激光加热物体的三维模型计算

将物体的热传导系数、比热容、密度、物体对激光的吸收系数考虑成温度的函数,并考虑到物体向周围空间有热辐射和对流换热交换能量等情况下,用控制容积法对激光加热物体作三维真实边界的计算分析.这一结果在激光加热物体温度场的计算上有广泛的实用性.     

Characterization and Comparative Studies on Conventional and Microwave Synthesis of Some Disulfides

Abstract

Some disulfide derivatives have been prepared by microwave assisted synthesis methodology from thiophthalimides(sulfenimides) and thiols in a modified microwave oven under reflux at 600 Watt in ethanol. Elucidation of the structures of the synthesized compounds has been performed by IR, ¹H NMR, and ¹³C NMR spectroscopic methods.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures]     

侧链型磺化聚芳醚酮质子交换膜材料的制备

本文通过对聚合物的结构设计, 采用均聚的途径将柔顺的大侧基(甲氧基苯基)引入聚芳醚酮侧链, 然后通过室温后磺化的方法成功制备出侧链型磺化聚芳醚酮材料. 此类材料表现出较好的热稳定性; 力学性能优异; 聚合物的质子传导率比报道过的类似材料有较大程度的提高; 于80 ℃时的质子传导率在0.190 S/cm以上, 超过了Nafion 117 薄膜的传导率(0.175 S/cm). 因此这类材料有望在质子交换膜领域得到应用.     

Irregular phenomenon induced by Ag atomic segregation during the heating process of Ag-Pd cluster

This paper studies the melting of icosahedral Ag-Pd bimetallic clusters by using molecular dynamics with the embedded atom method.It finds that the mixed Ag-Pd cluster shows an irregular phenomenon before melting,i.e.,the atomic energy decreases with the increase of temperature.It indicates that the segregation of Ag atoms results in this phenomenon by analysing atomic radius distribution.Since the surface energy of Ag is lower than that of Pd,this leads to the result that the decreased energy by the Ag atomic segregation is larger than the increased energy by the heating.This provides a new method to obtain irregular thermodynamic properties.     

新型的含芳香二腈基磺化聚芳醚腈酮的合成与表征

通过Diels-Alder反应合成了一种新型的含芳香二腈基的双酚单体, 并利用此单体与活性二卤化物共聚合成了一系列高分子量的磺化聚芳醚腈酮聚合物. 聚合物的结构通过元素分析和核磁共振谱进行表征. 结果表明, 该聚合物具有优良的导质子率、尺寸和化学稳定性及良好的力学性能.     

低热固相反应制备ni0.6cu0.2zn0.2fe2o4纳米晶铁氧体

低热固相反应;溶胶凝胶;nicuzn铁氧体     

Thermogravimetric characterization of sulfonated poly(styrene-isobutylene-styrene) block copolymers: effects of processing conditions

In this study, sulfonated poly(styrene-isobutylene-styrene) (S-SIBS) block copolymers were characterized by thermogravimetry as a function of four different processing conditions: sulfonation level, annealing temperature, film formation, and casting solvent. Sulfonated samples showed an increase in degradation temperature from 432 to 450 °C compared to the unsulfonated polymer, regardless of sulfonation level or other processing condition. Sulfonated samples also showed an additional minor loss of mass at approximately 290 °C, which was not observed in the unsulfonated polymer. At this temperature, desulfonation or a cleavage reaction of the aromatic carbon–sulfur bond occurs. In addition, annealing the sulfonated block copolymer at a higher temperature (180 °C) for an extended period of time also results in a partial desulfonation. These results were confirmed by a reduction in water sorption and in intensity of the infrared bands associated with sulfonic acid. There was no change in thermal stability in S-SIBS block copolymers as a function of film formation (solvent cast versus heat pressed) and casting solvent (six different solvents).     

The effect of the heating rate on the phase transition

ABSTRACT

The simple cubic spin-1 Ising model exhibits the ferromagnetic (F)–ferromagnetic (F) phase transition in the low temperature region for the interval 1.40 < d = D/J < 1.48 at k = K/J = –0.5. The degree of the F-F phase transition determines the special point on the (k_BT/J, d) phase diagram. In this paper, the critical behavior of the F-F phase transition was investigated for different heating rates using the cellular automaton heating algorithm. The universality class and the type of F-F phase transition were analyzed using the finite-size scaling theory and the power law relations. The results show that the F-F phase transition may be the second order, the first order or the weak first order depending on the heating rate in the interval 1.40 < d < 1.48 for k = –0.5.     

Characterization of Microwave and Conventional Heating on the Pyrolysis of Pistachio Shells for the Adsorption of Methylene Blue and Iodine

The production of activated carbon was investigated using the sequential combination of microwave and conventional heating of pistachio shells as the raw precursor with zinc chloride. Several techniques such as thermogravimetric and differential thermal analyses, infrared spectroscopy, scanning electron microscopy, and specific surface area analyses were performed to characterize the samples. The highest specific surface area value for the activated carbon prepared at a microwave power of 200?W with microwave time of 20?min, and flow rate of 50?mL?min^?1 was 1468?m²?g^?1. The methylene blue and iodine adsorption capacities were 331 and 1276?mg?g^?1, respectively. The results were compared to those obtained using physical and chemical activation methods and showed that the sequential combination of microwave and conventional heating reasonably influenced the micropore surface area of the samples as well as the specific surface area.     

Frequency Dependence of the Dynamic Heat Capacity at the Melting Temperature of Polyethylene Crystals

The dynamic heat capacity of polyethylene was measured in the heating process over two decades of the modulating frequency using the light heating modulated temperature DSC. The dynamic heat capacity exhibited clear frequency dependence from 95°C to the end of the melting of the crystals. Frequency dependence of this work was compared with that of the quasi-isothermal measurement. The relaxation time estimated in this work was much shorter than that of the quasi-isothermal measurement. It was found that notable heat exchange between the sample and reference sides occurred between 120 and 135°C. Frequency dependence of the heat exchange was studied.This revised version was published online in November 2005 with corrections to the Cover Date.