噻吨酮酰胺类光引发剂的合成及性能

合成了１２个噻吨酮酰胺类光引发剂，它们均为新化全物。经红外光谱，质谱及元素分析等方法确证结构。采用膨胀计法研究了它们的光引发性能，并和其它种类取代的噻吨酮作了比较。结果发现取代基的位置和结构对引发性能有一定影响。     

形状记忆合金相变温度的常用测量方法

讨论了形状记忆合金相变温度的常用测量方法的现状、优缺点及发展趋势,包括变温X射线法、热分析法、膨胀法、声发射法及电阻法．其中电阻法精度高,电路简单,测量过程对试样的影响小,速度快,被广泛采用.     

Kinetic study of austenite formation during continuous heating of unalloyed ductile iron

The austenite formation kinetics in unalloyed cast ductile iron was studied on the basis of dilatometry measurements, and Avrami's equation was used to estimate the material's kinetic parameters. A continuous heating transformation diagram was constructed using heating rates in the range of 0.06 to 0.83℃·s-1. As the heating rate was augmented, the critical temperatures, A_c1 and A_α, as well as the intercritical range, which was evaluated as the difference between the critical temperatures, ΔT=A_α - A_c1, increased. At a low heating rate, the kinetics of austenite formation was slow as a consequence of the iron's silicon content. The effect of heating rate on k and n, the kinetic parameters of Avrami's equation, was also determined. Parameter n, which is associated with nucleation sites and growth geometry, decreased with an increase in heating rate. In addition, parameter k increased with the increase of heating rate, suggesting that the nucleation and growth rates are carbon- and silicon-diffusion controlled during austenite formation under continuous heating.     

Effect of initial microstructure on austenite formation kinetics in high-strength experimental microalloyed steels

Austenite formation kinetics in two high-strength experimental microalloyed steels with different initial microstructures compris-ing bainite–martensite and ferrite–martensite/austenite microconstituents was studied during continuous heating by dilatometric analysis. Austenite formation occurred in two steps:(1) carbide dissolution and precipitation and (2) transformation of residual ferrite to austenite. Di-latometric analysis was used to determine the critical temperatures of austenite formation and continuous heating transformation diagrams for heating rates ranging from 0.03°C×s?1 to 0.67°C×s?1. The austenite volume fraction was fitted using the Johnson–Mehl–Avrami–Kolmogorov equation to determine the kinetic parameters k and n as functions of the heating rate. Both n and k parameters increased with increasing heat-ing rate, which suggests an increase in the nucleation and growth rates of austenite. The activation energy of austenite formation was deter-mined by the Kissinger method. Two activation energies were associated with each of the two austenite formation steps. In the first step, the austenite growth rate was controlled by carbon diffusion from carbide dissolution and precipitation;in the second step, it was controlled by the dissolution of residual ferrite to austenite.     

N-咔唑基RAFT试剂在RAFT聚合中的阻滞效应

采用膨胀计法研究了N-咔唑二硫代甲酸苄基酯（BCBD）、N-咔唑二硫代α-甲基苄基酯（PCBD）、N-咔唑二硫代甲酸异丙苯酯（CCBD）和N-咔唑二硫代异丁腈酯（CYCBD）4种RAFt试剂在苯乙烯、丙烯酸乙酯和甲基丙烯酸甲酯的RAFt聚合中的阻滞效应,并考察了RAFt试剂用量、单体种类和聚合温度对阻滞效应的影响,结果表明,上述4种以咔唑为z基团的RAFt试剂在RAFt聚合中表现出明显的阻滞作用,且阻滞效应与RAFt试剂的结构密切相关,在相同情况下,阻滞效应由大到小依次为CCBD〉PCBD〉BCBD〉CYCBD,