共查询到20条相似文献,搜索用时 31 毫秒
1.
The gaseous products of high temperature pyrolysis (300℃ to 960℃) of aerylonitrile polymers were measured continuously under nitrogen atmosphere by on-line Fourier Transform Infrared Spectroscopic method (FTIR). From the variations of characteristic peaks it was found that the nitrogen of macromolecules evolved were mainly in the form of hydrogen cyanide and ammonia. During the pyrolysis amorphous carbonaceous element was formed, and crosslinked to form network structure. Three kinds of samples were used for comparison. The experimental results show that the gaseous products of volatile small molecules were HCN, NH_3, CH_4, C_2H_6 and cyanide. CO and CO_2 were also formed when copolymers of PAN were thermally pyrolyzed. 相似文献
2.
G. Janowska A. Kucharska W. M. Rzymski A. Kasiczak 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1019-1024
The results of thermal analysis of speciality elastomers CSM with different chlorine and sulphur contents is presented in
the article. The thermal curves obtained under the atmosphere of inert gas have been interpreted from the point of view of
phase transitions and chemical reactions of the examined polymers during their heating. It has been stated that from among
the investigated chlorosulphonated polyethylenes, only CSM24, which has the lowest chlorine content, contains a crystalline
phase, clearly influences on its T
g temperature. Results of the thermal analysis obtained under inert gas atmosphere have been compared with results obtained
under termooxidative atmosphere. Irrespective of the research atmosphere, the thermal decomposition of investigated CSM takes
place in three stages. The maximum rate of thermal destruction of modified by heating elastomers, dm/dt, decreases with the increase in chlorine content in the sample having been heated. 相似文献
3.
The preparation and pyrolysis of a blended precursor possessing Ti? N and Al? N bonds were investigated. The precursor was prepared by mixing (HAlN iPr) n, whose main compo‐nent was a cage‐type compound, and an aminolysis product of Ti(NMe2)4 with MeHNCH2CH2NHMe with a molar ratio of Ti:Al = 2:1. IR analysis of the products pyrolyzed under NH3–N2 indicated that a large proportion of the organic groups in the precursor were removed by an amine‐exchange reaction during the pyrolysis under NH3; thus, the products contained only a small amount of carbon. On the contrary, a considerable amount of carbon was present in the product pyrolyzed under Ar. Composites consisting of AlN and an NaCl‐type compound were obtained after pyrolysis of the precursor under both NH3–N2 and Ar. The composition of the NaCl‐type compound depended significantly on the pyrolysis atmosphere. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
4.
在带有输送煤样的管式反应器上进行了霍林河褐煤加压快速氢解实验,分析了H2对煤/半焦的化学键断裂和对CH4生成规律的影响。在加压快速氢解条件下,CH4产率随着热解温度升高、压力的增大而增大;在50% H2气氛下,操作压力为1.0 MPa、温度为900 ℃时,CH4产率为8.08%,达到最大,较N2气氛下的提高了72.5%。H2或H·自由基诱发了芳环的开裂、侧链、脂肪链和醚键的断裂,促进了煤热解。CH4产率的增加主要是由于外部供H的结果;热解温度低于700 ℃时,H2对煤结构中活性基团的作用促进了煤热解,导致了CH4产率的增加;而热解温度高于700 ℃后,煤/半焦加氢气化促进了CH4产率的增加。 相似文献
5.
《European Polymer Journal》1985,21(8):747-751
The chloroallyl group contents of PVC and its low molecular weight fractions, soluble in chloroform or acetone, have been determined on the assumption that the reaction of AgNO3 with labile chlorine atoms occurs only with the allylic chlorines. Their amount is highest in the low molecular weight fractions. The thermal stability of the polymer in inert atmosphere increases if these groups are removed. Neither the labile chlorine content nor the dehydrochlorination rate (in the subsequent degradation) of the initial polymer, or the fractions insoluble in the two solvents, is affected by heat treatment at 180 for 60 min, whereas the amount of labile chlorine in the low molecular weight fractions increases on heat treatment exceeding 30 min. No direct dependence of the dehydrochlorination rate on the amount of labile chlorine in the polymers under study has been established. 相似文献
6.
Thermal degradation study of tetrabromobisphenol A under the presence metal oxide: Comparison of bromine fixation ability 总被引:1,自引:0,他引:1
Thermal degradation of mixture of tetrabromobisphenol A (TBBA) and metal oxide (ZnO, Fe2O3, La2O3, CaO and CuO) has been studied under inert atmosphere. The formation of hydrogen bromide and brominated organic compounds is observed for pyrolysis of TBBA. The addition of metal oxide gives rise to considerable suppression of HBr as well as brominated organic compounds. The suppression owes to the bromination of oxides. The influence of oxide on thermal degradation of TBBA is discussed with emphasis on the conversion of bromine. 相似文献
7.
Ao Hou Ze Wang Wenli Song Weigang Lin 《Journal of Thermal Analysis and Calorimetry》2012,109(1):337-343
Comparative studies on the Hailar lignite pyrolysis/gasification characteristics at N2/CO2 atmosphere and the influence of inherent mineral matters, external ash and pyrolysis temperature on its reactivity during gasification at CO2 atmosphere were conducted by non-isothermal thermogravimetric analysis, FTIR, and X-ray diffraction (XRD) analysis. Thermogravimetric test results show that the atmosphere of N2 or CO2 almost has no effects on the pyrolysis behavior, and the gasification reaction under CO2 atmosphere occurs over 943?K at the heating rate of 40?K?min?1. The external ash prepared at 1173 and 1223?K shows a certain catalytic effect on promoting the gasification reaction, although the inherent mineral matters of Hailar lignite are found in stronger catalytic effects on gasification than the external ash. The lignite gasification reactivity decreases with increasing pyrolytic temperature between 1073 and 1273?K. 相似文献
8.
Delynn M. Hayes Issifu I. Harruna 《Journal of polymer science. Part A, Polymer chemistry》1998,36(2):277-281
Poly(benzobisoxazoles) (PBOs), poly(benzobisthiazoles) (PBTs) and copolymers thereof containing the 2,5-dihydroxybicyclo[2.2.2]octane moiety have been prepared and studied. The homopolymers were synthesized by the polycondensation of 2,5-dihydroxybicyclo[2.2.2]octane-1,4-dicarboxylic acid with 4,6-diamino-1,3-benzenediol dihydrochloride or 2,5-diamino-1,4-benzenedithiol dihydrochloride in poly(phosphoric acid). Random and block copolymers (PBO–PBT) were also prepared. The polymers were characterized by solubility, X-ray diffraction, spectroscopy (infrared and solid-state 13C nuclear magnetic resonance), and thermal analysis such as differential scanning calorimetry and thermogravimetric analysis. Thermogravimetric analysis showed thermal stability of the polymers above 375°C in air and under argon atmosphere. The polymers exhibited high resistance to organic and inorganic solvents. The polymers were converted to the more stable aromatic polymers via dehydration and retro Diels–Alder reactions of the 2,5-dihydroxybicyclo[2.2.2]octyl moiety by pyrolysis. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 277–281, 1998 相似文献
9.
Takatsugu Obata Eiichi Kobayashi Sadahito Aoshima Junji Furukawa 《Journal of polymer science. Part A, Polymer chemistry》1994,32(3):475-483
A polyaddition of phenylphosphine (PH) to 1,4-divinylbenzene (DVB) or 1,4-diisopropenylbenzene (DIPB) was carried out by radical initiations or UV irradiation at 60–80°C in toluene under a nitrogen atmosphere. The soluble polymer with higher molecular weight () was obtained in a high yield with AIBN initiator for 95 h in the presence of 5% excess of PH to DVB (monomer feed ratio [DVB]0/[PH]0 = 1/1.05). On the other hand, a polyaddition of PH to DIPB proceeded much slower than the case of DVB, but the high polymer was obtained in a high yield by choosing polyaddition conditions such as polyaddition temperature and initiator concentration. From 1H-NMR, IR analyses, and phosphorus content of the polymers, it was characterized that both polymers have the alternating structure consisting of PH and DVB or DIPB units in 1 : 1 ratio. The glass transition and decomposition temperatures of both polymers under a nitrogen atmosphere were almost similar: 15–30°C and 380–385°C, respectively; but, the polymers were oxidized by heating under an atmosphere of air. The polymers had a self-extinguishing property and the polymer blend of the flammable polymers such as polystyrene and polyethylene with the phosphorus-containing polymers exhibited an excellent flame resistance. © 1994 John Wiley & Sons, Inc. 相似文献
10.
Qian Zhang Qingfeng Li Linxian Zhang Yitian Fang Zhiqing Wang 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1929-1938
The pyrolysis, combustion, and gasification behaviors of deoiled asphalt were studied by a thermogravimetric analyzer and the kinetics were also analyzed using a multi-stage first-order integral model. All the experiments were conducted at non-isothermal conditions with heating rates range of 10–40 K min?1 under N2 (pyrolysis), air (combustion), or CO2 (gasification) atmosphere, respectively. The results showed that, for pyrolysis, the reaction mainly occurred between 498 and 798 K and could be divided into two stages: the first was caused by the volatilization of small molecules and the second probably due to the cracking reactions. For combustion, the mass loss process could be divided into three stages: the devolatilization and oxidation first, the ignition and combustion of the volatiles second, and finally the combustion of the formed char. Under CO2 atmosphere, the mass loss behavior was similar with that of the N2 atmosphere at lower temperatures, but when the temperature was higher than 1,233 K, the gasification reaction obviously happened. The results of kinetic investigation showed that the multi-stage first-order integral method agreed well with the above experiments. 相似文献
11.
J. M. Nazzal 《Journal of Thermal Analysis and Calorimetry》2001,65(3):847-857
Jordan oil shale from El-Lajjun deposit was pyrolysed in a fixed-bed pyrolysis reactor and the influence of the pyrolysis
temperature between 400 to 620°C and the influence of the pyrolysis atmosphere using nitrogen and nitrogen/steam on the product
yield and gas composition were investigated. The gases analysed were H2, CO, CO2 and hydrocarbons from C1 to C4. The results showed for both nitrogen and nitrogen/steam that increase the pyrolysis bed temperature from 400 to 520°C resulted
in a significant increase in the oil yield, after which temperature the oil yield decreased. The alkene/alkane ratio including
ethene/ethane, propene/propane, and butene/butane ratios, can be used as an indication of pyrolysis temperature and the magnitude
of cracking reactions. Increasing alkene/alkane ratio occurring with increasing pyrolysis temperature. The alkene/alkane ratio
for nitrogen/steam pyrolysis atmosphere was lower than the one found under nitrogen atmosphere.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
小龙潭褐煤不同气氛下液化性能的研究 总被引:2,自引:1,他引:1
根据褐煤含水量高的特点,研究了以水为溶剂,不同气氛条件下小龙潭褐煤的液化行为。结果表明,小龙潭褐煤具有较好的液化活性,在420℃,H2气氛下以四氢萘为溶剂时煤的液化转化率可达到94.5%。煤液化过程中,稳定热解产生的自由基活性氢主要来自于供氢溶剂,而气相H2不具活性,不能直接为液化过程提供活性氢。当以水为溶剂取代四氢萘进行褐煤直接液化时,相对于H2和N2气氛,CO 气氛下表现出较好的液化性能。这表明发生了水煤气变换反应并生成了活性氢,该活性氢可以使得煤热解产生的自由基稳定,生成低分子的液化产物,提高了液化转化率。由于在较低的CO初压下反应生成的活性氢数量有限,因而液化转化率不高。实验表明,以水为溶剂在CO气氛下进行褐煤的液化是一种新的褐煤直接液化技术。 相似文献
13.
《Journal of Analytical and Applied Pyrolysis》2007,78(2):291-300
An innovative way of catalysis was investigated for its potential to reduce the amount of condensable hydrocarbons produced during the pyrolysis of oak wood. The experiments were carried out in a horizontal tubular reactor, fed with a controlled flow rate of nitrogen and equipped with accessories to collect char, liquid and gaseous products. Pyrolysis was performed at 700 °C with different wood sample series impregnated with either Ni or Fe nitrates (in aqueous solution) and by varying the metal concentration in the wood. In the blank run the biomass was acid-washed to determine the impact of demineralization. The influence of the metal type and content introduced into the wood to reduce the fraction of condensable organic compounds produced during pyrolysis was determined.Depending on the experimental conditions, the gas yield increases from 20.0 to 33.1%. Condensable hydrocarbons are cracked into gaseous components and the concentration of H2 is significantly increased, by 260% compared to the reference sample. In particular, the Ni-loaded wood samples give much higher H2 yields than the Fe-loaded ones under similar conditions but less toxic products are formed with the latter. These results show that biomass impregnation with either nickel or iron salts is a promising way to reduce the fraction of condensable organic compounds produced during pyrolysis. 相似文献
14.
Sandip Halder Theodor Schneller Rainer Waser Florian Thomas 《Journal of Sol-Gel Science and Technology》2007,41(3):203-207
Nickel thin films have been sputtered on standard Si/SiO2 substrates with TiO2 as an adhesive layer. The thermal stability of these substrates was analyzed. SEM images show an increase in grain size with
annealing temperature. They were found to be stable till 800°C, beyond which the nickel layer disintegrated. These substrates
were used for deposition of BaTiO3 and (Ba,Sr)TiO3 dielectric thin films under a reducing atmosphere. The dielectric thin films were processed with various pyrolysis and annealing
temperatures in order to optimize the dielectric properties. Increased pyrolysis temperatures showed an increase in the grain
size. Results on these nickelised substrates were finally compared with dielectric films deposited on platinized silicon substrates
under identical conditions but crystallized in an oxygen atmosphere. 相似文献
15.
《Journal of Analytical and Applied Pyrolysis》2006,77(1-2):138-143
In this work, a study of the degradation of PE and an EVA copolymer under air atmosphere, in the presence and absence of mesoporous MCM-41, was carried out using thermogravimetric analysis (TGA), focusing on the analysis of the EVA behaviour during this the process. The results obtained show that the air atmosphere causes an increase of the complexity of the process, with respect to the thermal and catalytic pyrolysis in N2 atmosphere, exhibiting more decomposition steps. The results obtained for both polymers show that the presence of MCM-41 does not practically affect the temperature of the oxidative decomposition processes, but a clear effect has been found on the main step of degradation, that supports the existence of cracking or incomplete oxidation reactions, and clearly it enhances the carbonaceous residue formation. 相似文献
16.
The goal of this investigation was to optimize the synthesis of silazane-based polymers for processing fibre-reinforced ceramic matrix composites (CMCs). Liquid oligomeric silazanes were synthesized by ammonolysis of chlorosilanes and characterized spectroscopi- cally (FTIR, NMR) as well as by elemental analysis. The silazanes were obtained in high yield and purity. Different functional groups (system S1: Si—H, Si—CH3, Si—CH=CH2) and different degrees of branching in the Si—N backbone [system S2; Si(NH)3, Si(NH)2] were realized in order to study the properties of the silazanes that are dependent on the molecular structure. For processing ceramics via pyrolysis of pre-ceramic oligomers, molecular weight, rheological behaviour, thermosetting and ceramic yield were investigated systematically and correlated with the molecular structure of the silazanes. Low molecular weights (500–1000 g mol−1) as well as low viscosity values (0.1–20 Pa s) enable processing of the silazanes in the liquid phase without any solvent. Due to the latent reactivity of the functional groups, curing of the polymers via hydrosilylation is achieved. Structural changes and weight loss during polymer curing as well as the organic/inorganic transition were monitored by FTIR spectroscopy and differential thermogravimetric analysis. With increasing temperature (room temperature to 800 °C) the hydrogen content decreases from 7 to < 0.5 wt% due to the formation of gaseous molecules (NH3, CH4, H2). High ceramic yields up to 80% were reached by branching the oligomers, thus reducing the amount of volatile precursor fragments. Up to 1300 °C, ceramic materials remained amorphous to X-rays. At higher temperatures (1400–1800 °C) either SiC or SiC/Si3N4 composites were selectively crystallized, depending on the pyrolysis conditions. The utility of the optimized precursors for CMCs has been demonstrated by infiltration of fibre preforms and subsequent pyrolysis. © 1997 by John Wiley & Sons, Ltd. 相似文献
17.
High refractive index materials: A structural property comparison of sulfide‐ and sulfoxide‐containing polyamides
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ali Javadi Ebrahim Abouzari‐Lotf Shahram Mehdipour‐Ataei Masoumeh Zakeri Mohamed Mahmoud Nasef Arshad Ahmad Adnan Ripin 《Journal of polymer science. Part A, Polymer chemistry》2015,53(24):2867-2877
High‐refractive‐index polyamides (PAs) are developed by incorporation of sulfide‐ or sulfoxide linkages and chlorine substituents. The PAs are synthesized through the polycondensation of two novel diamine monomers, 2,2′‐sulfide‐bis(4‐chloro‐1‐(4‐aminophenoxy) phenyl ether (3a) and 2,2′‐sulfoxide‐bis(4‐chloro‐1‐(4‐aminophenoxy) phenyl ether (3b), with various aromatic diacids (a–e). The ortho‐sulfide or sulfoxide units, pendant chlorine groups, and flexible ether linkages in the diamine monomers endowed the obtained PAs with excellent solubilities in organic solvents. The resulting PAs showed high thermal stability, with 10% weight loss temperatures exceeding 415 °C under nitrogen and 399 °C in air atmosphere. The combination of chlorine substituents, sulfide or sulfoxide linkages, and ortho‐catenated structures provided polymers with high transparency along with high refractive index values of up to 1.7401 at 632.8 nm and low birefringences (<0.0075). The structure–property relationships of the analogous PAs containing sulfide or sulfoxide linkages were also studied in detail by comparing the results. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2867–2877 相似文献
18.
The pyrolysis behaviors of l-tyrosine-based phthalonitrile(TPN) resin were investigated by thermogravimetric-Fourier transform infrared spectrometry-mass spectrometry (TG-FTIR-MS) and Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The small molecules produced during pyrolysis process of TPN resin were tracked in real time by TG-FTIR-MS. The larger molecules (m/z > 40) from fast pyrolysis at 900 °C of the TPN resin using Py-GC/MS were identified. From TG-FTIR-MS and Py-GC/MS results, the production pathways of pyrolysis products such as CO2, CO, NH3, benzonitrile and phenol were analyzed. The possible pyrolysis mechanism of TPN resin under non-oxidizing gaseous environment was proposed. The results of this study provide the useful information for designing the molecular structure of l-tyrosine-based polymers which possessing high thermal stability. 相似文献
19.
Summary The following parameters were analyzed 2 to 4 times a year from 37 sampling sites; T, O2, O2%, Turbidity, Suspended solids, Conductivity, Alkalinity, pH, Color, CODMn, Total nitrogen, Total phosphorus, Cl, Fe, Mn, Total sulphur, K, Na, Ca, Mg, SiO2, Total organic chlorine and Total organic bromine. Samples were taken from waters loaded by chemical pulp mills, other industries, municipal waste waters and agriculture. Also waters under natural conditions were included. Water samples have been collected and analyzed in co-operation with the National Board of Waters and the Environment. The data set was analyzed by Principal Component Analysis (PCA) to determine correlations between variables, especially between Total organic chlorine and Total organic bromine and others. Typically Total organic chlorine and Total organic bromine correlated with Na, Cl and Total sulphur. It is interesting to note that Total organic chlorine and Total organic bromine did not follow each other in all components. Total organic chlorine was predicted using other variables and Partial Least Squares (PLS) method. Very satisfactory correlation was obtained between analyzed and predicted lgTOCl values. Optimally three different object classes were found from the whole data using fuzzy clustering analysis. One class represents waters in a natural condition, one water loaded mainly by agriculture and one represent the rest of the waters. 相似文献
20.
R. Bacskai L. P. Lindeman J. Q. Adams 《Journal of polymer science. Part A, Polymer chemistry》1971,9(4):991-1004
The low-temperature chlorination of poly(vinyl fluoride) (PVF) proceeds readily in CCl4 suspension. The rate of chlorination is high initially, but the reaction slows down considerably when the chlorine content of the polymer reaches 40–50%. At long reaction times, polymers containing 62% chlorine (1.88 chlorine atoms per monomer unit) can be obtained. As the degree of chlorination increases, the solubility of PVF in organic solvents increases. Polymer crystallinity and polymer softening point decrease with chlorination. Polymers containing 40% chlorine appear to be completely amorphous by x-ray analysis. In this respect, PVF differs from poly(vinyl chloride) (PVC), where chlorination increases the softening point, and it resembles polyethylene where both crystallinity and softening point decrease with chlorination. 19F NMR analysis of the polymers indicates that up to a degree of chlorination of 1 chlorine atom per monomer unit, 50% of the substitution occurs on the α-carbon of the PVF molecule. This result is very different from the predominant β-chlorination of PVC reported by several workers. The chemical selectivity observed in the chlorination of PVF is in quantitative agreement with the results of free-radical chlorination of organic compounds and can be rationalized by considering the size and the electronic properties of the fluorine atom. The results of 1H NMR analysis are also in support of a polymer structure where the chlorine atoms are distributed between α- and β-carbons. Based on a comparison of the 19F and 1H NMR data, the average composition of chlorinated PVF at the 1 chlorine atom per monomer unit level can be represented as: C200H200F100Cl100 = (CH2)63(CHF)50(CHCl)24(CClF)50-(CCl2)13. 相似文献