- Definition of molecular weight
The molecular weight of general polyethylene (such as HDPE) is about 200,000-500,000 g/mol;
The molecular weight of UHMWPE is usually 3 million-10 million g/mol, or even higher. - Effect of molecular weight on main performance
| Performance index | Trend of change when molecular weight increases | Description |
| Wear resistance | Significantly improved | The molecular chain is longer, the interchain entanglement is more, the wear resistance is excellent, and it is suitable for sliding parts |
| Impact resistance | Improved | The molecular chain has a strong ability to absorb impact energy and has enhanced toughness |
| Stress cracking resistance | Improved | Less prone to cracking due to stress concentration |
| Friction coefficient | Reduced | The molecular surface is more lubricated and the self-lubricating performance is better |
| Heat deformation temperature | Slightly reduced | The softness of the molecular chain increases and the heat deformation point decreases slightly |
| Processing difficulty | Significantly increased | The molecular chain is more tightly entangled and not easy to melt. It is not suitable for traditional injection molding. Pressing, sintering, extrusion, etc. are usually used |
| Crystallinity | Slightly reduced | Molecular arrangement is more difficult, affecting some mechanical properties |
The higher the molecular weight of UHMWPE, the better its performance (especially wear resistance, impact resistance, and self-lubrication), but the processing difficulty also increases. Therefore, the selection of the appropriate molecular weight should be a balance between application requirements and processing costs.