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31.
为考察聚磷酸铵(APP)干粉灭火剂的聚合度对其灭火性能的影响,选用3种不同聚合度的APP,结合其晶体结构、粒度分布及热性能测试,并通过粉体杯式燃烧器进行小尺寸灭火实验,对比3种样品的灭火性能及灭火机理,研究聚合度与其灭火性能的关系。热性能测试结果显示,聚合度的升高会导致APP的热稳定性下降,随着聚合度从80升至1 500,其初始分解温度从326.11 ℃降低至321.54 ℃,失重率从75.21%增加至79.66%。实验结果表明:随着APP聚合度的增加,火焰降温速率升高,最小灭火浓度(MEC)降低,灭火性能增强,当聚合度为1 500时,MEC为118.143 g/m3。聚合度的升高有助于APP在进入火场后更早、更充分地与火焰发生反应,从而使灭火性能得到提升。 相似文献
32.
新型甲醛捕获剂的合成及其捕获性能研究 总被引:1,自引:0,他引:1
游离甲醛是室内空气中最主要的污染物之一,对人体造成的危害越来越受到关注.因此,研制新型甲醛捕获剂及其捕获性能具有重要的实际意义.采用亲水性单体丙烯酰胺和亲油性单体苯乙烯为反应物,以氧化还原引发剂,经霍夫曼降解反应合成了含氨基的两亲性共聚物.通过单因素实验考察了不同原料比、引发剂剂量时所合成的产物对人造板游离甲醛捕获率的影响,然后根据单因素实验的结果设计正交试验以优化合成条件.结果表明:苯乙烯单体和丙烯酰胺单体的摩尔比为1:3,引发剂与单体摩尔比为9%,丙烯酰胺单体和NaClO的摩尔比为1:1.2时产品捕获率最好,可达60.40%.实验合成的两亲性共聚物在常温下不挥发,相对稳定而且捕获效果较好,是一种理想的新型甲醛捕获剂. 相似文献
33.
Ahmed E. Bishara Habib I. Shaban Hamad Al-Adwani Sami H. Ali 《Journal of Polymers and the Environment》2001,9(4):137-147
A novel copolymer system has been synthesized using methyl hydroquinone diacetate (MHQDA), 1,4 naphthalene dicarboxylic acid (1,4 NDCA), and polybutylene terephthalate (PBT) using the melt polymerization technique. The optimum kinetic parameters pertinent to this system are reported in this study. A simple second-order reaction sequence summarizes catalyzed and uncatalyzed reactions between MHQDA, 1,4 NDCA, and PBT. The kinetic parameters for the copolymerization reaction were determined using a new second-order model. This technique was used to compute the moles of acetic acid generated in the polymerization process. The model was compared to that of the experimentally determined data. Close comparison (percentage error of less than 5%) was obtained between the experimental and theoretical data. The kinetic data support block copolyester formation. The thermal data also supports formation of block polymers. 相似文献
34.
35.
John E. Kemnitzer Richard A. Gross Stephen P. McCarthy John Liggat David J. Blundell Mike Cox 《Journal of Polymers and the Environment》1995,3(1):37-47
Predominantly syndiotactic poly(-hydroxybutyrate), syn-PHB, of variable syndioregularity (syndyad fractions 0.59, 0.62, 0.64, and 0.71) and molecular weight was prepared by the dibutyltin dimethoxide catalyzed ring opening of racemic-butyrolactone (BL). The crystallization behavior of the syn-PHB polymers was investigated by DSC and X-ray diffraction analyses. DSC of films after melting and annealing showed at least one, and often two distinct melting transitions occuring over a broad (often 40°C) temperature range. These results indicate that syn-PHB chain segments of variable syndioregularity form crystalline regions with very different thermodynamic stabilities. Maximum degrees of crystallinity for melt annealed 0.64- and 0.71-syn-PHB was observed at an annealing temperature (T
c
) of 30°C. AtT
c
values at 45°C and higher, crystallization of relatively lower syndioregular chain segments was apparently excluded to variable degrees dependent onT
c
and sample syndiotactic dyad content. After crystallization of syn-PHB samples at elevated temperatures, ambient temperature annealing resulted in an observed lower temperature melting transition at 50°C. This result showed little to no dependence on syn-PHB syndio-regularity andT
c
. Both solution precipitated 0.62-syn-PHB and 0.71-syn-PHB have WAXS patterns with poorly resolved crystalline reflections superimposed on amorphous haloes indicating low levels of crystallinity (17% and 25%, respectively) and poorly formed crystals. Isothermal crystallization monitored by DSC showed that the syn- and natural origin PHB showed fastest crystallization rates at temperatures between 50°C and 70°C and 60°C and 90°C, respectively. From the dependence of the higher melting transition onT
c
it was determined that the equilibrium melting temperatures for 0.62-syn-PHB (M
n
=83,700 g/mol) and a 0.64-syn-PHB (M
n
=11,900 g/mol) were 157 and 154°C, respectively. An Avrami analysis of syn-PHB yielded results similar to that found for natural origin PHB indicating that crystal growth occurs by a two-dimensional mechanism.Guest Editor: Dr. Graham Swift, Rohm & Haas. 相似文献
36.
结合工程实例,介绍了“低阻、中温、大流量”除尘系统工艺在电炉上的应用,以及除尘系统各组成部分的性能特点和所采用的关键技术,阐述了关键技术的理论依据、设计原则和设计参数。 相似文献
37.
仿生脂肪细胞制备以及对水体中林丹去除的研究 总被引:1,自引:0,他引:1
利用生物体脂肪组织可以对脂溶性有机物有效富集的原理,通过界面聚合合成了类似脂肪细胞结构的仿生脂肪细胞,并对其结构进行了初步表征.仿生脂肪细胞具有亲水性膜以及亲脂性的内部结构,亲水性的膜允许携带脂溶性有机物的水体穿过膜,亲脂性的内含物将脂溶性有机物富集截留.仿生脂肪细胞对林丹具有较好的去除效果,15%三油酸甘油酯含量的仿生脂肪细胞与粉末活性炭具有相当的林丹去除能力.仿生脂肪细胞对林丹的去除机理包括内含物的生物富集以及膜上空腔的物理吸附两部分,而内含物的生物富集作用则是主要作用方式. 相似文献
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39.
40.
Thermal runaway can occur during the styrene bulk polymerization process because of easily formed local hotspots resulting from the high viscosity of reactants and the difficulty of heat dissipation. To obtain the thermal hazard characteristics, the polymerization behavior of styrene was investigated using differential scanning calorimetry (DSC) at a scanning rate of β = 2 °C/min. Experimental results showed that the exothermic peaks obtained for heat initiation were different from those obtained when initiator was added. The exothermic peak changed from one to two after the initiator was added. The exothermic onset temperature (T0) was also reduced. Phi-tech II was utilized to study the bulk polymerization of styrene in an adiabatic environment. The adiabatic temperature rise (ΔTad), starting temperature of uncontrolled polymerization (Tstar), maximum temperature (Tend), and heat of polymerization (ΔH) under different conditions were acquired. When the dose of the additive was increased, the starting temperature of uncontrolled polymerization (Tstar) decreased and the adiabatic temperature rise (ΔTad) increased gradually. Severity grading was performed based on the severity evaluation criteria of runaway reaction. The results can help designers decide whether it is necessary to take certain measures to reduce risk. 相似文献