Flame retarding polyamide 6 with melamine cyanurate and layered silicates

The flammability behavior of the system polyamide 6 (PA 6) + melamine cyanurate (MC) with or without organically modified layered montmorillonite (OMMT) or sodium montmorillonite (Na⁺MMT) was studied. The high degree of flame retardancy (FR) obtained with 13 wt% MC is maintained upon adding up to 0.2 wt% OMMT or Na⁺MMT. Increase mass % of OMMT is antagonistic to the MC effect. The rate of dripping decreases while the size and mass of drops in the UL‐94 tests increases with increasing wt% OMMT indicating increase in viscosity of the melt and decrease in the rate of sublimation of melamine. Addition of poly vinyl pyrrolidone (PVP) decreases the viscosity and partially restores the FR rating. Na⁺MMT does not increase the viscosity and the FR ratings are partially preserved. The peak of heat release rate (PHRR) in the cone calorimeter decreases with increased loading of OMMT. Addition of Na⁺MMT or PVP has little influence on the PHRR. The time of ignition decreases with increase in OMMT, but is not affected when Na⁺MMT is used. This is explained by the low thermal conductivity of the clay containing surface layer of samples during pyrolysis and combustion. Mechanistic considerations are presented. Copyright © 2008 John Wiley & Sons, Ltd.     

Flame retardancy mechanisms of poly(1,4‐butylene terephthalate) containing microencapsulated ammonium polyphosphate and melamine cyanurate

The flame retardancy mechanisms of poly(1,4‐butylene terephthalate) (PBT) containing microencapsulated ammonium polyphosphate (MAPP) and melamine cyanurate (MC) were investigated via pyrolysis analysis (thermogravimetric analysis (TGA), real‐time Fourier transform infrared (FTIR), TG‐IR), cone calorimeter test, combustion tests (limited oxygen index (LOI), UL‐94), and residue analysis (scanning electron microscopy (SEM)). A loading of 20 wt% MC to PBT gave the PBT composites an LOI of 26%, V‐2 classification in UL‐94 test and a high peak heat release rate (HRR) in cone calorimeter test. Adding APP to PBT/MC composites did not improve their flame retardancy. In comparison with the addition of ammonium polyphosphate (APP) to PBT, MAPP with silica gel shell and MAPP with polyurethane shell both promoted the intumescent char‐forming and improved the flame retardancy of PBT through different mechanisms in the presence of MC. These two halogen‐free PBT composites with V‐0 classification according to UL‐94 test were obtained; their LOI were 32 and 33%, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

丙烯酸甲酯-三烯丙基氰尿酸酯和二乙烯苯共聚物MA/TD的合成及其孔结构的研究(Ⅲ)

制备了一系列丙烯酸甲酯(MA)-三烯丙基氰尿酸酯(TAC)和二乙烯苯(DVB)混合交联剂的共聚物小球,测定和讨论了混合交联剂、致孔剂用量和性质等诸因素对共聚物的比表面积、孔容、平均孔径,孔径分布和孔度的影响。同时,初步探讨活性相对较低的三烯丙基氰尿酸酯在混合交联共聚中的作用。     

Interdigitated crystalline MMT‐MCA: Preparation and characterization

A novel nanomaterial, montmorillonite–melamine cyanurate (MMT‐MCA), was successfully synthesized, in which the number of MCA layers in between 2 MMT layers can be controlled at 1 or a very large value (over 100 nm thick). Its interdigitated crystalline structure was thoroughly characterized. The MMT‐MCA shows outstanding dispersion ability in different polymers to easily prepare MMT nanocomposites by melt blending due to the π‐π stacking exfoliation between MCA layers. The paper opens the way to the synthesis of novel interdigitated nanomaterials.     

Second harmonic generation properties of Ca3(O3C3N3)2 ‐Sr3(O3C3N3)2 solid solutions

Solid solutions of the second harmonic generation (SHG) materials Ca₃(O₃C₃N₃)₂ (CCY) and Sr₃(O₃C₃N₃)₂ (SCY) were prepared via exothermic solid state metathesis reactions from appropriate amounts of the corresponding metal chlorides and potassium cyanate at 525 °C. The change in SHG intensity caused by the successive cation substitution is reported. Differential thermal analyses are used to explore the SCY–K(OCN) phase diagram as a medium for the growth of SCY crystals.     

SOLVENT EFFECT ON GELATION IN THE RADICAL POLYMERIZATION OF TRIALLYL ISOCYANURATE

Radical solution polymerization of triallyl isocyanurate was conducted in methyl benzoate or hexyl benzoate as good or poor solvent, respectively, using AIBN as initiator at 60°C. An increased rate of polymerization, enlarged primary chain length, and promoted gelation were observed in the poor solvent. The actual gel point was compared with the theoretical one; the discrepancy between these points was great, although no substantial solvent effect was detected. These results are discussed in comparison with the results obtained from the polymerizations of its isomer triallyl cyanurate and diallyl terephthalate, a typical diallyl ester. The swelling ratio of the gel obtained just beyond the gel point was quite high, suggesting no microgelation up to the gel point conversion even in the solution polymerization.     

大孔交联甲基丙烯酸缩水甘油酯共聚物的合成及其吸附性能研究(Ⅱ)对磷的吸附性能

前文[1]介绍了大孔交联甲基丙烯酸缩水甘油酯（GMA）与三烯丙基氰尿酸酯（TAC）共聚物（GT）的合成及其孔结构性能。本文研究了GT共聚物经与甘露醇进行功能基化反应制得新型吸磷吸附剂（GTG）。并观察了该吸附剂在诸因素（如pH值、温度及时间等）对磷的吸附性能。实验结果表明：该吸附剂在磷酸盐缓冲液中，pH＝7．0时，温度为37℃，磷的初始含量为10mg／dl时，吸附剂对磷的吸附量可达8．60mg／g吸附剂。     

三聚氰胺氰尿酸盐对玻纤增强尼龙66复合材料阻燃性能的影响

将三聚氰胺氰尿酸盐(MCA)阻燃剂添加到玻纤增强的尼龙66复合材料(GF-PA66)中。利用UL-94实验对MCA在复合材料中的阻燃效果进行研究;通过扫描电子显微镜(SEM)分析了燃烧后的样品形貌,并利用热重分析法对复合材料的热分解行为进行了研究。结果表明:MCA可使玻纤增强尼龙66复合材料达到UL-94V-0级阻燃效果;MCA晶体被均匀地分散于尼龙基体中,在燃烧时MCA通过自身吸热分解,产生不可燃气体,实现气相阻隔,从而起到阻燃作用,并在复合材料自熄面上留下纳米级气孔。     

Hydrogen bonded complexes of cyanuric acid with pyridine and guanidinium carbonate

Hydrogen bonded complexes of cyanuric acid (CA) with pyridine, [C₃N₃H₃O₃:C₅H₅N], 1, and guanidinium carbonate [C₃H₂N₃][C(NH₂)₃],2, have been prepared at room temperature and characterized by single-crystal X-ray diffraction. Structure of 1 shows pyridine molecules substituting the inter-tape hydrogen bond in CA by N-H… N and C-H…O hydrogen bonds. The structure reveals CA-pyridine hydrogen-bonded single helices held together by dimeric N-H…O hydrogen bonding between CA molecules. In2, the CA tapes, resembling a sine wave interact with the guanidinium cations through N-H…O and N-H…N hydrogen bonds forming guanidinium cyanurate sheets.     

Effect of organo‐modified montmorillonite on flame retardant poly(1,4‐butylene terephthalate) composites

In this paper, the effect of organo‐modified montmorillonite (OMMT) on a novel intumescent flame retardant (IFR) system was studied in poly(1,4‐butylene terephthalate) (PBT) composites containing microencapsulated ammonium polyphosphate (MAPP) and melamine cyanurate (MC). Nanocomposite morphology was characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal decomposition analysis was studied via thermogravimetric analysis (TGA). Combustion behavior was investigated by microcombustion calorimeter (MCC), limited oxygen index (LOI), and UL‐94 test. Residues obtained after samples treated in muffle furnace at 500°C under air condition for 10 min were analyzed through X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM). It was found that the addition of OMMT improved the flame retardancy of PBT/IFR composites significantly. A mass of microcomposite structure particles formed in the heating or combustion process of PBT/IFR/OMMT nanocomposites were found for the first time in the SEM images, which is strong evidence to confirm the migration or accumulation of montmorillonite and carbonaceous‐silicate materials during the heating or combustion process. Copyright © 2010 John Wiley & Sons, Ltd.