Thermal degradation study of intumescent flame retardants by TG and FTIR: Melamine phosphate and its mixture with pentaerythritol

Thermal degradation of intumescent flame retardants, such as melamine phosphate (MP) and the mixture of MP and pentaerythritol (PER) was studied by TG, FTIR gas analyser (G-FTIR), and FTIR spectrometry. The results indicate that the degradation behavior of MP or PER itself is different from the one of them in the mixture. The volatile degradation products of MP contain mainly NH₃, and H₂O, as well as small amounts of melamine (MEL), whereas no MEL is found in the degradation of the mixture of MP and PER. Moreover, degradation products of PER are composed of a lot of volatile combustibles such as formaldehydes, alcohols, and C–H compounds except for H₂O. The mixture of MP and PER, however, produces much less volatile combustibles during its degradation leading to the production of more charring materials.     

乙醇或乙醇-水为新的溶剂体系沉淀聚合制备单分散聚合物微球

以三羟甲基丙烷三丙烯酸酯(TMPTA)作交联剂,, 苯乙烯 (St) 作共聚单体,, 偶氮二异丁腈(AIBN)作引发剂,, 在低毒性乙醇和乙醇-水混合物这一新的溶剂体系中沉淀聚合反应4 h制备了单分散交联微球. 通过提高交联剂用量、引发剂用量和改变反应介质中水的用量探讨了提高单体转化率的方法. 结果表明,, 提高引发剂用量和增加溶剂中水的用量都能有效提高单体转化率并制得粒径均匀的微球. 保持其他条件不变,, 在乙醇中使用2 wt% AIBN仅能得到79%的单体转化率,, 提高AIBN用量至6 wt%或在介质中增加水的用量至28 vol%,, 在制得单分散微球的同时单体转化率可以达到95%以上. 文中对微球的形成机理和提高单体转化率的方法给出了理论解释.     

Flammability and thermal degradation of flame retarded polypropylene composites containing melamine phosphate and pentaerythritol derivatives

The flammability of polypropylene (PP) composites containing intumescent flame retardant additives, i.e. melamine phosphate (MP) and pentaerythritol (PER), dipentaerythritol (DPER) or tripentaerythritol (TPER) was characterized by limiting oxygen index (LOI), UL 94 and the cone calorimeter, and the thermal degradation of the composites was studied using thermogravimetric analysis (TG) and real time Fourier transform infrared (RTFTIR). It has been found that the PP composite containing only MP does not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composite, the LOI values of the PP/MP/PER (PP/MP/DPER or PP/MP/TPER) ternary composites at the same additive loading are all increased, and UL 94 ratings of most ternary composites studied are raised to V-0 from no rating (PP/MP). The cone calorimeter results show that the heat release rate and smoke emission of some ternary composites decrease in comparison with the binary composite. It is noted from the TG data that initial decomposition temperatures of ternary composites are lower than that of the binary composite. The RTFTIR study indicates that the PP/IFR composites have higher thermal oxidative stability than the pure PP.     

新型树状化合物1,3,5-三{3-[2,4,8,10-四氧杂\|9(3,5-二(2,6-二氧杂-4,4-二羟甲基环己基)苯基]螺[5.5]十一烷基}苯的制备

本实验采用季戊四醇与苯三甲醛缩合, 制成树状化合物1,3,5-三{3-|[2,4,8,10-四氧杂-9(3,5-二(2,6-二氧杂-4,4-二羟甲基环己基)苯基)螺[5.5]十一烷基}苯. 该类树状分子具有手性螺环结构, 手性密度很高, 可开发成理想的高效手性催化剂[3~8], 具有诱人的应用前景.     

Mixed-mode reversed-phase and ion-exchange monolithic columns for micro-HPLC

This paper describes the fabrication of RP/ion-exchange mixed-mode monolithic materials for capillary LC. Following deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (gamma-MAPS), monoliths were formed by copolymerisation of pentaerythritol diacrylate monostearate (PEDAS), 2-sulphoethyl methacrylate (SEMA) with/without ethylene glycol dimethacrylate (EDMA) within 100 microm id capillaries. In order to investigate the porous properties of the monoliths prepared in our laboratory, mercury intrusion porosimetry, SEM and micro-HPLC were used to measure the monolithic structures. The monolithic columns prepared without EDMA showed bad mechanical stability at high pressure, which is undesirable for micro-HPLC applications. However, it was observed that the small amount (5% w/w) of EDMA clearly improved the mechanical stability of the monoliths. In order to evaluate their application for micro-HPLC, a range of neutral, acidic and basic compounds was separated with these capillaries and satisfactory separations were obtained. In order to further investigate the separation mechanism of these monolithic columns, comparative studies were carried out on the poly(PEDAS-co-SEMA) monolithic column and two other monoliths, poly(PEDAS) and poly(PEDAS-co-2-(methacryloyloxy)ethyl-trimethylammonium methylsulphate (METAM)). As expected, different selectivities were observed for the separation of basic compounds on all three monolithic columns using the same separation conditions. The mobile phase pH also showed clear influence on the retention time of basic compounds. This could be explained by ion-exchange interaction between positively charged analytes and the negatively charged sulphate group.     

Flame retardation and char formation mechanism of intumescent flame retarded polypropylene composites containing melamine phosphate and pentaerythritol phosphate

The flame retardation of polypropylene (PP) composites containing melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was characterized by cone calorimeter. The formation mechanism of the char obtained from the combustion of the composites after cone calorimeter testing was studied by scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman diffusion. Results demonstrated that the PP composite containing MP and PEPA showed good flame retardancy. It had been found that the intumescent char could be principally divided into three parts, i.e. outer, middle and inner char layer, according to their different structures and components.     

季戊四醇三丙烯酸酯-丙烯酸丁酯共聚微球的合成及孔结构特性研究

以季戊四醇三丙烯酸酯、丙烯酸丁酯为共聚单体,乙酸丁酯为致孔剂,用悬浮聚合法合成了-系列不同表面结构的共聚微球.使用扫描电镜、BET氮气吸附,傅立叶红外光谱等分析手段,对微球进行了结构测定,并研究了单体与致孔剂比例、两种单体比例及不同致孔剂对于聚合物孔结构的影响.经过合成条件的筛选,得到了平均孔径为100nm左右的球形聚合物.     

Monolithic capillary columns based on pentaerythritol acrylates for molecular‐size‐based separations of synthetic polymers

Monolithic capillary columns based on pentaerythritol triacrylate and pentaerythritol tetraacrylate were synthesized using different compositions of polymerization mixtures and different polymerization conditions. The impact of porogen type and porogen/monomer ratio on the porosity of synthesized monoliths was investigated. Porogen type appears to be the main factor influencing the separating properties of the monolithic sorbent. Using optimal polymerization conditions (porogen type, porogen/monomer ratio, reaction temperature, time etc.) monoliths with a porous structure optimized for polymer separations can be obtained. The monolithic capillary columns containing porous sorbents with optimized porosity are capable of separating 10 to 12 polystyrene standards in one chromatographic run utilizing both size exclusion chromatography and hydrodynamic chromatography separation mechanisms.     

A NOVEL ROUTE TO SPIRO PHOSPHORUS-HETEROCYCLE VIA LAWESSON'S REAGENT

ABSTRACT

2-Aryl-spiro-[5,5]-1,3,2-dioxaphosphorinane-2-sufides were prepared by the cyclization reaction of Lawesson's reagent with pentaerythritol and monobenzalpentaerythritol, respectively.     

Chemoselective Thioacetalisation of Aldehydes Catalysed by Fe3+-Montmorillonite #

Aldehydes were cleanly and selectively converted to the corresponding dithioacetals almost quantitatively with catalytic amounts of Fe³⁺-exchanged montmorillonite (Fe³⁺-mont) even in the presence of ketones.