Chemical and diffusion-controlled curing kinetics of an underfill material

AbstractCuring kinetics of guaiacol based benzoxazine synthesized from guaiacol, furfurylamine and formaldehyde forming bio-based polybenzoxazine was investigated. The curing process showed complex polymerization behavior, as the exothermal signal consisted of several overlapped peaks. Differentiation and fitting of overlapped peaks was performed by Pearson VII distribution obtaining two separate exothermal signals further associated to stage 1 and stage 2. The apparent activation energies of both stages were determined to be 113.8 kJ mol-1 and 117.5 kJ mol-1, respectively, according to Kissinger. The first could be explained by benzoxazine ring-opening and electrophilic substitution, whereas the second stage corresponds to the rearrangement and diffusion-controlled step. Kinetics of each stage was studied separately. As a result, the first stage was described by Šesták-Berggren autocatalytic model, whereas the second stage appeared to follow nth order kinetics proved by the Friedman method. Application of both kinetic models demonstrated that the predicted curves fit well with the non-isothermal DSC thermograms and as such sufficiently describes the complex curing behavior of guaiacol based benzoxazine.

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Vacancy-Mediated Diffusion and Diffusion-Controlled Processes in Ordered Binary Intermetallics by Kinetic Monte Carlo Simulations

Diffusion Foundations ◽

10.4028/www.scientific.net/df.29.95 ◽

2021 ◽

Vol 29 ◽

pp. 95-115

Author(s):

Rafal Kozubski ◽

Graeme E. Murch ◽

Irina V. Belova

Keyword(s):

Monte Carlo ◽

Kinetic Monte Carlo ◽

Simulation Studies ◽

Self Diffusion ◽

Monte Carlo Techniques ◽

Diffusion Controlled ◽

Kinetic Monte Carlo Simulations ◽

Kinetic Effects ◽

Kinetics Of ◽

And Diffusion

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

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Refinement of Size Distributions for Primary Crystallizations

MRS Proceedings ◽

10.1557/proc-481-213 ◽

1997 ◽

Vol 481 ◽

Author(s):

E. Pineda ◽

T. Pradell ◽

D. Crespo ◽

N. Clavaguera ◽

J. ZHU ◽

...

Keyword(s):

Grain Size ◽

Metastable Phase ◽

Primary Crystallization ◽

Controlled Growth ◽

Diffusion Controlled ◽

Average Grain Size ◽

Soft Impingement ◽

Single Grain ◽

Kinetics Of ◽

And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

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Chapter 11. KINETICS OF COARSENING AND DIFFUSION-CONTROLLED MINERAL GROWTH

Contact Metamorphism ◽

10.1515/9781501509612-014 ◽

1991 ◽

pp. 507-582 ◽

Cited By ~ 24

Author(s):

Raymond L. Joesten

Keyword(s):

Mineral Growth ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion

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Thermal and Mechanical Stability of Polycrystalline Nanowires

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.264.133 ◽

2007 ◽

Vol 264 ◽

pp. 133-140

Author(s):

Leonid Klinger ◽

Eugen Rabkin

Keyword(s):

Plastic Deformation ◽

Applied Load ◽

Mechanical Stability ◽

Deformation Behaviour ◽

High Yield ◽

Morphological Stability ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion ◽

Shape Changes

We considered a polycrystalline cylindrical nanowire with bamboo microstructure strained uniaxially by an external load. Our molecular dynamic computer simulations demonstrated that grain boundary grooving plays an important role in determining the morphological stability of nanowires. Also, an exceptionally high yield stress of nanowires emphasizes the importance of diffusion in their plastic deformation under applied load. We formulated a phenomenological diffusion-based model describing morphological stability and diffusion-controlled deformation behaviour of polycrystalline nanowires. The kinetics of the shape changes was calculated numerically.

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