聚乙二醇／聚乙烯醇共混物的相变特性与结晶

通过溶液共混法制备了系列PEG4000／PVA共混物，并采用DSC、WAXD、FT-IR等手段对共混体系的相变特性及结晶进行了探讨。结果表明：共混体系具有可逆的固-固相转变特性。共混物的熔点（Tm）基本保持不变，而结晶峰值温度（Tc）与PEG／PVA质量百分含量有关。其相变焓是随着PEG含量的增加而逐渐增加。聚乙烯醇的存在对共混体系中PEG的结晶和熔融过程均有所影响，但共混体系与纯PEG4000具有相同的衍射线、衍射角和面间距，且并未发现新的衍射峰出现。共混体系中x射线衍射峰的半峰宽度大于纯PEG的半峰宽度，说明共混过程使PEG结晶粒子变小。     

等规度分布对双向拉伸聚丙烯非等温结晶动力学的影响

利用差示扫描量热仪研究了等规度分布对两种双向拉伸聚丙烯(BOPP)薄膜专用料的非等温结晶动力学的影响。非等温结晶动力学结果表明:随降温速率的增大,两种BOPP膜的结晶起始温度T0、结晶终了温度T∞、结晶峰值温度Tp、结晶焓均降低;结晶速率常数Zc增大,半结晶时间t1/2逐渐缩短,结晶过程中的生长维数n在1~3之间;F(T)逐渐增大,a值逐渐减小。样品的等规度分布越均一,则其结晶速率越慢,半结晶时间t1/2越长,结晶速率常数Zc越小。     

接枝共聚法制备PEG/CDA高分子固-固相变材料及其表征

通过接枝共聚法制备了PEG/CDA复合高分子固一固相变材料,用DSC差示扫描量热法及FTIR对其进行了表征,用正交试验法L9(34)研究了PEG分子量、PEG/CDA的质量比对相变材料储热性能,相变温度等的影响,以及反应时间对接枝反应的影响.结果表明,当PEG相对分子量为6000,PEG/CDA质量比为9:1,接枝反应时间为150 min时,材料的储热性最好.     

PEG/PVA复合物相变焓的影响因素研究

通过接枝共聚法制备了PEG/PVA复合高分子固-固相变材料,用DSC差示扫描量热法对其相变曲线进行了测试,讨论了影响PEG/PVA复合物相变焓的影响因素.结果表明,PVA含量、反应温度和反应时间都对复合物的相变焓有影响,且PVA含量对复合物相变焓值影响最大.     

木粉聚丙烯复合材料的等温结晶动力学

应用差示扫描量热法(DSC)研究了有无相容剂(m-TMI-PP)的木粉聚丙烯复合体系的等温结晶行为,采用Avrami方程处理等温结晶过程,计算结晶动力学参数。结果表明,随着结晶温度的升高,各体系的结晶速率下降,结晶速率常数K、n降低,半结晶时间t1/2增大。在同一结晶温度下,木粉起到成核剂的作用,提高了基体的结晶速率;m-TMI-PP的加入,使基体的结晶速率下降。纯PP的等温结晶过程具有异相成核与均相成核的机理,复合材料的等温结晶过程属于异相成核机理。     

共混法制备高分子固-固相变材料及其表征

通过共混法制备了PEG/CDA高分子固-固相变材料,用DSC差示扫描量热法对其相变行为进行了研究,讨论了PEG/CDA质量比对所得相变材料相变行为的影响.结果表明,该材料呈现出固-固相转变特性;其相变温度和相变焓比纯PEG低,并随着PEG含量的增加而升高.     

纳米金刚石/PP复合材料的非等温结晶行为

采用熔融共混的方法制备了纳米金刚石/聚丙烯(PP)复合材料,并研究了纳米金刚石在非等温条件下对PP非等温结晶动力学和结晶形态的影响。用Jeziorny法和Mo法对非等温结晶动力学分析发现,添加适量的纳米金刚石,提高了PP的结晶峰值温度Tp,加快了结晶速率。当纳米金刚石添加量为1%时,复合材料的Avrami速率常数(Zt)最大,结晶速率[F(T)]和半结晶时间(t1/2)最小。偏光显微镜观察结晶形态发现,纳米金刚石/PP复合材料的晶粒尺寸减小,结晶完善程度有所下降。复合材料的结晶活化能随着纳米金刚石含量的增加呈现先减少后增加,当纳米金刚石含量为3%时,复合材料的结晶活化能达到最低值21.08kJ/mol。     

聚丙烯/赤泥复合材料非等温结晶行为研究

以不同含量的赤泥(Red Mud)作为成核剂改性聚丙烯(PP),采用差示扫描量热仪(DSC)研究了PP/Red Mud复合材料的非等温结晶行为,并分析了基于Jeziorny理论和莫志深理论的结晶动力学,最后利用Kissinger法计算结晶迁移活化能(ΔE)。结果表明:PP中加入Red Mud后,复合材料的结晶起始温度To、结晶峰值温度Tp均有所提高;与纯PP相比,PP/Red Mud复合材料的半结晶时间t1/2和F(T)升高,而结晶速率常数Zc降低。当Red Mud含量为10%时,t1/2最小,Zc最大,说明加入10%的Red Mud对PP的成核作用最明显。当Red Mud质量分数为20%时,复合材料的ΔE最小。     

HDPE/SiO2杂化材料的结晶行为

通过熔融接枝反应将乙烯基三甲氧基硅烷(A-171)接枝到高密度聚乙烯(HDPE)分子链上,以四乙氧基硅烷(TEOS)为前驱体,加入接枝的HDPE中,通过溶胶-凝胶法(Sol-Gel)制备了HDPE/SiO2杂化材料。采用DSC分析,研究了SiO2对HDPE结晶行为的影响。结果表明,SiO2在HDPE中起到异相成核的作用,使HDPE的结晶温度提高、微晶尺寸分布减小。随降温速率增大,结晶峰变宽,结晶温度Tp向低温方向移动。非等温结晶动力学研究表明,在冷却速率范围5℃/min~20℃/min内,杂化材料异相成核,近似一维生长。     

聚乙二醇/聚丙烯酰胺相变材料非等温固-固相变动力学

通过在丙烯酰胺聚合反应中加入聚乙二醇的方法制得的聚乙二醇(PEG)/聚丙烯酰胺(PAAm)相变材料具有固-固相转变的性质。对聚乙二醇及五种相变材料分别进行不同速率的非等温DSC测试,采用K iss inger和O zaw a两种动力学模型研究了非等温固-固相变动力学,计算了固-固相变过程的活化能和反应级数,两种方法求得的表观活化能Ea值相一致。     

La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的储氢性能研究

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。     

Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x取向晶体的结构与磁致伸缩

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。     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

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.     

Zr65Al7.5Ni10Cu15Co2.5合金的玻璃转变温度

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。     

Acousto-optic interaction in alpha-BaB(2)O(4)and Li(2)B(4)O(7) crystals

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.     

Nanomechanical characterization of one-step combustion-synthesized Al(4)B(2)O(9) and Al(18)B(4)O(33) nanowires

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.     

Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys

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.     

Plasma surface treatments of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)

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.     

An SANS Study of Decomposition Kinetics in Amorphous Cu_(12.5)Ni_(10)Zr_(41)Ti_(14)Be_(22.5)

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.