Concept:Dynamic viscosity (\(\eta\)) is a fluid's internal resistance to shear flow; high viscosity inhibits capillary penetration into porous micro-structures.
Formula / Reaction:$$\text{Poiseuille Penetration Rate: } \frac{dh}{dt} = \frac{r\gamma\cos\theta}{4\eta h}$$
Solution:- According to the Lucas-Washburn relation, the rate of capillary penetration (\(dh/dt\)) is inversely proportional to viscosity (\(\eta\)).
- Higher viscosity slows spreading, limits capillary draw, and reduces mechanical keying in porous adherends.
Why other options are incorrect:- Option A: Inversely contradicts fluid dynamics; higher viscosity restricts flow rate.
- Option C: Viscosity is a kinetic property of flow, whereas surface tension is a thermodynamic interfacial parameter.
- Option D: Viscosity alone does not determine the chemical reaction kinetics of cross-linking.
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