| The repeatability and reproducibility of material data is important in order that the application of the material may be correct. In order to achieve this repeatability and reproducibility, it is necessary that the specimen preparation and testing parameters be kept the same each time a test is performed. The material, test, instrument and lab are variables that were examined in order to determine the instrument that exhibits the best repeatability and reproducibility. Modulus data, E{dollar}spprime{dollar} and G{dollar}spprime{dollar} (dynes/cm{dollar}sp2),{dollar} received from the American Cyanamid, BASF, Tupperware and UMASS-Lowell labs that participated in an ASTM Round Robin were evaluated for the repeatability and reproducibility among laboratories. Polycarbonate, polycarbonate (glass-reinforced), polypropylene, aluminum and brass were tested on the Rheometrics Mechanical Spectrometer: RMS-605 and System Four by the forced torsion test and the three-point bending test. Polycarbonate, polycarbonate (glass-reinforced), aluminum and brass were tested on the Inverted Torsion Pendulum. Tan delta data recorded and calculated from each instrument were compared for each material and instrument.; The Rheometrics Mechanical Spectrometer exhibited the best repeatability and reproducibility of data based on the above mentioned variables. The Inverted Torsion Pendulum measured the tan delta of material specimens from one to two orders of magnitude smaller than the Rheometrics Mechanical Spectrometer. Therefore the Inverted Torsion Pendulum exhibited the potential for greater sensitivity and responsiveness to morphological changes within a specimen. However, there was tremendous error within the apparatus due to the inability to regulate the parameters, frequency and heat, as accurately and precisely as possible.; It was recommended that the Inverted Torsion Pendulum regulate its testing parameters on a more automatic, computer driven interface, rather than the current manually initiated modes of developing the testing parameters and correlating the frequency, heating rate, and time of data retrieval. |
