The present invention relates to an electrically conductive polymer composition comprising a thermoplastic polymer and one or more conductive components. The invention also relates to a process for preparing said composition, and to a process for moulding said composition into a moulded article. Furthermore, the invention relates to an article comprising the electrically conductive polymer composition.

Most of the commonly used thermoplastic polymers, such as most polyesters, polyamides and polyolefins, intrinsically have a very low electrical conductivity, and therefore not providing an effective barrier against electromagnetic radiation. However, by adding one or more conductive components, the polymer compositions so prepared can be made electrically conductive, and as a result thereof gain in electromagnetic shielding capabilities. This property is also known as electromagnetic interference shielding, or EMI shielding. Within the context of the present invention, a polymer composition showing good EMI shielding capabilities, is implicitly considered to also have good electrical conductivity properties.

Electrically conductive polymer compositions are used in electrical and electronic appliances, in particular for electromagnetic interference shielding, also known as EMI shielding. With the increased use of highly integrated and high power consuming electrical/electronic appliances, in particular in the growing market of e- vehicles, not only the demand for electrically conductive polymer compositions increases but also the requirements on their properties. Electrical vehicle power distribution systems must operate at higher voltage to deliver sufficient power to the vehicle, thereby increasing the need for proper insulation and EMI shielding. Furthermore, integration of functions, reduction of number of parts, saving of material and weight, and more reliable performance are important features for energy saving, long-lasting safety and economic use of cars. Key properties for the electrically conductive polymer compositions used herein are high electromagnetic shielding efficiency in combination with outstanding mechanical properties.

Electrically conductive polymer compositions are known in the art. For instance, document US2010163795A describes a polymer composition comprising: (A) a thermoplastic resin; (B) a conductive inorganic compound; and (C) a fibrous filler. The thermoplastic resin (A) used herein can be any thermoplastic polymer, including polyamides, polyesters, polyphenylene sulphide and the like. The conductive inorganic compound (B) is one having a volume resistance of less than about 10' ³ Qm and a relative permeability of more than about 5000. In US2010163795 for the conductive inorganic compound (B) a nickel iron alloy is used in amounts of 5 - 15 wt.%. As mentioned in US2010163795, with too low an amount of the inorganic compound, EMI/RFI shielding improvement may be insignificant, and too high an amount can have a negative effect on viscosity and specific gravity of the resin composition. According to LIS2010163795, the fibre filler includes without limitation carbon fibre, glass fibre, boron fibre, amide fibre, liquid crystalline polyester fibres, and the like, and combinations thereof. All examples are with carbon fibre.

However, the EMI shielding obtained with the electrically conductive polymer composition of the prior art, in particular the cited prior art, is generally low, i.e. lower than 30dB, unless the amount of conductive fillers used is very large (15 wt.%), or the conductive fillers (5 wt.%) are combined with a large amount of conductive fibres (40 wt.%) and/or other additional conductive fillers, more particular carbon nano tubes. However, the high filler content, and more particular the high filler and fibre content, does not only lead to a high density and high cost of the materials, but also results in poor processability of the polymer composition, hampering the production of complex moulded parts. Furthermore, the overall mechanical properties, in particular ductility, i.e., combination of tensile strength and elongation-at-break, are too low.

The objective technical problem of the present invention is therefore to provide an electrically conductive polymer composition that shows good EMI shielding (at least about 30 dB), preferably an improved EMI shielding (at least about 40 dB); has good mechanical properties in terms of stiffness and ductility, i.e., combines a high tensile modulus with a high tensile strength and elongation-at-break; and has good processability and can be easily processed into complex shapes.

This objective has been achieved with the electrically conductive polymer composition according to Claim 1. The inventive composition comprises or consists of (A) polyphenylene sulphide (PPS); (B) carbon nanostructure particles (CNP); and (C) non-metallized carbon fibres (NMCF). The composition comprises at least 50 wt.% of the PPS. The PPS (component (A)) constitutes a matrix for the other components. The CNP (component (B)) and the NMCF (component (C)) are preferably dispersed in the PPS (component (A)). The carbon nanostructure particles (CNP) comprise carbon nanotubes that are branched, and/or crosslinked, and/or share common walls with one another. These carbon nanostructure particles are present in an amount of 0.2 - 3.0 wt.%, relative to the total weight of the polymer composition. The non-metallized carbon fibres (NMCF) are present in an amount of 17 - 37 wt.%, relative to the total weight of the polymer composition.

It is noted that in expressions herein wherein an amount is mentioned, such as in an amount of 0.2 - 3.0 wt.% for the CNP, it is herein meant that the amount is in the range of 0.2 - 3.0 wt.%, and can be any amount in said range. The same holds for properties. Furthermore, where a range is mentioned, either for an amount, or a property, or otherwise, the range includes the upper and lower limit. For example, for the amount of 0.2 - 3.0 wt.% for the CNP, the range includes 0.2 wt.% and 3.0 wt.%.

It is noted that with the minimum amounts of 0.2 wt.% of CNP (component (B)) and 17 wt.% of NMCF (component (C)), the maximum amount of PPS (component (A)) is 82.8 wt.%. In preferred embodiments mentioned herein further below, wherein component (B) and/or component (C) are present in a higher minimum amount, or wherein one or more other components are present in the composition a minimum amount above zero, the maximum amount of PPS (component (A)) is lowered accordingly. The same holds for the amount of PPS used in the process according to the invention mentioned herein further below.

With the expression ‘distributed’ or ‘dispersed’ is herein understood that the PPS constitutes a continuous phase (matrix) and components (B) and (C) are distributed or dispersed in the PPS (matrix). These components are preferably dispersed in the matrix by using any methods known in the art, such as meltcompounding (e.g., by mixing the molten components in an extruder, such as a twinextruder).

With a ‘branched carbon nanotube’ is herein understood a carbon nanotube comprising a first or main backbone and one or more secondary backbones, the secondary backbones having an end-part attached to the main backbone, and the remainder of the secondary backbones protruding away from the main backbone. With ‘crosslinked carbon nanotubes’ are herein understood carbon nanotubes which cross each other at a crossing point and are attached to each other at the crossing point. With ‘carbon nanotubes sharing common walls with one another’ are herein understood a combination of at least two carbon nanotubes, wherein at least one carbon nanotube has a part of a backbone running parallel and attached to a part of a backbone of another carbon nanotube. The presence of carbon nanotubes that are branched or crosslinked and/or share common walls can be inspected by TEM techniques.

The expression ‘non-metallized’ in ‘non-metallized carbon fibres’ means that these fibres do not contain metal, neither incorporated in the fibres, nor coated on the fibres, nor otherwise.

The effect of the composition according to the present invention, comprising the CNP and the NMCF in the said amounts, is that moulded parts of the composition have a high EMI shielding as well as excellent mechanical properties, combining a high stiffness (high tensile modulus) with a high ductility (high tensile strength and high elongation-at-break, and may have a an impact strength that is sufficient for the use of the composition in different applications, according to the present invention. Furthermore, the processability of the composition is good. More particular, the combination of CNP and PPS have a synergistic effect on the EMI shielding, resulting in a significantly higher EMI shielding than for corresponding compositions with other thermoplastic polymers like PA and PBT, while the CNP and NMCF in the said amounts have a synergistic effect on the ductility, showing an optimum in both tensile strength and elongation-at-break. This in contrast with, for example, glass fibres, but also, with other highly conductive fibres, such metallized carbon fibres.

The polyphenylene sulphide (PPS) (component (A)) in the composition according to the invention can be any PPS polymer suitable for making thermoplastic moulding compositions and known in the art. Polyphenylene sulphide is a semi-crystalline polymer based on recuring units of aromatic rings alternating with sulphide linkages. According to the present invention, a polyphenylene sulphide (PPS) denotes any polymer of which at least about 50 mol. % of the recurring units consist of phenylene units alternating with sulphide linkages (mol. % are herein based on the total number of moles of recuring units in the PPS polymer). The PPS polymer can be a homopolymer or a copolymer. Suitably, the PPS polymer is such that at least about 60 mol. %, for example at least about 70 mol. %, or at least about 80 mol. %, or at least about 90 mol. %, or at least about 95 mol. %, and more particular at least about 99 mol. % of the recurring units in the PPS are recurring units (RPPS) of phenylene units alternating with sulphide linkages. Herein the mol.% are relative to the total molar amount of recurring units in the PPS polymer. The PPS homopolymer consists for 100% of recurring units (RPPS) of phenylene units alternating with sulphide linkages. Suitably, the PPS is characterized by a melt flow index (MFI) that may be in the range of 200 - 600 g/10 min. Preferably, the PPS used in the inventive composition has an MFI in the range of 300 - 400 g/10 min measured at 316°C and a load of 5 kg measured according to ISO 1133.

The carbon nanostructure particles (CNP) comprised by the composition according to the invention can be obtained by a compounding process comprising melt-mixing a carbon nanostructure material with a melt of polyphenylene sulphide. Herein the carbon nanostructure material used in the compounding process has a three-dimensional structure of a multitude of crosslinked, branched and entangled carbon nanotubes, as well as segments of carbon nanotubes sharing common walls with one another. The carbon nanostructure material can be prepared by special preparation processes. An example of such a process is described in US 2016/0362542. Herein the carbon nanostructure is prepared by producing carbon nanotubes on a growth substrate, and afterwards removing the substrate. The three- dimensional structure with crosslinks, branches and segments of carbon nanotubes sharing common walls and entanglements typically result from the preparation process of the carbon nanostructure material, but the entanglements can be lost during the compounding process by which the inventive composition can be obtained. Structural elements such as crosslinks, branches and segments of carbon nanotubes sharing common walls typically remain in the carbon nanostructure particles (CNP) typically dispersed in the PPS. With the expression and/or in the phrase ‘the carbon nanostructure particles (component (B)) comprise carbon nanotubes that are branched, and/or crosslinked, and/or share common walls with one another’ is meant that the carbon nanotubes can either be branched, or crosslinked or share common walls with one another, as well as any combination thereof. For example, a carbon nanotube can be branched, and be crosslinked with another carbon nanotube.

The carbon nanostructure particles (CNP; component (B)) are present in an amount of at least 0.2 wt.% preferably at least 0.35 wt.%, more preferably at least 0.5, relative to the total weight of the polymer composition. The advantage thereof the EMI shielding is increased.

The carbon nanostructure particles (CNP; component (B)) are present in an amount of at most 3.0 wt.%, preferably at most 2.75 wt.%, more preferably at most 2.5 wt.%, relative to the total weight of the polymer composition. The advantage thereof the ductility is better retained. More preferably, the carbon nanostructure particles (CNP; component (B)) are preferably present in an amount of 0.35 - 2.75 wt.%, more preferably 0.5 - 2.5 wt.%, relative to the total weight of the polymer composition. The advantage of the amount in the preferred range is that the EMI shielding is increased while the ductility is retained at a good level.

The non-metallized carbon fibres (NMCF; component (C)) in the electrically conductive composition according to the present invention can be any nonmetallized carbon fibres, known in the art, suitable for making fibre reinforced thermoplastic polymer compositions. The NMCF can be, for example, pitch-based carbon fibres, or polyacrylonitrile (PAN)-based carbon fibres, and any combination thereof. Examples thereof are PAN fibres with following properties: tensile modulus 220 GPa, tensile strength 3.5 GPa, and an electrical conductivity of 10000 S/m; and pitch carbon fibre having a diameter of 7 urn, a volume resistivity of 10' ⁵ (Q m) and a tensile modulus of 200 GPa. Such fibres have suitable properties for obtaining, in combination with the CNP in the PPS, compositions having good EMI shielding as well as good mechanical properties.

The carbon fibres in the NMCF may have dimensions of diameter (D) and length (L), and aspect ratio (L/D), varying over a wide range. Suitably, the carbon fibres in the NMCF have an average diameter in a range of 3 - 20 pm (micrometre), more particular in a range of 7 - 15 pm. Suitably, the NMCF used for the preparation of the composition is provided in the form of chopped strands, with a length, for example in the range of 5 - 50 mm (millimetres). The length of the carbon fibres of the NMCF in the polymer composition, as a result of the processing steps during the preparation of the polymer composition, may be reduced to, for example, to an average length in a range of 10 - 500 pm (micrometre), more particular in the range of 20 - 250 pm. The average length L can be determined by X-ray microtomography.

The NMCF (component (C)) is present in an amount of at least 17 wt.%, preferably at least 19 wt.%, more preferably at least 20 wt.%, and even more preferably at least 25 wt.%, relative to the total weight of the polymer composition. The advantage of the amount in the preferred higher amount is that the stiffness is further improved and a higher EMI is obtained, compared to a lower amount of NMCF, while good processing and high ductility are retained.

The NMCF (component (C)) is present in an amount in the range of at most 37 wt.%, preferably at most 36 wt.%, more preferably at most 35 wt.%, and even more preferably at most 33 wt.%, relative to the total weight of the polymer composition. The advantage of the amount in the preferred lower amounts is that he the processability and ductility are improved, compared to a higher amount of NMCF, while a good EMI shielding and a good stiffness are retained.

Also more preferably, the NMCF (component (C)) is present in an amount in the range of 19 - 36 wt.%, even more preferably 20 - 35 wt.%, and most preferably 25 - 33 wt.%, relative to the total weight of the polymer composition. The advantage of the amount in the preferred range is that an optimal balance stiffness, processability, EMI shielding and ductility are obtained.

Even more preferably, the composition comprises 0.35 - 2.75 wt.% of component (B) and 20 - 35 wt.% of component (C), wherein the weight percentages (wt.%) are relative to the total weight of the polymer composition. The advantage hereof is that the composition has an improved balance in properties in terms of EMI shielding, mechanical properties and processability.

Most preferably, the composition comprises 0.5 - 2.5 wt.% of component (B) and 25-35 wt.% of component (C), the weight percentages (wt.%) being relative to the total weight of the polymer composition. The advantage of this embodiment is that the composition has an optimal balance in properties in terms of EMI shielding, mechanical properties and processability.

Next to the NMCF (component (C)), the electrically conductive polymer composition may comprise other inorganic fibres (component (D)), more particular conductive inorganic fibres (CIF), provided that the amount of the inorganic fibres is relatively low, compared to the NMCF, i.e. at least lower than the minimum amount of the NMCF of 17 wt.% and the combined amount of NMCF and other inorganic fibres is at most 37 wt.%, relative to the total weight of the composition.

Preferably, the amount of the inorganic fibres (component (D)) is in the range of 0 - 10 wt.%. The effect of using inorganic fibres in an amount of at most 10 wt.% is that the stiffness of the composition is further increased, compared to the composition with the same amount of CNP and NMCF without other inorganic fibres, while still benefiting from the synergistic effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding, while maintaining a good processability. Preferably, the amount of inorganic fibres is in the range of 0 - 5 wt.%, and more preferably in the range of 0 - 2.5 wt.%, even more preferably in the range of 0 - 1.0 wt.%, relative to the total weight of the composition. The effect of using the inorganic fibres in these lower amounts, if at all, is that the beneficial effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding are even better retained.

The choice of inorganic fibres is not limited to a specific group and may by any inorganic fibre, other than non-metallized carbon fibre, suitable for use in a thermoplastic moulding composition. The inorganic fibres may be selected from, for example, a group consisting of metallized carbon fibres, glass fibres and metal fibres. The metal fibre may be, for example, a stainless-steel fibre. The glass fibres may be metal-coated or non-coated. Suitable examples of metals that can be used for a metal coating on glass fibres or carbon fibres, for producing metal-coated glass fibres or metallized carbon fibres, are metals selected from a group consisting of nickel, copper, copper/Ni alloys, Ni/Fe alloys and Cu/Sn alloys, and any combinations thereof. Metallized carbon fibres, metal-coated glass fibres and metal fibres are herein referred to as conductive inorganic fibres (CIF). Preferably, the conductive inorganic fibre (CIF) is a metallized carbon fibre, which are known in the art. More preferably, the conductive inorganic fibre is a nickel-coated carbon fibre.

The electrically conductive polymer composition may also comprise one or more other polymers (component (E)), different from PPS, or one or more other additives (component (F)), or any combination thereof.

With the expression of ‘one or more’ as in ‘one or more other additives’, is herein understood ‘one or more than one’, such as ‘one or more than one other additive’. Thus, one or more can by any integer starting from one, and included, for example, two, three, four, etc.

The other polymer (component (E)) may be any thermoplastic polymer or combination of polymers that is known in the art to be used in combination with PPS in PPS-based thermoplastic polymer compositions. Example thereof are polyamide and polyethylene. The amount of the other polymer is preferably kept low, more preferably below 10 wt.%, in order not to substantially detract from the beneficial synergistic effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding. More preferably, the amount of other polymer is in the range of 0 - 5 wt.%, even more preferably in the range of 0 - 2.5 wt.%, and most preferred in the range of 0 - 1.0 wt.%, relative to the total weight of the composition. The effect of using the other polymer in these lower amounts, if at all, is that the beneficial effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding are even better retained. The other additives (component (F)) may suitably be chosen from any auxiliary additives known in the art used in thermoplastic polymer compositions. Examples of such auxiliary additives are inorganic fillers, pigments and colorants, branching agents, nucleating agents, impact modifiers, flow improvers, UV and heat stabilizers, release agents and lubricants.

The amount of component (F), i.e. the amount of the one other additive present, or the combined amount of other additives, if more than one other additives is present, is preferably kept low, more preferably below 10 wt.%, in order not to substantially detract from the beneficial synergistic effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding. More preferably, the amount of other additives is in the range of 0 - 5 wt.%, even more preferably in the range of 0 - 2.5 wt.%, and most preferred in the range of 0 - 1.0 wt.%, relative to the total weight of the composition. The effect of using the other additives in these lower amounts, if at all, is that the beneficial effects of the combination of the PPS, the NMCF and the CNP on the ductility and EMI shielding are even better retained.

Preferably, the polymer composition according to the present invention consists of

(A) at least 50 wt.% of polyphenylene sulphide (PPS);

(B) 0.2 - 3.0 wt.% of carbon nanostructure particles (CNP);

(C) 20 - 35 wt.% of non-metallized carbon fibres (NMCF);

(D) 0 - 5 wt.% of other inorganic fibres;

(E) 0 - 5 wt.% of another thermoplastic polymer; and

(F) 0 - 5 wt.% of one or more other additives; wherein the weight percentages (wt.%) are relative to the total weight of the composition.

Also preferably, the polymer composition according to the invention consists of

(A) at least 50 wt.% of polyphenylene sulphide (PPS);

(B) 0.2 - 3.0 wt.% of carbon nanostructure particles (CNP);

(C) 20 - 35 wt.% of non-metallized carbon fibres (NMCF);

(D) 0 - 5 wt.% of non-metallized glass fibres;

(E) 0 - 5 wt.% of another thermoplastic polymer; and

(F) 0 - 5 wt.% of one or more other additives; wherein the other additives do not include metallic additives the weight percentages (wt.%) are relative to the total weight of the composition. The polymer composition consisting of the said components, from which conductive inorganic fibres and metallic additives are excluded, exhibit all the advantages of the present invention, in terms of high EMI shielding, good mechanical properties and good processability. The non-metallized glass fibres in the polymer composition according to this embodiment, can be any non-metallized glass fibres suitable for use PPS based polymer compositions, and are known in the art.

The composition according to the present invention has preferably an EMI shielding of at least 30 dB at 1 GHz 2 mm. More preferably, the polymer composition has an EMI shielding of at least 35 dB at 1 GHz 2 mm, even more preferably at least 40 dB at 1 GHz 2 mm. Herein the EMI shielding at a frequency of 1 GHz measured at a thickness of 2 mm by the method according to ASTM D4935-99 at 23°C.

The composition has preferably an E-modulus of at least 20000 MPa. More preferably, the polymer composition has an E-modulus of at least 22500 MPa, even more preferably at least 25000 MPa.

The composition has preferably a tensile strength of at 195 MPa. More preferably, the polymer composition has a tensile strength of at least 200 MPa, even more preferably at least 205 MPa.

Furthermore, the composition has preferably an elongation-at-break of at least 0.90. More preferably, the polymer composition has an elongation-at-break of at least 0.95%, even more preferably at least 1.00%.

Herein, the mechanical properties of E-modulus, tensile strength, and elongation-at-break are measured by the method according to ISO 527:2019 at 23°C, and at a drawing speed of 5 mm/min.

Also preferably, the composition of the invention has an EMI shielding of at least 30 dB at 1GHz 2mm, an E-modulus of at least 20000 MPa, a tensile strength of at 195 MPa and an elongation-at-break of at least 0.90%. More preferably, the composition has an EMI shielding of at least 35 dB at 1GHz 2mm, an E-modulus of at least 22500 MPa, a tensile strength of at 200 MPa and an elongation-at-break of at least 0.95%. Herein the EMI shielding is measured at a frequency of 1 GHz at a thickness of 2 mm by the method according to ASTM D4935-99 at 23°C; and the E- modulus, tensile strength, and elongation-at-break are measured by the method according to ISO 527:2019 at 23°C, and at a drawing speed of 5 mm/min.

These embodiments can be easily accomplished with the composition according to the present invention, comprising the components A-C while limiting the use of other components to low or very low amounts, and preferably not at all. These preferred embodiments can be easily accomplished by either increasing the amount of the NMCF or using the CNP in an amount closer to the midst of the indicated range, or a combination thereof.

The electrically conductive polymer composition according to the invention can be manufactured by any melt-mixing process known in the art and in any conventional melt-mixing apparatus that is suitable for preparing fibre filled thermoplastic polymer compositions. The process to make electrically conductive polymer composition can comprise blending a melt of a PPS material with the other components, with the PPS amount in excess over the other components, and typically results in a polymer composition comprising PPS as a continuous phase and the other components dispersed therein. The process for the preparation of the polymer composition according to the invention can be carried out, for example, in an extruder.

The invention also relates to a process for preparing the polymer composition of the present invention. The process comprises a melt-mixing step wherein a melt of polyphenylene sulphide (component A) is mixed with a carbon nanostructure material (component (M)) and non-metallized carbon fibres (NMCF) (component (C)). In the melt mixing step, the components A-C are optionally combined with and mixed with one or more further components selected from other inorganic fibres (component (D)), other polymers (component (E)), and other additives (component (F)). The process also preferably comprises a step of heating the polyphenylene sulphide (PPS) to a temperature above the melting temperature of the PPS, thereby melting the PPS and forming a PPS melt. Suitably, the PPS is herein heated to a temperature of at least 5°C, preferably at least 5°C higher than the melting temperature (Tm) of the PPS. Herein Tm is measured by the method according to ISO 11357-1/3 with a heating rate of 10°C/min.

Component (M) may be added prior to the heating of the PPS, or during the heating of the PPS, or to the PPS melt after the heating of the PPS, or any combination thereof. Component (M) is preferably added to and mixed with the PPS melt. Component (C) is preferably added after component (M) is being mixed with the polymer melt to minimize shear and maximize length of component (C) and EMI shielding of the final compound.

The carbon nanostructure material (component (M)) used in the process has a three-dimensional structure of a multitude of crosslinked, branched and entangled carbon nanotubes, and/or segments of carbon nanotubes sharing common walls one another. As mentioned herein above, the carbon nanostructure material can be prepared by special preparation processes. An example of such a process is described in US 2016/0362542, wherein the carbon nanostructure is prepared by producing carbon nanotubes on a growth substrate, and afterwards removing the substrate.

Preferably, in the process according to the invention, the amount of component (A) used is at least 50 wt.%; component (M) is used in an amount in the range of 0.2 - 3.0 wt.%, preferably in the range of 0.35 - 2.75 wt.%, more preferably in the range of 0.5 - 2.5 wt.%; component (C) is used in an amount in the range of 17 - 37 wt.%, preferably in the range of 20 - 36 wt.%, more preferably in the range of 25.0 - 35.0 wt.%, wherein the wt.% are all relative to the total weight of the composition.

The maximum amount of component (A) is 82.8 wt.%. In preferred embodiments mentioned herein further below, wherein component (M) and/or component (C) are present in a higher minimum amount, or wherein one or more other components are used in the preparation of the composition in a minimum amount above zero, the maximum amount of PPS (component (A)) may be lowered accordingly. However, wherein the minimum combined amount of other components is 0 wt.%, the amount of component (A) can be varied over the whole range of 50 - 82.8 wt.%.

Furthermore, in the process according to the invention, optionally further components (D), (E) and /or (F) are included. Herein component (D) is another inorganic fibre, or any specific or preferred embodiment thereof as described herein above. Component (E) is another polymer, different from PPS, and can be any specific or preferred embodiment thereof as described herein above. Component (F) is one or more other additives, as described herein above, and can be any specific or preferred embodiment thereof as mentioned herein above.

Herein components (D), (E) and /or (F) can be present in the following amounts: the amount of component (D) herein, if used at all, is in the range of 0 - 10 wt.%, preferably in the range of 0 - 5 wt.%, more preferably in the range of 0 - 2.5 wt.%, and most preferred 0 - 1.0 wt.%, while the combined amount of (B) and (D) is at most 40 wt.%; also more preferably, the combined amount of (B) and (D) is at most 37 wt.%; the amount of component (E) herein, if used at all, is in the range of 0 -10 wt.%, preferably in the range of 0 - 5 wt.%, more preferably in the range of 0 - 2.5 wt.%, and most preferred in the range of 0 - 1.0 wt.%; the amount of component (F) herein, if used at all, is in the range of 0 -10 wt.%, preferably in the range of 0 - 5 wt.%, more preferably in the range of 0 - 2.5 wt.%, and most preferred in the range of 0 - 1.0 wt.%, wherein the wt.% are all relative to the total weight of the composition, and the amounts of the components (A), (M), (C), (D), (E), (F) used in the process add up to and equals 100 wt.%.

Suitably, the process is carried out in an extruder, for example a twin- screw extruder, or in another apparatus suitable known in the art for melt mixing thermoplastic polymers with other components. Herein the components may, for example, be fed directly to the extruder and mixed in the extruder, or pre-mixed and then fed to the extruder or to another suitable apparatus, heating the mixture to melt the polyphenylene sulphide under stirring, thereby dispersing the other components in the molten polyphenylene sulphide, followed by extruding the melt of polyphenylene sulphide with the other components typically dispersed therein, thereby forming strands, and afterwards cooling the strands to solidify the molten material in the strands, thereby obtaining the electrically conductive polymer composition according to the present invention.

The addition and mixing of components may also be carried out stepwise; for example, by first heating and melting the polyphenylene sulphide, then adding under stirring the CNP, and successively adding the NMCF, and then adding, together or separately, if any, the other components; or alternatively, first adding, together or separately, the other components; then adding the CNP, and successively adding the NMCF.A masterbatch process may be used, e.g., the CNP can be first mixed with molten polymer in a concentration of the CNP higher than the final desired final concentration of CNP (also known as a masterbatch), which may then be followed by shaping of the obtained melt, such as by extrusion through a die, thereby forming strands. The strands are then typically cooled to solidify the molten material, and then pelletized by using any methods known in the art. The pellets may be then used as the CNP concentrate which is then mixed with the polymer melt to obtain the final polymer composition. This composition may be then mixed with other additives, e.g. NMCF.

The present invention also relates to a process for preparing an article. The process comprises injection moulding of a composition according to present invention, or any specific or preferred embodiment thereof as described herein above, into a pre-shaped mould, thereby forming a moulded article. The process preferably comprises steps of heating the composition thereby forming a melt of the polymer composition, injecting the melt into the pre-shaped mould, cooling the melt in the pre-shaped mould thereby solidifying the melt into a solid article, and removing the solid article from the pre-shaped mould. The injection moulding process can be carried out on any conventional equipment suitable for injection moulding of PPS-based compositions. The present invention also relates to an article comprising the electrically conductive polymer composition according to the invention. The articles can be prepared using any conventional moulding techniques such as but not limited to extrusion moulding, injection moulding, and the like. Said article may be, for example, an enclosure or housing, or a part thereof, for an electrical and electronic device. The articles made of the composition according to the invention can effectively help in reducing the malfunction of devices by interference: such as aircrafts, guidance systems, electrical vehicles and medical equipment such as electrocardiograph, pacemakers and related computer systems.

The invention will be elucidated on the basis of the following non- restrictive examples and comparative experiments.

Linear homopolymer PPS with a melt flow index of about 350 g/10 min at 316°C and a load of 5 kg measured according to ISO 1133 (PPS was made commercially available from Zhejiang NHU Co., Ltd., China).

Polyamide-6 (PA6):

Standard grade PA6 with viscosity number (VN) 130 cm ³ /g measured according to ISO 307 using 90% formic acid, 25°C, 0.5 g polymer content per 100 ml of solvent 90% formic acid; used in comparative experiments (material obtained from DSM Engineering Materials BV, The Netherlands). Polybutylene terephthalate (PBT):

PBT 1 : Standard PBT grade with intrinsic viscosity of 0.8 dl/g measured according to ASTM D2857 at 25°C by dissolving 0.5 gr of polymer per 100 ml of m-cresol (PBT 1 was made commercially available from DSM Engineering Materials BV, The Netherlands).

PBT 2 Standard PBT grade with intrinsic viscosity of 1 dl/gr measured according to ASTM D2857 at 25°C dissolving 0.5 gr of polymer per 100ml of m-cresol (PBT 2 was made commercially available from DSM Engineering Materials BV, The Netherlands).

Carbon fibres (NMCF):

A non-metallized grade of PAN based carbon fibres having an average diameter of 7 pm, a length of 6 mm, tensile modulus of 240 GPa (CF was made commercially available from SGL Carbon SE).

Glass fibres (GF):

A standard grade E glass fibre having an average diameter of 11 pm, a length of 3 mm, with a tensile modulus of elasticity according to ASTM D2343 of 82 GPa, a tensile strength measured according to DIN ISO 527-5 of 2600 MPa (GF was made commercially available from Nippon Electric Glass).

Carbon nanostructure material (CNS material):

The CNS material used for the preparation of the compositions is “Carbon Nanostructures 100 pellets” (having a bulk density of 0.135 g/cm3 and supplied in pellet form by Cabot Corporation), which is a material having a three- dimensional structure of a multitude of crosslinked, branched and entangled multiwalled carbon nanotubes, hereafter referred to as CNP in the tables.

For comparative experiments N, O, and P, carbon nano tubes were used which do not have a three-dimensional structure of a multitude of crosslinked, branched and entangled multiwalled carbon nanotubes, hereafter referred to as CNT, which is available as a masterbatch C7503S, commercially available from Qingdao Wedonk Polymers Materials Co, Ltd, which masterbatch contains 80wt% PPS and 20wt% CNT. Conductive carbon black:

A conductive carbon black, with CAN of 330 cc/100 g and a BET surface of 1375 g/m ² was used in the comparative experiments (material obtained from Cabot Corporation). methods

The polymer compositions in Tables below were produced using a ZE 25R co-rotating twin-screw extruder at a barrel temperature of 320°C (PPS), or 260°C (PBT, PA6), a screw speed of 400 rpm (PPS), or 300 rpm (PBT, PA6), and a throughput of 20 kg/h (PPS), or 15 kg/h (PBT, PA6).

The CNS was introduced in the extruder via a concentrate in PA6 (CNS concentration in the PA6 matrix was 10 wt%, based on the total concentration of PA6), PBT (CNS concentration in the PBT matrix was 8 wt%, based on the total concentration of PBT) and PPS (CNS concentration in the PPS matrix was 5 wt%, based on the total concentration of PPS).

The CNT was introduced in the extruder via a masterbatch in PPS (CNT concentration in the PPS matrix was 20 wt%, based on the total concentration of the masterbatch).

The compositions in the Tables 1 , 2 and 4 were made by obtaining first a PPS melt in the extruder, then dosing 5 wt% CNS concentrate in PPS via a first side feeder and allowing for the concentrate to melt, then mixing the molten PPS with the molten CNS concentrate in the extruder, followed by the addition of NMCF and/or GF, NiCF via a second side feeder. For Comparative experiments N, O and P, 5 wt% of CNT masterbatch was added in PPS via a first side feeder and allowing for the concentrate to melt, then mixing the molten PPS with the molten CNT masterbatch in the extruder, followed by the addition of NMCF via a second side feeder.

The compositions in the Table 3 were made by obtaining first a PPS melt in the extruder, then dosing CB in the amounts mentioned in Table 3 via a first side feeder, then mixing CB and molten PPS, followed by addition of NMCF via a second side feeder.

The compositions in Table 5 were made by obtaining a polymer melt (PBT or PA6 melt) in the extruder, then dosing in the extruder a CNS concentrate (CNS concentration was 10 wt% in PA6 and 8 wt% in PBT, based on the total amount of the polymer) via a side feeder, allowing the concentrate to melt and mixing the molten CNS concentrate with the polymer (PBT or PA6 matrix).

The compositions in Table 6 were made by obtaining a polymer melt (PPS or PBT melt) in the extruder, then dosing in the extruder a CNS concentrate, (CNS concentration was 5 wt% in PPS concentrate and 8 wt% in PBT concentrate, based on the total amount of the polymer) via a side feeder, allowing the concentrate to melt and mixing the molten CNS concentrate with the polymer (PPS or PBT melt), followed by addition of GF via a second side feeder.

The extruded strands obtained were cooled down through a water bath and granulated afterwards. All PPS polymer compositions obtained as granulated compounds were dried in a vacuum oven at 160°C under nitrogen for at least 16 hours before using in further moulding steps. All PBT polymer compositions obtained as granulated compounds were dried in a vacuum oven at 120°C under nitrogen for at least 10 hours before using in further moulding steps. All PA6 polymer compositions obtained as granulated compounds were dried in a vacuum oven at 80°C under nitrogen for at least 24 hours before using in further moulding steps.

The compositions in Tables 1-6 refer to final compositions obtained.

Injection moulding for the of test for the EMI shielding

The polymer compositions obtained as granulated compounds were injection moulded. Specimens of said granulated compounds were prepared by means of a FANUC A-100a injection moulding machine using a single cavity mould fed by a fan gate for 150*150* 2 mm*mm*mm plates.

Injection moulding for the PPS based materials was performed using a melt temperature of 325°C and a mould temperature of 150°C.

Injection moulding for the PBT based materials was performed using a melt temperature of 250°C and a mould temperature of 90°C.

Injection moulding for the PA6 based compositions was performed using a melt temperature of 270°C and a mould temperature of 70°C.

Injection moulding for the of test for the mechanical tests

The polymer compositions obtained as granulated compounds were injection moulded. Specimens of said granulated compounds were prepared by means of an Engels EVC 110 ton injection moulding machine using 2 cavity mould of ISO 527- 1A tensile bars. The injection moulding conditions for the PPS based materials was performed using a melt temperature of 325°C and a mould temperature of 150°C.

Injection moulding for the PBT based materials was performed using a melt temperature of 250°C and a mould temperature of 90°C.

Injection moulding for the PA6 based compositions was performed using a melt temperature of 270°C and a mould temperature of 70°C.

Test Methods

Tensile

Tensile properties were tested according to ISO 527:2019 using ISO 527-2 type 1A injection moulded bars. The tensile modulus (TM), the tensile strength (TS) and the elongation-at-break (EaB) were measured in a tensile test according to ISO 527/1 at 23°C, at a drawing speed of 5 mm/min.

Izod impact properties were measured at 23°C according to ASTM D256-2010 using 63.5x12.7x6.4 mm test bars.

EMI shielding test

The EMI shielding effectiveness (SE) was measured according to the method of ASTM D4935-18 at 23°C. The measurement set-up contained a flanged coaxial fixture that has a typical 50 Ohm characteristic impedance and a network analyser. Measurements using this fixture were carried out at a frequency range from 30 MHz to 1.5 GHz. The EMI shielding effectiveness measured at @ 1GHz was reported.

For the measurements, disk samples according to the required reference and load disk size of 133 mm in diameter, were prepared from moulded plates with dimensions of 150*150*2 mm ³ , with the use of a numerical control machine tool. S21 values (representing the power transferred from Port 1 (P1) to Port 2 (P2) from the network analyser, as specified in the method of ASTM D4935-18) were measured for all the samples. The EMI shielding effectiveness SE, mentioned above, is defined as the ratio in decibel between the power obtained without the shielding material to the power received when the shielding material is in place, and calculated according to formula (I):

Test Results

The compositions and results of the various Examples and Comparative Experiments have been collected in the Tables below. These results show the synergistic effects for the compositions of the present invention with the combination of PPS, CNP and NMCF on the combined EM l-shielding, stiffness and ductility, which synergistic effects are absent for compositions with other polymers used instead of PPS, conductive fillers used instead of CNP and or metallized carbon fibres or glass fibres used instead of NMCF.

Table 1. Compositions and results for Examples l-lll and Comparative experiments CE- A and B *) and Comparative experiments CE-N, CE-0 and CE-P

*) NMCF = non-metallized carbon fibres; CNP = carbon nanostructure (CNS) particles; wt. % = weight percentage; EaB = elongation at break. Table 1 shows the compositions and results for Examples l-lll according to the present invention and for Comparative experiments CE-A and B. The results for Examples l-lll, i.e. , PPS compositions with different amounts of carbon fibre in combination with 1 wt.% of CNP, reflect the synergistic effects of the invention, i.e. a high EMI value (all above 30 dB at 1GHz 2mm), a high modulus (all above 20 GPa) and high ductility, i.e. a high tensile strength combined with a high elongation-at-break, for all. Furthermore, the processability of all three compositions was good.

The results for the compositions of Comparative Experiments CE-A and CE-B, i.e., PPS compositions with different amounts of carbon fibre in combination with 3.5 wt.% of CNP, show a high EMI SHIELDING value and a high modulus, but lack the synergistic effects on the ductility. Moreover, these compositions were poor in processability.

The results for the compositions of Comparative Experiments CE-N, CE-0 and CE-P clearly show that an insufficient EMI value was achieved (all below 30 dB at 1 GHz 2mm), as well as insufficient elongation at break, and tensile strength and tensile modulus. These comparative experiments all employed carbon nano structures that do not comprise branched, crosslinked and/or share common walls.

Table 2. Compositions and results for Examples lll-VI and Comparative experiments

CE-B and C

*) NMCF = non-metallized carbon fibres; CNP = carbon nanostructure particles; wt.% - weight percentage; EaB = elongation at break.

Table 2 shows four Examples according to the present invention and two Comparative Experiments. All are PPS compositions with the same amount of carbon fibre (30 wt.%) but combined with different amounts of CNP. All four Examples show a high EMI SHIELDING value (all above 30 dB at 1GHz 2mm), a high modulus (all above 25 GPa) and a high tensile strength and high elongation-at break, and all four showed a good processability. The mechanical properties and processability of Comparative Experiment CE-C were good, however this composition showed a low EMI-shielding. The other Comparative Experiment CE-A, on the other hand, showed a very high EMI shielding and a high modulus, but is lower in tensile strength and elongation-at break, thus lower in ductility, and moreover, was poor in processability, but the Examples are much higher in ductility than the Comparative Experiment, thus illustrating the synergistic effect of the present invention on the ductility.

Table 3. Compositions and results for Comparative experiments CE-B and C *)

*) NMCF = non-metallized carbon fibres; CB = carbon black; wt. % = weight percentage; EaB = elongation at break.

The results for the two compositions CE-D and CE-E in Table 3, both Comparative Experiments, both PPS composition with 30 wt.% carbon fibre in combination with different amounts of carbon black (1 wt.% and 5 wt.%), show a high modulus (all above 20 GPa), and good ductility, based on high tensile strength and elongation-at-break, but the EMI shielding reaches a value above 30 dB at 1GHz 2mm, but only marginally so, only at the very high concentration of carbon black (5 wt.% CB). However, this composition hampers good processability. Table 4. Compositions and results for Comparative experiments CE-F, G and H *)

*) GF = glass fibers; NiCF = Nickel coated carbon fibres; CNP = carbon nanostructure (CNS) particles; wt.% = weight percentage, EaB = elongation at break.

The results for the three compositions in Table 4, all Comparative Experiments, one PPS composition with 30 wt.% glass fibres (30 wt.%) and two PPS composition with 15 wt.% nickel-coated carbon fibres, in combination with different amounts of CNP, show a high EMI shielding, but also a low modulus and a low ductility for all three.

Table 5. Compositions and results for Comparative experiments CE-I, J and K

*) P = polymer; CNP = carbon nanostructure (CNS) particles; wt.% - weight percentage; V.% - volume percentage; EaB = elongation at break.

Table 5 shows the results for three non-fibre reinforced compositions, all Comparative Experiments: one PPS composition, one PBT and one PA6 composition. All three comprise about 5 wt.%, corresponding with about 4 volume percent (V%) of CNP. For all three, the modulus and the tensile strength is low, but striking is the difference in EMI shielding. The EMI shielding is very high for the PPS composition, even above 50 dB, while it is much lower for the PBT and the PA6 based composition, well below 30 dB, thus illustrating the synergistic effect of the present invention on the EMI shielding. Table 6. Compositions and results for Comparative experiments CE-I, J and K *)

*) P-type = type of polymer used; GF = glass fibers; CNP = carbon nanostructure

(CNS) particles; wt.% = weight percentage; V.% - volume percentage; EaB = elongation at break.

Table 6 shows the results for two glass fibre reinforced compositions, both Comparative Experiments, one PPS composition and one PBT composition, both with about 4 volume percent of CNP. For both, the modulus and the tensile strength are very low, while the EMI shielding is strikingly different. The EMI shielding is high for the PPS composition CE-L, even above 40 dB, and much lower for the PBT composition CE-M, below 30 dB, this despite that the wt.% of CNP in CE-L is lower than in CE-M. These results thus illustrate the synergistic effect of the PPS-CNP combination as part of the present invention on the EMI shielding, as well as positive effect of the combination of the non-metallized carbon fibres (NMCF) and carbon nanostructure particles (CNP) in the restricted amounts of the invention on the mechanical properties and processing behaviour.