聚丙烯/硬石膏复合材料的非等温结晶动力学

采用DSC研究了聚丙烯(PP)及聚丙烯/硬石膏复合材料的非等温结晶动力学,对所得数据用修正Avrami方程的Jeziorny法和Mo法进行处理。结果表明:硬石膏的加入提高了PP的结晶温度Tp和结晶速率,降低了结晶活化能ΔE,使实际降温速率下PP更易结晶。同样的含量下,经铝酸酯偶联剂改性硬石膏使PP结晶速率加快,但ΔE有小幅上升。研究表明,硬石膏有异相成核作用,填加20%时异相成核多于填加10%时,铝酸酯偶联剂的改性对该作用无明显影响。     

微胶囊阻燃剂处理ABS的阻燃机理

用三聚氰胺-甲醛预聚物对CuO、Al(OH)3、Al2O3进行包覆制得微胶囊阻燃剂。采用热重分析、锥形量热分析研究添加阻燃剂的ABS的热解行为,从热量释放、烟气、CO和CO2排放等参数表征其阻燃性能,并用Kissinger方程计算ABS的动力学参数热解活化能的变化。结果表明,CuO微胶囊处理ABS热解反应活化能升高,阻燃主要在于CuO微胶囊提高了ABS热稳定性;Al(OH)3微胶囊主要通过脱水吸热对抑制发烟量效果明显;Al2O3微胶囊对ABS的热解具有催化成炭作用,使材料的热解活化能大大降低。     

套管TG22热轧钢带研究及产业化

为了适应深井及超深井应用需求,通过设计化学成分及优化轧制工艺,开发一种兼备强度和低温冲击韧性的油气井用TG22热轧钢带。结果表明:采用化学成分设计为Fe-0.24%C-0.20%Si-1.30%Mn-0.020%Nb时,加热炉目标出钢温度1170℃、中间坯厚度46mm、终轧温度830℃和卷取温度570℃时,热轧钢带力学性能为Rel 506～554 MPa、Rm 654～685 MPa、A₅₀29%～35%、Rel/Rm 0.75～0.82及KV₂（-10℃）45.5～63.6 J。     

水泥胶凝材料水化进程及力学特性研究

首先简述了热分析的测定原理及其在水泥化学研究中的应用;利用热重方法分析了水泥净浆的水化进程变化规律,研究了不同水灰比的水泥净浆水化程度;并从理论上解释了不同水灰比的水泥净浆水化程度发展规律;而且,对水泥净浆水化过程中的抗压强度进行了测试,试验结果发现其变化趋势与水化程度变化趋势是完全一致的,这充分反映了微观结构与宏观性能之间的关系.     

2.巯基吡啶汞(Ⅱ)的合成及热分解动力学

合成了以2-巯基吡啶为配体的汞(Ⅱ)配合物,通过元素分析、EDTA络合滴定分析和红外光谱对其进行了表征,同时采用TG-DTG技术研究了配合物的热分解机理及非等温动力学。结果表明:其配合物热分解过程经过二个阶段,第一步热分解属F2(化学反应)机理控制,非等温热分解的动力学方程为dα/dT=A/β.e-E/RT(1-α)2,表观活化能E=189.67 kJ/mol,指前因子A=3.79×1018/s。     

Globally optimal synthesis of heat exchanger networks. Part III: Non-isothermal mixing in minimal and non-minimal networks

In this work, the enumeration algorithms presented in Parts I and II for the globally optimal synthesis of minimal and non-minimal heat exchanger networks are extended to consider non-isothermal mixing. New mathematical models, including non-isothermal mixing constraints, are proposed to target the bounds of energy consumption and the binding exchanger minimum approximation temperature. These models are solved using the algorithms, which involve solving systems of equations instead of mathematical programming. Three global optimization strategies are proposed to optimize each enumerated structure, involving the use of a global solver directly, or the use of a Golden Search based on energy consumption and a flowrate optimization model considering non-isothermal mixing. The flowrate optimization model is reformulated as a convex problem, which is solved by using nonlinear programming or a mathematical programming-free methodology, that is, solving Karush–Kuhn–Tucker equations. A new Global Optimum Search Algorithm is developed and examples are tested comparing different optimization strategies.     

Kinetics study on non-isothermal crystallization of Ni1.5MnSn0.5Co alloy thin films

ABSTRACT

The crystallization kinetics of the Ni_1.5MnSn_0.5Co free-standing alloy thin films is investigated by continuous heating differential scanning calorimetry (DSC). The results show that all the DSC traces have a single exothermic peak, with a long high temperature tail. The DSC curves have been analyzed in terms of activation energy and kinetic model. We find that the activation energy of film obtained by both the Kissinger and Ozawa equation methods can give consistent results, the activation energy for crystallization is determined as 221.2 and 220.9 KJ/ mol, respectively. Moreover, the volume fraction crystallized has significantly influence on the local activation energy, and the regular of the nucleation and growth of films has been changed at crystallization process. Our work would enrich the mechanism of the crystallization kinetics for annealing applications of Ni-Mn-Sn-Co thin films in microelectro mechanical systems (MEMS).     

Non-isothermal crystallization of Ziegler Natta i-PP-graphene nanocomposite: DSC and new model prediction

Crystallization occurs in processing i-PP-GnP nanocomposites, and these nanocomposites have the potential to replace traditional fillers and be used to fabricate advanced materials and technology. Therefore, this subject was comprehensively investigated by applying a recent crystallization model, non-isothermal DSC experiments, Raman spectroscopy, and WAXRD. The multi-layer GnP-induced nucleation and the crystal growth rates were modelled. The overall modelling effort generated new insights, results, and explanations. This study confirmed and elucidated, or refuted several published conclusions. It has also been reported that the present model can pursue differences in catalyst-mediated i-PP backbone defects (stereo and regio) by simulating the relative crystallization profile and determining the crystallization kinetic triplet (n, k _o, and E _a). The multiple roles played by GnP were underscored, which exceed what the related literature currently reports. The Raman and XRD work revealed the interaction between GnP and i-PP. The shear-induced dispersion of GnP that occurs during extrusion significantly affected i-PP crystal size distribution. The present approach can also assess the effects of catalyst type and structure, and backbone defect types and their distribution on the non-isothermal crystallization of, in general, polyolefin blends and nanocomposites.     

Methacrylate monomer as an alternative to styrene in typical polyester–styrene copolymers

This study presents the research on the influence of crosslinking monomers [styrene and diethylene glycol dimethacrylate (DEGDMA)] on the properties of unsaturated polyester resins (UPRs). Syntheses of the unsaturated polyesters (UPs) modified with benzyl alcohol were carried out. Then, each polyester was used in preparation of five resin solutions with different amounts of crosslinking monomers acting as reactive diluents. These diluents improve the processability of UPs reducing their viscosities. They also take part in crosslinking of resins during copolymerization process. The properties of the prepared UPRs systems were investigated before and after the curing process. The measurements of their viscosity, reactivity, mechanical properties, thermal stability (thermogravimetry), and dynamic mechanical analysis were performed. Resins where DEGDMA was used as reactive diluent were characterized by the largest viscosities in comparison to styrene ones. The type of the used monomer influenced also degree of the resin crosslinking. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47735.     

Non-isothermal annealing of a cold rolled commercial twin roll cast 3003 aluminum alloy

It is shown that the recrystallization behavior of a cold rolled twin roll cast, commercial 3003 aluminum alloy under non-isothermal conditions, can be satisfactorily modeled by combining the approaches developed by Semiatin et al. and Puchi et al. The first approach allows the determination of the apparent activation energy for recrystallization without any ambiguity, information that can then be used in the second approach to define clearly the search range for the value of the apparent activation energy for recrystallization and to determine simultaneously the Avrami constants, from experiments conducted at a single heating rate. It is also shown that the apparent activation energy for recrystallization in this alloy varies between approximately 34 and 79 kJ/mol, with the trend being to find smaller values of this parameter as the strain applied to the material increases. Such low values of this energy were corroborated by isothermal experiments conducted in samples of the same material. The microstructural evolution of the samples annealed under non-isothermal conditions indicates that the rate of growth of the recrystallized grains in the rolling direction is significantly higher that in the short transverse direction, due to the pinning effect of the second phase particles aligned along the rolling direction, which leads to recrystallized structures with an aspect ratio significantly higher than 1. The effect of the strain applied to the material on the recrystallization kinetics is quantified by expressing the time required to achieve a given recrystallized fraction as a function of the effective strain, by a simple parametric relationship that involves three numerical constants. Recrystallization experiments conducted under non-isothermal conditions are found to be more suitable for the evaluation of the effect of the strain applied on the recrystallization kinetics in comparison with isothermal tests, since larger strains can be applied to material before the annealing treatment.