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D1601-18 – Standard Test Method Technical Guide
📘 Significance and Scope of ASTM D1601-18
This standard, issued under the fixed designation D1601, is under the jurisdiction of ASTM Committee D20 on Plastics and the direct responsibility of Subcommittee D20.70 on Analytical Methods. The current edition was approved in 2018. This test method covers the determination of the dilute solution viscosity of ethylene polymers at 135°C. It is applicable to a reasonably wide spectrum of ethylene polymers having densities from 0.910 to 0.970 g/cm³. Directions are given for the determination of relative viscosity (viscosity ratio), inherent viscosity (logarithmic viscosity number), and intrinsic viscosity (limiting viscosity number).
When used in conjunction with other flow and physical property values, the solution viscosity of ethylene polymers contributes significantly to characterizing the material. The values stated in SI units are to be regarded as the standard per IEEE/ASTM SI-10.
⚠️ Important Safety Notice: Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical issues. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for local regulations and safety information.
🧪 Test Method and Key Viscosity Measurements
The procedure requires dissolving the ethylene polymer at a precise concentration and measuring the flow time through a glass capillary viscometer at 135°C. The units, symbols, and abbreviations used in this test method are those recommended in IEEE/ASTM SI-10 and Terminologies D883 and D1600. The following parameters are central to the method:
| 🟦 Parameter | 📏 Historical Term | 📐 Description |
|---|---|---|
| Relative Viscosity | Viscosity Ratio | Ratio of the viscosity of the solution to the viscosity of the pure solvent. |
| Inherent Viscosity | Logarithmic Viscosity Number | Calculated as the natural logarithm of the relative viscosity divided by the concentration. |
| Intrinsic Viscosity | Limiting Viscosity Number | The limiting value of the reduced or inherent viscosity extrapolated to zero concentration. |
💡 International Alignment: ASTM D1601-18 is equivalent to ISO 1628-3. Additionally, Appendix X1 through Appendix X3 contain material from the previous version and are retained for informational purposes only.
🎯 Critical Precision: Kinematic viscosity is derived following Test Methods D445 and D446. Proper calibration and temperature control at 135°C are essential for accurate results.
📏 Referenced Documents and Standards
The execution of this standard requires familiarity with a number of other ASTM and ISO standards. Key references include:
| 📚 Standard | 🎯 Description / Relation |
|---|---|
| ASTM D445 / D446 | Test Method for Kinematic Viscosity / Specifications for Glass Capillary Viscometers |
| ASTM D4020 | Specification for Ultra-High-Molecular-Weight Polyethylene Molding and Extrusion Materials |
| ISO 1628-3 | Plastics—Determination of Viscosity Number and Limiting Viscosity Number |
| E2251 / E2935 | Specification for Liquid-in-Glass Thermometers / Practice for Equivalence Testing |
❓ Frequently Asked Questions
🔍 What is the density range for polymers tested in D1601-18?
The test method is applicable to a reasonably wide spectrum of ethylene polymers having densities from 0.910 to 0.970 g/cm³.
💡 What are the three main viscosity parameters determined by this method?
The standard provides directions for the determination of relative viscosity (viscosity ratio), inherent viscosity (logarithmic viscosity number), and intrinsic viscosity (limiting viscosity number).
⚡ At what temperature is the viscosity test performed?
The dilute solution viscosity is specifically determined at 135°C to ensure the polymer is fully dissolved and the solution is stable.
📌 How does ASTM D1601-18 relate to ISO standards?
This standard is equivalent to ISO 1628-3, which covers the determination of the viscosity number and limiting viscosity number of polyethylenes and polypropylenes in dilute solution.