四溴双酚-A阻燃体系在HIPS／OMMT复合材料中的阻燃性研究

采用熔融插层法分别制备高抗冲苯乙烯／有机蒙脱土（HIPS／OMMT）复合材料和四溴双酚-A／三氧化二锑（TBBPA—Sb2O3）体系阻燃的HIPS／OMMT复合材料,透射电镜研究表明,有机蒙脱土均匀地分散于HIPS基体当中,形成了插层复合结构,锥形量热仪和氧指数仪研究表明：与纯的HIPS相比,HIPS／OMMT复合材料的阻燃性和抑烟性有所提高,但阻燃性的提高幅度较有限：与仅添加OMMT时的HIPS／OMMT复合材料相比,添加相同量OMMT时TBBPA—Sb2O3体系阻燃的HIPS／OMMT复合材料的热释放速率（HRR）和热释放速率峰值（PHRR）均有所降低,氧指数有所增加,且随TBBPA—Sb2O3阻燃剂添加量的增加阻燃性能的提高越明显,但TBBPA—Sb2O3的加入会导致聚合物燃烧过程生烟速率和生烟量的显著增加．因此此类阻燃剂的加入量不宜过高。     

不同表面活性剂包覆的LMH对LLDPE性能影响

采用气泡液膜法制备了不同表面活性剂包覆的疏松型氢氧化镁(LMH),通过对常规力学性能和极限氧指数(LOI)的测试、燃烧实验和热重分析,研究了不同表面活性剂包覆的LMH对线型低密度聚乙烯(LLDPE)性能的影响.结果表明:不同表面活性剂包覆的LMH对LLDPE拉伸强度、弯曲强度和LOI的影响不大,但会显著影响材料的冲击强度、热释放速率、燃烧质量损失率及热稳定性;以聚乙二醇6000包覆的LMH可使LLDPE的力学性能、阻燃性能及热稳定性能较优.     

羟基锡酸锌包覆纳米氢氧化镁在PVC中的应用

通过均匀沉淀法制备了羟基锡酸锌包覆纳米氢氧化镁并将其应用到聚氯乙烯(PVC)中。利用XRD、TG、DTA对羟基锡酸锌包覆纳米氢氧化镁的性能进行了研究,并通过氧指数、烟密度研究了羟基锡酸锌包覆纳米氢氧化镁对PVC的阻燃和抑烟性能的影响,同时对其力学性能也进行了研究。结果表明:纳米氢氧化镁表面均匀地包覆了羟基锡酸锌;羟基锡酸锌包覆纳米氢氧化镁对PVC的阻燃和抑烟性能明显优于单独添加羟基锡酸锌、纳米氢氧化镁以及羟基锡酸锌包覆微米氢氧化镁和羟基锡酸锌与纳米氢氧化镁混和物时的阻燃、抑烟性能;纳米材料的加入对PVC的力学性能也产生了有利的影响。     

SEBS／蒙脱土复合材料结构与阻燃性能的研究

根据蒙脱土（MMT）特殊的片层结构,采用熔融插层法制备热塑性弹性体SEBS／蒙脱土插层复合材料。通过X射线衍射仪、透射电镜等表征手段研究复合材料的微观结构。使用锥形量热仪评价复合材料的燃烧性能。结果表明,有机蒙脱土（OMMT）片层的间距为1．948nm,SEBS／5％OMMT体系的片层间距为4．307nm,说明聚合物SEBS插入有机蒙脱土片层之间。SEBS／OMMT复合材料具有较低的热释放速率和质量损失速率,且随着OMMT添加量的增加,其热释放速率峰值降低愈明显。通过对复合材料的阻燃性能和微观结构的分析,探讨了其阻燃机理。     

阻燃剂的发展概况及氢氧化镁表面改性的研究进展

综述了阻燃剂的发展、氢氧化镁阻燃剂的特点和表面改性的现状以及氢氧化镁与偶联剂的相互作用机理.     

APP对木粉-HDPE复合材料阻燃和力学性能的影响

以聚磷酸铵(APP)对木粉-HDPE复合材料(WF-HDPE)进行阻燃处理,用锥形量热仪系统评价复合材料的阻燃性能,并进行等温燃烧反应动力学分析,用万能力学试验机进行静态力学试验。结果表明,在35 kW/m2热辐射流量下,APP添加量达到15%时,WF-HDPE燃烧热释放速率(RHR)峰值和总热释放量(THR)均降低约50%、成炭率提高150%,表现出显著的阻燃作用;可用动力学模型ln(1-α)=-kt+C描述WF-HDPE的等温燃烧反应,APP的加入使反应速率常数k降低、半衰期延长。APP对WF-HDPE的冲击性能有显著的不利影响,但能改善刚性,对弯曲强度和拉伸强度影响不大。综合阻燃性能与力学实验结果,APP的适宜添加量为15%左右。     

笼形八乙烯基硅倍半氧烷／ABS复合材料的热性能和阻燃性

通过螺杆挤出成型法制备了笼形八乙烯基硅倍半氧烷(OVP)/ABS复合材料,采用TGA、氧指数仪和锥形量热仪研究OVP的加入对复合材料热性能和阻燃性能的影响。研究结果表明,在添加引发剂(DCP)的条件下,当乙烯基OVP含量为6.25%时,复合材料的初始分解温度由纯ABS的174℃上升到209℃;氧指数由纯ABS的17.8%上升到的21.4%;热释放速率峰值降为529 kW/m2,比纯ABS降低了近30%。采用SEM对燃烧过后的残炭进行了分析,并探讨了其阻燃机理。     

等离子与火焰喷涂镍铝涂层性能研究

采用等离子和火焰两种方法制备NiAl涂层,对比了NiAl复合粉末在这两种喷涂工艺条件下所得涂层的硬度、结合强度和组织结构。实验结果表明采用等离子法制备的NiAl涂层致密,涂层孔隙率低,与基体的结合强度高,且涂层的硬度较高。     

Total metal concentrations and partitioning of Cd, Cr, Cu, Fe, Ni and Zn in sewage sludge

Application of the BCR three-step sequential extraction procedure to sewage sludge samples collected at an urban wastewater treatment plant (Dom ale, Slovenia) is reported. The total concentrations of Cd, Cr, Cu, Fe, Ni and Zn and their concentrations in fractions after extraction were determined by flame or electrothermal atomic absorption spectrometry (FAAS, ETAAS) under optimised measurement conditions. Total acid digestion including hydrofluoric acid (HF) treatment and aqua regia extraction were compared in order to estimate the efficiency of aqua regia extraction for determination of total metal concentrations in sewage sludge. It was found experimentally that aqua regia quantitatively leached these heavy metals from the sewage sludge and could therefore be applied in analysis of total heavy metal concentrations. The total concentrations of 856 mg kg⁻¹ Cr, 621 mg kg⁻¹ Ni and 2032 mg kg⁻¹ Zn were higher than those set by Slovenian legislation for sludge to be used in agriculture. Total concentrations of 2.78 mg kg⁻¹ Cd, 433 mg kg⁻¹ Cu and 126 mg kg⁻¹ Pb were below those permitted in the relevant legislation. CRM 146R reference material was used to follow the quality of the analytical process. The results of the BCR three-step sequential extraction procedure indicate high Ni and Zn mobility in the sludge analysed. The other heavy metals were primarily in sparingly soluble fractions and hence poorly mobile. Due to the high total Ni concentration and its high mobility the investigated sewage sludge could not be used in agriculture.     

Characterization of the thermal and fluid flow behavior of industrial ribbon burners

This study focuses on the key parameters that enhance the stability of ribbon burners used in various industrial processes, characterizing the flame environment and flow regimes that the burner creates under changing operating conditions. The research includes the exploration of ribbon-pack configurations in order to define the effects of separation distance and port arrangement on flame stability and thermal and fluid flow. Flow visualization studies reveal that burners having a 1.5–2.0 mm division between rows appear to be the most stable. More than four rows of ports in the ribbon-pack are required to resist entrainment of ambient air as a result of impinging surface motion. The flame environment created by the ribbon burner experiences higher levels of mixing, at a lower Reynolds number in comparison to a single non-reacting jet due to combustion-induced turbulence and jet interaction. Under these high flow velocity conditions there is little entrainment of ambient air along the impingement surface and a very stable flame environment is created.