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D6269-98 – Standard Test Method Technical Guide
🧪 Method Overview and Context
ASTM D6269-98 outlines a precise test method for determining the solidification point of p-Xylene, specifically for samples with a purity greater than 99.5%. This measurement is critical for quality assurance in the production of aromatic hydrocarbons. According to the standard, the test is used for process control during manufacturing, developing product specifications, and identifying contamination introduced during shipment.
💡 Editor’s Note: This standard has an editorial revision (D 6269 – 98e1) which added RR: D16–1027 in March 2002. The jurisdiction is held by ASTM Committee D16 on Aromatic Hydrocarbons and Related Chemicals.
The standard defines the solidification point as the temperature at which the liquid phase is in approximate equilibrium with a small portion of the solid phase. This definition specifically distinguishes the solidification point from the freezing point, as further explored in Test Methods D 1015 and D 1016.
⚙️ Apparatus Specifications and Test Procedure
The procedure requires drying the p-xylene using a 3A molecular sieve to achieve an anhydrous state. The dried sample is then placed in a thick-walled test tube of specified dimensions (18 mm OD, 14 mm ID, 150 mm length). The test is conducted in a temperature bath controlled at 10 ± 1 °C