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D5095-91 – Standard Test Method Technical Guide
📐 Apparatus and Reagents
The standard specifies the use of aluminum dishes with dimensions of 58 mm in diameter and 18 mm in height, featuring a smooth planar bottom surface. These dishes must be preconditioned for 30 minutes in an oven set at 110 ± 5 °C and stored in a desiccator prior to use to ensure accuracy. A forced draft oven conforming to Specification E145, Type IIA or IIB, is required for consistent heating. For precise liquid handling, 1 mL and 5 mL syringes are specified. An analytical balance capable of weighing to 0.1 mg is crucial for exact measurements.
Reagents include p-toluenesulfonic acid monohydrate as the catalyst, technical grade ethanol or isopropanol as the solvent, and reagent water as defined by Type IV of Specification D1193. The purity of water is critical unless otherwise indicated.
| 🟦 Apparatus | 📏 Specification |
|---|---|
| Aluminum Dish | 58 mm diameter × 18 mm height |
| Forced Draft Oven | Type IIA or IIB per E145, 110 ± 5 °C |
| Syringes | 1 mL and 5 mL |
| Analytical Balance | 0.1 mg sensitivity |
⚙️ Test Procedure and Conditions
The test procedure begins by weighing a designated quantity of test material into a preconditioned aluminum dish containing the catalyst solution. The mixture is thoroughly mixed and then allowed to stand at room temperature for 60 minutes. Subsequently, it is placed in the forced draft oven at 110 ± 5 °C for 60 minutes. After heating, the nonvolatile content is calculated by subtracting the solids contribution from the catalyst solution from the total solids of the test solution.
| 📐 Step | 🎯 Condition |
|---|---|
| Standing Time | 60 min at room temperature |
| Heating Time | 60 min at 110 ± 5 °C |
| Dish Preconditioning | 30 min at 110 ± 5 °C |
Tip: Always use a desiccator for storing preconditioned dishes to prevent moisture gain, which can affect weight measurements.
📊 Significance and Applications
This test method is vital for determining the nonvolatile content in silanes, siloxanes, and silane-siloxane blends for masonry water repellent treatments. The nonvolatile content (Ns) is calculated by subtracting the catalyst solution solids from the total solids weight. This metric is directly used to compute the volatile organic compound (VOC) content, which is regulated for environmental compliance. The method supports both solvent-based and water-based formulations, ensuring versatility in quality control and research applications.
Warning: p-Toluenesulfonic acid monohydrate is corrosive. Handle with care using appropriate safety equipment as detailed in Section 7 of the standard.
❓ Frequently Asked Questions
🔍 What is the scope of this test method?
It covers the determination of nonvolatile content in silanes, siloxanes, and their blends for masonry water repellents, applicable to solvent- and water-borne materials.
💡 Why is the catalyst solution used?
The catalyst solution with p-toluenesulfonic acid is necessary to promote the reaction and ensure accurate separation of nonvolatile components.
⚡ How are the results utilized?
The nonvolatile content is used to calculate the VOC content of the materials, which is important for environmental and regulatory purposes.
📌 What are the key temperature requirements?
Dishes are preconditioned and dried at 110 ± 5 °C, and the test material is heated at the same temperature for 60 minutes.