Effect of Orientation on Thermoset Frontal Polymerization

We observed that the velocities of descending thermoset polymerization fronts were strongly affected by the orientation of the tube. The front remained approximately perpendicular to the gravitational vector but propagated almost 1.8 times as fast at 75° along the axis of the tube. We performed a study of the velocity and front-shape dependence on orientation with propagating fronts of triethylene glycol dimethacrylate with peroxide initiator and acrylamide/bisacrylamide polymerization in dimethyl sulfoxide with persulfate initiator. The percentage increase of velocity was independent of the initiator concentration but strongly dependent on the viscosity. Convection under the front flowed away from the tube wall nearest the vertical axis and was stronger as the angle increased. The front shape also changed, becoming significantly distorted near the wall from which the convection originated. We applied a simple geometric argument to explain the angular dependence for small angles on the basis of the assumption that convection did not affect the velocity of propagation normal to the front. The increase in velocity along the tube axis could be explained by a projection of the normal velocity onto the tube axis, following a 1/cosθ dependence. For higher angles, the convection was not sufficiently strong to maintain a level front. When the difference from a 180° orientation was considered, the velocity dependence exactly followed the geometric relationship.

[1]  Alberto Mariani,et al.  Frontal Ring-Opening Metathesis Polymerization of Dicyclopentadiene , 2001 .

[2]  O. Steinbock,et al.  Frontal polymerization synthesis of temperature-sensitive hydrogels. , 2001, Journal of the American Chemical Society.

[3]  J. Pojman,et al.  Preparation of functionally gradient materials via frontal polymerization , 2000 .

[4]  J. Pojman,et al.  Solvent-free synthesis of polyacrylamide by frontal polymerization , 2000 .

[5]  J. Pojman,et al.  Convective chemical fronts in the 1,4-cyclohexanedione - Bromate - Sulfuric acid - Ferroin system , 1998 .

[6]  V. Volpert,et al.  The effect of convection on a propagating front with a liquid product: Comparison of theory and experiments. , 1998, Chaos.

[7]  Marc Garbey,et al.  Influence of natural convection on stability of reaction fronts in liquids , 1998 .

[8]  J. Pojman,et al.  Frontal Curing of Epoxy Resins: Comparison of Mechanical and Thermal Properties to Batch Cured Materials , 1997 .

[9]  Jennifer Simmons,et al.  Propagating Fronts of Polymerization in the Physical Chemistry Laboratory , 1997 .

[10]  V. Volpert,et al.  Mathematical Modeling of Free-Radical Polymerization Fronts , 1997 .

[11]  Marc Garbey,et al.  Effect of Convection on a Propagating Front With a Solid Product: Comparison of Theory and Experiments , 1997 .

[12]  L. Mathias,et al.  Binary frontal polymerization: A new method to produce simultaneous interpenetrating polymer networks (SINs) , 1997 .

[13]  Marc Garbey,et al.  Linear stability analysis of reaction fronts in liquids , 1996 .

[14]  J. Pojman,et al.  Frontal Polymerization in Solution , 1996 .

[15]  J. Pojman,et al.  Double-Diffusive Convection in Traveling Waves in the Iodate-Sulfite System Explained , 1996 .

[16]  J. Pojman,et al.  Free-Radical Frontal Polymerization: Self-Propagating Thermal Reaction Waves , 1996 .

[17]  J. Pojman,et al.  Traveling Waves in the Iodate-Sulfite and Bromate-Sulfite Systems , 1995 .

[18]  J. Pojman,et al.  Periodic Convection in the Bromate-Sulfite Reaction: A "Jumping" Wave , 1995 .

[19]  J. Pojman,et al.  Factors affecting propagating fronts of addition polymerization: Velocity, front curvature, temperatue profile, conversion, and molecular weight distribution , 1995 .

[20]  István Nagy,et al.  THERMOCHROMIC COMPOSITE PREPARED VIA A PROPAGATING POLYMERIZATION FRONT , 1995 .

[21]  J. Pojman,et al.  Chemical Waves in the Iodide-Nitric Acid System , 1994 .

[22]  John A. Pojman,et al.  Convective instabilities in traveling fronts of addition polymerization , 1992 .

[23]  I. Epstein,et al.  Gravity-induced anisotropies in chemical waves , 1986 .

[24]  P. V. Zhirkov,et al.  Problems of Non-isothermal Character in Polymerisation Processes , 1984 .