Extended Data Table 2 Definitions and ranges (II) of variables used in this study

v_p,z

Catalyst particle velocity along the z axis

-

m s⁻¹

0.0-0.2

v_tip

Velocity of the tip of the stirrer blade

\({v}_{{\rm{tip}}}=\frac{\pi ND}{60}\)

m s⁻¹

0-5

Ar

Archimedes number

\({\rm{Ar}}=\frac{{\rm{g}}{{d}_{{\rm{p}}}}^{3}{\rho }_{{\rm{m}}}({\rho }_{{\rm{p}}}-{\rho }_{{\rm{m}}})}{{\mu }^{2}}\)

-

10⁻⁷ -10⁻⁸

Stk

Stokes number

\({\rm{Stk}}=\frac{{\rho }_{{\rm{m}}}{{d}_{{\rm{p}}}}^{2}{v}_{{\rm{tip}}}}{18\mu \lambda }\)

-

10⁻² -10⁰

Ha

Hatta number

\({\rm{Ha}}=\frac{\sqrt{{k}_{{\rm{r}}}{D}_{{{\rm{H}}}_{2}}}}{{k}_{{{\rm{H}}}_{2}}}\)

-

1-7

K_s

Shape factor

\({K}_{s}=\frac{{v}_{p,z,\max }}{{v}_{tip}}\)

-

0.001-0.1 (dependent on stirrer type)

Re_p,z,max

Maximum Reynolds number of catalyst particles along the z axis

\(\begin{array}{c}{\mathrm{Re}}_{p,z,\max }=\frac{{\rho }_{{\rm{m}}}{v}_{p,z,\max }{d}_{p}}{\mu }\\ \approx \frac{\pi {\rho }_{m}}{60\bar{\mu }}N{K}_{{\rm{s}}}D{d}_{p}\end{array}\)

-

0-1.5 × 10⁻³ for tested configurations

χ_H2

Volumetric H₂ fraction in polymer melt

-

-

0-0.3 for tested configurations

N_p

Power number

\(\begin{array}{c}{{\rm{N}}}_{{\rm{p}}}=\frac{\tau \omega }{\bar{\rho }{N}^{3}{D}^{5}}=\frac{7200\pi \tau }{\bar{\rho }{N}^{2}{D}^{5}}\\ \approx \frac{14400{\pi }^{3}\bar{\mu }{D}_{{\rm{r}}}^{2}L}{(1-{\chi }_{{\rm{H2}}}){\rho }_{{\rm{m}}}{D}^{3}({D}_{{\rm{r}}}^{2}-{D}^{2})N}\end{array}\)

-

0-∞