Engineering Copilot

Q: How does molecular weight affect polymer melt viscosity?

Above the critical entanglement molecular weight ($M_c$), zero-shear viscosity ($\eta_0$) scales dramatically following the Fox-Flory power law: $\eta_0 = K \cdot M_w^3.4$. This creates significant flow resistance during injection moulding but enhances mechanical tensile elongation in solid state.