PP vs PP 2.0 Filament: What’s Changed in Printability, Toughness, and Performance?

Polypropylene (PP) is valued for its low density, toughness, fatigue resistance, and chemical resistance. These properties make it useful for functional parts such as living hinges, flexible containers, protective components, and parts exposed to repeated movement.

However, PP can be difficult to print consistently. Many users experience lifted corners, bed detachment, layer cracking, or dimensional changes when printing PP filaments.

At SUNLU, we have optimized the formula and introduced SUNLU PP 2.0, which is easier to print than SUNLU PP and provides much higher impact strength. Read on to find out what has changed between SUNLU PP and PP 2.0 in terms of printability, toughness, and overall performance.

Why Is PP Filament Difficult to Print?

But first, let’s take a step back and discuss why PP is difficult to print. Two characteristics of PP account for most printing problems: its semi-crystalline structure and low surface energy.

1. Semi-crystalline Shrinkage Creates Internal Stress

PP is a semi-crystalline polymer. When the extruded PP cools, some of its molecular chains change from a disordered state into more organized crystalline regions. This process causes the material to contract.

Because each layer and area of a part experiences a different thermal history, depending on its distance from the heated bed, its exposure to the air, and the airflow from the cooling fan (if the use of cooling fans is recommended), it does not cool and crystallize at exactly the same rate. Corners, outer walls, lower layers, and thicker sections may therefore shrink by different amounts.

Such uneven shrinkage creates internal stress. As this stress accumulates, it can pull the edges of the model upward, separate adjacent layers, or change the dimensions of the finished part. Large, flat, or wide models are especially sensitive because contraction occurs across a greater area.

For this reason, PP printing is strongly affected by nozzle temperature, bed temperature, ambient temperature, cooling, and print speed.

2. Low Surface Energy Makes First-Layer Adhesion Difficult

PP is also a non-polar material with low surface energy. Molten PP filament does not easily wet or bond to common printing surfaces such as glass and PEI.

If the first layer has weak adhesion, it may be unable to resist the contraction forces generated during cooling. The edges can begin to lift, and in more serious cases, the entire model may detach from the build plate.

A suitable build surface and PP-compatible 3D printing glue can help the first layer remain in place while the part cools.

What Has Changed in PP 2.0?

Compared with SUNLU PP, PP 2.0 features an optimized formulation that results in the following differences in material properties and printing performance.

The following four changes are particularly noticeable.

1. Lower Shrinkage

PP 2.0 3D printer filament has a molding shrinkage rate of 1.36%, compared with 1.50% for SUNLU PP. Its shrinkage rate is 0.14 percentage points lower, a difference of approximately 9.3%.

Lower shrinkage produces less contraction stress as the printed material cools. This can reduce the likelihood of warping and dimensional deformation, especially when printing large, flat, or wide models.

2. Higher Toughness

The notched Izod impact strength of SUNLU PP 2.0 is 23 ± 5 kJ/m², compared with 5.3 ± 1.5 kJ/m² for SUNLU PP. The nominal value of PP 2.0 is approximately 4.3 times as high.

This allows PP 2.0 to absorb more energy when a part is dropped, struck, or subjected to a sudden localized force. It is therefore suitable for clips, latches, protective housings, and frequently handled functional parts.

3. Lower Tensile Strength

PP 2.0 has a tensile strength of 15 ± 3 MPa, compared with 19 ± 3 MPa for SUNLU PP. Its nominal tensile strength is approximately 21% lower.

This means PP 2.0 is not always the more suitable option when a part must resist continuous pulling forces or when tensile strength is the main design priority. SUNLU PP may be more appropriate for these applications.

4. Higher Density

The density of PP 2.0 is 1.01 g/cm³, compared with approximately 0.90 g/cm³ for SUNLU PP. For parts of the same volume, PP 2.0 is approximately 12% heavier.

The additional mass may be useful for bases, fixtures, or other components where greater weight and a more substantial feel are desirable. PP 2.0 3D printer filament may be less suitable for drones, RC aircraft, wearable parts, and other applications where low weight is important.

Which Polypropylene 3D Printing Filament Should You Choose?

PP 2.0 does not improve every property of SUNLU PP. It exchanges some tensile strength and low-density performance for lower shrinkage and much higher impact resistance. The choice should therefore be based on the requirements of the finished part.

Choose SUNLU PP when low weight and tensile strength are the main requirements. Its lower density (about 0.90 g/cm³) suits lightweight housings and components that need to float, while its higher tensile strength (19 ± 3 MPa) helps parts that carry a steady pulling load. It also suits flexible containers and living hinges that are exposed to repeated bending or chemicals.

It is also worth noting that SUNLU PP does not always warp or separate from the bed. Experienced users can greatly reduce the chance of these problems by carefully controlling temperature, cooling, print speed, and first-layer adhesion.

Choose SUNLU PP 2.0 when impact resistance and print stability matter more than weight. Its notched impact strength of 23 ± 5 kJ/m² suits parts that face sudden loads, such as protective housings, clips, latches, and workshop fixtures. Its lower shrinkage (1.36%) also makes larger flat parts easier to print with less warping.

How to Get Better Printing Results with PP 2.0

We recommend a nozzle temperature of 240–260°C, a bed temperature of 40°C, and a printing-speed range of 30–170 mm/s for PP 2.0. The recommended retraction distance is 0.8–1.2 mm, with a retraction speed of 30–40 mm/s.

Use these values as a starting point, together with the following practices, to improve your PP 2.0 printing results:

• Apply a thin, even layer of PP-specific glue or PP-compatible 3D printing adhesive to improve first-layer adhesion.
• Print the first layer slowly and check that each line is firmly attached to the build surface.
• Keep the printer away from drafts. A stable ambient temperature is particularly helpful for large parts.
• Add a brim for models with sharp corners, a small contact area, or a wide base.
• Start at a moderate speed and increase it only after confirming stable extrusion, layer bonding, and dimensional accuracy.
• Allow the build plate to cool before removing the finished part.

Some of these practices also apply to SUNLU PP 3D printer filament, including the use of PP-compatible adhesive, a stable printing environment, and a brim where necessary.

Conclusion

Compared with SUNLU PP, PP 2.0 is easier to print, has a lower molding shrinkage rate, and offers higher notched Izod impact strength. These changes improve the practical printing experience and expand its use in impact-resistant functional parts.

The upgrade also involves trade-offs. PP 2.0 has lower tensile strength and higher density, so SUNLU PP may still be more suitable for lightweight parts or applications that prioritize tensile performance.

The final choice should consider mechanical requirements, printing stability, production efficiency, part weight, and the conditions in which the printed component will be used.

To share your experience and exchange printing tips with other users, visit the SUNLU Community.