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1.
采用光学解偏振法对4,4'-二苯醚二甲酸(OBBA)改性PET的等温结晶进行了研究。结果表明,随着OBBA添加量的增加,共聚酯的结晶诱导期延长,总结晶速度减慢,结晶活化能增大,与均聚酯相比,结晶趋于困难。  相似文献   

2.
采用示差扫描量热和热重分析的方法对合成的不同4,4'-二苯醚二甲酸(OBBA)含量的共聚酯的热性能进行了研究。结果发现共聚酯的熔点和热结晶温度与PET相比有所降低;而冷结晶温度则升高。随着OBBA添加量的增加,在恒温热重分析中热失重速率常数减小;在升温热重分析中,热失重活化能则增加。所有的实验结果皆表明,芳族醚键的引入对提高共聚酯的热性能有重要作用。  相似文献   

3.
全芳族热致液晶共聚酯的性能研究   总被引:3,自引:0,他引:3  
通过酯交换反应,合成了一系列以对乙酰氧基苯甲酸,4.4,一二乙酰氧基二苯基丙烷和对苯二甲酸为单体的三元共聚酯。采用热台偏光显微镜、示差扫描量仪和广角x射线衍射,较详细地研究了液晶共聚酯的结构、性能及其与分子链组成的关系。DSC和TOT结果表明,共聚酯的玻璃化温度较高,介于166-188℃之间,熔化温度一组成关系的相图具有最低共熔点;共聚酯中PHBA链节含量在10-50%时均呈现向列型液晶特征,随温  相似文献   

4.
4,4‘—二苯醚二甲酸改性PET的热性能研究   总被引:1,自引:1,他引:0  
采用示差扫描量热和热重分析的方法和对合成的不同4,4‘-二苯醚二甲酸(OBBA)的含量的共聚酯的热性能进行了研究。结果发现共聚酯的熔点和热结晶温度与PET相比有所降低;而冷结晶温度则升高。随着OBBA添加量的增加,在恒温热分析中热失重速率常数减小;在升温热重分析中,热失重活化能则增加。所有的实验结果皆表明,芳族醚键的引入对提高共聚酯的热性能有重要作用。  相似文献   

5.
4,4‘—二苯醚二甲酸改性PET等温结晶的研究   总被引:1,自引:0,他引:1  
采用光学解偏振法对4,4’-二苯醚二甲酸改性PET的等温结晶进行了研究。结果表明,随着OBBA添加量的增加,共聚酯的结晶诱导期期延长,总结晶速度减慢,结晶活化能增大,与均聚酯相比,结晶趋于困难。  相似文献   

6.
二胺改性BPDA—ODA型聚酰亚胺的H2/N2分离性能   总被引:1,自引:0,他引:1  
本文合成了一系列二胺改性的BPDA-ODA型共聚酰亚胺膜,改性聚酰亚胺与未改性的BPDA-ODA相比,透气性得到了明显的改善,改善的程度与第二种二胺单体的结构和用量有关。30℃时,在BPDA-ODA中加入20mol%三甲基间苯二胺(3MPDA)或四甲基对苯二胺(4MPDA)时,共聚酰亚胺BPDA-ODA/3MPDA(80/20)或BPDA-ODA/4MPDA(80/20)的透H2系数和H2/N2分  相似文献   

7.
本文合成了一系列二胺改性的BPDA-ODA型共聚酰亚胺膜,改性聚酰亚胺与未改性的BPDA-ODA相比,透气性得到了明显的改善,改善的程度与第二种二胺单体的结构和用量有关。30℃时,在BPDA-ODA中加入20mol%三甲基间苯二胺(3MPDA)或四甲基对苯二胺(4MPDA)时,共聚酰亚胺BPDA-ODA/3MPDA(80/20)或BPDA-ODA/4MPDA(80/20)的透H2系数和H2/N2分离系数分别大于6.5barrer和160,是比较好的气体分离膜材料。  相似文献   

8.
含介晶基因的半刚性共聚酯的合成及其性能研究   总被引:2,自引:1,他引:1  
通过介晶单体4,4’联苯分别与对苯二甲酰氯及4,4’(对苯二甲酰氧基)二苯甲酰氯进行高温溶液缩聚反应合成了两种含介晶基团的半刚性共聚酯BHHBP/TPC与BHHBP/TOBC。利用DSC、TG-DTA、偏光显微镜和X射线衍射等手段对介晶体BHHBP与共酯的相变行为以及共聚酯的热分解动力学及结晶性能进行了研究。结果表明,两共聚酯均为结晶性聚合物,其中BHHBP/TOBC具有向列相液晶相存在;共聚酯B  相似文献   

9.
对所合成的PHB/PET/HQ-TPA三元液晶共聚酯样品进行了热失重曲线测试。采用Freeman和Canrdl的微商法对TG曲线所得到的主要数据进行了处理,研究了共聚芳酯样品的热分解动力学。结果表明,随着第三单体(HQ-TPA)加入量的提高,共聚芳酯的热稳定性提高。由微商法求出热分解反应级数n=1~3,反应活化能E=167~293kJ/mol。  相似文献   

10.
Ce^3+,Tb^3+在Al4B2O9和Al18B4O33基质中的发光   总被引:5,自引:0,他引:5  
洪广言  刘春霞 《功能材料》1996,27(4):305-307
采用固相反应法在Al2O3-B2O3体系中合成了Al4B2O9和Al18B4O33两个相关化合物,测定了在两种基质中Ce3+,Tb3+和Ce3+-Tb3+的光谱,观察到在两种基质中Ce3+的光谱相似,Ce3+的发射峰位置在Al18B4O33中比Al4B2O9稍有红移。实验表明,Al18B4O33将是一种好的发光基质  相似文献   

11.
针对两种新型稀土型储氢合金La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2的储氢特性进行研究分析。实验表明,相同温度下,La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的PCT曲线基本重合,且都具有优良的吸氢动力学性能;相比之下,后者的滞后系数要小于前者,吸氢量较大,吸氢速率也较快,故其储氢性能较优。300次吸放氢循环实验结果表明,La0.5Y0.5Ni4.8Al0.2合金的吸氢动力学性能虽然略有下降,但抗粉化性能较好。  相似文献   

12.
Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x取向晶体的结构与磁致伸缩   总被引:1,自引:1,他引:0  
采用Czochralski方法生长了Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x(1.85≤x≤1.95)取向合金。所有合金主相为立方Laves相结构,择优取向不完整择优取向的方向与X的大小有关。研究了沿着这些样品的生长方向的磁致伸缩性能以及磁致伸缩性能与压力之间的关系。  相似文献   

13.
The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.  相似文献   

14.
根据Zr65Al7。5Ni10Cu15Co2。5合金的纳米晶,晶体,液体和玻璃比热的测量结果,研究了合金的玻璃转变温度与全金的热力学函数,动力学参数以及加热速度的关系。结果表明,非晶态合金玻璃转变所需转变激活能很小,玻璃转变温度实际上是由于加热速度引起的不同状态的玻璃与液体的热力学平衡温度。  相似文献   

15.
Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals.  相似文献   

16.
Tao X  Wang X  Li X 《Nano letters》2007,7(10):3172-3176
Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires.  相似文献   

17.
The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.  相似文献   

18.
The surfaces of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were modified by oxygen and nitrogen plasma treatments. The physical and chemical surface characteristics were evaluated by contact angle tests, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatments caused an increase in both contact angle and roughening, altered the surface morphology, inserted polar groups, and, consequently, enhanced the hydrophilicity for both PLLA and PHBV polymers.  相似文献   

19.
20.
Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction.  相似文献   

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