ASTM D6095 Standard Test Method for Longitudinal Measurement of Volume Resistivity for Extruded Crosslinked and Thermoplastic Semiconducting Conductor and Insulation Shielding Materials

    What is ASTM D6095? 

    ASTM D6095 describes a standard test method for the longitudinal volume resistivity of semiconducting conductors and insulating shielding materials for wire and cable, extruded or thermoplastic. The method measures the resistance between two electrodes on a single surface of the specimen and calculates volume resistivity based on the specimen’s geometry. The method gives electrical-resistance data which assists laboratories in characterizing semiconducting shielding compounds. When applied in conjunction with Thermal Vacuum (TVAC) testing, such electrical characterization can support the assessment of material performance under controlled temperature and vacuum environmental conditions. ASTM D6095 (Standard Test Method for Longitudinal Measurement of Volume Resistivity for Extruded Crosslinked and Thermoplastic Semiconducting Conductor and Insulation Shielding Materials) recognizes three factors that should be considered as significant factors in assessing the electrical characteristics of such materials: safety, static charges, and current transmission. 

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    Get Certified ASTM D6095

    ASTM D6095 is a standardized method to determine the electrical properties of semiconducting conductors and insulation shields. The test provides longitudinal volume-resistivity information, which is used in laboratories to characterize and compare materials for use in wire and cable. The method uses a simple specimen geometry and electrode arrangement to obtain resistance measurements, which are then converted to volume-resistivity values. This enables the consistent collection of data about the electrical properties of the material for material evaluation and quality-control activities. 

    What is the Scope of ASTM D6095? 

    ASTM D6095 is a standard test method used to determine the longitudinal volume resistivity of extruded crosslinked or thermoplastic semiconducting conductor and insulation shields for wire and cable.  This standard-

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    • Measures the resistance of the material along its length.
    • Covers extruded crosslinked semiconducting materials.
    • Covers thermoplastic semiconducting materials.
    • Insulates and covers conductors and insulation shields.
    • Applies to wire and cable materials.
    • Uses resistance and specimen geometry to calculate resistivity. 

    What are the Uses of ASTM D6095 Testing?

    ASTM D6095 testing helps assess the electrical properties of semiconducting shielding materials in the laboratory. The results can support material characterization, comparison, and quality-control activities for wire and cable products. This standard-

    • Measures Volume Resistivity of shielding materials.
    • Assesses the characteristics of electrical activity.
    • Assesses wire and cable material.
    • Helps evaluate properties associated with safety and static charges.
    • Helps to assess the current-transmission behavior. 

    What Materials Can Be Tested Under ASTM D6095? 

    ASTM D6095 applies to wire and cable extruded crosslinked and thermoplastic semiconducting conductor and insulation shielding materials. In common practice, the conductor shield is also known as the strand shield. 

    Why is ASTM D6095 Important? 

    ASTM D6095 is significant since the electrical characteristics of semiconducting extruded shielding materials affect safety, static charges, and current transmission. The method assists a laboratory in better predicting the behavior of these semiconducting compounds, using longitudinal volume-resistivity measurements. The standardized geometry and resistance measurement also enable laboratories to acquire similar resistivity data for various shielding materials. 

    ASTM D6095 Equipment and Sample Preparation Guide

    ASTM D6095 uses the apparatus described in ASTM D4496, except for the electrode system specified within ASTM D6095. The standard establishes sampling and specimen requirements for the testing of cables. 

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    Sample and Specimen DetailsTechnicians use representative samples of extruded crosslinked or thermoplastic semiconducting materials. The specimen must be clean, free from contamination, and representative of the material being tested. 
    Specimen PreparationTechnicians prepare the test specimen by cutting an extruded tape or removing material from a finished cable. The specimen must have a straight edge, a clean surface, and parallel sides to ensure accurate dimensions. 
    Specimen DimensionsSpecimen length depends on the electrode spacing (typically 1 in. or 2 in.). Specimen width must be uniform for accurate cross-sectional area calculation. Technicians measure specimen thickness at multiple points to ensure uniformity. 
    InstrumentationTechnicians use a DC voltage source (10–500 V), ammeter or electrometer, test fixture with fixed electrode spacing, standard resistors (10³ to 10¹¹ Ω) for calibration, and an insulation tester (if applicable). 

    Testing Procedures and Requirements for ASTM D6095 

    Technicians prepare and condition the specimens as per the procedure. For crosslinked shielding materials, the cable structure (without jacket) is conditioned overnight at 50 °C to remove possible acetophenone from the structure before the conditioning procedure. The laboratory then uses the prescribed electrodes, measures the resistance, and calculates the longitudinal volume resistivity from the specimen geometry. The standard tests the material under certain temperatures, such as 23 ± 2 °C (73 ± 4 °F) and the rated operating temperature of the insulation material. 

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    Specimen Measurement and Verification  Technicians measure specimen thickness at multiple points with micrometer accuracy of at least 0.001 in. (0.025 mm). They verify specimen dimensions, inspect for surface contamination, and ensure electrode alignment. 
    Specimen Mounting Technicians mount the specimen in the test fixture, ensuring proper contact between the electrodes and the semiconducting material. 
    Voltage Application and Resistance Calculation Technicians apply a DC voltage to the specimen, typically ranging from 10 to 500 V, and measure the resulting current through the specimen. Technicians calculate the resistance from the measured voltage and current values (R = V/I). 
    Volume Resistivity Calculation Technicians calculate the volume resistivity using the formula: ρ = (R × A)/L, where ρ is the volume resistivity in Ω·cm, R is the measured resistance in Ω, A is the specimen cross-sectional area in cm², and L is the distance between electrodes in cm. 
    Result Reporting Laboratories report volume resistivity values in ohm-centimeters (Ω·cm) and note test conditions. 

    ASTM D6095 Testing Process and Data Collection

    Technicians select the cable sample as per sampling requirements and prepare the required specimen. They condition the specimen as required, then load the electrode system onto the shielding material. The laboratory measures the resistance between the electrodes and records the relevant specimen dimensions. It then calculates these values based on the appropriate calculation and reports the longitudinal volume resistivity in Ω·cm. The test assesses each shielding material at the stated temperature conditions, and the laboratories describe the characteristics of the material with respect to the conditions stated in the test. 

    The image shows a laboratory setup measuring longitudinal volume resistivity of a semiconducting conductor or insulation shielding material used in wire and cable.
    ASTM D6095 Longitudinal Volume Resistivity Testing of Semiconducting Cable Shields

    Common Challenges and Troubleshooting

    Accurate results require proper specimen preparation, conditioning, electrode placement, and resistance measurement, as contamination on the specimen surface affects contact resistance and measurement accuracy. Technicians carefully remove the required cable layers and preserve the required geometry of the specimens. For crosslinked shielding materials, technicians complete the required 50 °C overnight conditioning before continuing with the applicable conditioning procedure.

    ASTM D6095 Analysis Results and Interpretation

    The laboratory report provides the longitudinal volume resistivity (Ω·cm) calculated from the resistance measurement and the specimen geometry.

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    • The technician notes the resistance value obtained across the electrode arrangement of the semiconducting shielding specimen.
    • The analyst uses the measured resistance and specimen dimensions to determine the longitudinal volume resistivity of the material being tested.
    • The engineer evaluates the measured volume-resistivity result based on the given material type, specimen condition, and test temperature.
    • Engineers use the measured longitudinal volume-resistivity values to characterize and compare extruded crosslinked and thermoplastic semiconducting conductor and insulation shielding materials for wire and cable applications. 

    Link to ASTM D6095

    FAQ

    Why is ASTM D6095 important?
    Semiconducting shields control the electric field and provide stress relief between the conductor and insulation in power cables. Volume resistivity is an important factor in field-stress distribution and cable performance. Standardized testing guarantees consistency of the product.
    ASTM D6095 is a test for determining the longitudinal volume resistance of semiconducting shielding materials in units of ohm-centimeters (Ω·cm). This value reflects the properties of the material in the direction of the extrusion.
    The test specimen is straight-sided, clean, and parallel-sided. It employs a four-electrode system with a 50 mm distance between potential electrodes and 1 inch between current electrodes. Resistivity is calculated from the cross-sectional area and length of the specimen between the electrodes.
    Dr Ruchika Yogesh
    About Author
    Dr Ruchika Yogesh
    Dr. Ruchika Yogesh is an entrepreneur, science and AI/ML enthusiast, medicinal chemistry subject matter expert (SME), scientific/medical copyeditor, and an independent researcher.
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