MEASURING EFFECTS OF SPECIMEN THICKNESS IN AN ENCAPSULATED SPECIMEN RHEOMETER

摘要

An Encapsulated Specimen Rheometer (ESR) is regularly used by AvPro for studying viscoelastic behavior of composite systems during and after reaching the gel point. The ESR design is such that a single specimen can be tested throughout all stages of cure with no need to change fixtures or even load new tests. Each test specimen is entirely captured within the test chamber with negligible amounts of resin bleed out. Consequently, it is important to understand the effects on the data results of under or overloading the instrument test chamber. A study was conducted on a commercial carbon fiber reinforced prepreg where in several specimen of various ply counts were tested in the rheometer under identical conditions. Each specimen's target weight was determined by calculating the "theoretical" specimen weight for the given volume and given densities, then deviating from this weight. The results of these tests were compared in order to demonstrate the tolerance in specimen thickness in the ESR. Using these results, the level of importance in exactly filling the instrument platen gap can be determined.