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991.
T. Kleps M. Piaskiewicz W. Parasiewicz 《Journal of Thermal Analysis and Calorimetry》2000,60(1):271-277
Thermogravimetry was employed to study the changes occurring in rubber vulcanizates during devulcanization carried out by
microwave treatment, a new promising method of recycling rubber waste. The thermogravimetric parameters T
i , T
5 and T
p and the compositions of devulcanizates in comparison with vulcanizates were determined. The results obtained allowed estimation
of the degree of destruction of the polymer chains in response to microwave treatment and permitted establishment of the most
advantageous conditions of devulcanization in order to obtain the best properties of rubber devulcanizates for reuse in rubber
processing.
The results demonstrated that thermogravimetry is a very useful method for investigation and control of the microwave devulcanization
process.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
992.
Anucha Wannagon Rikuo Ota Takashi Wakasugi Jiro Fukunaga 《Journal of Sol-Gel Science and Technology》2000,19(1-3):795-798
SiO2-TiO2-ZrO2 and 5Na2O·95(SiO2 + TiO2 + ZrO2) gels were synthesized and role of Na2O in gel formation and crystallization behavior of gels were studied. From Si(OC2H5)4, Ti(iso-OC3H7)4, Zr(n-OC3H7)4 and NaOCH3 solutions in EtOH without H2O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO2 or ZrO2 composition in Na2O containing SiO2-TiO2-ZrO2 system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO2-TiO2-ZrO2 system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO2-TiO2-ZrO2 gels, 5 mol% Na2O containing gels gave lower Tc in SiO2 rich compositions and higher in TiO2 rich or ZrO2 rich compositions. 相似文献
993.
TERESA HŁADOŃ JAN Pawlaczyk BARBARA Szafran 《Journal of inclusion phenomena and macrocyclic chemistry》2000,36(1):1-8
The ibuprofen--cyclodextrin inclusion complex was prepared by theco-precipitation method. The identity of the obtained product was verified by X-ray and thermogravimetric techniques. The effect of -cyclodextrin on the stability of ibuprofen was analysed. 相似文献
994.
钡对氧化铝的高温热稳定作用 总被引:3,自引:0,他引:3
在汽车正常工作状况下汽车催化剂所处的氛围常高达1000℃ ,这就要求催化剂有较高的热稳定性.催化剂的热稳定性除了依赖于活性组分的耐热性能外 ,还取决于涂层(γ Al2O3)的热稳定性 ,因此提高γ Al2O3 涂层的高温耐热性非常重要.研究表明 ,Al2O3 前驱体的结构、颗粒度及制备方法可以影响γ Al2O3 涂层的比表面积和热稳定性 [1 -3],而在涂层中引入某些添加剂 ,如稀土氧化物La2O3、碱土氧化物BaO、SrO等对提高Al2O3 的热稳定性更有效[4 -7].其中 ,La2O3 除了抑制Al2O3 的表相… 相似文献
995.
硅氮化合物的结构与水解稳定性的关系 总被引:1,自引:0,他引:1
采用硅氮化合物本体与水蒸汽直接作用的方法,研究了一系列硅氮化合物的结构与水解稳定性之间的关系.结果表明,空间位阻越大则硅氮化合物水解稳定性越好,环张力对硅氮烷的水解稳定性有一定的影响,但空间位阻的作用更为显著.带有苯基的环二硅氮烷、六苯基环三硅氮烷和含硅氮键的高分子聚合物具有较大的空间位阻,因此水解稳定性非常好. 相似文献
996.
新型镁基储氢合金的合成及电化学性能的研究 总被引:16,自引:1,他引:16
用扩散法成功地合成了Mg1.5Al0.5-xNiVx(x=0,0.1,0.2,0.3,0.4)系列合金。XRD结构分析表明,合金中出现一个新的物相,其化学式为Mg3AlNi2,属立方晶系,Fd3m空间群,新相具有很好的电化学性能。钒的添加使合金的容量进一步提高。未经任何预处理的Mg1.5Al0.3V0.2Ni合金的最大放电容量达到333mA·h·g-1(50mA·g-1,-0.5Vvs.Hg/HgO).Al对六方晶系Mg2Ni合金结构中Mg的部分取代对于延长合金的循环寿命有重要作用。 相似文献
997.
The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) was investigated by the dynamic differential scanning calorimetry
using varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS). The imide-amines were prepared
by reacting 1 mole of naphthalene 1,4,5,8-tetracarboxylic dianhydride (N) and 4,4′-oxodiphthalic anhydride (O) with 2.5 moles
of 4,4′-diaminodiphenyl ether (E) or 4,4′-diaminodiphenyl methane (M) or 4,4′-diaminodiphenylsulfone (S) and designated as
NE/OE or NM/OM or NS/OS. The mixture of the imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were
used to investigate the curing behaviour of DGEBA.
A single exotherm was observed on curing with mixture of imide-amines and DDS. This clearly shows that the two amines act
as co-curing agents. Curing temperatures were higher with imide-amines having sulfone linkage irrespective of anhydride. Curing
of DGEBA with mixture of imide-amines and or DDS resulted in a decrease in characteristic curing temperatures. The thermal
stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The
char yield was higher in case of resins cured imide-amines based on N and E. The activation energy of decomposition and integral
procedural decomposition temperature were also calculated from the TG data. 相似文献
998.
Mihaela Badea Rodica Olar Dana Marinescu Gina Vasile 《Journal of Thermal Analysis and Calorimetry》2008,92(1):209-214
A series of new complexes with mixed ligands of the type [ML(C3H3O2)2]·nH2O (((1)
M=Mn, n=1; (2)
M=Co(II), n=2; (3)
M=Ni(II), n=4; (4)
M=Cu(II), n=1.5; (5)
M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C3H3O2)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole
acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations
are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation
respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper. 相似文献
999.
Raj Kumar Gupta K.A. Suresh 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,320(1-3):233-239
The self-assembled monolayer of the thiocholesterol (TCh) exhibits interesting properties that can be used for various technological applications. TCh is predominantly a hydrophobic molecule, and it does not spread at the air–water interface to form a stable Langmuir monolayer. We have stabilized the TCh molecules in the cholesterol (Ch) monolayer. We find the mixed monolayer to be stable upto 0.75 mole fraction of TCh in Ch. The mixed monolayer shows an initial and a final collapse. On compressing the monolayer beyond the initial collapse, the TCh molecules squeeze out irreversibly from the mixed monolayer phase. The calculation of excess area per molecule for the TCh and Ch mixed monolayer system indicates an attractive interaction between the component molecules. Interestingly, the elasticity of the Ch monolayer reduces to less than half, and the monolayer becomes more fluidic due to the presence of even very minute quantity (5%) of TCh. 相似文献
1000.
Highly hydrolytic and thermally stable sandwich-type polyoxometallates of [(A-β-SiW9O34)2(MOH2)3CO3]13− (M = Y3+ and Yb3+) have been synthesized at room temperature by stoichiometric reactions of the trilacunary ligand with M3+ in 0.1 M carbonate solution. The new complexes were isolated as sodium and mixed sodium/potassium salts and were characterized by elemental analysis, IR, 13C and 29Si NMR, UV–Vis spectroscopy, TGA, DSC and single crystal structure analysis. The crystal structure of the complexes consist of two lacunary Keggin moieties which are linked by a (H2OMO)3C belt into an assembly of virtual C2 symmetry. Each M3+ ion adopts a mono-capped trigonal-prismatic coordination. The C2 axis of the complexes and the local 3-fold axis of the MO6 group lies in the (H2OMO)3C belt plane. The trigonal prismatic geometry is achieved by the two terminal oxygen atoms of an edge shared pair of WO6 octahedra from each moiety and two oxygen from the belt, and the cap by one external water ligand. The hydrolytic and thermal stabilities of the complexes and the reasons that prove the retention of the isomeric form of the trilacunary ligand upon complexation are discussed. 相似文献