Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.     

尼龙餐厨具在热氧条件下的老化行为研究

目的对尼龙餐厨具样品进行差示扫描量热(differential scanning calorimetry,DSC)原位热氧加速老化行为研究,分析老化温度和老化时间对样品熔点和热稳定性能的影响。方法采用傅立叶变换红外光谱法(Fourier transform infrared spectroscopy, FTIR)探究老化温度和老化时间与样品分子结构变化之间的关系。结果在模拟使用温度100～260℃范围内,随着DSC热氧老化温度的上升,样品的短期老化作用不明显。在模拟极限使用温度240℃条件下,样品的老化以氧化作用为主,且随热氧老化时间的延长,样品分子链的支化和断链程度加剧,同时伴随着交联现象,总体氧化稳定性变差。结论在极限使用温度240℃条件下,当热氧老化时间短于30min时,市售尼龙餐厨具具有良好的耐热氧稳定性,但若热氧老化时间在延长至60min以上时,其内在结构可能因热氧老化作用发生变化且产生酮等氧化产物,存在安全风险。     

Preparation of iron and nitrogen co-doped carbon material Fe/N-CCM-T for oxygen reduction reaction

In this paper, iron and nitrogen co-doped carbon material with nanotube structure (Fe/N-C_CM-T) was synthesized by pyrolyzing a mixture of Fe salt, chitosan and melamine and displayed high electrocatalytic performance for oxygen reduction reaction (ORR). The structure of the Fe/N-C_CM-T was characterized and their ORR performance in alkaline media was investigated by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Fe/N-C_CM-T displayed better ORR performance than other carbon materials like Fe/N-C_C-800. The Fe/N-C_CM-800 with a large surface area (302.5 m²/g) especially exhibited the best ORR electrocatalytic performance among the prepared carbon materials, which was also proved by its similar Tafel slope (76 mV decade^?1) to Pt/C catalyst (74 mV decade^?1). Fe/N-C_CM-800 showed similar ORR activity as commercial Pt/C catalyst, but superior tolerance to methanol and stability. Such high ORR performance of the Fe/N-C_CM-T can be attributed to its nanotube structure, high specific surface area (SSA), high graphitic-N and pyridinic-N contents.     

从铬离子析出量的检测结果谈谈不锈钢食具的质量控制

对大量不锈钢食具及其原材料的铬离子析出量检测结果进行分析后,发现从原材料的选择到加工过程中力的变化、热处理和冷处理的工艺、表面粗糙度等均会影响不锈钢食具的铬离子析出量,本文提出在工艺上对奥氏体材料进行固溶、稳定化和去应力退火处理等以提高其耐腐蚀性能,在管理上加强对产品原材料、中间环节半成品及最终的成品进行严格的检测、记录、跟踪、监督,利用检测结果指导工艺改进,监督工艺成效,从而提高产品合格率,达到从产品源头开始控制产品质量的目的。     

三聚氰胺装置干燥分离系统的操作分析

对干燥系统操作条件的确定、设备选择及工艺设计原理进行了分析,论述了经常出现的问题及其原因所在,并提出解决方案,使干燥系统的操作尽可能稳定.     

表面解吸常压化学电离质谱法直接测定宠物食品中三聚氰胺

采用表面解吸常压化学电离（SDAPCI）质谱法,在无需复杂样品预处理的情况下,建立直接、快速的宠物食品中三聚氰胺测定方法,并用串联质谱对测定结果进行鉴定。采用手动进样,单个样品获取信息时间少于30 s,对狗咬胶样品中三聚氰胺的回收率为89.2%～113.1%;相对标准偏差（RSD）在7.4%～9.5%之间;检出限为3.05μg/kg。应用本方法对A、B、C、D、E、F六种狗咬胶样品进行测定,测得三聚氰胺含量分别为25.4、17.3、148.4、130.6、10493.9、1168.0μg/kg,六种狗咬胶样品中三聚氰胺信号强度的相对标准偏差在4.7%～12.6%之间。本方法无需复杂的样品预处理,分析速度快,灵敏度高,在检测复杂基体样品时,特异性强,适用于批量样品的快速检测。     

浅析国内外对于"仿瓷餐具"技术要求的差异

介绍了我国标准和欧盟、美国和日本食品接触材料法规对于密胺、脲醛模塑制品的技术要求,对其主要差异进行了对比分析.     

Migration of formaldehyde and melamine from melaware and other amino resin tableware in real life service

ABSTRACT

The migration of formaldehyde and melamine monomers has been measured on 90 samples of plastic tableware in three different situations – new articles, already used articles and artificially aged articles – by using simulant, contact times and temperatures prescribed by Commission Regulation (EU) No. 10/2011. Formaldehyde was determined by ultraviolet spectroscopy analysis of the coloured complex obtained by reaction with chromotropic acid. Melamine was measured by an ultra high performance liquid chromatography method. Fourier Transformed – Infrared Analysis was applied to characterise the plastic. The results highlighted the presence of different amino resins based on formaldehyde-melamine, urea-formaldehyde or melamine-urea-formaldehyde with different migration behaviour. The migration of monomers was related to progressive degradation of the resins. Ageing studies demonstrated that the potential degradation of the resins and the consequent migration of the monomers may continue throughout the service life of the product. The specific migration limit (SML) of melamine was exceeded after ageing.     

Atomic force microscopy,X-ray diffraction,X-ray photoelectron spectroscopy and thermal studies of the new melamine fiber

This paper reports the characterization of unaged and aged melamine fibers using various characterization techniques including atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis. Since melamine fiber is a relatively new fiber, very few studies on its characterization have been made. Morphological studies of the fiber surface using SEM display die lines running along the filament surface, which are characteristics of synthetic fibers and generally occur during spinning of the molten prepolymer through the spinnerets. AFM studies show that the surface of a melamine fiber filament contains a large number of hills and valleys, which are triangular in shape. AFM roughness analysis shows that melamine fiber surface is considerably rough which may aid in adhesion of the fiber with polymeric matrices. Ageing causes an increase in the surface roughness with simultaneous increase in the crystallinity of the fiber from 19.4% to 22.6%. In XPS studies, high concentrations of carbonyl and hydroxyl groups on the filament surface have been detected. Ageing causes a reduction in the hydroxyl group concentration and an increase in the carbonyl group concentration due to surface oxidation. The reduction in the surface hydroxyl groups due to ageing has also been detected in the Fourier-Transform infrared (FT-IR) spectra of the aged fibers. Thermogravimetric (TG) studies reveal a high thermal stability of the melamine fiber even in an oxidative environment such as air.     

计算机单元模拟在三聚氰胺装置冷气风机分析上的应用

简述了三聚氰胺生产流程、冷气风机的作用和结构,介绍了冷气风机密封泄漏的计算机单元模拟过程,提出了以风机进出口温差作为判断其密封泄漏量大小的依据。