不同阻燃剂阻燃聚丙烯的火灾危险性分析

采用垂直燃烧法和锥形量热法研究了添加四种不同类型阻燃剂的聚丙烯(PP)试样的阻燃性能和燃烧行为,提出了火势增长指数、放热指数、发烟指数和毒气生成速率指数4个评价试样火灾危险性的指标,根据每个指标对不同试样的火灾危险性进行了评价。结果表明,四种阻燃试样的热释放速率都有所降低,但只有氮系阻燃试样降低了比消光面积,同时溴系和无机磷阻燃试样提高了一氧化碳释放速率,试样在4个不同指标的逐项评价下排序也不尽相同。通过熵权法对指标赋权,建立了综合评价火灾危险性的新方法。研究发现,毒气生成速率指数在各指标中所起作用最大,火势增长指数所起作用最小,四种阻燃PP试样火灾危险性排序由小到大为氮系阻燃PP膨胀阻燃PP纯PP无机磷阻燃PP溴系阻燃PP,该结果可为火灾的防治和阻燃材料燃烧性能研究提供借鉴。     

聚合物锥形量热法的测试操作与分析

应用锥形量热法测试聚合物阻燃性能,是目前一种必不可少的手段和理论依据,特别是在高分子材料的阻燃研究中,实用价值已越来越多地体现出来。了解锥形量热仪的结构,应用锥形量热法测试聚合物材料的热释放速率、质量损失速率、有效燃烧热、点燃时间、燃烧时间以及比消光面积、生烟速率等参数。对这些测试数据进行对比分析,从而确定材料的阻燃性能。本文综述了锥形量热仪的结构原理、测试操作方法和测试数据的图形分析。     

原竹纤维增强酚醛泡沫材料的燃烧特性

采用锥形量热仪研究了不同原竹纤维加入量对酚醛泡沫材料的燃烧性能和烟气释放特性的影响。结果表明,酚醛泡沫材料的引燃时间随着原竹纤维加入量的增大而缩短,热释放速率、总放热量、质量损失速率、生烟速率和总发烟量随原竹纤维加入量的增大而总体呈增大趋势,但由于酚醛泡沫材料具有良好的阻燃性能,其燃烧快速成炭特性阻碍了热量在材料内层传递,减缓了原竹纤维在0~480 s燃烧阶段的热释放和烟气释放,使得加入量为1.5 %~3.5 %的原竹纤维作为其增强材料时,对酚醛泡沫材料的阻燃性能影响较小;而原竹纤维的加入量≥5.0 %时,对酚醛泡沫材料的阻燃性能有较大的降低作用,必须进行阻燃改性。     

阻燃胶合板燃烧性能与产烟毒性风险监测探究

抽查市场不同领域的阻燃胶合板,按GB/T 20284-2006《建筑材料或制品的单体燃烧试验》和GB/T 20285-2006《材料产烟毒性危险分级》方法进行试验,测试阻燃胶合板的燃烧增长速率指数、烟气生成速率指数、产烟毒性等项目,对测试结果进行判别分析,得出样品整体质量状况。测试结果显示:10组阻燃胶合板中燃烧性能不合格的比例达到40%;产烟速率方面全部达到了S1级,表现较好;产烟毒性方面不合格的比例达到20%;综合燃烧性能和产烟毒性两个方面,不合格比例达到60%。市场上阻燃胶合板的质量状况不容乐观。     

最高阻燃级组合聚醚面世

B1级高阻燃喷涂型组合聚醚日前在山东东大聚合物股份有限公司研发成功。聚氨酯保温材料燃烧性能级别可分为三级,即B1难燃级、B2可燃级、B3易燃级。目前,聚氨酯保温材料市场大多     

实际安装方法对橡塑发泡保温材料燃烧特性的影响

通过对由简单机械安装、橡塑胶水粘贴安装与硅酮防火胶水粘贴安装固定的三种橡塑发泡保温材料(PVC/NBR)进行建筑材料或制品的单体燃烧试验(SBI),以热释放速率(HRR)、燃烧增长速率指数(FIGRA)与烟气生产速率(SPR)为主要评价参数进行分析不同的安装方法对泡沫保温材料燃烧特性的影响。     

轨道车辆用高分子保温材料燃烧行为研究与火灾危险性评价

选取三种典型的轨道车辆用高分子保温材料,借助NBS烟密度箱、傅里叶变换红外烟气毒性测试系统、锥形量热仪和火焰蔓延测试仪,分别从产烟、气体毒性、热释放以及火焰蔓延4个方面对材料的燃烧行为进行了分析研究,测得材料的烟密度最大值、毒性指数最大值、最大平均热释放速率、放热总量、火焰蔓延最远距离等燃烧特征参数,运用层次分析法建立...     

交联聚苯乙烯的热分解与燃烧性能研究

采用二乙烯基苯(DVB)为交联剂,与苯乙烯(St)单体进行共聚合成了一系列交联聚苯乙烯(PS)。采用热重分析、高温热分解、水平燃烧、氧指数、锥形量热分析等方法研究了交联PS的热分解行为和燃烧性能。结果表明:与线型PS相比,交联PS的热分解温度提高,成炭量增加,热稳定性显著增强;交联PS在燃烧时熔融滴落和发烟量显著减少,热释放速率、质量损失速率和燃烧速率降低,氧指数增加,阻燃性能增强;当St/DVB的质量比为100/3时得到的交联PS的阻燃性能最佳;交联PS在燃烧时生成的大量炭残余物覆盖在聚合物表面形成保护层,对热量传递、氧气和燃料分子的迁移产生屏蔽和阻隔作用,降低了聚合物的热分解速率,提高了其阻燃性能。     

溴化环氧树脂协同三氧化二锑阻燃PET的燃烧性能及阻燃机理研究

研究了溴化环氧树脂(BER)协同不同粒径的三氧化二锑（Sb2O3）阻燃PET的燃烧性能、垂直燃烧性能（UL94）、烟气释放、物理性能高和力学性能,研究了炭层的红外光谱和阻燃PET的裂解特性,分析了阻燃PET的阻燃机理。锥形量热分析表明,BER协同Sb2O3阻燃PET的燃烧性能显著减低,均可以达到UL94 V-0级,且Sb2O3粒径越小,阻燃效果越好,但溴-锑协同不能抑制烟毒的产生,平均CO生成量和材料释烟量显著上升。BER协同Sb2O3阻燃PET的熔体流动速率、维卡软化点、邵氏硬度、弯曲强度和弯曲模量提高,缺口冲击强度和断裂伸长率下降。红外和裂解色谱分析表明,阻燃PET与纯PET的燃烧残炭结构不完全相同,裂解产物的主要出峰保留时间也不相同,说明了BER协同Sb2O3不仅在气相发挥阻燃作用,在固相也同样发挥阻燃作用。     

基于动物染毒试验的不同聚合物材料烟气毒性研究

采用动物染毒试验法研究了小鼠对8种不同建筑聚合物材料的烟气的生理反应、体重变化以及存活情况,并根据小鼠的症状对各种材料的烟气毒性进行级别判定,同时对它们的烟气产生和毒性来源进行了分析探讨。结果表明,酚醛树脂的烟气毒性可以达到AQ1级,橡塑保温材料和聚苯乙烯材料为ZA3级,铝塑复合板的烟气毒性受芯材的影响很大,而聚氨酯泡沫、PC聚碳酸酯中空板的烟气毒性高至WX级。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.