Electric heating property from butyl rubber-loaded boron carbide composites

We researched the electric heating property from butyl rubber-loaded boron carbide composite. The effects of boron carbide content on bulk resistivity, voltage-current characteristic, thermal conductivity and thermal stability of boron carbide / butyl rubber （IIR） polymer composite were introduced. The analysis results indicated that the bulk resistivity decreased greatly with increasing boron carbide content, and when boron carbide content reached to 60%, the bulk resistivity achieved the minimum. Accordingly, electric heating behavior of the composite is strongly dependent on boron carbide content as well as applied voltage. The content of boron carbide was found to be effective in achieving high thermal conductivity in composite systems. The thermal conductivity of the composite material with added boron carbide was improved nearly 20 times than that of the pure IIR. The thermal stability test showed that, compared with pure IIR, the thermal stable time of composites was markedly extended, which indicated that the boron carbide can significantly improve the thermal stability of boron carbide / IIR composite.     

Thermal stability assessment of anti-explosive ammonium nitrate

The explosivity experiment of anti-explosive ammonium nitrate (AEAN) shows that the explosive characteristic of AEAN is eliminated. The adiabatic decompositions of ammonium nitrate and AEAN were investigated with an accelerating rate calorimeter (ARC). The curves of thermal decomposition temperature and pressure versus time, self-heating rate and pressure versus temperature for two systems were obtained. The kinetic parameters such as apparent activation energy and pre-exponential factor were calculated.The safety of AEAN was analyzed. It was indicated that AEAN has a higher thermal stability than AN. At the same time, it can be shown that the elimination of its explosive characteristic is due to the improvement on the thermal stability of AEAN.     

Dielectric Properties of Polytetrafluoroethylene/CaCu_3Ti_4O_(12) Composites

Polymer-based composite was investigated by embedding calcium copper titanate(CaCu_3Ti_4O_(12); CCTO) fillers into polytetrafluoroethylene(PTFE) matrix. The dielectric performances of the composite were investigated within the frequency range from 100 Hz to 1 MHz. It is indicated that dielectric permittivity(ε) and dielectric loss(tanδ) increase gradually as the filler content increases. Dielectric permittivity for the composite with 50 vol% CCTO filler loading is 33.5, approximately 16 times higher than that of pure PTFE(ε = 2.1) at 100 Hz. As the frequency increases, the dielectric loss decreases rapidly and reaches stability, and then remains low when the frequency rises to 1 MHz. The values for dielectric permittivity and dielectric loss in the microwave frequency(8-13 GHz) are lower than that in low frequency of 10 kHz for the composites because of different polarization modes. Several theoretical models were implemented to compare the experimental results with the theoretical calculations and the modified Lichtenecker equation was found to fit the best.     

Adiabatic Decomposition of Two Kinds of Organic Peroxides by Accelerating Rate Calorimeter

The accelerating rate calorimeter was applied to study the thermal hazard of two kinds of organic peroxides, i.e. methyl ethyl ketone peroxide (MEKPO) and benzoyl peroxide (BPO). And their thermal decomposition characteristics were discussed. Meanwhile, thermal decomposition characteristics of MEKPO and BPO vvere compared. The result indicated that MEKPO is more sensitive to thermal effect than BPO. While once the thermal decomposition takes place. BPO will be more hazardous than MEKPO due to its serious pressure effect. Thermal kinetic analysis of these two kinds of organic peroxides was also taken, and the kinetic parameters for them were calculated. The study of thermal decomposition of MEKPO solution with different initial concentrations indicated that, the lower concentration MEKPO solution is, the higher onset temperature will be. And with the addition of organic solvent, it becomes more difficult for MEKPO to reach a thermal decomposition. Therefore, its thermal hazard is reduced.     

Thermal stability and oil absorption of aluminum hydroxide treated by dry modification with phosphoric acid

The dry modification of aluminum hydroxide powders with phosphoric acid and the effects of modification of technological conditions on thermal stability, morphology and oil absorption of aluminum hydroxide powders were investigated. The results show that the increase of mass ratio of phosphoric acid to aluminum hydroxide, the decrease of mass concentration of phosphoric acid and prolongation of mixing time are favorable to the improvement of thermal stability of aluminum hydroxide; when the mass ratio of phosphoric acid to aluminum hydroxide is 5:100, the mass concentration of phosphoric acid is 200 g/L and the mixing time is 10 min, the initial temperature of loss of crystal water in aluminum hydroxide rises from about 192.10 to 208.66 ℃, but the dry modification results in the appearance of agglomeration and macro-aggregate in the modified powders, and the oil absorption of modified powders becomes higher than that of original aluminum hydroxide.     

Shape-stablized EP/paraffin composite for latent heat storage

62# and 56# paraffin mixtures were impregnated into expanded perlite (EP) by vacuuming method. Effects of impregnation with/without vacuum, vacuuming time, and thermal cycles were discussed. The appropriate mass fraction of paraffin mixture in the composite and vacuuming time were found respectively to be 80% and 20 min. Fourier transform infrared spectrometer (FT-IR) analysis shows that it has a good compatibility between paraffin mixture and EP. From differential scanning calorimetry (DSC) analysis, the latent heat of EP/Paraffin mixture composite is almost linearly related with the mass fraction of paraffin mixture in the composite. After 100 thermal cycles, the deviation of phase change temperatures is acceptable, but more deviation of latent heat appears. The calcium stearate dispersing granule coated by epoxy resin can effectively lower leakage during thermal cycles.     

Influence of Sodium Carbonate Amount on Crystalline Phase and Structure Stability for Doping Nickel Hydroxide

Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni(OH)_2 upon aging in a strong alkaline solution. In this study, the Al-Co, Al-Yb, Yb-Co and Al-Yb-Co multiple doping was used respectively. By controlling the amount of sodium carbonate, the α-Ni(OH)_2 was prepared by ultrasonic-assisted precipitation. And the influence of sodium carbonate on the crystalline phase and structure stability for alpha nickel hydroxide was studied. The results demonstrate that, with increasing amount, the biphase nickel hydroxide transforms to pure alpha nickel hydroxide gradually, and the structure stability is also improved. When the amount of sodium carbonate is 2 g, the sample still keeps α-Ni(OH)_2 after being aged for 30 days, for Al-Yb-Co-Ni(OH)_2. And when the amount is less than 2 g, the phase transformations exist in the samples with different extents. These results demonstrated that the amount of sodium carbonate is a critical factor to maintain the structural stability of α-Ni(OH)_2.     

Dynamic analysis of a concentrating photovoltaic/concentrating solar power (CPV/CSP) hybrid system

Concentrating photovoltaic/concentrating solar power(CPV/CSP) systems suffer from varying irradiation and extreme working conditions. In this study, a dynamic physical model is developed for the CPV/CSP hybrid system to analyze the dynamic responses of several key parameters, such as the solar radiation saltation or linear variation to represent the typical weather variations. The results show that the hybrid system could rapidly reach the steady state in less than about 53 s after the solar radiation saltation increases or decreases by 10%. The response time reflects that the thermal hysteresis of the hybrid system is mainly determined by varying the outlet temperature of R134 a from the solar thermal receiver. Meanwhile, when the solar radiation changes linearly, a lower gradient is beneficial to remit the thermal hysteresis of the hybrid system and improve the thermal stability, and the parameters could be treated as the steady state values with a gradient of less than 0.2 W m~(–2) s~(–1).Afterward, the quasi-steady state model was used to analyze the all-day dynamic performance of the hybrid system. It shows that the power output and the flow rate are directly related to the direct normal irradiance(DNI), while the outlet temperature of R134 a vapor could be almost constant except for the starting and stopping periods.     

Effect of magnetic field on property and structure of polyaniline doped with multiple sulfonic acids

Polyaniline（PAn） doped with multiple sulfonic acid system of dodecylbenzenesulfonic acid（DBSA） and sulfosalicylic acid（SSA） was synthesized by emulsion polymerization using ammonium persulfate（APS） as an oxidizing agent in the presence and the absence of a constant magnetic field（MF）of 0.8 T. The structure and properties of the PAn were characterized by X-ray diffractometer（XRD）, thermogravimetric apparatus（TGA）, FT-IR spectroscope（FT-IR） and four probe digital multimeter. The results indicate that, when the molar ratio of DBSA to SSA is 1/3, that of dopant to An is 3/2, that of APS to An is 4/5 in the synthesizing media, and the doping time is 3 h, the conductivity of the PAn synthesized in the presence of the MF of 0.8 T reaches 5.88 S/cm, which is higher than that of the PAn synthesized in the absence of the MF. The thermal stability, the crystallinity and the doping degree of the PAn synthesized in the presence of the MF are also improved. MF not only enhances the conductivity, but also reduces the doping time, the dosage of the dopant and the oxidizing agent when the conductivity reaches the maximum.     

Properties and mechanism of CFBC fly ash-cement based stabilizers for lake sludge

Circulating fluidized bed combustion(CFBC) fly ash was mixed with cement or lime at a different ratio as a stabilizer to stabilize lake sludge.In order to understand the influences of stabilizers on the lake sludge properties,tests unconfined compressive strength,water stability and SEM observation were performed.The experimental results show that with the increase of the curing time,the strength of all the stabilized specimens increase,especially the samples containing cement.The strength of the specimens is decreased with the increasing of the CFBC fly ash/cement ratio,the optimum ratio between CFBC fly ash and cement is 2:3.The water stability of CFBC fly ash-cement based stabilizers is higher than those of cement and lime.Moreover,the lake sludge stabilization mechanism of CFBC fly ash-cement based stabilizers includes gelation and filling of the hydration products,i e,C-S-H gel and the AFt crystal,which act as benders to solidify those particles together and fill in the packing void of the aggregates.     

Synthesis and thermal stability of antimony tris (thioethyl stearate) for PVC

ＰＶＣｉｓｉｎｔｒｉｎｓｉｃａｌｌｙｕｎｓｔａｂｌｅｂｅｃａｕｓｅｏｆｍｏｌｅｃｕｌａｒｄｅｆｅｃｔｓｉｎｓｏｍｅｏｆｔｈｅｐｏｌｙｍｅｒｃｈａｉｎｓ ,ａｎｄｗｈｅｎｓｕｂｊｅｃｔ ｅｄｔｏｈｅａｔｔｈｅｙｉｎｉｔｉａｔｅａｓｅｌｆ ａｃｃｅｌｅｒａｔｉｎｇｄｅｈｙｄｒｏｃｈｌｏｒｉ ｎａｔｉｏｎｒｅａｃｔｉｏｎ .ＳｔａｂｉｌｉｚｅｒｓｎｅｕｔｒａｌｉｚｅｔｈｅＨＣｌｐｒｏｄｕｃｅｄａｎｄｉｎｔｒｏｄｕｃｅｎｕｃｌｅｏｐｈｉｌｉｃｓｕｂｓｔｉｔｕｔｉｏｎｒｅａｃｔｉｏｎｓｔｈａｔｐｒｅ ｖｅｎｔｆｕ…     

有机锑高效PVC热稳定剂的合成

为开发有机锑类高效ＰＶＣ热稳定剂,以三氧化二锑与自制的十二烷基硫醇为原料,合成了三（十二烷基硫醇）锑,。产率可达８７．８％;以三氧化二锑与自制的巯基乙酸异辛酯为原料,合成了三锑,产率可达９３．８％,通过正交实验对反应条件进行了优化。对两产物中间产品进行了分析鉴定。结果与文献值相符。     

Preparation and application of antimony mono (isooctyl thioglycolate) di(n-dodecanethiol)

ＡｎｔｉｍｏｎｙｍｅｒｃａｐｔｉｄｅｉｓａｎｅｗｔｙｐｅｏｆｈｅａｔｓｔａｂｉｌｉｚｅｒｆｏｒＰＶＣ,ｗｈｉｃｈｈａｓｔｈｅｆｏｌｏｗｉｎｇｃｈａｒａｃｔｅｒｉｓｔｉｃｓ：ｈｉｇｈｅｆｆｉｃｉｅｎｃｙ,ｎｏｎｔｏｘｉｃｏｒｈａｒｍｆｕｌｅｓ,ｌｏｗ...     

SYNTHESIS，PROPERTY AND HEAT STABILITY FO RPOLYVINYLCHLORIDSOFANTIMONYTRIS（MERCAPTOACIDESTER）

ＳＹＮＴＨＥＳＩＳ，ＰＲＯＰＥＲＴＹＡＮＤＨＥＡＴＳＴＡＢＩＬＩＴＹＦＯＲＰＯＬＹＶＩＮＹＬＣＨＬＯＲＩＤＳＯＦＡＮＴＩＭＯＮＹＴＲＩＳ（ＭＥＲＣＡＰＴＯＡＣＩＤＥＳＴＥＲ）ＳＹＮＴＨＥＳＩＳ，ＰＲＯＰＥＲＴＹＡＮＤＨＥＡＴＳＴＡＢＩＬＩＴＹＦＯＲＰ...     

有机钙锌热稳定剂在硬质PVC中的热稳定性

采用热失重等方法研究了有机钙锌热稳定剂在硬质PVC中的热稳定性,考察了其与不同辅助热稳定剂的协效作用。结果表明:与硬脂酸钙锌、低铅热稳定剂相比,有机钙锌热稳定剂明显延长了PVC变色的时间;β-二酮与有机钙锌热稳定剂的协效性较好;在空气和氮气2种气氛下,有机钙锌热稳定剂对PVC的热稳定性无明显变化。     

Synthesis of lanthanum tris (mono- i -octyl phthalate) and its thermal stability for polyvinyl chloride

A novel type of thermal stabilizer—lanthanum tris (mono-i-octyl phthalate) (LTMP) was synthesized by double-decomposition reaction of sodium mono-i-octyl phthalate with lanthanum chloride at 60 °C. Sodium mono-i-octyl phthalate was prepared by sodium hydrate and mono-i-octyl phthalate prepared by reaction of isooctyl alcohol and phthalic anhydride in the presence of sulfuric acid catalyst at 110 °C. The yield of lanthanum tris (mono-i-octyl phthalate) is about 84.5%. Its thermal stabilities were measured by heat-ageing oven test when incorporated into PVC. The experimental results show that the heat stability time is about 40min at 190 °C when adding 3phr (per hundred resin) to PVC. The thermal stability of this product is better than that of Ca-Zn complex and basic lead salt stabilizers, and equal to that of dibutyltin diaurate. Foundation item: The Key Program of 9^th Five-Year Plan of China(No. 96-119-04-03-05) Biography of the first author: LIU You-nian, associate professor, born in Oct. 1964, majoring in fine chemical engineering & separation processes.     

硬脂酰氧基乙酸锌作为PVC热稳定剂的研究

以硬脂酸锌和氯乙酸为原料,制备了硬脂酰氧基乙酸锌．以硬脂酸锌作为对照物。通过热老化箱实验法、刚果红试纸法等多种方法对硬脂酰氧基乙酸锌及硬脂酰氧基乙酸锌／硬脂酸钙进行了热稳定性的研究．结果表明,硬脂酰氧基乙酸锌对PVC具有一定的热稳定性能,与硬脂酸钙具有较好的协同作用。     

硬脂酰氧基乙酸锌作为PVC热稳定剂的研究

以硬脂酸锌和氯乙酸为原料,制备了硬脂酰氧基乙酸锌.以硬脂酸锌作为对照物,通过热老化箱实验法、刚果红试纸法等多种方法对硬脂酰氧基乙酸锌及硬脂酰氧基乙酸锌/硬脂酸钙进行了热稳定性的研究.结果表明,硬脂酰氧基乙酸锌对PVC具有一定的热稳定性能,与硬脂酸钙具有较好的协同作用.     

从铅阳极泥中制备纳米三氧化二锑粉体的研究

以铅电解精炼过程中的副产物——铅阳极为原料，通过加入碳粉，使铅阳极泥中的高价锑还原成三氧化二锑；在低压下，用直接蒸发冷凝的方法制备了纳米三氧化二锑。此方法无需对铅阳极泥中所含其它成份进行分离，生产成本低。经XRD分析，产品为立方晶型三氧化二锑。SEM分析表明，产品为球形；粒度分布测定表明：平均粒度为66nm，标准差（GSD）为1．67，粒度分布均匀；化学分析表明，产品中所舍三氧化二锑大于97．5％。     

论酸法锑白工艺

本文叙述了酸法锑白工艺中与其产品质量密切相关的若干技术要点,指出了该工艺在锑业中的地位以及酸法立方体锑白研制成功是该工艺发展的重要进程。