Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D1239-22 – Standard Test Method Technical Guide
📐 Standard Scope and Test Significance
This test method, designated D1239 – 22a, establishes a rapid empirical procedure for measuring the resistance of plastic films to extraction by chemicals. The fundamental metric derived is the weight loss of a film specimen after controlled immersion in a selected reagent. According to Terminology D883, a “film” is defined as sheeting with a nominal thickness not greater than 0.25 mm (0.010 in.). Intended to simulate real-world exposure, this test specifically evaluates the loss of plasticizers or other extractable components when the film comes into contact with liquids commonly found in households (Section 4.1).
Values are expressed in SI units as the standard, with other units provided for reference only. The method references related ASTM standards, including D543 (Practices for Evaluating the Resistance of Plastics to Chemical Reagents) for supplementary reagents and procedures.
🧪 Specimen Geometry, Reagents, and Apparatus
Consistency is maintained through strict specifications for the test specimens, reagents, and equipment. Specimens must be cut into precise squares of 50 ± 0.25 mm (2 in.) on each side. A minimum of three specimens must be tested for each sample and each chemical reagent combination to ensure reliable data.
Reagent Specifications
| 🟦 Reagent | 📐 Specification & Preparation |
|---|---|
| Distilled Water | Freshly prepared distilled or deionized water. |
| Soap Solution (1%) | 12 g of dehydrated pure white soap flakes dissolved in 1200 mL of distilled water. |
| Cottonseed Oil | Standard household cooking grade. |
| Mineral Oil (USP Heavy) | Specific gravity between 0.875 and 0.905. |
| Kerosine | As specified in the standard materials list. |
| Ethyl Alcohol (50%) | Prepared in accordance with Test Method D543. |
Critical Apparatus Requirements
| 🛠️ Apparatus | ⚡ Key Specification |
|---|---|
| Analytical Balance | Capable of weighing to 0.0001 g. (See Warning Note below for allowable exceptions). |
| Test Containers | Diameter of at least 65 mm (2.5 in.) with a minimum volume to hold one specimen plus 400 mL of solvent. |
⚠️ Balance Sensitivity Allowance (Note 3): An analytical balance capable of weighing to 0.001 g can be used when the specimen thickness is greater than 0.05 mm (0.002 in.) AND the extracted weight loss exceeds 0.005 g. Always verify the specific conditions of your test before opting for a lower precision balance.
💡 Practical Application: As stated in Section 4.1, this method is a rapid empirical test. It is not a replacement for long-term immersion studies but is highly effective for comparative quality control and assessing the immediate susceptibility of a plastic film formulation to extraction by specific household chemicals.
❓ Frequently Asked Questions
🔍 What is the primary purpose of the D1239-22 test?
The test method measures the weight loss of a plastic film specimen after immersion in a chemical. It serves as a rapid empirical test to determine the resistance of plastic films to extraction, specifically focusing on the loss of plasticizers or other extractable components.
💡 What are the exact dimensions required for the test specimen?
The test specimens must be squares measuring 50 mm ± 0.25 mm (approximately 2 inches) on each side. The film itself must have a nominal thickness not greater than 0.25 mm (0.010 in.) to qualify under the standard.
⚡ When can a less sensitive analytical balance (0.001 g) be used?
Per Note 3, a balance with 0.001 g sensitivity is permissible only when both conditions are met: the specimen thickness is greater than 0.05 mm, and the measured weight loss extracted from the specimen exceeds 0.005 g.
📌 How many specimens are required for a valid statistical test?
A minimum of three specimens of each sample must be tested with each chemical reagent to provide a statistically relevant average for the extraction resistance measurement.