Thermal decomposition kinetics of photooxidized nylon 66

The thermoanalytical method offers a convenient means for testing a starting material before the end application. Differences in the kinetic parameters between neat and irradiated nylon 66 samples were estimated in the temperature range of 25°C–800°C by thermogravimetric analysis (TGA) and in the range of 25°C–300°C by differential scanning calorimetry (DSC). Under nitrogen flux the average activation energy for decomposition was in the range of 12.2–26.9 kcal/mol for the neat sample and 15.7–33.1 kcal/mol for the irradiated sample (250 h). Activation energy is affected by the process of bond breaking at the C? N bonds, which is the rate‐determining step of the decomposition in nylon 66. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2146–2150, 2003     

Thermal decomposition of cellulose ethers

The thermostability and thermal decomposition kinetics of methyl cellulose (MC), ethyl cellulose (EC), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), and hydroxypropyl–methyl cellulose (HPMC) were characterized in nitrogen and air by thermogravimetry (TG). Various methods of kinetic analysis were compared in case of thermal degradation of the five cellulose ethers. The initial decomposition temperature (T_d), temperature at the maximum decomposition rate (T_dm), activation energy (E), decomposition reaction order (n), and pre-exponential factor (Z) of the five cellulose ethers were evaluated from common TG curves and high-resolution TG curves obtained experimentally. The decomposition reactions in nitrogen were found to be of first order for MC, EC, and HPMC with the average E and ln Z values of 135 kJ/mol and 25 min⁻¹, although there were slight differences depending on the analytical methods used. The thermostability of cellulose ethers in air is substantially lower than in nitrogen, and the decomposition mechanism is more complex. The respective average E, n, ln Z values for HEC in nitrogen/air were found to be 105/50 kJ/mol, 2.7/0.5, and 22/8.3 min⁻¹, from constant heating rate TG method. The respective average E, n, and ln Z values for three cellulose ethers (EC/MC/HPMC) in air are 123/144/147 kJ/mol, 2.0/1.8/2.2, 24/28/28 min⁻¹ by using high-resolution TG technique. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2927–2936, 1999     

热分析法研究SnSO4在催化剂制备中的分解行为

引言 热重分析（TG）是在程序控制温度下测量物质质量随温度变化的技术[1],其特点是简单、方便、快速、准确.将热失重曲线进行处理,可估算分解反应活化能,判断分解反应机理及影响因素,可为化学动力学的理论研究提供数据[2].     

腐殖酸热分解动力学

采用热重分析法（DTA-TGA）研究了腐殖酸的热分解过程及其动力学,分析其DTA-TGA曲线可得：热分解反应发生在284.65～417.16℃; 用红外光谱（FT-IR）、核磁氢谱（¹H NMR）、核磁碳谱（¹³C NMR）对腐殖酸结构进行表征,用Flynn-Wall-Ozawa（F-W-O）法、Kissinger法及Šatava-Šesták法计算出腐殖酸热分解反应的表观活化能为210.83 kJ·mol^-1,指前因子对数为17.55;确定了其热分解反应的级数和动力学参数,且热分解反应机理为二级反应;腐殖酸在氮气氛围下维持1min寿命的最高使用温度为278℃;同时,计算出腐殖酸样品热力学参数焓变、熵变及摩尔自由能变分别为67.99 kJ·mol^-1、-164.83 J·（mol·K）^-1 和176.36 kJ·mol^-1。     

Nonisothermal decomposition kinetics of nylon 1010/POSS composites

The thermal stability of nylon 1010/polyhedral oligomeric silsesquioxane (POSS) composites prepared by melt blending was investigated with thermogravimetric analysis. The octavinyl POSS (vPOSS) and epoxycyclohexyl POSS (ePOSS) were used, and it was found that nylon/vPOSS composites have higher integral procedure decomposition temperature and char yield at 800°C than nylon/ePOSS composites. The Doyle–Ozawa (model‐free) and Friedman (model‐fitting) methods were used to characterize the nonisothermal decomposition kinetics of nylon 1010 and its composites. The activation energy (E_a), reaction order (n), and the natural logarithm of frequency factor of nylon 1010 were 267 kJ/mol, 1.0, and 47 min^?1, respectively, in nitrogen. After the addition of POSS, the E_a of nylon 1010 considerably increased, whereas n had less change. The E_a steadily increased with increasing conversion and with increasing heating rate. The lifetime of nylon 1010 and its composites decreased with increasing temperature. At a given temperature, POSS significantly prolonged the lifetime of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

40%DCP溶液的热分解模型

准确的热分解动力学模型有助于人们采取各种安全措施预防和控制物料热失控导致的燃烧爆炸事故。以40%过氧化二异丙苯（DCP）的2,2,4-三甲基戊二醇二异丁酯（DIB）溶液为研究对象,运用差示扫描量热仪（DSC）和绝热量热设备（VSP2）进行了量热实验,并采用TSS软件（Thermal Safety Software）对数据进行动力学分析,建立了两种分解模型：“N级+N级”模型（模型1）和“N级+自催化”模型（模型2）,采用Friedman法和非线性拟合方法求算其动力学参数。在运用所建立的两种模型拟合曲线时,发现两种模型对同种量热模式数据拟合的相关系数非常接近,说明单一量热模式在求算动力学上存在局限性。联合采用基于动态扫描模式的DSC数据及基于绝热模式的VSP2数据共同求算动力学,发现相对于模型2,模型1可以更好地反映分解过程,其两步反应的活化能分别为115.5 kJ·mol^-1和135.7 kJ·mol^-1,指前因子的对数分别为28.3和31.6,反应级数分别为0.40和0.84。研究结果表明采用基于不同量热模式的数据求算动力学有助于确定正确的动力学模型,从而获得准确的动力学参数,并克服单一量热模式下动力学求算的局限性。     

六氨氯化镁热解过程及其非等温动力学

利用热重（TG）分析技术对六氨氯化镁的热分解过程及动力学进行了研究,考察了六氨氯化镁在4、7、10、13、16 K·min^-1线性升温速率和空气气氛下热分解机理,六氨氯化镁热解过程分为3个阶段。提出了一种整体优化的多升温速率迭代的等转化率求取活化能方法,采用该方法,得到六氨氯化镁热解3个阶段的活化能分别为51.38、64.70、73.55 kJ·mol^-1。采用整体优化的多升温速率等温法确立了六氨氯化镁热解3个阶段的热解机理函数与指前因子：第1步反应的热解机理属于固体相边界反应机理（n=1/4）,指前因子为3.281×10⁵ s^-1;第2步反应的热解机理属成核与生长机理（n=1.8）,指前因子为5.624×10⁶ s^-1;第3步反应属化学反应机理（1.5级反应）,指前因子为5.862×10⁵ s^-1。     

Thermal decomposition of poly(tetramethyloxydisilaethylene)

Thermal decomposition of poly[oxybis(dimethylsilylene)] having chains terminated with trimethylsiloxy groups was studied by thermogravimetry, pyrolysis-mass spectrometry, and infrared spectroscopy. The polymer is thermally less stable than poly(dimethylsiloxane). Depolymerization occurs at temperatures of 250–350°C, although this process also takes place at lower temperatures. The depolymerization produces cyclic oligomers of general formula [(Me₂Si)₂O] _n , with predominant formation of the oligomern=2. The depolymerization is accompanied by processes which are referred to as restructurization because they change the structure of the polymer backbone. Decomposition may lead also to the formation of branching points. The shape of the thermograms taken under isothermal conditions is in agreement with an unzipping mechanism for depolymerization involving random initiation. Excluding the short initial period of the process, the unzipping is terminated at a restructurization point. A low activation energy points to initiation induced by electron transfer, presumably involving traces of contaminant. At higher temperatures, 350–600°C, loss of organic parts of the polymer takes place along with further restructurization. At higher temperatures the polymer was also found to undergo easily oxygenation of its backbone with atmospheric oxygen, which leads to the formation of siloxane groups.     

脱氢枞酸在空气中的热分解动力学

采用TG/DTA/DSC热分析技术,在线性升温速率为5、10、15和20 K·min^-1和静态空气条件下,研究了脱氢枞酸在空气气氛中的热分解动力学。由热重/差热法(TG/DTA)得到脱氢枞酸在空气中是一步分解;运用差示扫描量热法(DSC)测定了脱氢枞酸的熔点为445.05K,摩尔熔化焓为19.74 kJ·mol^-1和摩尔熔化熵为44.35J·mol^-1·K^-1;分别利用Kissinger法和Flynn-Wall-Ozawa法对脱氢枞酸非等温热分解数据进行了动力学分析,同时利用Satava-Sestak法研究了脱氢枞酸的热分解机理。结果表明,脱氢枞酸的热分解机理为收缩球状界面反应模型R3,热分解反应的表观活化能为107.89 kJ·mol^-1,指前因子为9.33×10⁸ s^-1)。     

新型多叠氮磷酸酯的热安定性及其热分解机理

用DSC法测定了两种新型链状多叠氮磷酸酯——三(β-叠氮乙基)磷酸酯(TAEP)与2,2-二(氯甲基)-1,3-亚丙基四(β-叠氮乙基)双磷酸酯(MPAEDP)及两种新型双环叠氮磷酸酯——1-氧代-4-(β-叠氮乙氧羰基)(或(β,β′-二叠氮异丙氧羰基)-2,6,7-三氧杂-1-磷杂双环[2．2．2]辛烷(AEPEPA及AIPEPA)的热安定性,并求得了它们的热分解动力学参数(Ea、Aa及ka),讨论了可能热分解机理。     

2,4-二氯过氧化苯甲酰的热分解及等温动力学模型

引言2,4-二氯过氧化苯甲酰(双-2,4,DCBP)工业上常用作自由基引发剂、高温硅橡胶固化剂和无模硫化剂。因用该物质生产的硅橡胶制品无毒,可用于人工脏器、牙托、奶瓶等,也可用作高功率发电机绝缘用品,尤其适用于导弹、航天器中密封圈及耐热胶管带[1]。有机过氧化物中含有不稳定的"—O—O—"键,导致此类物质易受热分解,并引     

布洛芬热分解及其动力学研究

通过布洛芬(ibuprofen)的热分解及其动力学研究,运用简单的热分解动力学方法进行计算分析,求出相关的活化能,指前因子和动力学参数。将布洛芬每个温度范围下的热分解过程分为3个阶段分别进行分析计算,发现每个阶段都满足一级反应方程。从而算出布洛芬热分解过程的活化能,指前因子和相关系数。通过对布洛芬热分解过程的研究,及对布洛芬TG和DTG曲线的研究,得出布洛芬在热分解过程中分为3个阶段,分别进行脱水,C-C键断裂和分子键断裂。并且随着升温速率的提高,布洛芬失重速率会逐渐趋向于温度升高的方向发展,即温度升高,布洛芬最大失重速率越大。     

结合胶的热分解反应动力学研究

应用TG/DSC技术研究了天然橡胶(NR)和以普通炭黑、碳纳米管(MWNT)分别作为填料制备的结合橡胶。应用FWO(Ozawa-Flynn-Wall)计算了NR、炭黑结合胶及MWNT结合胶的热分解动力学,并利用多元非线性拟合法求得NR、炭黑结合胶及MWNT结合胶的热分解反应机理及机理函数。     

Synthesis and characterization of nylons based on hexadecane diacid

A series of nylons with long alkane segments between amide groups were synthesized by using hexadecane diacid and various diamines, and the resulting polyamides were characterized comprehensively. It was shown that the molecular weights of nylons 6 16, 8 16, 10 16, and 12 16 in our studies exceed 1.1 × 10⁴, whereas nylons 2 16 and 4 16 have relatively low molecular weights. In addition, the melting temperatures, the decomposition temperatures, and the glass transition temperatures of the nylons obtained were measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2462–2467, 2003     

甲基磺酸亚锡的热分析研究

用热重和示差扫描热分析法研究了甲基磺酸亚锡的热分解过程,其热分解过程分为三个阶段;在60～100℃脱水,在390～407℃甲基磺酸亚锡分解生成无机盐SnSO4;在407～425℃生成SnO.采用DTA-TGA技术研究了甲基磺酸亚锡在氮气中的非等温热分解机理及动力学. 根据TGA曲线确定了热分解过程中的中间产物及最终产物.运用Achar法和Coats-Redfern法对非等温动力学数据进行分析,得到热分解反应的机理函数和动力学参数.     

Thermal decomposition of precursor of SmBiO3 buffer layer for YBCO high-temperature superconducting tape

In order to explore the rapid preparation process of the buffer layer of the high-temperature superconducting tape, the thermal decomposition and the phase formation kinetics of buffer layer precursor were studied. The precursor solution was prepared by using lactic acid as solvent, and nitrates as solutes. The synthesis mechanism of SmBiO₃ phase was determined by the combination of universal integral method, differential method and multi-rate scanning Kissinger method, and the related kinetic parameters were solved. The results show that the thermal decomposition processes of the precursor is divided into two stages from room temperature to 800 °C. The second stage of SmBiO₃ phase synthesis reaction obeys the second order chemical reaction model. The average apparent activation energy and the pre-exponential factor of the synthesis reaction calculated by the integration and the differential methods are 73 kJ/mol and 3.24 × 10⁴/min, respectively.     

Thermal decomposition of ammonium nitrate

The thermal decomposition reactions of ammonium nitrate (AN) are reviewed. Both neat AN and AN containing various contaminants are examined, however quantitative kinetics results are not encompassed. Also not included is the performance of AN as the oxidizer in rocket propellants or in explosives such as ANFO. The review is intended to be the most comprehensive review of decomposition reactions of AN since Berthelot's treatise of 1892. Despite hundreds of papers on the topic that have appeared in the intervening years, understanding of decomposition mechanisms remains only modestly more complete than it was in Berthelot's day. However, some additional reaction steps and mechanisms have been identified and these are discussed. Explosions of AN most commonly involve fire as the proximate cause, yet chemical-mechanism research on the topic is nil. A modest number of studies have explored the potentiation of AN decomposition by organic contaminants. These have, thus far, not produced guidance useful for promoting of safety from fire-related causes. Contamination from inorganic sources, notably chlorides is better understood and some mechanisms have been studied. The UN classification of AN as an oxidizer, instead of as an explosive, should not be interpreted literally, since AN has been associated with numerous detonation disasters.     

水氯镁石的热解机理及动力学

采用热重差热质谱联用技术(TG-DTA-MS)和热分析技术(TG-DTA)研究了水氯镁石热解过程的反应机理和动力学行为. 结果显示,水氯镁石热解分4个阶段,前2个阶段共脱除4个结晶水,后2步脱水和水解并存,第1步的分解反应属于球形对称相界面反应为控制步骤的R3机理,后3步属于Avrami-Erofeev的成核及核成长为控制步骤的A1机理,4步表观活化能Ea分别为81.13, 125.4, 230.4和164.1 kJ/mol,频率因子分别为2.95×1010, 2.70×1015, 4.07×1026和4.75×1016 s-1.     

典型垃圾材料的热分解动力学

对垃圾材料的热分解动力学研究目的在于研究垃圾材料的热解特性,文中对典型垃圾材料聚氯乙烯(PVC)和纸进行热分解动力学研究.用综合热分析仪分别测试PVC及纸在升温速率为10,15,20,30 K/min时的TG-DSC曲线,获取PVC和纸在最大质量损失速率时的温度Tmax及其他动力学参数.然后用Kissinger法和Fl...