scope:

Note: Nothing in this standard supersedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose.

Accurate and fast measure for degree of cure using thermal mechanical analysis intended for but not exclusive of ethylene acrylic (AEM), fluorocarbon (FKM), hydrogenated nitrile (HNBR), polyacrylate (ACM), and silicone (MVQ) elastomers. This procedure accommodates small to moderate size specimens with equipment available in most plant or independent test labs. As cure state increases, hysteresis decreases. Tan delta is a measure of hysteresis. As cure state increases, tan delta decreases (see 1.3.5). This procedure aids in the determination of optimum production part process conditions for new compounds; verification of process conditions for existing compounds; and problem solving (see 1.3). No other uses are intended or recommended.

Foreword.

This document describes a procedure for evaluating the state of cure of non post cured or post cured elastomers. For non post cured elastomers a rheometry curve (e.g. Moving Die Rheometer) of the compound under evaluation is generated. At points along the curve (t50, t70 and t90) specimens are removed and cooled to prevent further curing. Each t'x specimen is tested using Dynamic Mechanical Analysis to find the tan delta (d) value. The part specimen tan delta is measured and compared to the t'x values taken at controlled points on the cure curve. For post cured elastomers tan delta values are compared from known post cure conditioned specimen to verify if the unknown specimen was post cured. Also if the unknown was post cured for sufficient time at the correct temperature.

Applicability.

Test new, un-used or assembled parts not exposed to actual operating heat or fluids after assembly.

Parts from dyno durability, bench testing, field, warranty returns or consumer use are not to be evaluated.

The compound molder uses this procedure to set-up optimum production part cure conditions as a reference, process verification, or when required for problem solving.

This procedure is relevant if the Dynamic Mechanical Thermal Analysis (DMTA) data produced can discriminate between reference specimen cure conditions.

Some types and grades of polyacrylate (ACM) post cure specimens can exhibit chemical structure rearrangement ((low energy state) resulting in an increase in tan delta (decrease expected). This may imply a full post cure looks like a marginal press cure. If you see this post cure tan delta increase (see Table 1), avoid post cure testing of these types of ACM compounds.