Conductive Masterbatch by Polymer: PP, LLDPE, PET, ABS, PA6/PA66 and PC

A masterbatch only performs as well as its carrier allows. The carrier resin must be compatible with the base polymer of the final part and mix uniformly with it during processing. Otherwise, even a well-dispersed concentrate can lead to streaks, specks or inconsistent properties. This is why masterbatch is usually specified by polymer: a PP part needs a PP-compatible masterbatch, a PC part needs a PC-compatible one. This short guide explains what to watch for in six common thermoplastics and which CNT conductive masterbatch fits each one. All grades are listed in our masterbatches category.

Why the Polymer Matters

Three factors decide whether a masterbatch works in a given resin:

• Chemical compatibility: A carrier from the same polymer family supports compatibility with the base resin and helps limit adverse effects on mechanical properties.
• Melt flow match: The melt flow behavior of the masterbatch should be evaluated alongside the base resin and processing conditions. Melt flow rate measured according to ISO 1133 is a useful indicator, but it does not have to closely match that of the base resin.
• Processing window: Drying requirements, processing temperature and shear sensitivity differ strongly between polymers.

For conductive masterbatch, the polymer also affects the percolation threshold, the loading at which the conductive network forms. Crystallinity, melt viscosity and processing history all shift this threshold, so the same CNT content can give different resistance values in different polymers.

The type of conductive additive also interacts with the polymer. When adequately dispersed, high aspect ratio multi-walled carbon nanotubes can achieve the target resistance at lower loadings than conductive carbon black. This can offer an advantage in retaining mechanical properties and processability. Conductive carbon black needs higher loadings but remains a cost-effective choice for commodity parts. A detailed comparison of both, together with graphene nanoplatelets, is given in What Is Conductive Masterbatch? CNT, Carbon Black and Graphene Compared.

Polypropylene (PP)

PP is one of the most widely used polymers in automotive parts, containers and housings. It processes easily and normally does not require drying, which simplifies processing when using masterbatch. Homopolymer and impact copolymer grades differ in flow and toughness, so the specific PP grade should also be considered when selecting the masterbatch. Research on masterbatch-based MWCNT and PP composites has shown that the masterbatch dilution route can provide good nanotube dispersion, while CNT loading influences rheology and mechanical properties. Typical conductive uses include ESD containers, fuel system components and automotive parts that are painted electrostatically. Recommended grade: CNT conductive masterbatch for PP, 20 wt.%.

Processing tips for PP: keep the melt temperature within the range recommended for the base grade, because excessive heat can reduce molecular weight and change flow behavior. In injection molding, flow length and wall thickness influence how the nanotube network forms, so resistance should be measured at several points of the part, not only near the gate. Glass-fiber reinforced PP and talc-filled PP can also be made conductive, but the fillers change the viscosity and the required let-down ratio.

Linear Low Density Polyethylene (LLDPE)

LLDPE combines good flow, toughness and a low melting point, which makes it a common carrier for polyethylene applications in general, including LDPE and HDPE blends. It is the material of choice for blown and cast films, rotomolded tanks and flexible packaging. In thin films, dispersion quality is critical, because undispersed agglomerates can cause visible defects or weak points in the film. Conductive LLDPE is used in antistatic bags, liners and packaging for electronic components. Recommended grade: CNT conductive masterbatch for LLDPE, 20 wt.%.

In blown film, draw-down and orientation change the connections between CNTs and the structure of the conductive network. Films and molded parts made from the same blend can therefore have different electrical properties, and the measurement direction can also affect the results in films. Trials should therefore be run on the final film thickness. To retain flexibility and reduce overall additive use, multilayer constructions with conductivity confined to the required layer can be considered as an alternative to making the entire structure conductive.

Polyethylene Terephthalate (PET)

PET is used in fibers, sheets and packaging. It is sensitive to moisture: at processing temperature, water breaks the polymer chains by hydrolysis and reduces intrinsic viscosity. Both the masterbatch and the base resin must therefore be dried thoroughly before processing. A PET-compatible polyester-based carrier supports blend compatibility and helps retain melt strength. Conductive PET finds use in antistatic fibers and sheets for electronics trays. Recommended grade: CNT conductive masterbatch for PET, 15 wt.%.

In fiber spinning, the dispersion requirements are particularly strict, because agglomerates can block spinneret holes and cause filament breaks. Melt filtration and a well-dispersed concentrate are essential. For sheet and thermoformed trays, thinning and stretching during thermoforming can disrupt the continuity of the conductive network in deep-drawn areas, so the let-down ratio should be validated on formed parts rather than on flat sheet.

Acrylonitrile Butadiene Styrene (ABS)

ABS is valued for impact strength, dimensional stability and surface finish, which is why it dominates electronic housings, trays and carriers. An ABS-compatible carrier helps retain the material’s impact strength and surface quality. Because carbon additives can reduce impact strength at high loadings, the lower loading achievable with carbon nanotubes can offer an advantage over carbon black in ABS. Two concentrations are available for different dilution needs: CNT masterbatch for ABS, 15 wt.% and CNT masterbatch for ABS, 20 wt.%.

ABS parts for electronics often require both a static dissipative surface and a clean, low-particle surface for cleanroom use. Nanotube-based compounds can be considered for these applications, but suitability for cleanroom use should be verified through particle release testing on the finished part. When an ABS part is later painted or plated, the surface resistance and the adhesion of the coating should be checked together.

Polyamide 6 and Polyamide 66 (PA6, PA66)

Polyamides are engineering polymers used in under-the-hood automotive parts, connectors and technical components. They absorb moisture and must be dried before processing, and PA66 processes at a higher temperature than PA6. The carrier should match the polyamide type, because a mismatch can affect crystallization and dimensional stability. Conductive polyamides are used in fuel line parts, connectors and housings that need static dissipation. Recommended grades: CNT masterbatch for PA6, 15 wt.% and CNT masterbatch for PA66, 15 wt.%.

Many polyamide parts are glass-fiber reinforced. Glass fibers orient during injection molding and can disturb the conductive network, so the CNT content may need to be adjusted for reinforced grades. Moisture uptake after molding can also affect the electrical behavior of polyamide parts, so measurements should be carried out under the conditioning conditions specified in the relevant test standard. For polar matrices such as polyamides, carboxyl-functionalized nanotubes like MWCNT, >92%, -COOH are an option for formulation work when interfacial bonding is a priority.

Polycarbonate (PC)

PC offers high impact strength, heat resistance and dimensional precision. It is processed at high temperatures and must be dried carefully to avoid degradation. Melt-mixing studies with multi-walled carbon nanotubes in polycarbonate have shown that the masterbatch dilution route is an effective way to reach good nanotube dispersion. Conductive PC is used in wafer and chip handling, electronics and precision parts where cleanliness and tight tolerances matter. Recommended grade: CNT conductive masterbatch for PC, 15 wt.%.

PC is also widely used in blends such as PC/ABS, which combine the heat resistance of polycarbonate with the processability of ABS. For blends, the carrier should be agreed with the supplier, because nanotubes tend to locate preferentially in one phase of the blend, which affects the resistance at a given loading. At high processing temperatures, thorough drying and avoiding unnecessarily long residence times in the barrel are important to reduce the risk of yellowing and molecular weight loss.

Polymer Comparison at a Glance

Practical Checklist Before Ordering

Share the following information with your masterbatch supplier to shorten the sampling stage:

1. The exact base resin grade and, if possible, its melt flow rate.
2. The processing method: injection molding, extrusion, blown film, fiber spinning or thermoforming.
3. Fillers, reinforcements and other additives in the formulation, such as glass fibers, talc or flame retardants, along with their loading levels.
4. The target property and the test method, for example surface resistance according to a named standard.
5. Color, surface finish and mechanical requirements of the finished part.

With this information, an initial range for the masterbatch let-down ratio can be determined, then validated through testing on finished parts. If no standard grade fits your polymer or blend, Nanografi can develop a tailored conductive masterbatch based on your matrix and performance targets. Contact us through our quotation page or at sales@nanografi.com.

Frequently Asked Questions

Can I use a PE masterbatch in PP?

PE and PP are both polyolefins, but they are not fully miscible. Small additions of a PE-based color masterbatch are often tolerated. For functional and conductive grades, a carrier compatible with the base polymer, preferably from the same polymer family, is recommended.

Why do PET and polyamide need drying?

Both polymers absorb moisture, and at processing temperature the water breaks the polymer chains by hydrolysis. Drying the masterbatch and the base resin protects molecular weight, mechanical properties and surface quality.

Does the same CNT content give the same conductivity in every polymer?

No. The percolation threshold depends on the polymer, its crystallinity and the processing conditions. The final CNT content needed to achieve the target conductivity should be validated by measuring resistance on parts made using the intended polymer and process.

Can conductive masterbatch be used in glass-fiber reinforced grades?

Yes, but glass fibers change the melt viscosity and the way the conductive network forms during molding. The masterbatch let-down ratio should be reassessed for the reinforced grade, and the target electrical properties should be verified.

What if my polymer is not on this list?

Other thermoplastics and blends, such as PC/ABS, PBT or TPU, can also be made conductive. Existing grades should first be evaluated for compatibility with the base resin and the target resistance; a tailored masterbatch can be developed if needed.

References

Prashantha, K., Soulestin, J., Lacrampe, M. F., Krawczak, P., et al. (2009). Masterbatch-based multi-walled carbon nanotube filled polypropylene nanocomposites: Assessment of rheological and mechanical properties. Composites Science and Technology, 69(11-12), 1756-1763. https://doi.org/10.1016/j.compscitech.2008.10.005

Pötschke, P., Bhattacharyya, A. R., Janke, A. (2004). Melt mixing of polycarbonate with multiwalled carbon nanotubes: microscopic studies on the state of dispersion. European Polymer Journal, 40(1), 137-148. https://doi.org/10.1016/j.eurpolymj.2003.08.008

Bauhofer, W., Kovacs, J. Z. (2009). A review and analysis of electrical percolation in carbon nanotube polymer composites. Composites Science and Technology, 69(10), 1486-1498. https://doi.org/10.1016/j.compscitech.2008.06.018

Manas-Zloczower, I. (Ed.) (2009). Mixing and Compounding of Polymers: Theory and Practice (2nd ed.). Carl Hanser Verlag, Munich. ISBN 978-3-446-40773-2.

ISO 1133-1. Plastics: Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics, Part 1: Standard method. International Organization for Standardization, Geneva.