新型无卤膨胀型阻燃剂的制备

以工业季戊四醇、三聚氰胺、三氯氧磷为原料,研究了新型无卤膨胀型阻燃剂季戊四醇双磷酸酯蜜胺盐的制备,确定了适宜的反应条件：温度80℃时间5h。通过傅立叶变换红外光谱对产物进行鉴定,所得中间产物双氯螺磷的纯度高,产率达50．76％;最后对产物的阻燃性能进行了测试,结果表明它是一种优良的阻燃剂。     

Highly Elastic Melamine Graphene/MWNT Hybrid Sponge for Sensor Applications

The rapidly increased interest in multifunctional nanoelectronic devices, such as wearable monitors, smart robots, and electronic skin, motivated many researchers toward the development of several kinds of sensors in recent years. Flexibility, stability, sensitivity, and low cost are the most important demands for exploiting stretchable or compressible strain sensors. This article describes the formation and characteristics of a flexible, low-cost strain sensor by combining a commercial melamine sponge and a graphene/carbon nanotubes hybrid. The composite that emerged by doping the highly elastic melamine sponge with a highly conductive graphene/carbon nanotubes hybrid showed excellent piezoresistive behavior, with low resistivity of 22 kΩ m. Its function as a piezoresistive material exhibited a high sensitivity of 0.050 kPa⁻¹ that combined with a wide detection area ranging between 0 to 50 kPa.     

氮掺杂碳气凝胶电极材料的制备及性能

以三聚氰胺（M）、间苯二酚（R）和甲醛（F）为原料,经溶胶-凝胶法、超临界干燥和高温碳化制备了系列的氮掺杂碳气凝胶（NCAs）。X射线光电子能谱(XPS)分析表明,氮元素成功地引入到碳气凝胶中,并且可以通过调节三聚氰胺掺杂量来控制氮掺杂量;扫描电子显微镜（SEM）和N2吸附测试显示出不同氮掺杂量的碳气凝胶的微观结构差异较大,随着氮含量的增加,比表面积有先减后增的趋势;在6 mol/L KOH溶液中进行的恒流充放电和循环伏安测试表明,引入氮元素能够极大地改善碳气凝胶的电化学性能,最高比电容量达176 Fg-1,并且凝胶具有良好的电容特性和可逆性。     

Structure–property relationships of anionic poly(urethane–urea) dispersion cross-linked with partially methylated melamine formaldehyde

An anionic poly(urethane–urea) dispersion (PUD) was cross-linked with different amount of partially methylated melamine formaldehyde (PMMF). The isothermal curing behavior was observed by a rigid-body pendulum rheometer. The test results showed that cure response of PUD cross-linked with PMMF was a function of the concentration of PMMF. Also, PMMF self-condensation could take place during the curing process. In this experiment, the anionic poly(urethane–urea) dispersion has a large number of >N–H cross-linking or branching sites in urethane and urea groups per molecule that allow a large number of PMMF to couple into elastic PUD backbone to form branched structure with partial cross-linking. The dynamic mechanical properties of PUD cross-linked with PMMF were affected by the concentration of PMMF. It was further shown that the tensile properties were strongly influenced by the concentration of PMMF and curing temperature.     

三聚氰胺磷酸盐阻燃剂的合成及性能表征

以新方法合成了三聚氯胺磷酸盐自膨胀阻燃剂(MP)，其结构经元素分析、XRD，TG，DSC，IR等表征。测定了含MP阻燃材料的阻燃性能，讨论了其阻燃机理及特点。用MP对聚丙烯进行阻燃处理后其氧指数可达27．1；徐覆含MP自膨胀防火涂料的五层板在模拟火灾中的耐火极限达39min，发泡倍数为90倍-100倍。     

三聚氰胺焦磷酸盐阻燃剂的合成及性能表征

三聚氰胺焦磷酸盐自膨胀阻燃剂[1]无卤、低烟、低毒,其热解温度与被阻燃材料的降解温度的匹配,效果很好。本文合成了三聚氰胺焦磷酸盐(MPP)[2],用元素分析,XRD、TG、DSC、IR等表征,并对其阻燃性能进行了测定,讨论了阻燃机理。1　实验部分1.1　仪器与试剂三聚氰胺(化学纯,含量不少于98.5%,北京化工厂);焦磷酸钠(Na4P2O7·10H2O,分析纯,含量不少于99.0%,上海科昌精细化学品公司);浓硫酸(分析纯,成都新都金牛王化工厂);硝酸(分析纯,成都有机化学试剂厂)。岛津TG 50H热重分析仪和DSC 50H差热分析仪;PerKin Eimer240C元素分析仪;…     

Melamine driven supramolecular self‐assembly of nucleobase derivatives in water

Water‐soluble supramolecular polymers, especially made up of biomolecules, are ideally suited to build new biomaterials that can mimic or interact with dynamic, biological environments. Here, two derivatives from thymine (T), that is N‐[2‐(3,4‐Dihydro‐5‐methyl‐2,4‐dioxo‐1(2H)‐pyrimidinyl)acetyl]‐L‐phenylalanine (T‐phe) and N‐(2‐Aminoethyl)‐3,4‐dihydro‐5‐methyl‐2,4‐dioxo‐1(2H)‐pyrimidineacetamide (T‐NH₂) were synthesized. Then the optimal condition for self‐assembly of T‐phe and T‐NH₂ driven by melamine (M) was explored. It was observed that M/T kept at 1:3 with equivalent T‐phe and T‐NH₂ under neutral environment resulted in long fibers (>1 μm) with extremely high aspect ratios, which suggested that electrostatic and π‐stacking interactions could be effectively orchestrated by hydrogen bonds to direct the hierarchical assembly. Furthermore, hydrogels were spontaneously generated with a concentrated solution of T‐phe, T‐NH₂, and M due to the fibril entanglement. Given its biomimetic nature and efficient self‐assembly process, this newly developed supramolecular polymer stacked by tetrameric structures represented an innovative concept and pathway for novel bio‐inspired materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 789–796     

Pd immobilized on polyamide based on melamine and terephalic acid as an efficient and recyclable catalyst for Suzuki‐Miyaura coupling reaction

A simple synthetic strategy of polyamide was described from melamine and terephalic acid via one‐step polycondensation. PdCl₂ was then immobilized on the polyamide (denoted as Pd/MPA). Melamine and terephalic acid not only acted as monomers but also provided the ligand sites to help the polyamide to coordinate with Pd(II). The Pd/MPA catalyst was characterized by FT‐IR, TGA, SEM, TEM, XPS, N₂ adsorption‐desorption and atomic absorption spectroscopy. The catalyst was used in Suzuki‐Miyaura coupling reaction of various aryl halides, including less reactive chlorobenzene and benzyl chloride, to give the coupling products in moderate to excellent yields. High turnover frequencies (TOF) up to 29400 h^‐1 can be also obtained. In addition, it behaved truly as a heterogeneous catalyst with high reusability after being recycled 6 times and palladium leaching was negligible during the process. This work provides a practical polyamide support to develop heterogeneous palladium catalysts with simple synthetic procedure and low cost.     

Preparation and characterization of microencapsulated LDHs with melamine‐formaldehyde resin and its flame retardant application in epoxy resin

Layered double hydroxides (LDHs) are emerging as a new and green high‐efficient flame retardant. But LDHs aggregate seriously because of their hydrophilicity, which affect deeply the mechanical and flame retardant properties of their composites. For the first time in this paper, microencapsulated LDHs (MCLDHs) with melamine‐formaldehyde (MF) resin were prepared by microencapsulation technology to enhance their compatibility and dispersion within epoxy resin (EP). The mechanical and flame retardant performances of EP/MCLDH composite were studied by comparing with EP/LDH composite. Results showed that the water contact angle of MCLDHs increased from 8.9° to 122.1°, which indicated good compatibility. The particle size of MCLDHs decreased sharply, and more than one‐third were up to submicron scale, which can be conducive to dispersion. Moreover, the tensile strength and elongation at break of EP/MCLDHs with different flame retardant contents were higher than those of EP/LDHs. And the addition of MCLDHs increased the glass transition temperature (Tg) of EP/MCLDHs, which meant a strong interfacial interaction. Besides, compared with EP/LDHs, the limiting oxygen index values of EP/MCLDHs were higher, and its peak of heat release rate and total heat release decreased by 16.3% and 5.5% respectively. EP/MCLDHs achieved from V‐1 to V‐0 rate with the increasing content of MCLDHs from 20% to 30%, while LDHs/EP never passed tests. In the process of heating, H₂O, CO₂, and NH₃ released from MCLDHs formed gaseous phase, and the remaining dense char layers and oxides produced condensed phase, which played an important role in inhibiting combustion.     

Melamine as a Green and Reusable Catalyst for Knoevenagel Condensation at Room Temperature Under Solvent-Free Conditions

A rapid, efficient, and ecofriendly protocol has been developed for the Knoevenagel condensation of active methylene compounds such as malononitrile or ethyl cyanoacetate with aldehydes in the presence of melamine with good to excellent yields at room temperature without solvent.