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D1076-23 – Standard Test Method Technical Guide
📜 Scope and Categories of D1076–23
ASTM D1076-23, under the jurisdiction of Committee D11 on Rubber and Rubber-like Materials, provides the specification for five categories of first-grade concentrated natural rubber latex. This standard, originally approved in 1949 and updated in 2023, covers latices stabilized and preserved by specific means, including ammonia stabilization and centrifugation or creaming processes.
The material is required to be processed in accordance with best commercial practice and must be of uniform composition (Section 3.1). The specification defines distinct categories for Hevea brasiliensis latex, guayule latex, and other natural rubber sources, with strict purity and stabilization requirements.
| 🟦 Category | 📏 Description (Section 1.1) | ⚙️ Stabilization | 🎯 Specific Requirement |
|---|---|---|---|
| 1 | Centrifuged Hevea natural latex | Ammonia only | Standard first-grade specification |
| 2 | Creamed Hevea natural latex | Ammonia only | Standard first-grade specification |
| 3 | Centrifuged Hevea natural latex | Low ammonia | Low-ammonia preservation |
| 4 | Centrifuged/creamed guayule or other NR latex | Ammonia or other hydroxide | < 200 µg total protein per g dry weight |
| 5 | Centrifuged Hevea latex treated with Al(OH)₃ | Ammonia only | < 0.5% non-rubber content |
Important Applicability Note: This specification does not apply to compounded latex concentrates or latices prepared by other stabilization methods (Section 1.2). Category 4 explicitly extends to guayule and other natural rubber latex sources containing less than 200 µg total protein per gram dry weight.
⚙️ Key Test Methods and Analytical Procedures
D1076-23 prescribes a comprehensive set of analytical procedures ranging from Sections 6 through 48 to verify conformity. The required tests cover physical, chemical, and stability properties of the latex concentrate. Precision for all test methods is addressed in Section 48, and the values stated in SI units are regarded as the standard (Section 1.4).
| 📏 Test Property | ⚡ Reference Sections | 🎯 Key Purpose / Note |
|---|---|---|
| Sampling | 6 – 7 | Guidelines for obtaining representative test samples |
| Total Solids | 8 – 17 | Quantifies total non-volatile content |
| Dry Rubber Content | 18 | Direct measurement of rubber hydrocarbon |
| Protein Content | 19 | Measures total protein in the latex |
| pH | 25 | Measured per Test Method E70 |
| Mechanical Stability | 26 | Resistance to coagulation under shear force |
| Volatile Fatty Acids (VFA) | 41 – 45 | Indicator of latex quality and preservation state |
| Copper & Manganese | 27 | Trace metal analysis per Test Methods D1278 |
| KOH Number | 24 | Measures acid components in the latex serum |
Technical Tip: The test methods listed in Section 1.3 also integrate standards from D1278 (Chemical Analysis), D4483 (Precision Evaluation), D5712 (Aqueous Extractable Protein), and D6499 (Antigenic Protein). Reference to these documents is essential for complete compliance with the specification.
❓ Frequently Asked Questions
🔍 What latices does ASTM D1076–23 cover?
It covers five categories of first-grade concentrated natural rubber latex from Hevea brasiliensis and other sources like guayule. The categories depend on the concentration method (centrifuged, creamed), stabilization type (ammonia, low ammonia, hydroxide), and specific purity requirements such as protein and non-rubber content.
💡 What are the specific purity requirements for Category 4 and Category 5 latices?
Category 4 latex must contain less than 200 micrograms of total protein per gram of dry weight. Category 5 latex must contain less than 0.5% non-rubber content and is typically treated with aluminum hydroxide or equivalent means.
⚡ Does D1076-23 apply to compounded latex concentrates?
No. Section 1.2 explicitly states that the specification shall not be construed as limiting the desirability of other categories of latices and does not apply to compounded latex concentrates. It applies strictly to the specific concentrated natural latices defined in Section 1.1.
📌 Which referenced standards are critical for chemical analysis?
Key referenced standards include ASTM D1278 for rubber chemical analysis, ASTM E70 for pH measurement, ASTM D5712 and D6499 for protein analysis, and ASTM D4483 for evaluating precision of the test methods.