Guimei WANG
,
Xigao JIAN
,
Gongxiong LIAO
,
Lihao WU
材料科学技术（英文）
Poly (phthalazinone ether sulfone ketone) (PPESK) was melt blended with bisphenol-A polysulfone oligomer (O-PSF) to produce a thermoplastic polymer blends. The miscibility, thermal stability, rheological and mechanical properties of the blends were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and capillary rheometry. The blends showed single Tg over the composition range and possess homogeneous microstructure. The addition of O-PSF slightly affected the thermal properties of the blends. PSF oligomer, as a processing aid, could markedly improve the processability of the PPESK. In addition, the mechanical properties of the blends were increased, to some degree, by adding O-PSF.
关键词:
PPESK
,
null
,
null
,
null
,
null
,
null
Xiongjian ZHANG
,
Qin HAN
材料科学技术（英文）
The thermal stability of α-Fe2O3 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe2O3 nanowires are transformed into α-Fe2O3 under the strong laser beam.
关键词:
Fe2O3 nanowire
,
nanowire
,
Thermal
,
stability
,
Structu
Haiping XIA
,
Zhaoyang JIANG
,
Jianli ZHANG
,
Jinhao WANG
,
Yuepin ZHANG
,
Qiuhua NIE
材料科学技术（英文）
Water soluble fullerenols were synthesized and incorporated in SiO2, SiO2-TiO2, GPTMS- SiO2, GPTMS-ATPS inorganic and organic-inorganic materials by sol-gel processes. The maximum concentrations of C60 (OH) n and C70 (OH) n in the obtained SiO2 gels were estimated to be about 0.6% and 1.5% in weight, respectively. The characteristics of the UV/visible spectra of fullerenols in H2O and various gels were measured and compared. The thermal stability of fullerenols in gels was investigated with differential thermal analysis (DTA). The results indicate that the absorption features of fullerenols in solid gels are similar to those in H2O and the fullerenols in SiO2 are stable at 400ºC. The optical limiting effect of the fullerenols was investigated preliminarily.
关键词:
Water soluble fullerenol
,
null
,
null
,
null
Junjie ZHANG
,
Shixun DAI
,
Shiqing XU
,
Guonian WANG
,
Liyan ZHANG
,
Lili HU
材料科学技术（英文）
In this work, a new TeO2-BaO-BaF2-La2O3-LaF3 oxyfluorotellurite glass system is investigated. Differential thermal analysis (DTA) and structural analysis by Raman scattering spectra are reported on the glasses. The DTA results indicated that an increase of fluoride content in the glasses decreases the glass transition temperature (Tg) and increases the crystallization onset temperature (Tx). As a result the 70TeO2•20BaF2•10LaF3 glass showed a large Hruby's parameter, possessing excellent thermal stability. Changes in glass network structure with fluoride content are discussed based on the Raman scattering spectra of glasses. The glass network structures in the 70TeO2• (20-x)BaO•xBaF2• (10-y)La2O3•yLaF3 glasses are basically composed of both Te(O, F)4 and Te(O, F)3 units, but the Te(O, F)4/Te(O, F)3 ratio in the glass becomes higher with increasing fluoride content. This may be considered one of the reasons why the 70TeO2•20BaF2•10LaF3 glass exhibits excellent thermal stability.
关键词:
Raman spectrum
,
null
,
null
Dongbing HE
材料科学技术（英文）
Divalent metal fluorides MF2 (M=Sr, Mg, Ca) in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides MF2 (M =Sr, Mg, Ca) on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.
关键词:
Divalent metal fluorides
,
null
,
null
Min XU
,
Minxiu QUAN
,
Zhuangqi HU
,
Y
,
ong WANG
,
Liang ZUO
材料科学技术（英文）
Fe62Co8-xCrxZr6Nb4B20(x=0–4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both δs and Hc.
关键词:
Cr addition
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null
,
null
赵雨花
,
李其峰
,
王军威
,
亢茂青
,
王心葵
新型炭材料
采用原位聚合法和浇注模压工艺合成出一系列经不同方法处理的炭纤维( CF)/聚醚型聚氨酯( PU)弹性体。通过机械性能测试，热失重分析和扫描电子显微镜等手段研究不同处理方法和CF含量对CF/PU弹性体复合材料的物理机械性能、热性能和微观形态的影响。结果表明，偶联剂中以胺基硅烷KH5501、KH602和钛酸酯类TCAˉK44处理CF对CF/PU复合材料的机械性能改善效果明显；硝酸氧化的CF对复合材料的机械性能和热稳定性均明显改善；硝酸氧化处理CF与PU间的黏接性优于偶联剂处理CF/PU间的黏接性。
关键词:
炭纤维
,
聚氨酯
,
复合材料
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机械性能
,
耐热性
阳雪
,
杨林颜
,
林嗣煜
,
周仁贤
催化学报
doi:10.1016/S1872-2067(14)60157-1
以La改性的Al2O3为载体，采用共吸附浸渍法制备了一系列不同CeO2含量的单Pd密偶催化剂，并对其进行了表征。 PdOx和CeO2之间的强相互作用改善了Pd0再氧化为PdO的能力，同时增强了反应条件下硝酸盐，亚硝酸盐和异氰酸盐在载体上的吸附。因
此适量CeO2的添加明显改善了新鲜催化剂对HC和NOx的催化性能，且当CeO2添加量为2%时催化效果最佳。 Pd-Ce界面上PdOx和CeO2间强相互作用也使得PdOx物种在高温时仍能以小颗粒的形式分散在载体上，从而显著地提高催化剂的热稳定性。经1100°C高温老化后， CeO2(2%-4%)的存在明显拓宽了HC和NOx的操作窗口，这对于提高单Pd密偶催化剂在汽车尾气处理上的催化性能有重要意义。
关键词:
单钯密偶催化剂
,
催化性能
,
氧化铈
,
热稳定性
,
原位红外光谱
