蜜胺泡沫塑料性能与应用

蜜胺泡沫塑料是以蜜胺为主要原料生产的柔性泡沫塑料,不但具有一般泡沫塑料的性能,还具有优异的阻燃、无毒卫生、吸声、隔热等性能。作为一种新型材料,在许多领域具有非常广泛的市场前景。     

Effects of melamine on the Maillard reaction between lactose and phenylalanine

The effects of melamine on Maillard reaction were investigated in chemical model systems. The reaction products in the model systems with/without melamine were analysed by GC–MS and LC–MS/MS. Impact of melamine on Maillard browning in the above models was also examined by colourimetric methods. It was found that melamine can react directly with lactose and Strecker aldehydes formed in Maillard reactions to produce new adducts. In addition, the presence of melamine in chemical model systems also affects the formation of Maillard flavours and browning.     

Confocal Raman microscopy study of the melamine distribution in polyester–melamine coil coating

Hexamethoxymethylmelamine, a common crosslinker used in combination with polyester resins to prepare thermosetting coatings, can self-condense during curing and in theory build up regions with high crosslink density (melamine enrichment). This distribution may affect such properties as the “local” glass transition temperature and structural heterogeneity and thereby modify formability, stain resistance, and weatherability. The self-condensation regions have not previously been observed in detail so their distribution in the film is unclear. Confocal Raman microscopy (CRM) has been used to characterize the melamine distribution in three polyester–melamine paint systems: one clear and two pigmented coil coatings. Both the surface mapping and depth profiling features of CRM were used to perform a 3D analysis. The depth profiling of the clear coating was performed in a nondestructive way, but due to the opaque nature of the pigments, cross sections of the pigmented coatings were prepared in order to facilitate the analysis of the melamine distribution through the film thickness. Melamine-enriched zones were found on the surfaces of all three samples. They appeared to be approximately spherical with diameters of around 5 μm. It was also observed from the cross sections that the melamine-enriched zones appeared as “particles” distributed randomly through the coating. The Raman spectra collected at these regions show significantly higher triazine ring band intensity. All of these findings confirm the hypotheses constructed over the past 20–30 years. This paper was awarded Second Place in the 2008 FSCT Roon Awards competition held as part of the FutureCoat! conference sponsored by the Federation of Societies for Coatings Technology, in Chicago, IL, on October 14–16, 2008.     

Melamine and cyanuric acid do not interfere with Bradford and Ninhydrin assays for protein determination

In the fall of 2007 pet food contaminated with melamine and cyanuric acid caused kidney stones in thousands of animals. In the summer of 2008, a more serious outbreak of adulterated dairy food resulted in the deaths of six infants and sickened about 290,000 children in China. In all cases, melamine was likely concentrations added to inflate the apparent protein content of the foods. To determine if we could measure protein without interference from melamine and cyanuric acid we tested these compounds in the Bradford and Ninhydrin assays, two common dye-based assays for protein, as well as by ammonia release, the most common assay used in the food industry. Neither compound was detected in the Ninhydrin and Bradford assays at concentrations of >100 μg/ml. The ammonia assay detected melamine but was inconclusive with respect to cyanuric acid. To develop an accurate test for food that would not detect either chemical as a protein, assays were run on cat food and reconstituted milk powder. The Bradford assay readily measured the protein content of each food, and importantly, the addition of melamine or cyanuric acid to reconstituted milk did not affect the readings. The protein concentrations obtained for reconstituted milk powder were as expected, but those for the cat food were 10–30-fold lower, due to its low solubility. We conclude that dye-binding assays can be employed to detect protein in food without interference from melamine and cyanuric acid, thus reducing the incentive to use them as additives.     

三聚氰胺衍生物分子的相互识别

借助于电化学方法研究了三聚氰胺衍生物分子的电荷转移行为。研究结果表明，这两种分子之间具有明显的相互电子阻断行为，这种特性可以用于分子识别，是制做分子敏感或识别器件的良好材料。     

蜜胺浆液吸收低浓度SO_2动力学研究

本文采用双全混搅拌反应器,对蜜胺浆液吸收低浓度SO_2气体这一气、液、固三相反应过程的规律进行了研究。通过理论分析和实验考察,证明在该三相反应过程中,SO_2与蜜胺的化学反应是在极其靠近气液界面的液膜内进行的瞬时反应;SO_2在气相中的传质为三相反应过程的速率控制步骤。该三相反应过程的动力学模型可简化为: N_A=k_(Ag)p_A 并且用实验证明了该模型的正确性。通过对实验数据回归,得到了双全混搅拌反应器中气相传质系数的关联式: k_(Ag)=1.2706×10~(=5)+8.1108×10~(=9)Re     

AC800F系统在三聚氢胺装置中的应用

本文主要介绍四川锦华股份有限公司三聚氢胺装置中DCS系统的使用情况,详细介绍了该系统的结构、软硬件配置和组态,以及系统维护等。     

聚酰亚胺泡沫材料吸声性能对比研究

通过阻抗管法研究了聚酰亚胺(PI)、三聚氰胺(MFF)和聚氨酯(PU)3种泡沫材料对声音的吸收特性。结果表明:与MFF和PU泡沫材料相比,PI泡沫材料具有优异的吸声降噪性能;随着材料密度的增大,3种泡沫的吸声降噪性能都有相应提高。     

ZIF-derived wrinkled Co3O4 polyhedra supported on 3D macroporous carbon sponge for supercapacitor electrode

Co₃O₄/melamine-derived carbon sponge (MCS) nanocomposite in which wrinkled ball-in-dodecahedral Co₃O₄ nanoparticles derived from ZIF-67 were homogeneously dispersed on the interconnected MSC was fabricated via a simple immersion and thermolysis route. As-prepared ultralight Co₃O₄/MCS possessed mechanically robust characteristic and unique 3D macroporous framework anchored with corrugated Co₃O₄ dodecahedra. Utilized as a pseudocapacitor electrode, Co₃O₄/MCS hybrid exhibited a great specific capacitance of 1409.5 F g⁻¹ at the current density of 0.5 A g⁻¹ and excellent long-term cycling stability of 93.2% after 1000 charge/discharge cycles, which might be ascribed to the synergistic effect of the inherent high redox activity from Co₃O₄ polyhedra combined with excellent electrical conductivity of MCS. This work demonstrates that tunable structure design and rational morphology control are efficient approaches for manufacturing novel electrode materials with extraordinary electrochemical performance.     

Effect of melamine polyphosphate on thermal degradation of polyamides: a combined X-ray diffraction and solid-state NMR study

The effect of melamine polyphosphate (MpolyP) on the thermal degradation of both polyamide 66 (PA66) and polyamide 6 (PA6) was studied using a combination of solid-state techniques. The mixtures of MpolyP with polyamides were heated for different times at 350 and 450 °C. The residues were then analyzed by X-ray diffraction and both solid-state ¹³C NMR and ³¹P NMR. The chemical structures formed in these oven experiments were used to study the chemical changes that take place during a standard flammability test. The mixtures of MpolyP with polyamides were also characterized by frequency-dependent rheological experiments. It was shown that MpolyP could induce significant cross-linking in PA66 and leads to dramatic depolymerization of PA6. These results were used to explain the performance of MpolyP as a flame retardant in these polyamides.