Within the LATI Industria Termoplastici S.p.A. compound range, Laticonther 83 CP/85 is classified as a thermally conductive, impact-modified polyamide 12. The designation identifies PA12 as the base polymer, selected for low equilibrium moisture uptake and for resistance to zinc chloride stress cracking relative to PA6 and PA66. The thermally conductive filler system raises through-plane thermal conductivity above the 0.24 W/m K value typical of unfilled PA12, while the impact-modified matrix reduces crack propagation in thin-wall heat-dissipation geometries. The grade is specified for injection-moulded heat sinks, LED carriers, battery-pack cooling frames, and housings requiring simultaneous heat transfer and electrical insulation.

Which Supplier-Published Values Define the Material Boundary?

Typical values from the LATI technical datasheet for Laticonther 83 CP/85 are summarised in Table 1. These values refer to dry-as-moulded specimens conditioned according to ISO 291 at 23 °C and 50 % relative humidity unless otherwise indicated. Batch-to-batch variation should be expected within the standard tolerances for mineral-filled polyamide compounds.

The notched Charpy value of 6 kJ/m² is moderate relative to unfilled impact-modified PA12 because the mineral filler network provides crack-initiation points. The unnotched value of 35 kJ/m² indicates that ductile deformation is still available when no sharp notch is present. The nominal strain at break of 15 % confirms that this grade is not a high-elongation PA12; it is a stiffened, thermally conductive variant with improved toughness relative to non-impact-modified filled PA12 compounds.

Melt Compounding and Injection Moulding Parameters Control Final Conductivity

During compounding of the impact-modified PA12 with the thermally conductive filler, co-rotating twin-screw extruders with L/D ratios of 40:1 to 48:1 are used. The filler is introduced downstream through side feeders after the PA12 melt seal is established. Melt temperature is held at 240 °C to 260 °C, and screw speeds of 300 min⁻¹ to 600 min⁻¹ are typical. Specific mechanical energy input above 0.25 kWh/kg can produce filler attrition and lower thermal conductivity, while insufficient dispersion produces surface roughness and variable conductivity across a batch. Vacuum devolatilisation below −0.08 MPa gauge is applied to extract residual moisture and low-molecular-weight volatiles.

On production-scale injection-moulding lines, Laticonther 83 CP/85 requires desiccant drying at 80 °C until residual moisture falls below 0.10 %. Barrel temperature profiles from feed throat to nozzle are typically set between 240 °C and 270 °C; melt temperature above 280 °C or residence time greater than 10 min may cause polymer degradation and a measurable loss of impact performance. Mould-wall temperatures in the range 50 °C to 80 °C promote crystallisation of PA12 and reduce post-mould warpage in asymmetric heat-sink structures. Screw rotation speeds below 150 min⁻¹ and back pressure below 0.5 MPa limit filler attrition. Gate diameter should not be less than 1.2 mm for thin-wall sections. Hot-runner manifolds should be externally heated and free of dead spots; black specks and local viscosity increase are observed when thermally conductive compound stagnates in hot-runner corners.

Thermal Conductivity Stability Under Humid Service Conditions

Unlike PA66-based Laticonther grades, the PA12 matrix absorbs approximately 0.7 % moisture at equilibrium in 23 °C and 50 % relative humidity according to ISO 62. Thermal conductivity in mineral-filled PA12 is less sensitive to water than in PA6 or PA66 because the thermally conductive filler network remains continuous and the matrix contributes less to phonon transport. However, absorbed water acts as a plasticiser and lowers the glass transition temperature; this can influence creep in clamped heat-sink assemblies. Published multi-batch creep data for this precise grade at elevated temperature remain limited, so component-level validation under ISO 16750-4 thermal cycling is required for automotive power-electronics housings. Surface resistivity remains above 1.0 × 10¹² Ω after standard conditioning, which permits use as an electrically insulating heat-dissipation component.

Through-plane thermal conductivity is measured according to ISO 22007-2 using the transient plane source method; laser flash analysis per ASTM E1461 is used during development. For a 2 mm plaque, conductivity is typically reported at 2.5 W/m K; thicker sections above 4 mm can show slight reduction due to skin-core morphology. Surface resistivity is measured after conditioning at 23 °C and 50 % relative humidity using a 500 V DC test voltage per IEC 62631-3-2. In-plane thermal conductivity can differ from through-plane by a factor of 1.2 to 2.0 in moulded plaques depending on gate position and thickness. The through-plane value of 2.5 W/m K is therefore not a single-point design property; it is a specimen-level measurement. For simulation, a two-region model with a high-conductivity skin layer and a lower-conductivity core layer has been used for mineral-filled PA12, but published data for this specific configuration is limited.

Electrical insulation is retained because the thermally conductive filler is selected from ceramic or mineral types rather than carbon-based conductive fillers. The comparative tracking index of 600 V supports use on primary circuit carriers, but creepage and clearance distances must still be designed according to IEC 60664-1. Black grade variants may contain carbon black for colouration; if carbon black is present at levels above 0.5 %, surface resistivity can decrease, so the electrically insulating specification should be confirmed on black mouldings.

When Impact Modification Shifts the Stiffness–Conductivity Trade-Off

The impact-modified character of Laticonther 83 CP/85 differentiates it from unfilled PA12 and from higher-modulus thermally conductive compounds. The elastomer phase raises the notched Charpy value, but it also reduces tensile modulus and may introduce a slight reduction in thermal conductivity relative to a non-modified equivalent at the same filler loading. The material is therefore not the optimum choice when maximum through-plane conductivity above 5 W/m K is the sole design criterion; in such cases a PA66- or PPS-based grade with higher filler content is required. For snap-fits and clip systems subjected to repeated thermal cycling from −40 °C to 85 °C, the impact-modified PA12 grade reduces the probability of brittle fracture at the junction between the heat-sink fin and the housing wall.

Table 2 compares representative values for Laticonther 83 CP/85 with a mineral-filled thermally conductive PA66 and unfilled PA12. The comparison is based on supplier-published typical data where available and standard PA12 reference values.

Compared with Laticonther 82 CP/50 PA66, Laticonther 83 CP/85 offers lower moisture absorption, better resistance to hydrolysis in hot water-glycol mixtures, and lower tensile modulus. The main trade-off relative to unfilled PA12 is reduced strain at break and increased density. In two-component moulding with unfilled PA12, adhesion is improved when the thermally conductive grade is injected over a hot core at 80 °C; surface contamination from mould-release agents must be eliminated because silicone-based releases reduce weld-line strength. Component thickness below 1.5 mm combined with flow-path-to-thickness ratios above 150:1 can cause hesitation lines and anisotropic thermal conductivity. Flow-direction conductivity may be lower than through-plane conductivity in injection-moulded plaques because platelet filler aligns with the flow front. For heat-sink bases, a thickness of 2.0 mm to 3.0 mm is typically used to maintain through-plane conduction and sufficient melt flow.

Field failures in thermally conductive PA12 parts typically originate at weld lines, where filler is depleted and local thermal conductivity can fall below 1 W/m K. Weld-line strength in impact-modified Laticonther 83 CP/85 is higher than in non-impact-modified filled PA12, but gate placement should avoid weld lines at load-bearing bosses. Arborescent fracture has been observed at the base of deep ribs when the mould temperature is below 50 °C and the material freezes before full packing. Raising mould temperature to 80 °C and extending holding pressure improve rib-tip filling and reduce internal voids. Linear mould shrinkage is typically 0.5 % to 0.8 % in the flow direction, but the anisotropic filler orientation can produce differential shrinkage. Tool design should account for post-mould shrinkage over 24 h at 23 °C; full crystallisation may take longer in thick sections.

Thermal ageing in air at 120 °C for 1000 h can produce surface oxidation and a decline in Charpy impact; data for this specific grade under continuous high-temperature exposure are limited, but PA12 grades generally retain mechanical properties better than PA6 at 120 °C due to lower moisture regain. Antioxidant packages are incorporated, and the supplier recommends avoiding contact with copper-based alloys at temperatures above 100 °C because copper ions catalyse polyamide oxidation. The PA12 matrix provides resistance to hydrocarbons, greases, and dilute acids. It is not recommended for strong acids or phenols. Stress-cracking resistance under zinc chloride exposure is superior to PA6 and PA66, making the grade suitable for automotive underhood brackets where road salts are present. Testing per ISO 22088-2 is recommended for chemical compatibility validation.

Regulatory documentation for Laticonther 83 CP/85 is governed by REACH Regulation EC No 1907/2006 and RoHS Directive 2011/65/EU. No intentionally added per- and polyfluoroalkyl substances are declared in the supplier safety data sheet. Food-contact status must be confirmed for the specific lot because the thermally conductive filler and impact modifier are not automatically covered by the generic FDA 21 CFR 177.1500 listing for PA12. Replacement of aluminium heat spreaders with Laticonther 83 CP/85 is structurally viable only where the heat load is below the conductivity limit of the polymer. The compound is not a direct substitute for copper or aluminium in power density applications above 5 W/cm² unless thin walls and forced-air cooling are combined. The advantage is net-shape moulding of electrically insulating cooling frames, mass reduction, and elimination of secondary isolation layers. Continuous use in air is not recommended above 120 °C; the heat deflection temperature of PA12 at 1.8 MPa is approximately 75 °C, so load-bearing thermal modules require additional heat ageing and creep assessment.