Diffusion Coefficient Formula:
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Definition: The Diffusion Coefficient of Solute in Polymer Matrix is the proportionality constant between the molar flux due to molecular diffusion and the negative value of the gradient.
Purpose: This calculator helps determine the diffusion coefficient in the polymer matrix when considering the effects of filler materials in composites.
The calculator uses the formula:
Where:
Explanation: The formula accounts for how filler particles affect solute diffusion by considering the tortuous path (ζ) and the volume occupied by filler (Φ).
Details: Accurate diffusion coefficient values are crucial for predicting mass transport in polymer composites, which affects material performance in applications like membranes, drug delivery systems, and packaging materials.
Tips: Enter the diffusion coefficient in the composite (D), tortuosity coefficient (ζ), and volume fraction of filler (Φ). The volume fraction must be between 0 and 1 (exclusive).
Q1: What is the tortuosity coefficient?
A: It's an intrinsic property of porous materials, defined as the ratio of actual flow path length to the straight distance between path ends.
Q2: How does filler volume fraction affect diffusion?
A: Higher filler fractions reduce the available space for diffusion and typically increase the tortuosity, decreasing the effective diffusion coefficient.
Q3: What are typical values for the tortuosity coefficient?
A: Values typically range from 1 (straight path) to 3-5 for highly tortuous paths in filled polymers.
Q4: Can the volume fraction be 1?
A: No, the formula becomes undefined at Φ=1 (complete filler with no polymer matrix).
Q5: How do I measure the diffusion coefficient in composite?
A: Common methods include sorption/desorption experiments, permeation tests, or inverse analysis of concentration profiles.