Don't let liquidity drag down production capacity: An In-Depth Look at Viscosity Reduction and Pressure Drop Technology in Plastic Modification

Essentially, processing polymers into parts involves forcing a melt through a mold or die. Poor flowability of this viscous fluid (the melt) can trigger a chain reaction of problems.

Molding Challenge Uneven pressure transmission of the melt within the mold leads to insufficient filling (short shot) in thin-walled areas.

Inefficiency Higher processing temperatures and pressures are required, which not only increases energy consumption but also extends the production cycle.

Mold wear Sustained high temperature and high pressure can shorten mold life and increase maintenance costs.

The fluidity (typically measured by Melt Flow Index, MFI) is mainly constrained by the following factors:

Molecular weight effect High molecular weight means long chains with severe entanglement between chain segments, leading to high resistance to movement.

Rigid body constraint The more rigid a molecular chain, the weaker its migration ability when heated.

Intermolecular forces Strong hydrogen bonds or ionic interactions can form natural "shackles" that impede flow.

Fill volume interference (core pain point) During compounding, the addition of high concentrations of fillers creates a physical barrier and increases internal melt friction, making it difficult for polymer chains to slide past each other.

Internal lubrication using elastomers. Blend low-force, flexible chain rubbers with plastics. These rubber particles can migrate between molecular chains under stress, reducing friction.

Low molecular weight plasticizer Increase free volume to make molecular chains move more easily.

In high-loading formulations, use Coupling agent Pretreating the filler to reduce its physical hindrance to polymer flow.

Liquidity optimization is never isolated; it's often accompanied by a trade-off in mechanical properties. As the article states, the interplay between filler content and fluidity, and the balance between molecular weight and toughness, are precisely the subtleties of formulation development.