Kinetics and Mechanism of the Late Stage of Cure Reaction-induced Microphase Separation

2001 ◽  
Vol 48 (2) ◽  
pp. 225-235 ◽  
Author(s):  
Lyudmila I. Kuzub ◽  
Boris A. Komarov ◽  
Vadim I. Irzhak
Author(s):  
Liangfeng Sun ◽  
Arthur M. Sterling ◽  
Su-Seng Pang ◽  
Ioan I. Negulescu ◽  
Michael A. Stubblefield

Abstract The curing process of epoxy prepreg was studied by means of Differential Scanning Calorimeter. The dynamic, isothermal, and combinations of dynamic and isothermal measurements were done over selected temperature ranges and isothermal cure temperatures. The heats of reaction for dynamic and isothermal cure were determined. The results show that the heat of isothermal-cure reaction increased with the increment of temperature. The degree of cure was calculated from the heat of isothermal-cure reaction. The complete cure reaction could be achieved at 220 °C within the very short cure time. The changes of cure rate with time were given for the studied isothermal cure temperatures. To simulate the relationship between the cure rate and degree of cure, the autocatalytic model was used and the four parameters were calculated. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into the model. The modified model greatly improved the predicated data at the late stage of cure reaction.


1999 ◽  
Vol 10 (08) ◽  
pp. 1513-1520 ◽  
Author(s):  
YUTAKA OKABE ◽  
TSUKASA MIYAJIMA ◽  
TOSHIRO ITO ◽  
TOSHIHIRO KAWAKATSU

We report the application of the Monte Carlo simulation to phase separation dynamics. First, we deal with the phase separation under shear flow. The thermal effect on the phase separation is discussed, and the anisotropic growth exponents in the late stage are estimated. Next, we study the effect of surfactants on the three-component solvents. We obtain the mixture of macrophase separation and microphase separation, and investigate the dynamics of both phase separations.


Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.


10.1002/kin.7 ◽  
1996 ◽  
Vol 28 (9) ◽  
pp. 687-691 ◽  
Author(s):  
M. Calzadilla ◽  
A. Malpica ◽  
P. M. Diaz

1973 ◽  
Vol 70 ◽  
pp. 918-922 ◽  
Author(s):  
R. K. Srivastava ◽  
V. K. Srivastava ◽  
M. N. Srivastava ◽  
B. B. L. Saxena

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