Thermal degradation of polymers. XII. Synthesis,polymerization and thermal characterization of polymers of m-N,N-dimethylaminostyrene in nitrogen

The monomer m-N,N-dimethylaminostyrene has been synthesized from acetophenone and homopolymerized and copolymerized with styrene, using 2,2′-azobisisobutyronitrile as free-radical initiator. The polymers have been characterized by thermal analysis (DTA, DSC, and TG). Glass transition temperatures have been measured and activation energies for degradation in nitrogen have been established by a variety of methods for comparative purposes.     

Thermal degradation of polymers. XI. Synthesis,polymerization, and thermal characterization of polymers of p-N,N-diethylaminostyrene in nitrogen

The monomer p-N,N-dimethylaminostyrene has been synthesized from p-N,N-diethylaniline and homopolymerized and copolymerized with styrene using 2,2′-azobisisobutyronitrile as free-radical initiator. The polymers have been characterized by thermal analysis (DTA, DSC, and TG). Glass transition temperatures have been measured and activation energies for degradation in nitrogen have been established by a variety of methods for comparative purposes.     

Thermal degradation of polymers. Part XIX. The thermal cyclization and characterization of quinazolone pre-polymers

A series of pre-polymers prepared from 4,4′-diaminodiphenyl-3,3′dicarboxylic acid and aromatic diacetamido compounds have been thermally cyclized and their structures have been investigated using infrared spectroscopy, combustion analysis, and weight loss techniques. The structures obtained on cyclization are discussed in terms of concurrent cyclization and decarboxylation reactions resulting in incomplete cyclization. Specific structural features due to the lability of main chain bonds at the cyclization temperatures are also discussed. Dynamic thermogravimetry and isothermal weight loss studies have been used to evaluate thermal stability and kinetic parameters. The results are discussed in terms of the overall complexity of the polymer structure and the complexity of the degradation process. It is concluded that in such systems, where the structural variations are large, it is not possible to define a meaningful stability sequence because like systems are not under comparison.     

Thermal degradation of polymers. X. Thermal analysis studies on poly(p-N,N-dimethylaminostyrene) homopolymers and copolymers with styrene in nitrogen

Studies have been made on the effect of the molecular weight of p-N,N-dimethylaminostyrene homopolymers and the composition of its copolymers with styrene on the glass transition temperature. Comparative thermal degradation studies have been made on polystyrene and p-N,N-dimethylaminostyrene polymers by thermal analytical methods (TG, DTA, and DSC). The differences in thermal stability and overall thermal degradation behavior of the two systems are discussed in terms of the differences in their degradation mechanisms.     

Synthesis and thermal stability of methylanisole-1,2-dichloro ethane resins

Resin samples have been prepared by the Friedel-Crafts polymerization of methylanisole with 1,2-dichloro ethane. The samples were characterized by IR-spectra and number average molecular weights M _n by vapour pressure osmometry (VPO). The thermal characterization has been carried out by differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC). Kinetic parameters for the decomposition are determined from TG- and DTA-studies. Thermal stability is found to be dependent upon the position of the methyl group on the aromatic nucleus.     

Weather-Induced Degradation of LLDPE: Calorimetric Analysis

Studies of polymer degradation over the past decade have increasingly been carried out using thermoanalytical methods. These methods involve the measurement of a convenient variable during a gradual, linear increase in temperature. The most widely used of these techniques are thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The morphology of a polymer sample (i.e., the crystallinity, shape and size of the crystals, the structure of the surface of the crystals, and the strain of amorphous regions) influences the heat content and its dependence on temperature. The latter can be satisfactorily investigated by calorimetry measurement in a differential scanning calorimeter.     

聚醚酮酮和磺化聚醚酮酮的热稳定性研究

用差热分析法,差示扫描量热法、换失重法,等热分析方法对聚醚酮酮和磺化聚醚酮酮的热稳定及其差异进行了研究,结果表明聚醚酮酮有更好的热稳定性。     

Preparation,thermal characterization and tribological evaluation of some polyquinazolinediones and polyquinazolones

The preparation of a series of pre-polymers by solution polycondensation of 4,4′-diaminodiphenyl-3,3′-dicarboxylic acid (BDC) and di-isocyanates, and the melt polycondensation of BDC and diacetyl derivatives of aromatic diamines is described. These pre-polymers have been characterized and cyclized to yield polyquinazolinediones and polyquinazolones whose structures and thermal stabilities have been investigated. The physical characteristics of films made from these materials were determined after cyclization, and friction and wear characteristics of composite films containing polytetrafluoroethylene, lead oxide and graphite were evaluated in a journal bearing bush configuration. The relationship between wear behaviour and polymer structure, thermal stability and physical properties is discussed.     

X-ray diffraction spectroscopic and thermal studies on 1,3,5-trinitro-hexahydropyrimidine (TNP)

TNP, a heterocyclic nitramine containing a C NO₂ functionality, has been studied as regards the kinetics and mechanism of thermal decomposition, morphology and the gaseous products evolved therof, using thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and hot stage microscopy. The elementary cell parameters obtained form the XRD pattern are: a = 18.818 ± 0.005 Å, b = 18.818 ± 0.005 Å and c = 4.867 ± 0.005 Å. The crystal belongs to the hexagonal system with c/a ratio = 0.259. IR spectra of TNP have also been recorded and the bands assigned. Kinetics of thermolysis has been followed both by isothermal TG and IR. The best linearity with a correlation coefficient of 0.986 was obtained for the three-dimensional diffusion controlled Jander-equation. Kinetic parameters were evaluated from the induction period as well as from isothermal TG. Activation energy was found to be 202.05 kJ/mol and log A(in s-¹) 22.78 from TG and 181.133 kJ/mol and log A (in s¹) 20.97 from IR, respectively. The corresponding values were 171.17 kJ/mol and log A (in s-¹) 21.20 from the induction period data. The effect of a series of additives incorporated to the extent of 5 %, on the initial thermolysis of TNP, has also been studied. Evolved gas analysis by IR showed that CO₂, NO₂, NO and N₂O are produced in larger amounts than CO and HCN. The cleavage of the N N bond appears to be the primary step in the thermolysis of TNP.     

1,1′-二硝氨基-5,5′-偶氮双四唑钾盐的合成、结构及性能

以水合肼和叠氮氰为原料,经环化、缩合、氧化偶联、酸解、硝化、中和等反应,合成了1,1′-二硝氨基-5,5′-偶氮双四唑钾盐(K_2DNAABT);利用红外、核磁(~1 H NMR、~(13) C NMR)、元素分析和单晶X射线衍射表征了目标化合物的结构;采用DSC和TG方法研究了K_2DNAABT的热性能;基于晶体密度和计算的生成热,采用EXPLO5程序软件预估了K_2DNAABT的爆轰性能。结果表明,K_2DNAABT热分解峰温为194.27°C,晶体密度为2.11g/cm~3,生成热为617.0kJ/mol,爆速为8 367m/s,爆压为31.5GPa,具有较好的热稳定性,优良的爆轰性能,有望作为叠氮化铅的绿色替代物。     

Synthesis,characterization, and fluorescence properties of lanthanide complexes with poly(styrene‐co‐methacrylic acid)

A series of new complexes of poly(styrene‐co‐methacrylic acid) with Ln(III) (Ln = La, Eu, Tb) were synthesized and well characterized by means of elemental analysis, FTIR, differential scanning calorimetric (DSC) analysis, TG‐DTA analysis, X‐ray diffraction (XRD), and fluorescence determination. The elemental analysis and FTIR studies showed that a large part of carboxylic groups on the side chain of the copolymer are coordinated with Ln(III) ions. The TG‐DTA and DSC analysis results indicated that the complexes have good thermal stability. XRD experiments showed that copolymers and the complexes are amorphous. Among these complexes, Eu(III) complexes and Tb(III) complexes exhibit characteristic fluorescence with comparatively high brightness and good monochromaticity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Addition polyimides. I. Kinetics of cure reaction and thermal decomposition of bismaleimides

The thermal polymerization of four structurally different bismaleimide resins, prepared by reacting maleic anhydride with four aromatic diamines, viz., 4,4′-diaminodiphenyl methane, 4,4′-diamino diphenyl ether, 4,4′-diamino diphenyl sulfone, and 3,3′-diamino diphenyl sulfone, was followed by differential scanning calorimetry (DSC). The enthalpy change and the kinetic constants for the polymerization reactions were evaluated from the DSC curves. Thermal stability of the cured polymers was studied by thermogravimetry (TG). The kinetic parameters, viz., activation energy E and preexponential factor A, for the thermal decomposition of the cured bismaleimides were calculated from the TG curves using three nonmechanistic integral equations. The kinetic constants (E and A) follow a trend similar to the thermal stability of the polymers.     

Preparation and characterization of soluble polyimides

Two kinds of soluble polyimides from pyromellitic dianhydride with Congo red and 4-sulfanilamide were prepared, respectively. Their structures were characterized by IR and ¹H-NMR, and the thermal properties were investigated by DSC and TG–DTA. © 1995 John Wiley & Sons, Inc.     

New polyhydrazides and poly(1,3,4-oxadiazole)s containing pendent phenoxy groups

A series of new polyhydrazides containing pendent phenoxy groups has been synthesized by low-temperature solution polycondensation of equimolar amounts of diacid dichlorides and 2-phenoxyterephthalic dihydrazide in N-methyl-2-pyrrolidi-none (NMP). The thermal cyclization of the polyhydrazides gave the corresponding poly(1,3,4-oxadiazole)s containing pendent phenoxy groups. The polymers were characterized by viscometry, solubility measurements, IR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis.     

The effect of microencapsulation with nitrocellulose on thermal properties of sodium azide particles

Based on the coacervation principle a solvent/non-solvent method has been used for microencapsulation of sodium azide (NaN₃) with fibrous nitrocellulose (NC). Scanning electron microscopy (SEM) was employed to examine the coating morphology. The thermal behavior of solid samples has been studied by means of thermogravimetry (TG) and differential scanning calorimetry (DSC). The results of TG–DTA analysis revealed that the main thermal degradation for the pure NC and NaN₃ occurs in the temperature ranges of 192–220 and 415–420 °C, respectively. The effects of some parameters, such as NC to NaN₃ weight ratio and volume and addition time of non-solvent, on coating quality and thermal properties have been investigated by SEM and thermal methods. The results of these experiments showed that the decomposition temperature of most stabilized coated sodium azide is about 50 °C higher than that of the pure sample. The DSC experiments were conducted to study the influence of the heating rate (5, 10, 15 and 20 °C/min) on the thermal decomposition processes of the pure NC, coated and pure NaN₃ samples. The results revealed that, as the heating rate was increased, decomposition temperature of the compounds was increased. Also, the kinetic parameters such as activation energy and frequency factor of the decomposition processes were obtained from the DSC data by non-isothermal methods proposed by ASTM E696 and Ozawa. Our finding showed that coated NaN₃ has lower decomposition rate with respect to the pure one.     

Polymaleamide–polymaleimide networks

Polymaleamide–polymaleimide networks were obtained as films by the thermal treatment of mixtures with different ratios of an aliphatic–aromatic polymaleamide (PMA) and 4,4′‐bis(maleimidodiphenylmethane) (BMI), in N‐methyl‐2‐pyrolidinone (NMP) as a solvent. The polymaleamides were synthesized by ring‐opening polyaddition of 1,6‐hexamethylene–bisisomaleimide with 4,4′‐diaminodiphenylmethane in NMP at room temperature. The networks are infusible and insoluble in organic solvents; therefore, they were studied by solid‐state techniques such as IR, DSC, thermooptical analysis (TOA), TG/DTG analysis, and TEM. Thermal treatment of pure PMA and BMI occurs with the formation of crosslinked structures as proved by IR spectra. DSC and TOA curves show the appearance of chemical interactions between PMA and BMI in cured films and the formation of ordered morphologies, especially when BMI is the major component. TG/DTG and TEM results supported these observations. The PMA–polymaleimide network films present electrical insulator properties superior to individual polyamides or polyimides. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 779–788, 2004     

Preparation and characterization of metal‐containing aromatic polyimides

A series of novel metal‐containing aromatic polyimides were synthesized from divalent metal oxide/hydroxide (MO/M(OH)₂) (M = Ba, Sr, Ca, Mg, Zn, Cd, Co, Ni, Pb, Cu), p‐aniline sulfonic acid (ASA), and 3,3′‐4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). The C, H, N, and S contents were determined by elemental analysis, their structures were characterized by proton nuclear magnetic resonance (¹H‐NMR) and Fourier transform infrared (FT‐IR) spectroscopy, and the thermal properties of the polymers were also studied by TG–DTA. It is found that metal‐containing polyimides have a higher thermal stability. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2363–2369, 2000     

加巴喷丁的热分解过程及动力学

采用热重法(TG)和差示扫描量热法(DSC)测定加巴喷丁(GBP)在氮气氛和空气氛中的热分解过程,测定GBP、热分解过程中不同阶段残余物和气化物的红外光谱,探讨GBP的热分解机理.根据不同升温速率下的热重曲线计算GBP热分解反应的动力学参数,采用Dakin方程推算GBP在各种温度下的预期寿命.结果表明,GBP的热分解过...     

Addition polyimides. II. Synthesis and characterization of bisitaconimide prepolymers

N,N′-bis(3,3′-itaconimidophenyl) sulfone has been synthesized by reacting itaconic anhydride with 3,3′-diamino diphenyl sulfone. The bisitaconimides and the intermediates were characterized by chemical analysis, IR, NMR, TG, and GPC. The degree of polymerization (DP) of the prepolymers of the bisitaconimide was followed by GPC and from the NMR data on vinylidene and aromatic proton ratios. The correlation between DP and intrinsic viscosity of the prepolymers was made use of to determine the Mark–Houwink constants (K and α). The thermal stability and the decomposition kinetics of the prepolymers were evaluated from TG data. The kinetic parameters, viz. energy of activation, E, and preexponential factor A, were computed using four nonisothermal integral equations, and their values are not appreciably affected by the degree of polymerization, within the range studied.     

热分析技术在催化研究中的应用进展

综述了TG、DTA和DSC三种常用热分析技术在金属催化剂、金属氧化物催化剂和沸石分子筛与多孔材料研究中近年来的应用进展。热分析技术与MS、FTIR和GC等技术联用具有较好的应用前景。