Exablend® POK CF20 TRM — carbon-fiber-reinforced polyketone for precision parts in chemically aggressive environments

Exablend® POK CF20 TRM — carbon-fiber-reinforced polyketone for precision parts in chemically aggressive environments

Exablend® POK CF20 TRM is an engineering compound based on polyketone, reinforced with 20% carbon fiber. The grade is designed for parts that require not only high stiffness but also dimensional stability, low moisture absorption, resistance to fuel, oils and technical fluids, and controlled behavior in assemblies with elevated precision requirements.

This material should not be regarded as a direct analogue of a conventional glass-filled POK. Carbon fiber changes the character of the compound: it increases the modulus, reduces weight relative to highly filled GF grades, improves stiffness at a lower density and adds functional properties, including lower surface resistance compared with typical insulating polymer materials.

Engineering rationale of the grade

POK CF20 TRM is worth considering for parts where not only strength and modulus are critical, but also stable behavior in the actual service environment. In a fuel system, an electrical connector, a precision housing or an element with small fitting clearances, the material does not work against a single load. It is simultaneously affected by temperature, moisture, technical fluids, repeated assembly, local stresses, friction and the requirement not to change geometry after cycles.

It is precisely in such applications that the polyketone matrix has strong engineering logic: it combines chemical resistance, low moisture absorption, hydrolytic stability and barrier properties. Carbon fiber adds stiffness and reduces deformation under load, but it requires careful design due to fiber orientation, anisotropy and the possible sensitivity of critical zones of the part to weld lines.

Where the material performs best

Exablend® POK CF20 TRM is most interesting where ordinary mechanical strength is not enough. The material makes sense in assemblies that simultaneously require precision, chemical resistance, stability in humid environments and increased stiffness without moving to excessively heavy or highly filled solutions.

• fuel system components;
• parts in contact with fuel, oils or technical fluids;
• electrical connectors and precision housing elements;
• functional parts with low moisture absorption requirements;
• housings and elements with high dimensional accuracy;
• parts that require stiffness at a lower density than highly filled GF compounds;
• assemblies where clearance stability, chemical resistance and molding repeatability are important.

Why CF20 rather than GF30 or GF50

Glass-filled POK grades are logical when the main requirement is stiffness, mechanical strength and cost-effective reinforcement. Carbon-filled POK CF20 TRM plays a different role. It is appropriate when you need a high modulus at a more moderate density and higher precision of the part in service, while retaining the advantages of POK in chemically aggressive or humid environments.

The tensile modulus of the material reaches 12 700 MPa at a density of only 1.30 g/cm³. This matters for parts where weight, geometric stability and stiffness must be considered together rather than as separate parameters.

Key advantages of Exablend® POK CF20 TRM

• 20% carbon fiber for high stiffness and shape stability;
• tensile modulus of 12 700 MPa at a density of 1.30 g/cm³;
• tensile strength of 155 MPa;
• low water absorption — 0.4% at 23°C and 50% RH;
• HDT of 213°C at 1.8 MPa load;
• resistance to chemical media, fuel and technical fluids;
• barrier properties for assemblies involving hydrocarbons and gases;
• surface resistance of about 10³ Ω for applications where fully insulating material behavior is not desired;
• good suitability for precision molded parts with geometry stability requirements.

Technical specifications

The main physical-mechanical, thermal and functional characteristics are given in the table below. For this grade it is especially important to evaluate not a single figure but the material profile as a whole: stiffness, density, water absorption, HDT, surface resistance, thermal conductivity and behavior in contact with the actual service environment.

Processing recommendations

Exablend® POK CF20 TRM is processed by injection molding. For carbon-filled materials it is especially important to control melt temperature, residence time in the barrel, drying, mold filling and shear loads. Carbon fiber raises the requirements for process stability, since fiber orientation affects the mechanics, shrinkage, thermal conductivity and behavior of the part after cooling.

The material is supplied in moisture-proof packaging, but after opening it must be stored and processed with humidity control. For regrind or material from an opened bag, drying before processing is recommended.

Design considerations

For parts made of POK CF20 TRM, the flow direction, carbon fiber orientation, weld line locations, local stress concentrations and contact of the material with metal components must be taken into account. In some designs carbon fiber can be not only an advantage but also a factor that requires compatibility checks with other parts of the assembly, especially where electrical, galvanic or tribological risks are present.

The material delivers its best results when it is selected not as a “stronger plastic” but as a functional engineering compound for parts where the chemical environment, moisture, precision and stiffness are parts of a single task.