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通过热重分析(TGA)法研究了聚对苯二甲酸丁二醇酯(PBT)在氮气气氛中不同升温速率下的热分解过程,采用不同的动力学数据处理方法研究了PBT的热分解机理。结果表明:采用Kissinger法、FlynnWall-Ozawa法和Friedman法计算PBT的热分解反应活化能分别为179.93,175.83,161.07 kJ/mol,平均值为172.28 kJ/mol,与Coast-Redfern法计算的活化能180.41 kJ/mol接近,取PBT热分解反应活化能为180.41kJ/mol,计算得指前因子为2.68×10~(10)s~(-1);采用Coast-Redfern法和Criado法研究了PBT的固相热分解反应机理,认为PBT的热分解机理属于相边界控制的收缩圆柱体反应机理,反应级数为0.5。 相似文献
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采用双酚A型环氧树脂为基体,短切玻璃纤维和纳米玻璃粉为填料,通过模压加工工艺制备了双酚A型环氧树脂基复合材料。使用热失重分析仪和扫描电子显微镜分析研究了纳米玻璃粉含量对复合材料热稳定性能的影响,同时利用Kissinger法和Flynn?Wall?Ozawa法求解了双酚A型环氧树脂基复合材料的热分解动力学参数。结果表明,添加短切玻璃纤维后,双酚A型环氧树脂的最大热分解温度从365 ℃提高至369 ℃,而随着纳米玻璃粉的加入,其最大热分解温度进一步提升5 ~16 ℃。且复合材料的残炭率在65.41 %~69.15 %之间,相比双酚A型环氧树脂、短切玻璃纤维增强双酚A型环氧树脂基复合材料分别提高了69.88 %~71.51 %、22.95 %~27.11 %。同时纳米玻璃粉的加入也使得复合材料的热分解活化能得到提升,最高为153.14 kJ/mol,相比双酚A型环氧树脂单体及短切玻璃纤维材料增强双酚A型环氧树脂基复合材料的热分解活化能135.65 kJ/mol、137.46 kJ/mol显著增加。结果表明,纳米玻璃粉的引入改变了双酚A型环氧树脂基复合材料的内部微观结构,从而提高了其热稳定性能。 相似文献
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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。 相似文献
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以TG-DTG为手段,研究了1,3,5-三(5,5-二溴甲基-1,3-二氧杂己内磷酰氧基)苯(TDDB)在氮气气氛中的热分解动力学,利用Kissinger法、Flynn-Wall-Ozawa(FWO)法对TDDB进行热分解动力学分析,求出该物质的热分解动力学参数,利用Coast-Redfen法研究该物质的热分解机理.结果表明:Kissinger法所求得的活化能为344.48 kJ/mol,指前因子lnA为66.02;Flynn-Wall-Ozawa法所求得的活化能为337.61 kJ/mol.TDDB的热分解的动力学方程为g(α)=α2.反应级数n=2. 相似文献
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《国际聚合物材料杂志》2012,61(4):295-306
Poly(N-1-alkylitaconamic acid) (PNAIA) containing ethyl, propyl, butyl, hexyl, octyl, decyl and dodecyl groups and random N-1-alkylitaconamic acid-co-styrene copolymers (NAIA-co-S) of three different compositions were selected and studied by dynamic thermogravimetric analysis (TGA). The thermal stability of homopolymers and copolymers depends on the structure of the NAIA and on the composition of the copolymer. The kinetic analysis of the degradation data shows that the thermal decomposition of the PNAIA can be described by zero order kinetic model. In the case of NAIA-co-S copolymers, the degradation process can be described by two different kinetic orders depending on the copolymer and on the composition. The thermal stability of the PNAIA in general increases as the length of the side chain increases. In the case of copolymers with styrene the relative thermal stability depends clearly on the composition and on the type of substituent in the side chain. 相似文献
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X. D. Liu 《Drying Technology》1999,17(9):1813-1826
An attempt was made to determine the kinetic model, which describes the degradation of activity and viability during thermal drying of baker's yeast. The pellels of baker's yeast were dried under a variety of conditions using a laboratory scale VFB dryer to generate a broad database. The data used in determining the parameters for the kinetic model, such as the average moisture content, temperature as well as the relative activity and viability of baker's yeast were measured under dynamic procedure. The extensive data from the experiments under variety conditions enable the model to predict the quality retention of baker's yeast in a rather wide range during thermal drying, The interpretation procedure of raw data was described in detail. 相似文献
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SUMMARY: The kinetics of thermal degradation of thermotropic liquid-crystalline aromatic polymers under nitrogen and air was systematically investigated by dynamic thermogravimetry. The thermal degradation temperature and kinetic parameters such as activation energy, decomposition order and frequency factor, have been determined by three methods on the basis of a single heating rate measurement. The effect of polymer molecular structure, end group, testing atmosphere and calculatingethod on the characteristic temperatures, kinetic parameters, and lifetime have been discussed. The initial decomposition temperature and estimated lifetime for the most thermotropic aromatic polymers are above 420°C and larger than 26 days at 200°C or 2.3 hours at 300°C, respectively. Some theoretical explanations of variation of thermal and kinetic parameters have been proposed. 相似文献
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新型膨胀阻燃聚丙烯的热分解动力学研究 总被引:4,自引:0,他引:4
卢林刚;张晴;徐晓楠;董希琳;王大为 《中国塑料》2009,23(5):53-60
通过极限氧指数法 (LOI)和锥型量热仪(Cone)考察了膨胀阻燃聚丙烯体系(IFR/PP)的阻燃性能;利用热重分析法 (TG)研究了聚丙烯 (PP)及IFR/PP体系在不同升温速率下的热稳定性及热分解动力学,采用Kissinger及Flynn-Wall-Ozawa方法分析PP和IFR/PP的热分解表观活化能;利用Coast-Redfern方法确定了PP和 IFR/PP热分解动力学机理及其模型,得出了聚合物主降解阶段的非等温动力学方程,结果表明,IFR的添加提高了聚丙烯的阻燃性能,阻燃剂的提前分解降低了聚合物的热稳定性,PP和IFR/PP热分解反应均属于随机成核和随后增长反应,其机理函数为g(α)= -ln(1-α),反应级数n=1 相似文献
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Leo C. K. Liau Thomas C. K. Yang Dabir S. Viswanath 《Polymer Engineering and Science》1996,36(21):2589-2600
A TG/FTIR system was used to identify the products of thermal oxidative degradation of PVB, and also to elucidate the mechanism of degradation. This technique is useful in the kinetic analysis of fast reactions such as polymer degradation, unlike the use of a TG/GC/FTIR system, in which long retention times are needed to separate the products. A computer resolution method based on a pattern recognition technique is proposed to resolve the dynamic mixture IR spectra of the degradation products. A four-component synthetic mixture was used to evaluate the performance of the resolution algorithm and was found to be accurate within ±5%. The method was then applied to PVB degradation. The dynamic information of PVB thermal oxidative degradation obtained by resolving the mixture IR spectra was used to elucidate the reaction mechanism and to determine the kinetic parameters. Results showed that PVB degradation in air took place at a temperature 50K lower and the overall activation energy dropped from 338 kJ/mole (in nitrogen) to 200 kJ/mole (in air) compared with the degradation in a nitrogen atmosphere. 相似文献
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The mechanical and thermal properties of poly(phthalazinone ether sulfone) (PPES)/poly(aryl ether sulfone) (PES) blends prepared by melt-mixing were investigated by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The dynamic mechanical thermal analysis results show that the incorporated PES has a large influence on the heat stability of PPES. The DMTA results display that the blends with a single glass transition temperature, which increases with increasing PPES content, indicates that PPES and PES are completely miscible over the studied composition range. The thermodegradative behavior of PPES/PES blends was used to analyze their thermal stability. The Friedman technique was used to determine the kinetic parameters (i.e., the apparent activation energy and order of reaction of the degradation process). The results indicate that the presence of the PES component influences the thermal stability of the PPES. On the basis of the kinetic data derived from Friedman' approach, the lifetime estimates for pure PPES, pure PES, and the blends generated from the weight loss of 5% were constructed. 相似文献
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Thermal degradation of poly(phenylene sulfide ether) (PPSE) was investigated by using thermogravimetry (TG) under air and nitrogen atmosphere. It was found that the existence of oxygen depressed the thermal stability of PPSE and changed the mechanism of thermal degradation. The influences of molecular weight and heating rate on the decomposition of PPSE were also investigated under N2 atmosphere. The results showed that the thermal stability of PPSE was excellent and can be further enhanced by increasing molecular weight. A simple kinetic model concerning two parallel reactions in overall temperature range was proposed to describe the thermal degradation process of PPSE in nitrogen. Kinetic analysis of the dynamic TG curves for PPSE was carried out by using Kissinger, Flynn–Wall–Ozawa, and Coats–Redfern methods. The kinetics of PPSE degradation displayed that the two parallel reactions were in accordance with the first‐order equation. The kinetic model was further validated by comparing the experimental and calculated results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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Kinetics of the thermal degradation of wax materials obtained from pyrolysis of mixed waste plastics
We did a kinetic analysis of the thermal degradation of wax materials obtained from pyrolysis of mixed waste plastics using
the nonisothermal weight loss technique with heating rates of 10, 20, 30 and 40 °C/min. The weight loss data according to
degradation temperature were analyzed by using the integral method based on Arrhenius form to obtain the kinetic parameters.
To verify the effectiveness of the proposed kinetic analysis method, the experimental values were compared with those of the
numerical integration results using kinetic parameters obtained in this work. It was found that the proposed kinetic analysis
method gave reliable kinetic parameters of the thermal degradation of wax materials obtained from pyrolysis of mixed waste
plastics. 相似文献
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X. D. LIU 《Drying Technology》2013,31(9):1813-1826
Abstract An attempt was made to determine the kinetic model, which describes the degradation of activity and viability during thermal drying of baker's yeast. The pellels of baker's yeast were dried under a variety of conditions using a laboratory scale VFB dryer to generate a broad database. The data used in determining the parameters for the kinetic model, such as the average moisture content, temperature as well as the relative activity and viability of baker's yeast were measured under dynamic procedure. The extensive data from the experiments under variety conditions enable the model to predict the quality retention of baker's yeast in a rather wide range during thermal drying, The interpretation procedure of raw data was described in detail. 相似文献
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The thermal degradation of plasticized polyvinyl chloride (plastisol) is reported here. Plastisols used in the present work were prepared with the plasticizer diethylhexyl phthalate in different proportions. Thermogravimetric analysis has been applied to study the behavior of plastisols at high temperatures and to evaluate their degradation kinetics. Several tests were carried out at different heating rates and the variation of the degree of reaction with time and temperature was calculated. The influence of the heating rate in dynamic measurements (5–40°C/min) on kinetic parameters, such as activation energies and reaction orders, has also been studied. These parameters were calculated from dynamic thermogravimetric analysis tests using Friedman analysis and a kinetic model for the degradation of poly(vinyl chloride) and plastisols has been then developed. The obtained model was able to simulate the thermal degradation process of plastisols in dynamic conditions and was used to evaluate the effects of additives in the degradation. The results of this study can be used to optimize the concentration of plasticizers and stabilizers in poly(vinyl chloride) formulations. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1069–1079, 1999 相似文献