ASTM D707-15 pdf download.Standard Classification System and Basis for Specification for Cellulose Acetate Butyrate Molding and Extrusion Compounds (CAB).
6. Materials and Manufacture
6.1 Materials supplied in these forms shall be as uniform in composition and size, and as free of contamination as can be achieved by good manufacturing practice.
6.2 If these materials contain colorants in the nominal amounts ordinarily employed, such additives shall not alter the ability of the materials to meet the specified properties.
6.3 The color of material supplied shall be comparable, within commercial match tolerances, to the color of standard samples prepared by the manufacturer.
7. Physical Requirements
7.1 Test specimens of the material shall conform to the requirements prescribed in Table CAB.
7.2 Molded specimens, for those tests requiring them, shall be prepared in accordance with Section 10. 7.3 Conformance to the requirements of this classification system shall be determined in accordance with Section 11.
8. Sampling
8.1 Sampling shall be statistically adequate to satisfy the requirements of 12.4.
8.2 A batch or lot shall be constituted as a unit of manufac- ture as prepared for shipment and can consist of a blend of two or more “production runs.”
9. Number of Tests
9.1 Routine testing of each batch or lot shall be limited to properties designated in Table CAB of this classification system.
9.2 One set of samples for those tests that are designated (Section 12) shall be considered sufficient for testing the batch or lot. The average results from those samples shall comply with the requirements prescribed in this classification system.
10. Specimen Preparation
10.1 Physical property requirements in Table CAB are based on injection-molded specimens 3.2 mm thick. Specimens machined from compression-molded blanks or extruded strips can be used, provided it can be shown that the results are comparable.
10.2 Prior to molding cellulose acetate butyrate, dry the material to a moisture content of 0.2 % or less. The primary reason for drying the material is to eliminate visual defects such as surface imperfections and bubbles. Material spread in a tray to a maximum depth of 50 mm and exposed in a circulating-air oven at 75 to 90°C for 3 h is recommended. Formulations containing either very low or very high levels of plasticizer can require slightly higher or lower drying tempera- tures respectively. Control the injection molding cycles in accordance with Practice D3641, using a material temperature of 25 to 35°C above the “cold point.” (The “cold point” is the lowest material temperature at which it is possible to obtain a full shot when all other operating variables are held constant within the normal operating range.) Mold temperatures be- tween 35 and 60°C have been found desirable. As a rule, thin-section moldings and higher hardness materials (lower plasticizer content) require higher mold temperatures.
10.3 Test specimens injection molded from cellulosic ma- terials are subject to “overpacking” if the gate size is too large, and this can result in brittleness in the gate area as well as throughout the entire specimen. A gate size 1.5 mm square has been found to produce satisfactory test specimens.ASTM D707 pdf download.