椴木材(UZ)进行了系统的热解行为研究。TG和DTG分析结果表明，当FRW受热达到分解温度时，其组分的热分解是独立的：硼酸在95和160℃依次分解为偏硼酸和三氧化二硼，GUP在180、285和385℃依次分解为聚磷酸胍(GPP)、聚磷酸铵(APP)和多聚磷酸(PPA)。用阻燃剂FRW及其组分处理的木材，其热解均不同于传统的木材热解模式，其中，BZ在较低的温度下(约165℃)即发生明显的失重，说明硼酸的阻燃机理除了传统理论认为的物理覆盖作用以外尚存在化学催化作用(催化脱水)；GUP处理使紫椴木材的最大失重速率出现的温度从375℃(uz)降到314℃(GZ)，同时失重率也显著降低，而成炭率升高；FZ的失重率低于其他处理材。此外，与各种药剂TG曲线之间的相互关系不同，FZ曲线不等于BZ曲线与GZ曲线的简单加和，这3条曲线相互交叉，预示着GUP与硼酸之间存在阻燃协同作用。DTA分析支持了上述结果。此外，BZ的DTA曲线在约425℃产生一个放热峰，说明硼酸的分解产物可能在高温下催化木材热解产物的芳构化。     

用CONE法研究木材阻燃剂FRW的阻燃性能

利用锥形量热仪 (CONE)系统地测定了新型木材阻燃剂FRW的阻燃性能 ,讨论了FRW对阻燃木材在燃烧时的热释放、质量变化及耐点燃性的影响 ,并与Dricon阻燃剂进行了对比。结果表明 ,在 5 0kW·m2 的热辐射功率下 ,FRW阻燃处理木材的热释放速率 (RHR)和总热释放量 (THR)随FRW载药率的升高而降低 ,至载药率达到 10 %左右时 ,RHR及THR降低为未处理木材的 5 0 %左右 ,并且降低的趋势明显变缓 ;FRW与Dri con阻燃木材的有效燃烧热 (EHC)曲线基本重合 ,说明二者的阻燃机理类似 ;FRW阻燃木材的质量损失速率(MLR)曲线与RHR曲线相似 ,失重和热释放主要发生在有焰燃烧阶段 ;FRW阻燃处理能显著提高木材燃烧时的成炭率 ,但对木材的点燃时间影响不大 ;FRW与Dricon的阻燃效力相当 ,属高效木材阻燃剂。     

木材阻燃剂FRW的阻燃机理

在综合分析热分析法、锥形量热仪法和FTIR法获得的FRW阻燃机理研究结果并吸收木材阻燃机理研究现有成果的基础上,推导进而提出了木材阻燃剂FRW的阻燃机理。其主要内容是:1)FRW阻燃木材受热时,阻燃剂FRW分解产生不燃性气体和不挥发的酸性熔融物质,具有降低体系温度和氧气浓度及屏蔽热辐射的作用,降低了木材的热解速度;2)FRW的组分硼酸和GUP的酸性分解产物催化木材脱水、降解,以及木材热解产物的缩合、聚合、芳构化等反应,能改变木材的热解途径并使其向着有利于炭化的方向变化,FRW显著的催化成炭作用,使阻燃木材的燃烧放热量大大降低,这是FRW阻燃机理的主要方面;3)硼酸与GUP起阻燃作用的温度和方式不同,并且有相互补充的作用,因而表现出阻燃协同效应。     

用FTIR法研究木材阻燃剂FRW的阻燃机理

采用FTIR显微分析技术,对FRW阻燃处理红松木材限制燃烧固相产物的结构进行分析;采用GC_FTIR联机分析方法,对经FRW阻燃剂及其主要组分处理的紫椴木材试样的热解挥发性产物进行分析和鉴定;讨论FRW阻燃处理木材的热解炭化过程、阻燃剂的作用以及热解产物的结构特点。结果表明:FRW阻燃木材受热时,随着温度的升高,在FRW及其分解产物的催化下,木材逐步发生聚糖脱水、半纤维素脱乙酸、聚糖降解、木质素降解、木材热解产物聚合、脂肪族聚合物脱氧及芳构化等反应,最终炭化;FRW阻燃剂改变了木材的热解途径,并且显著降低了挥发性有机化合物的生成量。     

FRW阻燃刨切薄竹的阻燃特性

采用FRW阻燃剂对刨切薄竹进行阻燃处理,用锥形量热仪(CONE)测定不同载药率下处理材与未处理材的阻燃性能。结果表明:在25kW·m-2的热辐射功率下,刨切薄竹经FRW阻燃处理后,热释放速率、总热释放量和总烟释放量随着载药率的增大而减小,处理材在燃烧过程中不会出现较高火焰的燃烧过程;处理材与未处理材相比,点燃时间延长,残余物质量增加;FRW阻燃处理刨切薄竹的阻燃和抑烟效果明显。     

木材阻燃剂FRW与聚磷酸铵复配的阻燃协同效应研究

为开发阻燃效率高、成本低的阻燃剂,将木材阻燃剂FRW与水溶性聚磷酸铵(APP)复配,进行樟子松木材处理和处理试样的热重分析,及热释放速率、总热释放量、有效燃烧热、质量损失和烟气浓度检测。结果表明,与FRW和APP单独处理试样相比,FRW和APP之间具有阻燃协同效应,复配制剂处理试样的成炭率提高,阻燃性能明显提高。     

用CONE法研究木材阻燃剂FRW的抑烟性能

采用锥形量热仪 (CONE)法系统地测定了新型木材阻燃剂FRW的抑烟性能 ,讨论了FRW对木材燃烧时发烟及烟气毒性的影响 ,并与Dricon阻燃剂进行了对比。结果表明 ,当热辐射功率为 5 0kW·m- 2 时 ,FRW阻燃处理木材的烟化率SR、比消光面积SEA、二氧化碳浓度CO2 及二氧化碳产率YCO2 比未处理木材显著降低 ;FRW阻燃处理对木材燃烧时一氧化碳的生成元显著影响 ;FRW与Dricon均具有很强的抑烟作用 ,二者的抑烟效力相当     

用锥形量热仪测试思茅松阻燃胶合板的阻燃性能

为了研究出一种阻燃性能良好的阻燃胶合板,以无机阻燃剂、聚磷酸铵阻燃剂、有机高温阻燃剂和钼酸铵阻燃剂4种阻燃剂处理思茅松单板制备胶合板,采用锥形量热仪对胶合板阻燃性进行测试和评价。研究结果表明,4种阻燃剂处理的胶合板热释放速率峰较素板显著降低。阻燃剂首先可以延缓木材炭化,表现为第一个热释放速率峰出现的时间较素板均有延长,其中以无机阻燃剂处理的胶合板阻燃效果最好。阻燃剂处理的胶合板热释放速率曲线较平坦,成碳速率较素板高,燃烧耗氧量和龟裂程度较素板低。     

氧浓度对阻燃木材发烟性能的影响

采用可控气氛锥形量热仪,在辐射功率为50 kW·m-2,氧浓度为15%～21%的条件下,对磷酸二氢铵(MAP)阻燃紫椴木材及其素材的燃烧发烟性能进行对比研究.通过对烟释放速率(RSR)、总烟释放量(TSR)、比消光面积(SEA)以及一氧化碳(CO)生成速率(PCO)和CO产率(YCO)等相关动态烟参数的综合分析,总结不同氧浓度下,MAP阻燃紫椴木材及其素材燃烧时的浓烟和有毒气体CO的释放规律.结果表明:对于所有试样,有焰燃烧阶段的浓烟释放(RSR、TSR和SEA)要远大于红热燃烧阶段.当氧浓度在16%左右时,MAP阻燃木材和素材的烟释放(RSR、TSR和SEA)相当.在相同的氧浓度下,当氧浓度在16%以上时,MAP阻燃木材燃烧过程中的浓烟释放(RSR、TSR和SEA)小于素材;而当氧浓度在16%以下时,MAP阻燃木材燃烧过程中的浓烟释放(RSR、TSR和SEA)反而高于素材.在试验氧浓度范围内,MAP阻燃木材的CO释放(PCO和YCO)要高于素材.随着氧浓度的增加,MAP阻燃木材燃烧过程中的烟释放(RSR、TSR和SEA)和CO释放(PCO和YCO)均降低;素材燃烧过程中的烟释放(RSR、TSR和SEA)和CO生成速率(PCO)均增加,但CO产率(YCO)降低,前者主要是由于素材燃烧过快而使体系缺氧造成的,而后者主要是由于在单位木材质量损失下热解产物更充分燃烧.总之,随着空气中氧浓度的降低,MAP阻燃木材燃烧时的烟(包括CO)释放均呈增加趋势.     

锥形量热仪法研究FRW系列阻燃剂的抑烟性能

采用锥形量热仪法,对FRW系列木材阻燃剂产品FRW-C1和FRW-C2的抑烟性能进行了评价。结果发现:FRW-C1和FRW-C2阻燃处理木材的烟比率、比消光面积、CO2质量分数及产生速率,均比未处理木材显著降低;二者均能有效地降低木材燃烧时的烟浓度和烟释放量,而对木材燃烧时的CO释放无显著影响。     

Fire-retardant and smoke-suppressant performance of an intumescent waterborne amino-resin fire-retardant coating for wood

An intumescent waterborne amino-resin fire-retardant coating for wood (C) was synthesized and its fire-retardant and smoke-suppressant properties were investigated. The main film-builder of C was urea-formaldehyde resin blended with polyvinyl acetate resin. The intumescent fire-retardant system of C consisted of guanylurea phosphate (GUP), ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL). Specimens of plywood painted, respectively, with a commercial intumescent fire-retardant coating (A), a synthesized coating (C), and the main film-builder of coating C (B), as well as an unpainted plywood (S-JHB), were analyzed by cone calorimetry (CONE). The results show a marked decrease in the heat release rate (HRR) and the total heat release (THR), an increased mass of residual char (Mass), a marked postponement in time to ignition (TTI) and a reduced carbon monoxide production rate (P _CO). The smoke production rate (SPR) and total smoke production (TSP) of the plywood painted with coating C were observed with the CONE test. The overall fire-retardant and smoke-suppressant performance of the synthesized coating C was much better than that of the commercial coating A. The thermo-gravimetric analysis (TGA) results of coating C and its film-builder B indicated that the thermal degradation process of B was slowed down by the addition of the intumescent fire-retardant system; the increase in the amount of charring of coating C was considerable. __________ Translated from Scientia Silvae Sinicae, 2007, 43(12): 117–121 [译自: 林业科学]     

Fire-retardant mechanism of fire-retardant FRW by FTIR

The structures of the solid state products formed by the partial combustion of Korean pine wood treated with fire-retardant FRW were analyzed by microscopic FTIR. The volatile pyrolytic products of basswood (Tilia amurensis) specimens treated with FRW and its components guanylurea phosphate and boric acid were analyzed by GC-FTIR. The pyrolytic and charring process, the effects of fire-retardant, and the structural characteristics of the pyrolytic products were discussed. It was concluded that upon heating and by the catalysis of FRW and its decomposition products reactions of wood took place successively, namely the dehydration of polysaccharide, the elimination of acetic acid from hemicellulose, the degradation of polysaccharide, the degradation of lignin, the polymerization of the pyrolytic products of wood, reactions of oxygen-element-elimination of aliphatic polymers and the structural change of the latter to form aromatic structures, and charring. The pyrolysis process of wood was altered and the yield of volatile pyrolytic products was decreased by FRW treatment. __________ Translated from Scientia Silvae Sinicae, 2005, 41(4): 149–154 [译自: 林业科学, 2005, 41(4): 149–154]     

杨木纤维/无机纳米Al2O3复合材料的阻燃性能

采用锥形量热仪法研究了杨木纤维／无机纳米Al2O3复合材料的点燃时间、热释放速率、总热释放量、有效燃烧热、质量损失速率等。实验结果表明,通过无机纳米Al2O3改性后,点燃时间延长了1倍;45s和175s出现的热释放峰值明显减弱,热释放速率明显降低,平均热释放速率下降了38％,热释放速率峰值下降了25％;总释放热下降了38％;175s的放热峰出现前,其有效燃烧值略低于空白纤维板材,并且两者都比较平缓;质量损失与燃烧时热释放速率同步。     

Chemical mechanism of fire retardance of boric acid on wood

It is commonly accepted that the fire retardant mechanism of boric acid is a physical mechanism achieved by the formation of a coating or protective layer on the wood surface at high temperature. Although a char-forming catalytic mechanism has been proposed by some researchers, little direct experimental support has been provided for such a chemical mechanism. In this paper, new experimental results using thermal analysis, cone calorimetry (CONE), and gas chromatography–Fourier transform infrared spectroscopy (GC–FTIR) analysis are presented and the fire retardant mechanism of boric acid on wood is discussed. Basswood was treated with boric acid, guanylurea phosphate (GUP), and GUP–boric acid. Treated wood was then analyzed by thermogravimetry (TG/DTG), differential thermal analysis (DTA), CONE, and GC–FTIR analysis. Thermogravimetry showed that the weight loss of basswood treated with boric acid was about three times that of untreated or GUP-treated wood at 165°C, a temperature at which GUP is stable. The DTA curve showed that boric acid treated basswood has an exothermal peak at 420°C, indicating the exothermal polymerization reaction of charring. CONE results showed that boric acid and GUP had a considerable synergistic fire retardant effect on wood. The GC–FTIR spectra indicated that compounds generated by boric acid treated wood are different than those generated by untreated wood. We conclude that boric acid catalyzes the dehydration and other oxygen-eliminating reactions of wood at a relatively low temperature (approximately 100–300°C) and may catalyze the isomerization of the newly formed polymeric materials by forming aromatic structures. This contributes partly to the effects of boric acid on promoting the charring and fire retardation of wood. The mechanism of the strong fire retardant synergism between boric acid and GUP is due to the different fire retardant mechanisms of boric acid and GUP and the different activation temperatures of these two chemicals.The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin. This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain and not subject to copyright. The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.     

Study on Flame-retardation and Smoke-suppression Characteristics and Mechanism of NSCFR Flame Retardant or Wood

NSCFR flame retardant is one of key factors of non-smoke combustible wood-based materials.Thermal analysis,cone calorimetry,Py-GC/MS, scanning electron microscopy(SEM) were utilized to investigate the flame-retardation and smoke-suppression characteristics and mechanisms of NSCFR flame-retardant.The results show that NSCFR flame-retardant could significantly shorten the combustion duration of wood-based materials and completely eliminate the second peak of heat release rate curve,greatly reduce heat release rate, total smoke release,mass loss rate,specific extinction area,and carbon monoxide production and carbon dioxide production,obviously enhance the mass of combustion char residue,effectively retarding the combustion and inhibiting smoke release of the wood-based material;NSCFR flame-retardant exhibits the ability of flame retardancy on wood by the conjunct mechanism of capturing free radical, diluting combustible gas,and catalyzing charring; NSCFR flame-retardant displays smoke suppression effects on wood by absorption action of nano alveolate structure together with the active catalyzing action of ironic molybdate.     

FRW阻燃胶合板的DMA分析

目前世界范围内木材资源短缺的情况日益加剧,发展人造板工业已成为世界各国解决木材资源严重不足的重要途径.其中,胶合板作为室内装饰的主要材料,其产量和需求量都在急剧增长.我国胶合板产量从1980年的33.00万m3增长到2004年的2 098.62万m3,呈现大幅度增长的趋势(张文标等,2000).但由于普通胶合板具有易燃性,在许多领域的应用上受到限制.因为一旦发生火灾,不仅造成重大的经济损失,而且往往会发生人员伤亡.1950-2003年全国共发生火灾4 177 730起,直接经济损失2 434.525 1亿元,因火灾死亡174 855人,受伤329 352人.     

基于CONE法的热处理杨木燃烧特性研究

利用锥形量热仪CONE对不同热处理工艺下的杨木燃烧行为进行研究。结果表明:热处理后杨木中亲水的羟基、羰基数量明显减少,大量半纤维素降解。木材试样从外部热源引燃到燃烧结束,出现两个主要放热峰。热处理后杨木引燃和燃烧过程的发烟量较大,且热处理杨木引燃时间更短。热处理材的热释放峰值pk-HRR、平均热释放速率av-HRR和总热释放量THR均低于未处理材,表明其燃烧强度低于未处理材。热处理杨木燃烧过程的总烟释放量TSP较未处理材有所增加,同时其引燃时间也有所缩短。因此,对用于家具和室内装饰的热处理木材,建议进行恰当的阻燃处理。     

Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]