有机过氧化物安定性的差示扫描量热测定

1 引言有机过氧化物是一种自反应性物质.这类物质在制造、使用、贮存过程中或由于自分解发热、热积累导致燃烧、爆炸,或由于冲击、摩擦、电火花、明火等外部作用导致燃烧爆炸而造成人员伤亡.差示扫描量热法(DSC)、压力容器试验法(PVT)是评价这类物质安全性的基本方法.本文利用DSC法对7种有机过氧化物进行了加热分解试验研究,探讨其热安定性、发生热爆炸的难易程度及剧烈程度.     

高温下渣熔融对煤焦-CO2气化反应特性的影响

在STA449F3型热天平上采用等温热重法研究了加入不同比例粗渣的煤焦在反应温度900～1380 ℃的气化反应性。利用热重-差示扫描量热法(TG-DSC)对煤焦的热行为进行分析,主要考察了加入不同比例粗渣、反应温度对煤焦反应性的影响。结果表明,煤焦-CO₂反应过程中,气化反应性和碳转化率可根据煤灰熔融流动温度分为相对低温段和高温段。在低温段,加入粗渣增加了煤焦的气化反应性和碳转化率;在高温段,加入粗渣会减小煤焦的碳转化率,并当粗渣加入量超过一定比例时,会降低煤焦的气化反应性。气化初期反应速率可根据粗渣熔融流动温度分为低温区域的化学反应控制和高温区域的扩散控制。     

Effects of molten slag on coal gasification reaction with CO2 at elevated temperature

在STA449F3型热天平上采用等温热重法研究了加入不同比例粗渣的煤焦在反应温度900～1 380℃的气化反应性.利用热重-差示扫描量热法(TG-DSC)对煤焦的热行为进行分析,主要考察了加入不同比例粗渣、反应温度对煤焦反应性的影响.结果表明,煤焦-CO2反应过程中,气化反应性和碳转化率可根据煤灰熔融流动温度分为相对低温段和高温段.在低温段,加入粗渣增加了煤焦的气化反应性和碳转化率;在高温段,加入粗渣会减小煤焦的碳转化率,并当粗渣加入量超过一定比例时,会降低煤焦的气化反应性.气化初期反应速率可根据粗渣熔融流动温度分为低温区域的化学反应控制和高温区域的扩散控制.     

Co-gasification properties of coal char and biomass char

以晋城无烟煤和生物质(肉骨粉Meat and Bone Meal∶MBM)为原料,在固定床上采用快速热解法制备了煤和生物质焦样.采用扫描电子显微镜结合X射线能谱分析仪(SEM-EDX)分析了煤焦和MBM焦的表面形态和组成；在热天平上采用等温热重法进行了煤焦/MBM焦混合物的水蒸气气化研究.实验结果表明,煤/MBM焦混合物的共气化实验碳转化率高于两者不存在协同作用时的计算值,这是由于MBM焦含有较多的Na、Ca等元素,这些物质对煤焦气化起到了催化作用.当对MBM焦进行脱灰处理后,其气化反应性显著下降.混合物中MBM焦的质量分数在20％～80％时,随着MBM焦含量的增加,混合物中的煤焦反应性相应提高.     

煤焦与生物质焦共气化反应特性研究

以晋城无烟煤和生物质(肉骨粉Meat and Bone Meal:MBM)为原料,在固定床上采用快速热解法制备了煤和生物质焦样。采用扫描电子显微镜结合X射线能谱分析仪(SEM-EDX)分析了煤焦和MBM焦的表面形态和组成;在热天平上采用等温热重法进行了煤焦/MBM焦混合物的水蒸气气化研究。实验结果表明,煤/MBM焦混合物的共气化实验碳转化率高于两者不存在协同作用时的计算值,这是由于MBM焦含有较多的Na、Ca等元素,这些物质对煤焦气化起到了催化作用。当对MBM焦进行脱灰处理后,其气化反应性显著下降。混合物中MBM焦的质量分数在20%~80%时,随着MBM焦含量的增加,混合物中的煤焦反应性相应提高。     

应用量子化学反应性指数评估化合物的亲核能力

评估化合物的亲核性能,对于设计化学反应的条件、研究反应机理、探讨药物与受体或酶作用靶点提供量子化学反应性参数,具有重要意义。本文在概念密度泛函理论的基础上,以得失电子前后化学势的变化,评估分子的反应性指数;用福井函数值,计算分子中各原子的反应性指数。选择脂肪胺、氨基酸和芳香胺三类胺及常用阴离子为研究对象,采用Gaussian软件分别对化合物分子及其失电子态进行结构优化和单点能计算。结果显示,建立的化学势变化值作为反应性指数的评估方法,与实验值基本吻合;所研究的几种有机分子的福井函数值与实际亲核能力基本一致。这表明可以采用得失电子前后的化学势变化值和福井函数值来预测分子和原子的亲核反应性。     

反应性挤出加工制备无卤阻燃高分子材料

聚合物反应性加工集聚合物加工与化学反应为一体,以聚合物加工装置为反应器,通过聚合物加工过程中的化学反应形成新物质和新结构,实现高分子材料的高性能化和功能化,是高分子材料科学的研究前沿之一.本文简要介绍了我们研究小组近年来采用反应性挤出加工制备高性能无卤阻燃高分子材料方面的研究进展.利用反应性挤出加工剪切力强、温度可控以及易于传质传热的特点实现了常规方法难以合成的高黏阻燃剂三聚氰胺磷酸盐季戊四醇酯（MPP）和三聚氰胺氰尿酸（MCA）的高效合成,制备了综合性能优良的聚丙烯/MPP、尼龙6/MCA等无卤阻燃高分子材料.研究所涉及的化学和物理方法,为聚合物无卤阻燃提供了高效、经济、环保和易于工业化的新技术,并拓宽了聚合物反应性加工的应用领域.     

可反应性纳米二氧化硅填充聚氯乙烯树脂在空气中的热分解行为

利用热重分析和差热重量分析(TG/DTG)技术研究了可反应性纳米二氧化硅填充聚氯乙烯(PVC/n-SiO2)树脂在空气气氛中的热分解行为,利用Ozawa-Flynn-Wall (OFW)方程和Friedman方程对其热分解进行了动力学分析.结果表明,可反应性纳米SiO2对PVC树脂热分解的第一阶段影响比较明显,当纳米S...     

热分析法评价反应性热溶胶的初粘强度

热粘指数;热分析法评价反应性热溶胶的初粘强度     

煤直接液化残渣焦CO2气化反应的研究

比较了流化床条件下神华煤及其直接液化残渣焦在CO2气氛中的气化反应性,考察了添加液化催化剂、脱除矿物质以及脱除重质油对煤直接液化残渣气化反应的影响规律。结果表明,残渣焦的气化反应性比原煤焦好,残渣焦在1000℃和1100℃的气化反应性指数为0.135和0.290,而原煤焦的则为0.118和0.200。脱灰后残渣焦气化反应性低于脱灰后的煤焦,说明直接液化反应后剩余的难液化物质的气化反应性低于煤焦;未经脱灰处理的残渣焦气化反应性高于煤焦,反映了液化过程中富集的矿物质及铁系催化剂的催化气化活性。脱除残渣中的重质油会降低残渣焦的气化反应性。     

Storage lifetime management and thermal hazard assessment of thermally reactive material

This is a novel idea: replacing highly dangerous and complex testing of solid thermally reactive materials through smart technology. We investigated the prediction of the storage lifetime and the thermal impact of thermally reactive material by different thermal analysis models: differential scanning calorimetry (DSC) for non-isothermal tests versus DSC isothermal tests. Two kinds of kinetic models were compared for evaluating appropriate kinetic parameters of thermal decomposition, and then the thermal hazard parameters were estimated by cartridge package simulation, which could result in reliable thermal hazard properties of a thermal reactive material’s thermal decomposition. We also determined the unsafe characteristics of a thermally reactive material stored in a depot under lifetime, so as to prevent runaway reactions that induce incidents by heat attack during storage. We were interested in an effective and smart analysis technology to reduce energy consumption of the dangerous testing. There are also calls for a smart testing technology which is the achieved object here for reducing energy consumption and avoiding runaway reaction disaster of thermally reactive materials.     

Thermal hazard evaluation of complex reactive substance using calorimeters and Dewar Vessel

In this paper, several small-scale screening test methods were discussed on evaluating the thermal hazard of reactive substances. Generally the sensitivities of DSC and ARC are not high enough to evaluate the thermal hazards for all reactive substance, especially, for those of complex reactions containing a phase and/or chemical reaction mechanism change in the lower temperature range. Using the C80, however, the reaction can easily be detected in the lower temperature range due to its high sensitivity. Therefore, the C80 gives generally more accurate results than DSC and ARC. Data from C80 and Dewar vessel were compared and it indicates that the Dewar vessel has also high enough sensitivity to evaluate the thermal hazard and determine the heat flux in lower temperature range of reactive substances. This revised version was published online in July 2006 with corrections to the Cover Date.     

Stepwise pyrolysis—gas chromatography of viscose fibres

Thermogravimetry and pyrolysis—gas chromatography are well known methods for investigating the thermal stability and structure of polymeric materials. In this paper, the possibilities of applying the little known stepwise pyrolysis—gas chromatography for evaluating the thermal stability of modified viscose fibres are discussed. The temperature dependence of the evolution of water, carbon monoxide and carbon dioxide on thermal degradation of flameproved viscose fibres has been investigated and the data are compared with the thermogravimetric curves.Stepwise pyrolysis—gas chromatography provides reproducible quantitative data on the decomposition of polymers and combines some of the advantages of thermogravimetry and pyrolysis—gas chromatography.     

Applications of micro-scale combustion calorimetry to the studies of cotton and nylon fabrics treated with organophosphorus flame retardants

Effective testing methods are critical for developing new flame retardant textiles by the industry. However, the current testing methods all have limitations. In this research, we applied micro-scale combustion calorimetry (MCC) for evaluating the flammability of the cotton woven fabric treated with a traditional reactive organophosphorus flame retardant in combination with a synergistic nitrogen-containing additive and the nylon-6,6 woven fabric treated with a hydroxyl-functional organophosphorus oligomer and crosslinkers. We found that MCC is capable of differentiating small differences among the treated fabric samples with similar flammability. MCC is able to make quantitative measurement of the peak heat release rate, the most important parameter related to fire hazard of materials, of textile whereas such analysis is more difficult using cone calorimetry due to textile fabrics’ low thickness. By using the thermal combustion parameters measured by MCC, we were able to calculate the limiting oxygen index (LOI) of various treated cotton fabric samples with near-perfect agreement between the experimentally measured and the predicted LOI values of treated cotton fabrics. We also compared the capability of MCC and differential scanning calorimetry for analyzing flame retardant cotton textiles.     

Circumneutral electrosynthesis of ferrate oxidant: An emerging technology for small,remote and decentralised water treatment applications

Although sophisticated water treatment technologies exist, the transportation, storage, and safe handling of chemical supplies can present major challenges for small and remote communities, putting the security of their access to potable water at risk. In-situ electrochemical methods can remove the need for chemical additives by generating reactive species on demand from the constituents of raw waters. This paper is a concise review of current literature concerning the advancement of in-situ technologies for the electrosynthesis of ferrate, which is a high-valent, strongly oxidising and environmentally benign species of iron. Synthesis mechanisms and operational parameters influencing generation in circumneutral conditions are discussed, as well as the viability of strategies to address the challenges presented by standards for drinking water and materials for constructing electrodes.     

复杂条件下高分子材料老化规律、寿命预测与防治研究新进展

复杂条件下有机高分子材料的老化、寿命预测和防治研究对满足相关行业发展的迫切需求,实现节能减排、环境保护及可持续发展等战略目标具有重大意义。本文重点综述了近年来针对聚烯烃、工程塑料、橡胶、涂料等大宗高分子材料在我国复杂大气环境中的自然老化及人工模拟加速老化研究的新进展,对材料老化失效基本规律和分子机理、老化数据库的建立及老化分级图谱的绘制进行了介绍,探讨了户外自然环境和人工模拟环境下材料老化失效规律的对应关系、服役寿命理论的预测模型及失效防治延寿新方法,并对其中存在的问题及下一步发展方向进行了展望。     

Layer‐by‐Layer Assembly for Surface Tethering of Thin‐Hydrogel Films: Design Strategies and Applications

Manipulation and engineering of the surfaces has a key role in improving the materials properties. Anchoring of thin hydrogels on the materials surface is one of the recently developed methods to achieve surfaces with high potential applications. Layer‐by‐layer (LBL) has been used widely as a strong strategy for immobilization of thin hydrogel films on the surface of various organic/inorganic substrates. Electrostatic LBL and covalent LBL are two main strategies used in this regard. In electrostatic LBL, negatively and positively hydrophilic polymers are sequentially assembled to create a multilayer hydrogel which subsequent covalent crosslinking of multilayers improved the stability of the inserted layers. On the other hand, covalent LBL requires hydrophilic polymers bearing reactive telechelic groups. These reactive polymers are prepared by various polymerization techniques or by post‐functionalization of biopolymers. The principles of hydrogel anchoring have described along with representative examples. Besides, the potential applications of the modified surfaces in specific cases have been addressed and overviewed.     

Biodegradable and biocompatible inorganic–organic hybrid materials. I. Synthesis and characterization

The hydroxyl or vinyl end-groups of linear or three-arm star-shaped poly(ε-caprolactone) (PCL) chains have been derivatized into triethoxysilane groups reactive in the sol-gel process. New transparent hybrid materials that combine tetraethylorthosilicate (TEOS) and PCL known for biodegradability and biocompatibility have accordingly been prepared. The sol-gel process is, however, limited by the early vitrification of the reactive system. However, thermal posttreatment can overcome these diffusional and/or kinetic limitations as assessed by a set of analytical methods. The thermal stability of PCL is improved by incorporation into the silica network. Conversely, the thermal stability of the ceramer depends on the effective PCL content. The extent of PCL incorporation into the silica network depends on PCL molecular weight, number, and reactivity of the PCL functional groups. IR spectroscopy has shown that hydrogen bonding occurs between the ester groups of PCL and residual OH groups of the silicate component. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2295–2309, 1997     

Ageing Effect on the SiO2-based Inorganic-Organic Hybrid Materials

It is well known that SiO₂ -based inorganic-organic hybrid materials present significant differences due to the organic moieties bound to the inorganic network and to the preparation conditions. In the present work the ageing effect on the thermal stability of the SiO₂ -based inorganic-organic hybrid materials prepared using tetraethoxysilan (TEOS), triethoxymethylsilan (MTEOS), triethoxyvinylsilan (VTEOS), tetramethoxysilan (TMOS), trimethoxymethylsilan (MTMOS) and trimethoxyvinylsilan (VTMOS) was studied. TG/DTA-MS was used to study the decomposition process of the materials. The structural modifications of the materials during ageing were studied using spectral methods. The gels obtained starting with more reactive alkoxides, of methoxy-type, present more complex structures and are less stable during ageing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Methods of Organic Matter Maturation Monitoring During a Composting Process

The possibility to use thermal analysis for a quick characterisation of chemical changes in the organic matter of composted materials was tested. Nine samples were taken at progressive stages of maturation from the same trench of a fully automated composting plant. DSC and TG were simultaneously performed in static air conditions on whole ground composts. Progressive stages in the composting process yielded samples whose DSC traces revealed appreciable modifications in thermal patterns that agreed well with quantitative data obtained from TG measurements. The ratio between the mass losses associated with the two main exothermic reactions (R1) showed a good sensitivity in detecting the changes in the level of stabilisation during the composting process. Thermal methods seem to be a valid comparative method in evaluating the level of bio-transformation of materials during a composting process. This revised version was published online in July 2006 with corrections to the Cover Date.