TG-FTIR分析技术在PVC热降解过程研究中的应用

利用热失重-红外光谱联机分析技术(TG-FTIR)研究了聚氯乙烯(PVC)共混物在氮气气氛下、30～900℃范围内的热降解行为。结果表明:PVC共混物的热降解过程可分为3个阶段,分别在200～380℃,380～570℃和570～758℃范围内。其中,第一阶段主要为PVC脱HCl反应阶段,热降解产物主要为HCl;第二阶段主要为共轭多烯结构的裂解和环化,产物为低烃类化合物、苯及其衍生物;第三阶段为碳酸钙的分解反应,产物为CO2。     

PVC／CaCO3热降解过程及多元醇对PVC的热稳定作用

利用热失重一红外光谱联机（TG-FTIR）分析技术研究了PVC／CaCO3共混物在氮气气氛下、30-900℃范围内的热降解行为。结果表明：PVC共混物的热降解过程可分为3个阶段,分别在170-380℃,380-570℃和570-758℃范围内。其中,第一阶段主要为PVC脱HCl反应阶段,热降解产物主要为HCl：第二阶段主要为共轭多烯结构的裂解和环化,产物为低烃类化合物、苯及其衍生物;第三阶段为碳酸钙的分解反应。产物为CO2。研究了几种多元醇化合物对PVC的热稳定作用,发现双季戊四醇与硬脂酸钙、硬脂酸锌之间的协同作用最好,其添加量愈多,共混物的稳定性愈好。     

PPS／PES共混物热降解行为的研究

本文运用热重分析(TG)、差示热重分析(DTG)方法研究了聚苯硫醚/聚醚砜共混物的热降解行为,考察了热裂解气氛、共混物组成对共混物热降解行为的影响。结果表明:在空气或氮气气氛下。共混物具有不同的热降解行为,共混物的热稳定性随着聚醚矾的含量增加而提高。在空气气氛下,不但存在聚苯硫醚和聚醚砜分子内的交联,而且可能存在分子间的交联。     

空气气氛CR-g-BMA热降解机理研究

用热重分析法研究了氯丁橡胶/甲基丙烯酸丁酯接枝共聚物(CR-g-BMA)在空气气氛条件下的热降解过程。结果表明,CR-g-BMA 热降解分两步完成,其特征起始降解温度为571.66 K;特征终止降解温度为754.35 K。通过Achar 方程和 Coats-Redfern 方程对30种常见机理函数进行计算比较,得到 CR-g-BMA 第一步热降解反应和第二步热降解反应的微分和积分机理函数,并进一步计算出第一步和第二步热降解反应的活化能分别为176.03 kJ/mol 和171.09 kJ/mol。最后,提出相应的热降解动力学模型,确定 CR-g-BMA 热降解动力学参数。     

偏氟乙烯—六氟丙烯共聚弹性体热降解动力学的研究

本文采用热重法(TG)研究了偏氟乙烯—六氟丙烯二元共聚弹性体(氟橡胶—26)的热降解动力学,结果表明:氟橡胶—26的热降解按二个热失重阶段进行,计算了它在空气、氯气气氛中二个热失重阶段的热降解反应级数、热降解活化能和频率因子。     

壳聚糖季铵盐铜配合物的热降解行为研究

采用热重分析(TG)研究壳聚糖季铵盐铜配合物在30℃～600℃的温度范围内的热降解行为,探讨壳聚糖季铵盐铜配合物的热稳定性。研究结果表明:壳聚糖季铵盐铜配合物的热降解为一步反应,取代度对壳聚糖季铵盐的热降解有明显的影响,壳聚糖季铵盐铜配合物的特征降解温度都随取代度的增加而降低。     

低蛋白天然橡胶在空气和氮气气氛中的热降解行为

采用热重分析法研究了低蛋白天然橡胶(LPNR)在氮气和空气气氛下的热降解和热氧降解行为,并与天然橡胶(NR)在同样条件下的降解行为进行了比较.结果表明,在氮气气氛下,LPNR和NR的热降解都是1步进行,LPNR的起始降解温度(T0)、最大降解温度(Tp)和反应活化能都比NR高,说明其耐热性比NR好;在空气气氛下,LPN...     

气氛对低氮天然橡胶热降解的影响

采用热重分析(TG),研究了恒定升温速率下,低蛋白橡胶在氮气和空气气氛中的热降解行为,考察了反应气氛对降解速率、降解率和动力学参数的影响,分析了两者降解机理的可能差别。发现降解温度和降解率,氮气中均高于空气中;表观反应级数氮气中为2.0级,空气中为1.9级。     

阻燃热塑性聚酯弹性体的热降解动力学研究

采用阻燃剂与单体共聚合成阻燃共聚热塑性聚酯弹性体(FR-TPEE),对FR-TPEE进行热失重分析,并采用Kissinger法,Flynn-Wall-Ozawa法和Coats-Redfern法对FR-TPEE热降解动力学进行研究。结果表明:FR-TPEE热降解过程分3个阶段,Kissinger法计算其活化能偏小,Flynn-Wall-Ozawa法和Coats-Redfern方法不适用于处理FR-TPEE热降解第三阶段。Coats-Redfern方法得知FR-TPEE第一阶段的降解机理是相界面控制反应机理,第二阶段是一维扩散机理。     

热失重角度研究高密度聚乙烯降解产物

国内外学者对聚乙烯进行热解产物分析,但通过热重曲线进而分析降解产物比较缺乏,研究了高密度聚乙烯(HDPE)在300°C～600℃热降解曲线,发现HDPE的热解汽化突变区为430℃～490℃,热裂解主要产物常温下为固态蜡状物,各裂解温度下产物均为混合物,热失重角度定性分析HDPE高温热解产物可行。     

Effect of cupric ion on thermal degradation of chitosan

The thermal degradation of chitosan and chitosan–cupric ion compounds in nitrogen was studied by thermogravimetry analysis and differential thermal analysis (DTA) in the temperature range 30–600°C. The effect of cupric ion on the thermal degradation behaviors of chitosan was discussed. Fourier transform-infrared (FTIR) and X-ray diffractogram (XRD) analysis were utilized to determine the micro-structure of chitosan–cupric ion compounds. The results show that FTIR absorbance bands of  N H,  C N ,  C O C etc. groups of chitosan are shifted, and XRD peaks of chitosan located at 11.3, 17.8, and 22.8° are gradually absent with increasing weight fraction of cupric ion mixed in chitosan, which show that there are coordinating bonds between chitosan and cupric ion. The results of thermal analysis indicate that the thermal degradation of chitosan and chitosan–cupric ion compounds in nitrogen is a two-stage reaction. The first stage is the deacetylation of the main chain and the cleavage of glycosidic linkages of chitosan, and the second stage is the thermal destruction of pyranose ring of chitosan and the decomposition of residual carbon, in which both are exothermic. The effect of cupric ion on the thermal degradation of chitosan is significant. In the thermal degradation of chitosan–cupric ion compounds, the temperature of initial weight loss (T_st), the temperature of maximal weight loss rate (T_max), that is, the peak temperature on the DTG curve, and the peak temperature (T_p) on the DTA curve decrease, and the reaction activation energy (E_a) varies with increasing weight fraction of cupric ion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The impact of cupric ion on thermo‐oxidative degradation of chitosan

The thermal degradation of chitosan and chitosan–cupric ion compounds in air was studied using thermogravimetric and differential thermal analyses in the temperature range 30–600 °C. The impact of cupric ion on the thermo‐oxidative degradation of chitosan was investigated. Fourier transform infrared and X‐ray diffraction analyses were utilized to determine the microstructure of the chitosan–cupric ion compounds. Kinetic parameters such as activation energy, pre‐exponential factor, Gibbs energy, and enthalpy and entropy of activation were determined using the Coats–Redfern equation. The results show that the thermo‐oxidative degradation of chitosan and chitosan–cupric ion compounds is a two‐stage reaction. The impact of cupric ion on the thermo‐oxidative degradation of chitosan is significant, and all thermodynamic parameters indicate that the thermo‐oxidative degradation of chitosan and chitosan–cupric ion compounds is a non‐spontaneous process and proceeds via a mechanism involving nucleation and growth, with an Avrami–Erofeev function (A₄) with the integral form [?ln(1 ? α)]⁴. Copyright © 2010 Society of Chemical Industry     

A kinetic study of the thermal degradation of chitosan‐metal complexes

The thermal degradation of metal complexes formed by chitosan with Cu(II), Ni(II), Co(II), and Hg(II), at different metal concentrations, was studied by thermogravimetric analysis in a nitrogen atmosphere over the temperature range 25–800°C. The results indicate that thermal degradation of chitosan and chitosan‐metal ion complexes could be of one or two‐stage reaction. In the thermal degradation of chitosan with metal complexes, the temperature of initial weight loss and the temperature of maximum weight loss rate decrease. Fourier transform infrared spectroscopy was used to probe the interaction of chitosan with metal ions. The bands of ? N? H, ? C?O, ? C? O? C? groups of chitosan are shifted or change their intensity in the presence of metal. These changes in the characteristic bands are taken as evidence of the influence of metal ions on the thermal stability of chitosan. Broido's method was employed to evaluate the activation energies as a function of the degree of degradation. The presence of metal ions provoked a decrease in the thermal stability of chitosan, which became more marked when the concentration of metal was increased. The dynamic study showed that the apparent activation energy values of the main stage of the thermal degradation of chitosan‐metal complexes decrease as the strength of the polymer‐metal interaction increases. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chitosan from Muga silkworms (Antheraea assamensis) and its influence on thermal degradation behavior of poly(lactic acid) based biocomposite films

The research work is focused on extraction of chitin from Muga silkworms (MS) and its conversion into chitosan by chemical treatment process. The extracted amount of chitin and chitosan from MS were obtained ～8 wt % and ～7 wt %, respectively. Potentiometric titrations, conductometric titrations, elemental analysis, ¹H‐NMR and FTIR analyses were employed to calculate the degree of deacetylation of chitosan (extracted at 80 ºC after 10 h) and found as 77% ± 2, 81% ± 1.8, 82% ± 2.4, 97.77% ± 0.3, and 82% ± 1.8, respectively. The deacetylation process of chitin showed pseudo‐first order reaction kinetics and activation energy was estimated as ～15.5 kJ/mole. The extracted chitosan (at 80 ºC after 10 h) showed higher crystallinity and improved thermal stability with respect to chitosan extracted from other marine sources. Subsequently, poly(lactic acid) (PLA) and extracted chitosan dispersed biocomposite films were prepared by solution casting method. Significant dispersion of chitosan (extracted at 80 ºC after 10 h) micro‐particles were observed in biocomposite films using FESEM analysis. Due to chitosan interaction with PLA, significant reduction in thermal degradation and activation energy was observed during nonisothermal degradation scan of such films using Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose models. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43710.     

铝试剂热氧降解历程的研究

本文采用热重法（ＴＧ）、微分热重法（ＤＴＧ）和差热分析法（ＤＴＡ）研究铝试剂（Ｃ２２Ｈ２３Ｎ３Ｏ９）在空气流中的热氧降解历程，从而发现铝试剂的热氧降解历程由四个紧连步骤组成。     

Thermogravimetric analysis of chitosan

The thermal degradation of chitosan at different heating rates B in nitrogen was studied by thermogravimetric analysis. The results indicate that the thermal degradation of chitosan in nitrogen is a one‐step reaction. The degradation temperatures increase with B. Experimentally, the initial degradation temperature (T₀) is (1.049B + 326.8)°C; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve (T_p), is (1.291B + 355.2)°C; and the final degradation temperature (T_f) is (1.505B + 369.7)°C. The degradation rates at T_p and T_f are not affected by B, and their average values are 50.17% and 72.16%, respectively, the maximum thermal degradation reaction rate, that is, the peak height on a differential thermogravimetry curve (R_p), increases with B. The relationship between B and R_p is R_p = (1.20B + 2.44)% min^?1. The thermal degradation kinetic parameters are calculated with the Ozawa–Flynn–Wall method. The reaction activation energy (E) and frequency factor (A) change with an increasing degree of decomposition, and the variable trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relatively steady, and finally reach a peak during the last stage. The velocity constants of the thermal degradation vary with the degree of decomposition and increase with the reaction temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

聚丙烯管材专用料热稳定性研究

采用热重分析仪(TG)分析了国内外几种典型的聚丙烯管材专用料的热降解稳定性,并对这几种聚丙烯管材专用料的热降解动力学进行了研究,发现这些专用料的热稳定性存在显著差异.通过对6种专用料的热降解动力学机理验证发现,聚合法生产的聚丙烯专用料的热降解机理比较相似,改性PPHB的热降解机理则较为复杂.     

聚碳酸酯的热降解

综述了聚碳酸酯的热稳定性及其影响因素,并详细论述了一些添加剂如偶联剂甲基三甲氧基硅烷、钛酸四丁酯、阻燃剂二苯砜磺酸钾(KSS)、聚氨丙基苯基倍半硅氧烷(PAPSQ)等对聚碳酸酯热稳定性的影响,阐述了Kissinger法和Ozawa法等聚合物热降解动力学的分析方法。重点介绍了近期国内外有关聚碳酸酯热降解产物和热降解机理方面的研究成果。     

Thermal and photochemical degradation of PPO/HIPS blends

In general, polymer blends show a degradation behavior different from a simple combination of the individual components, making any forecast difficult without experiments. Interactions between polymers can sensibilize or stabilize the blend against degradation. In this work, the thermal and photooxidative degradation of blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) and high impact polystyrene (HIPS) have been studied under accelerated conditions. The extent of degradation was accompanied by infrared spectroscopy (FTIR) and Raman spectroscopy (FT‐Raman) and impact resistance and strain–stress testing followed its influence on the macroscopic properties of the blends. The results showed that HIPS and the blend containing 60 wt % of PPO are more susceptible to thermal and photochemical degradation, while the blends containing 40 and 50 wt % of PPO are more stable. Infrared and Raman spectroscopic analyses showed that the degradation of HIPS and its blends is caused not only by degradation of the polybutadiene phase. Effects of interactions, such as exchange of energy in excited state between the PPO and PS components of the polymeric matrix may also be responsible for the degradation and loss of mechanical properties of the PPO/HIPS blends. The chemical degradation directly affects the mechanical properties of the samples with photodegradation being more harmful than the thermal degradation at 75°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007