PEEK vs PEKK vs PPSU vs Ultem (PEI)

PEEK, PEEK CF, PEKK, PPSU and Ultem (PEI) are all high performance polymers offering dimensional stability, heat resistance, high strength and broad chemical resistance. All of these filament materials are also UL 94-V0 rated – self-extinguishing in <10 seconds. 



PAEK refers to all the materials within the Poly Ether Ketones family, including PEEK, PEEK-CF and PEKK.

Whilst both PEEK and PEKK have high mechanical strength, high temperature resistance, fatigue resistance and low flammability, chemical differences exist. The molecular structure of PEKK provides higher heat resistance than PEEK – a heat deflection temperature (HDT) of 160°C versus 145°C. PEKK is inherently more expensive compared to PEEK.

PEEK, PEEK CF, PEKK, PPSU and Ultem (PEI) Filament

PEEK-CF is PEEK reinforced with carbon fibre – this improves the stiffness and compressive strength enormously which makes this material suitable for dynamically stressed parts. Furthermore, HDT is significantly higher than PEEK and even PEKK, at 280°C.

Ultem is the brand name for PEI products. A key difference between PEEK and Ultem is their different morphological structures – Ultem is amorphous while PEEK is semi-crystalline. This influences the performance at elevated temperatures. 


The biggest difference between these two plastics is cost. PEEK is one of the most expensive polymers on the market, on the other hand, Ultem offers comparable properties at lower cost. In regards to heat resistance, whilst Ultem offers continuous use up to 170 ºC, PEEK can operate well above 250°C without deforming. This makes PEEK more suited to high-load, high-temperature applications. Ultem is more easily (post)-processed than PEEK, which typically requires CNC milling for machining purposes.

PPSU is similar to Ultem in that it is a similar material that is also amorphous, but exhibits impact resistance and chemical resistance superior to Ultem. It can operate in temperatures up to 180°C and offers an excellent resistance to hydrolysis, making it perfectly suited to plumbing applications. Versus PEEK, PPSU is inferior when it comes to compressive strength, tensile strength and elasticity

Mechanical Properties Overview

Product Tensile strength at yield Tensile strength at break Elongation strain at break Elongation strain at yield Tensile (E) modulus Flexural strength Flexural modulus
PEI ULTEM 9085 88 MPa (ISO 527) 71 MPa (ISO 527) 50% (ISO 527) 6.7% (ISO 527) 3050 MPa (ISO 527) 90 MPa (ISO 178) 2750 MPa (ISO 178)
PEI ULTEM 1010 105 MPa (ISO 527) 54 MPa (ISO 527) 60% (ISO 527) 6% (ISO 527) 3200 MPa (ISO 527) 160 MPa (ISO 178) 3200 MPa (ISO 178)
PPSU 77 MPa (ISO 527) 77 MPa (ISO 527) 60-120% (ISO 527) 7.3% (ISO 527) 2410 MPa (ISO 527) 108 MPa (ISO 178) 2380 MPa (ISO 178)
3F PEEK CF 9676 126 MPa (ISO 527) 3.9% (ISO 527) 7800 MPa (ISO 527)
3F PEEK 9581 97 MPa (ISO 527) 5% (ISO 527) 3800 MPa (ISO 527) 145 MPa (ISO 178) 3400 MPa (ISO 178)
3F PEKK 50082 90 MPa (ISO 527) 5% (ISO 527) 3000 MPa (ISO 527) 150 MPa (ISO 178) 2500 MPa (ISO 178)


Thermal Properties Overview

Product Vicat softening temp. Heat deflection temp
PEI ULTEM 9085 173°C (ISO 306) 152°C (ISO 75)
PEI ULTEM 1010 211°C (ISO 306 B50) 200°C (ISO 75-2)
PPSU 207°C (ASTM D648 1.8MPa)
3F PEEK CF 9676 280°C (ISO 75)
3F PEEK 9581 145°C (ISO 75)
3F PEKK 50082 160°C (ISO 75 – Printed)


Filamentive PRO is a specialised portfolio of high performance and engineering 3D printing filament for industrial applications.

Filamentive PRO currently offers the following filament for 3D printing: