膨胀型聚氨酯防火涂料阻燃机理的研究

用自制的新型成炭剂和聚磷酸铵复配作为聚氨酯防火涂料的阻燃体系。采用热失重分析、扫描电镜、红外光谱和元素分析等手段对膨胀型聚氨酯防火涂料的阻燃机理进行了较为深入的研究．     

KF–KBr–K<Subscript>2</Subscript>SO<Subscript>4</Subscript> system

The KBr–D (K₃FSO₄) quasi-binary system and the KF–KBr–K₂SO₄ ternary system were studied by differential thermal analysis. The melting points and compositions of eutectic mixtures were determined. In-, mono-, and divariant equilibria were described.     

Study of the NaF–NaBr–Na<Subscript>2</Subscript>SO<Subscript>4</Subscript> system

The NaBr–D (Na₃FSO₄) quasi-binary system and the NaF–NaBr–Na₂SO₄ ternary system were studied by differential thermal analysis. The melting points and compositions of eutectic mixtures were determined, and in-, mono-, and divariant equilibrium states were described.     

Phase equilibria in the ternary system NaF–KF–CsF

The ternary eutectic system CsF–KF–NaF was studied by differential thermal analysis. The melting point and composition of the ternary eutectic were determined, and so was the boundary of the region of limited series of solid solutions within the composition triangle. The compositions of crystallizing phases were confirmed by X-ray powder diffraction analysis. The specific enthalpy of melting of the ternary eutectic was experimentally found.     

Synergistic effects of zeolites on a novel intumescent flame-retardant low-density polyethylene (LDPE) system

A char forming agent and silica-gel microencapsulated APP were selected to form novel intumescent flame-retardant system (IFR) to prepare flame-retardant low-density polyethylene (LDPE) composites, and then the influence of zeolites on the thermal and flame-retardant properties of flame-retardant LDPE composites were studied. With the addition of 1 wt% zeolites to LDPE/IFR system, the LOI value increases from 29.0 to 34.0 %. The results of cone calorimetry show that the heat release rate peak and total heat release of the intumescent flame-retardant LDPE composite with 1 wt% zeolites decreases remarkably compared with that of without zeolites. The scanning electron microscopy indicates zeolites with suitable content can improve the quality of the char layer of flame-retardant LDPE composite which is more coherent and dense. The zeolites with the appropriate content can remarkably improve the flame-retardant properties of the LDPE composites.     

Syntheses and physical properties of two-component polyurethane flame-retardant coatings using chlorine-containing modified polyesters

Two-component polyurethane flame-retardant coatings were prepared by blending chlorine-containing modified polyesters (DCAOs) and polyisocyanate. DCAOs used were synthesized by polycondensation of dichloroacetic acid, a flame-retardant aliphatic carboxylic acid, with 1,4-butanediol, trimethylolpropane, and adipic acid. The content of dichloroacetic acid was varied in 10, 20, and 30 wt % for the polycondensation reaction. Various physical properties of these new flame-retardant coatings were comparable to nonflame-retardant coatings. They showed desirable properties for flame-retardant coatings such as rapid drying and 8–10 hours of pot-life. Coatings with 30 wt % dichloroacetic acid were not fired by the vertical burning test. © 1996 John Wiley & Sons, Inc.     

Lattice parameters and melting behavior of the B2-phase in the ternary gold-cadmium-zinc system

Lattice parameter and DTA-measurements were performed in the range of the ternary B 2-phase in the gold-cadmium-zinc system. It could be shown that a continuous range of homogeneity exists between β′-AuCd and β′-AuZn. Lattice parameter values are reported for a number of compositions. The ternary liquidus projection is given between about 40 and 60 at % Au. The congruent melting point of the binary β′-AuZn phase was found to be at 51.5±0.5 at % Au and 758±3°C.     

BeSO4-Al2(SO4)3-Na2SO4三元熔盐体系相图的研究

热分析法研究了BeSO₄-Al₂(SO₄)3-Na₂SO₄三元熔盐体系的状态图。体系中存在三元转熔(包晶)点P,温度490℃,组成为BeSO₄18.8Wt%,Al₂(SO₄)₃15.0%,Na₂SO₄66.2%;三元低共熔(共晶)点E₁,温度为476℃,组成为BeSO₄20.0%,Al₂(SO₄)₃11.2,%,Na₂SO₄68.8%。另一低共熔点E₂温度为595℃,组成未能确定。体系中无三元化合物生成。     

冷冻过程中胞内溶液均相成核温度的确定

为了研究冷冻过程中胞内溶液均相成核温度下降值与平衡凝固点下降值的关系, 提出了一种求解变组元系统成核温度的方法, 并联合细胞脱水方程, 进行了数值求解. 研究发现, 甘油-氯化钠-水三元系统的均相成核温度下降与平衡凝固点下降存在如下的线性关系: ⊿Th=1.17⊿Tm, 表明水溶液均相成核温度与溶质有关.     

Corresponding-states correlation for the saturated liquid density of metals and metal mixtures

A corresponding-states correlation for the prediction of the orthobaric liquid density of molten metals has been developed. The correlation is the extension of the recently developed correlation by Iglesias-Silva and Hall, which needs the values of the critical and triple point constants as well as an adjustable parameter. The critical constants are scarce for almost all metals. Our corresponding-states correlation uses the normal boiling and melting point constants plus an adjustable parameter. While the present correlation is simpler in form than the correlation by Iglesias-Silva and Hall, all of its input data are more readily available for almost all metals. In this work, we have applied the present correlation to molten alkali metals, mercury, bismuth, tin, and lead. From about 150 data points for pure liquid metals the average absolute deviation and the maximum deviation are 0.29 and 1.06%, respectively. Also, we have extended the correlation to mixtures of any number of components. The predicted results for the liquid densities of K–Cs and K–Na mixtures over the whole range of concentrations and that of a ternary molten eutectic of K–Na–Cs at temperatures ranging from melting point up to several hundred degrees above the normal boiling point are in excellent agreement with experimental data. From 247 data points examined for molten alloys, the average absolute deviation and the maximum deviation are 0.59 and 1.91%, respectively.     

Theoretical Study on the Structures and Thermal Properties of Ag–Pt–Ni Trimetallic Clusters

The structures and thermal properties of Ag–Pt–Ni ternary nanoclusters varying with different compositions and sizes are studied by Monte Carlo and molecular dynamics simulations. It can be found that silver atoms tend to occupy the surface and platinum atoms favor the subsurface occupation, whereas the inner is occupied by nickel atoms due to the different surface energies and lattice parameters. In addition, there is a non-monotonous relationship between the melting points and compositions of Ag–Pt–Ni ternary nanoclusters according to molecular dynamics simulations. In addition, a linear decrease in melting point with \(N^{ - 1/3}\) is found for both monometallic and trimetallic clusters. This behavior is consistent with Pawlow’s law.     

Phase study of the system Li2Se-In2Se3

The binary system Li₂Se-In₂Se₃ was investigated in the range of 40 to 100 mol% In₂Se₃ by thermoanalytical and X-ray methods. The system is characterized by two eutectic points. Beside the two binary components and the known ternary compound LiInSe2 another ternary compound crystallizes in this binary system at 83.3 mol% In₂Se₃. This compound was identified as LiIn₅Se₈. In contrast to (Cu, Ag)^IB₅ ^IIIC₈ ^VI compounds such as CuIn₅S₈ [1] it does not crystallize in the spinel structure. LiIn₅Se₈ shows a stratified structure. The melting point was determined to be at 810°C. Starting from room temperature up to the melting point no phase transitions were observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Intumescent flame retardants for polymers. II. The polypropylene-ammonium polyphosphate-polyurea system

The mechanism of action of ammonium polyphosphate (APP) and polyurea (PU) as flame retardant (FR) agents for polypropylene (PP) was examined. The APP–PU system behaves as an intumescent flame-retardant (IFR) formulation. Comparison of the oxygen index (OI) measured on molded pellets and rods, values of the polymer temperature measured just below the burning surface, and visual considerations describe the IFR action of this system. A strong synergism between APP and two of the four polyureas investigated here was ascertained with a maximum 3:1 ratio. Thermogravimetric (TG), OI, nitrous oxide index (NOI), and char-residue measurements were made. On the basis of our data, it can be concluded that polyurea acts as a catalyst for the charring reactions of the APP on PP.     

Ammonium bisulfate/water: a pseudobinary system

We have studied the ammonium bisulfate/water system using thermal analysis (differential scanning calorimetry) and infrared spectroscopy of thin films. Our results for the melting points for ice and letovicite are in good agreement with other experimental work. However, we report here the first measurements of the ice/ammonium bisulfate/letovicite invariant point. We have used our observations and solubility data to construct a complete phase diagram for this system. Utilizing phase diagram theory and the Gibbs phase rule, we conclude that this system is not a true binary system but rather a pseudobinary system, which has a range of concentrations that cannot be represented by a simple binary phase diagram and thus must be viewed as part of the ternary system: H(2)SO(4)/(NH(4))(2)SO(4)/H(2)O. We also compared our results to the phase diagram predictions of the aerosol inorganics model and found the predicted melting points are in good agreement with experimental work over a limited concentration range, but the transitions predicted by the model at lower temperatures are not in agreement with experimental results.     

Li,Cs||F,NO<Subscript>3</Subscript> ternary reciprocal system

The Li, Cs||F, NO₃ ternary reciprocal system was for the first time described and experimentally studied by differential thermal analysis and differential scanning calorimetry. Phase equilibrium states were determined, and so were the compositions and melting points of two ternary eutectics. Reactions describing the chemical interaction in the system were presented.     

Phase diagrams of diphenyl–<Emphasis Type="Italic">n</Emphasis>-dodecane and diphenyl–diphenyl oxide–<Emphasis Type="Italic">n</Emphasis>-dodecane systems

The phase equilibria in the binary diphenyl–n-dodecane and ternary diphenyl–diphenyl oxide–n-dodecane systems was studied by differential scanning calorimetry. The melting temperatures and eutectic compositions were determined. The physicochemical characteristics of eutectic alloys such as the flash point, density, and enthalpy of fusion were given. The kinematic viscosity of eutectic alloys was determined in the temperature range 25–50°C.     

Double-layered co-microencapsulated ammonium polyphosphate and mesoporous MCM-41 in intumescent flame-retardant natural rubber composites

Double-layered co-microencapsulated ammonium polyphosphate (APP) and mesoporous MCM-41 (M(A&M)) were prepared using melamine–formaldehyde resin and zinc borate by in situ polymerization. The structure of the microcapsules was characterized by particle size analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Double-layered microencapsulation gave APP narrow particle size distribution. The flame-retardant and mechanical effects of M(A&M) in natural rubber (NR) were evaluated using the limiting oxygen index, UL 94 test, thermogravimetric analysis, and tensile test. Results indicated that the NR/M(A&M) composites had much better flame-retardant and mechanical properties than the NR/APP/MCM-41 composites. The limited oxygen index value of the NR/M(A&M) composite reached the maximum, and the UL-94 ratings were increased to V-0 when the ratio of APP to MCM-41 was 39:1 in microcapsule. The occurrence of a synergistic effect between MCM-41 and intumescent flame-retardant in the NR composites was proved. This investigation provided a promising formulation for flame-retardant NR composites.     

Nanoclay and carbon nanotubes as potential synergists of an organophosphorus flame-retardant in poly(methyl methacrylate)

This study explores whether nanoparticles incorporated in polymers always act as synergists of conventional flame-retardant additives. For this purpose, two different filler nanoparticles, namely organically modified layered-silicate clay minerals or nanoclays and multi-walled carbon nanotubes, were incorporated in poly(methyl methacrylate) filled with an organophosphorus flame-retardant that acts through intumescence. Effective dispersion techniques specific to each nanoparticle were utilized and prepared samples were thoroughly characterized for their nanocomposite morphologies. Nanoclays were shown to outperform carbon nanotubes in respect of improving the fire properties of intumescent formulations assessed by cone calorimeter analysis. An intriguing explanation for the observed behaviour was the restriction of intumescence by strong carbon nanotube networks formed on the flaming surfaces during combustion contrary to enhanced intumescent chars by nanoclays. Carbon nanotubes surpassed nanoclays considering the thermal stability of intumescent formulations in thermogravimetry whereas mechanical properties were significantly superior with nanoclays to those with carbon nanotubes.     

Cu-Zn-Sn体系富Sn区液相限的研究

近些年来,无铅低熔点填料日渐引起人们的兴趣,且将得到广泛的应用。Cu-Zn-Sn合金正是无铅低熔点填料的一种基本合金。该体系相图虽有一些报道,但他们的研究只涉及富铜区(>50Wt％)的液相限和等温截面(500℃)。我们颇感兴趣的富Sn区的液相限,尚未见文献报道,因此测定该体系富Sn区的液相限是必要的。关于Cu-Zn-Sn体系的三个相关二元体系,已有文献报道,也较成熟。对于Cu-Zn体系,富Zn区600℃以下存在两个转熔反应,其转熔点分别为Q(～88Wt％Zn,598℃),W(97.5-98.5Wt％Zn,424℃);Cu-Sn体系富Sn区有一个转熔反应,其转熔点