新型硬质聚氨酯泡沫的热分解行为及动力学

利用热重分析法比较研究了新型硬质聚氨酯泡沫[超支化聚氨酯多元醇型(HBPU型)]和硬质聚氨酯泡沫(RPUF)在氮气中的热分解行为,探讨了HBPU型RPUF在不同升温速率下的热分解动力学,运用Kissinger最大失重率法和Flynn-Wall-Ozawa等失重百分率法计算获得了其热分解过程的活化能。研究结果表明,HBPU型RPUF的初始分解温度(T5%)为205℃,半寿温度(T50%)为361℃,略低于传统的RPUF。Kissinger法得到的HBPU型RPUF的热分解表观活化能为159.8 kJ/mol;Flynn-Wall-Ozawa法得到的热分解过程分为三个阶段:第一阶段的平均活化能为82.8 kJ/mol,第二阶段的平均活化能为140.7 kJ/mol,第三阶段的平均活化能为111.3 kJ/mol,HBPU型RPUF具有较好的热稳定性。     

杯［4］芳烃的热分解动力学研究

通过热失重分析法（TG）研究了杯［4］芳烃与对叔丁基杯［4］芳烃在氮气氛围下的热稳定性,利用Kissinger方法和Flynn?Wall?Ozawa方法分析计算二者的热解表观活化能,通过Coats?Redfern方法确定了热分解动力学机理与模型,并分别求出了材料主降解阶段的非等温动力学方程。结果表明,Kissinger和Flynn?Wall?Ozawa方法求得的杯［4］芳烃的表观活化能分别为166.64 kJ/mol和175.79 kJ/mol,求得的对叔丁基杯［4］芳烃脱叔丁基过程的表观活化能分别为153.97 kJ/mol和166.81 kJ/mol,其自身苯环热分解过程的表观活化能分别为248.38 kJ/mol和252.92 kJ/mol,两物质的热性能在氮气氛围下都表现得较为稳定,且分解温度对于高分子材料的适应性较强;杯［4］芳烃热分解机理函数为g（α）=［-ln（1-α）］^3/2,反应级数n=3/2,其非等温热分解机理属于随机成核和随后生长反应,对叔丁基杯［4］芳烃脱叔丁基过程的热分解机理函数为g（α）=［-ln（1-α）］^2/3,反应级数n=2/3,其非等温热分解机理属于随机成核和随后增长反应,自身苯环热分解过程的热分解机理函数为g（α）=α²,反应级数n=2,其非等温热分解机理属于一维扩散反应。     

Co-pyrolytic behaviors of biomass and polystyrene: Kinetics,thermodynamics and evolved gas analysis

The pyrolytic degradation mechanism of chestnut shell (CNS) and its blend with waste polystyrene (PS) were investigated. Individual pyrolysis behavior of samples obtained separately was compared with those of the blends using a combined TGA/MS/FT-IR system. To elaborate kinetic analysis and to determine kinetic parameters, distributed activation energy model (DAEM) was used. The average activation energy of co-pyrolytic decomposition reaction was 191.6 kJ/mol, while the activation energy of the pyrolysis of CNS and PS was 175.2 and 208.9 kJ/mol, respectively. Friedman and Flynn-Wall-Ozawa iso-conversional methods were applied and the results were found to be consistent with the models. To express the presence of complex reaction mechanisms and the interactions of the radicals, thermodynamic parameters were also calculated. Finally, the pathways for main volatiles were established, and their relationship with the pyrolytic degradation was suggested.     

聚酰胺12非等温热分解动力学研究

在不同升温速率下,利用热重分析法研究了聚酰胺12（PA12）在氮气氛围中的热分解动力学。运用Freeman Carroll、Kissinger、Ozawa、Achar和Coats Redfern方法计算和确定了PA12在氮气氛围中的热分解活化能和热分解机理及其模型。结果表明,在氮气氛围中,PA12的热分解活化能为246.5 kJ/mol,指前因子为1014.71;PA12热分解机理为收缩球体法则,机理方程的微分形式为f(α)=3(1-α)2/3,积分形式为G(α)=1-(1-α)1/3。     

Extraction of gold and silver in the selective chlorination roasting process of cyanidation tailing

The selective chlorination of cyanidation tailing (CT) for the extraction of gold and silver has been investigated. The reaction operated at different conditions and their effect on the extraction of Au and Ag was studied. The mineral samples were characterized by fire assay, X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electronic microscopy (SEM). The best recovery values were 95.32% of Au and 85.32% of Ag at 1373 K and 1.5 h with 5% KCl. The results show that gold chlorination reaction was controlled by the interfacial chemical reaction, and the apparent activation energy was 40.05 kJ/mol. Silver has an activation energy of about 8.97 kJ/mol, and silver removal is performed by diffusion control.     

Decomposition of ozone on Ag/SiO2 catalyst for abatement of waste gases emissions

A silica-supported Ag system made by the incipient wetness impregnation method was investigated in the reaction of heterogeneous catalytic decomposition of ozone. It was established that the catalytic ozone decomposition on Ag/SiO₂ proceeded in the temperature interval −40 °C to 25 °C as a first order reaction with activation energy of 65 kJ/mol (pre-exponential factor 5.0 × 10¹⁴ s⁻¹). Based on the results from the instrumental methods (SEM, XRD, XPS, EPR, TPD) it can be concluded that in presence of ozone the silver is oxidized to a complicated mixture of Ag₂O₃ and AgO. Due to the high activity and stability of the Ag/SiO₂ catalyst, it is promising for neutralization of waste gases containing ozone.     

碳酸氢钾溶液的热分解研究

研究了碳酸氢钾在水溶液中的热分解动力学及其分解机理。通过计算得到碳酸氢钾热分解是二级反应,表观活化能为89.54 kJ/mol。分析了反应温度,搅拌速度,溶液中K+浓度对分解率的影响,结果表明在温度为140℃的条件下,分解率可达到92%。     

葡萄糖和蔗糖热分解过程的动力学分析

对葡萄糖和蔗糖的热分解过程进行了TG-DTA研究,采用Kissinger法、Friedman法及非线性拟合法获得了分解过程的反应机理和动力学参数. 结果表明,葡萄糖比蔗糖更易分解. 葡萄糖的分解过程分别为二级和一级反应,蔗糖的分解过程分别为n级和一级反应. 利用非线性拟合法给出了葡萄糖与蔗糖热分解过程的完整反应途径和动力学参数,葡萄糖三阶段的活化能分别为132, 150和253 kJ/mol,指前因子分别为11.6, 11.1和19.6 s-1;蔗糖两阶段的活化能分别为105和229 kJ/mol,指前因子分别为8.2和18.6 s-1.     

铝粉粒度对RDX热分解动力学的影响

采用DSC研究了10.7μm、2.6μm和40 nm铝粉对RDX热分解的影响.结果表明,微米铝粉对RDX的热分解基本没有影响;40 nm铝对RDX的一次分解和二次分解均有明显的促进作用;随着40 nm铝含量的增加,RDX的二次分解峰凸显出来并提前,峰形变得尖锐;当40 nm铝质量分数为30％时,二次分解峰掩盖一次分解峰...     

TATB的热分解及其在[Emim]Ac/DMSO溶剂中的热爆炸特性

用DSC-TG研究了TATB的热分解过程。根据升温速率分别为5、10、15、20K/min的DSC和TG-DTG曲线计算了分解反应的活化能(E)、指前因子(A)和120℃时的速率常数(k120),并计算了升温速率为5K/min时,TATB分解峰值温度时的分解反应活化焓、活化熵和活化自由能,用小容量测试法研究了TATB在1-乙基-3-甲基咪唑醋酸盐/二甲基亚砜([Emim]Ac/DMSO)溶剂中的热爆炸特性。结果表明,采用Kissinger法和Ozawa法计算得到TATB分解反应的活化能分别为212.1和212.0kJ/mol,采用Rogers公式和Arrhenius公式计算得到A和k120值分别为5.87×1016s-1和3.87×10-12s-1;升温速率为5K/min条件下,TATB分解峰值温度时的分解反应活化焓、活化熵和活化自由能分别为206kJ/mol、61.42J/(K·mol)和167.39kJ/mol,TATB粉末的临界爆炸温度为336.6℃;TATB在[Emim]Ac/DMSO溶剂中不爆炸。     

纳米碳管对CL-20热分解性能的影响

用DSC和TG研究了含纳米碳管的CL-20热分解特性。结果表明,纳米碳管的加入降低了CL-20的起始分解温度和分解峰温度,活化能由原来的184．3kJ／mol降低为172．2kJ／mol,放热量也由原来的2604．48J／g降低到2256．69J／g。同时,随着纳米碳管百分含量的增大,CL-20的起始分解温度、分解峰处温度、活化能以及放热量都逐步降低。     

不同粒径磷石膏的脱水动力学

为研究粒径对磷石膏脱水反应动力学的影响,测定了流动N₂气氛中,不同粒径磷石膏脱水反应的TG-DSC同步热分析数据。运用Flynn-wall-Ozawa法、Kissinger法和Satava-Sestak法相结合计算动力学参数,得出不同粒径（105～125μm、125～150μm、150～200μm和200～300μm）磷石膏脱水动力学模型,利用动力学方程对不同粒径磷石膏在相同条件下等温热分解进行预测,得出不同粒径、不同温度下磷石膏脱水率与时间的关系。结果表明：当磷石膏粒径由200～300μm减小到105～125μm时,磷石膏第一步脱水活化能从114.62kJ/mol减小到82.55kJ/mol,第二步脱水活化能由96.30kJ/mol减小到78.5kJ/mol。磷石膏脱水活化能随粒径的减小而减小,机理函数均符合Avrami-Erofeev方程。在相同的煅烧温度下,粒径小的磷石膏完全脱水所需时间缩短。     

过氧化氢危险性分析

利用C80微量量热仪对不同浓度过氧化氢在空气气氛中的热分解进行实验研究。通过热分析研究得到了不同扫描速率对过氧化氢热分解的影响以及热分解的活化能、绝热条件下达到最大反应速率所需的时间（TMRad）。 结果表明,随着扫描速率的提高各浓度过氧化氢的初始放热温度和最大放热温度都升高;质量分数为27.5%、50%、70%的过氧化氢热分解的活化能范围分别为51.05～94.30、16.40～66.72、32.50～76.15 kJ/mol;环境温度最高40 ℃下各浓度过氧化氢对应的TMRad分别为26.16、6.74、5.73 h。     

二甲基苯基硅氧基封端聚(二甲基-甲基苯基)硅氧烷共聚物的热分解性能及动力学研究

以1,1,3,3-四甲基二苯基二硅氧烷为封端剂,八甲基环四硅氧烷与甲基苯基环硅氧烷混合物为共聚单体,在阴离子催化剂作用下合成了二甲基苯基硅氧基封端的聚(二甲基-甲基苯基)硅氧烷共聚物。采用非等温TG技术,在惰性气氛和5.0、10.0、15.0和40.0 K min 1线性升温速率条件下,考察了共聚物非等温热降解机理及反应动力学,采用Friedman-Reich-Levi、Flynn-Wall-Ozawa和Kissinger等方法对非等温动力学数据进行分析,所得平均表观活化能分别为113.64、115.69和145.80 kJ mol 1。采用等转化率法确定出共聚物热分解反应符合Avrami-Erofeev方程,反应机理为随机成核和随后生长。采用Crane和Doyle方法研究了不同升温速率对反应级数、活化能和指前因子的影响,结果表明降解反应为一级反应,反应活化能介于152.46~183.13 kJ mol 1之间,指前因子介于4.25×109~4.02×109s 1。同时采用等温TG技术得到失重5%和10%条件下的寿命方程,对共聚物的寿命进行了预测。     

阻燃剂聚丙烯酸五溴苄基酯的热分解动力学

用热分析法研究了阻燃剂聚丙烯酸五溴苄基酯在空气和氮气气氛中的热分解动力学。该阻燃剂在空气气氛中为两步分解,在氮气气氛中为一步分解,利用Friedman法求出聚丙烯五溴苄基酯的第一步分解反应的活化能变化趋势,同时利用Satava-Sestak法研究了其热分解机理。结果表明,在0.10至0.90的转化率范围内,聚丙烯酸五溴苄基酯在空气气氛下的活化能为167.35kJ/mol,在氮气气氛下的活化能为171.94kJ/mol,热分解机理均为Avrami-Erofeev方程,随机成核和随后生长,反应级数分别为n=23和n=12。动力学方程分别为G(a)=[-ln(1-a)]23和G(a)=[-ln(1-a)]12。     

1-甲基-4,5-二硝基咪唑热分解行为研究

采用DSC-TG联用技术对1-甲基-4,5-二硝基咪唑(4,5-MDNI)的热分解行为进行了研究,采用DSC-TG技术,在2.0、5.0、10、15.0℃/min线性升温速率和氮气气氛条件下,考察了4,5-MDNI的非等温热分解机理及反应动力学,运用多种方法对非等温热分析数据进行分析,确定了4,5-MDNI热分解反应的...     

Pb-TKX-50燃烧催化剂的合成及热分解性能

以二氯乙二肟、二甲基甲酰胺、叠氮化钠、盐酸羟胺和硝酸铅等为原料,合成了1,1-二羟基-5,5′-联四唑羟胺铅盐(Pb-TKX-50)燃烧催化剂,研究了Pb-TKX-50对推进剂机械感度的影响以及与推进剂组分的相容性;利用差示扫描量热法和热重法研究了Pb-TKX-50在不同升温速率下的热分解过程,计算其表观活化能(E K和E O)和指前因子(A K),得到其热分解动力学参数、热分解机理函数、热爆炸温度和热力学性质。结果表明,在推进剂配方中加入Pb-TKX-50燃烧催化剂,可以改善其撞击感度和摩擦感度,且与推进剂组分的相容性良好;Pb-TKX-50的主峰分解温度相对于TKX-50的主峰分解温度显著提高,说明其热稳定性显著提高。Ozawa法和Kissinger法得到Pb-TKX-50的表观活化能分别为181.45 kJ/mol和182.49 kJ/mol,且热分解过程符合Avrami-Erofeev方程;Pb-TKX-50的自加速分解温度和爆炸临界温度分别为500.53 K和544.33 K,表明其热稳定性良好;Pb-TKX-50催化剂的热分解自由能(ΔG^≠)为158.87 kJ/mol,活化焓(ΔH^≠)为187.03 kJ/mol,活化熵(ΔS≠)为52.98 kJ/mol。     

芳纶Ⅱ与芳纶Ⅲ的热分解行为比较

利用热重分析研究了芳纶Ⅱ(Kevlar49)和芳纶Ⅲ(FanglunⅢ)在不同升温速率和氮气气氛下的热分解过程,用Kissinger方法、Flynn-Wall-Ozawa方法和Coats-Redfern方法研究了芳纶Ⅱ和芳纶Ⅲ的热分解动力学及热降解机理。结果表明:聚酰胺苯并咪唑嵌段使芳纶Ⅲ的热分解温度较芳纶Ⅱ稍有降低,但残炭率升高;芳纶Ⅱ和芳纶Ⅲ的起始热分解温度随升温速率加快而升高;芳纶II的热分解活化能(E)比芳纶Ⅲ稍高,用Kissinger方法、Flynn-Wall-Ozawa方法求得芳纶Ⅱ的E值分别为210.93,200.96 kJ/mol,芳纶Ⅲ的E值分别为208.35,196.98 kJ/mol,两种芳纶的固态热分解机理都为相边界反应,一维收缩,反应级数为1。     

新型复合油相乳化炸药基质的非等温热分解特性

为了掌握新型复合油相制备的乳化炸药的热分解特性,利用TG-DTG技术测试了其制备的乳化炸药基质在氮气气氛中的热分解过程,用Kissinger法和Ozawa法进行动力学分析,求解相关动力学参数。通过模型拟合法推测其热分解机理,并用非模型拟合法进行验证。结果表明,新型复合油相制备的乳化炸药基质分解率为15%~95%时,其热分解平均活化能(E)和指前因子lg(A/s~(-1))分别为142.12kJ/mol和13.26,热稳定性高于复合蜡制备的乳化炸药基质,热分解过程符合三维(3D)扩散控制机理(n=2)。     

Effect of zeolite filler on the thermal degradation kinetics of polypropylene

In this study, the thermal degradation behavior of polypropylene (PP) and PP–zeolite composites was investigated. Clinoptilolite, a natural zeolitic tuff, was used as the filler material in composites. The effects of both pure clinoptilolite and silver‐ion‐exchanged clinoptilolite on the thermal degradation kinetics of the PP composites was studied with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Polymer degradation was evaluated with DSC at heating rates of 5, 10, and 20°C/min from room temperature to 500°C. The silver concentration (4.36, 27.85, and 183.8 mg of Ag/g of zeolite) was the selected parameter under consideration. From the DSC curves, we observed that the heat of degradation values of the composites containing 2–6% silver‐exchanged zeolite (321–390 kJ/kg) were larger than that of the pure PP (258 kJ/kg). From the DSC results, we confirmed that the PP–zeolite composites can be used at higher temperatures than the pure PP polymer because of its higher thermal stability. The thermal decomposition activation energies of the composites were calculated with both the Kissinger and Ozawa models. The values predicted from these two equations were in close agreement. From the TGA curves, we found that zeolite addition into the PP matrix slowed the decomposition reaction; however, silver‐exchanged zeolite addition into the matrix accelerated the reaction. The higher the silver concentration was, the lower were the thermal decomposition activation energies we obtained. As a result, PP was much more susceptible to thermal decomposition in the presence of silver‐exchanged zeolite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 143–148, 2006