Development of an ASTM draft standard for the elevated temperature moisture conditioning of pultruded fiber reinforced polymer composites

The objective of this study was to develop a new ASTM standard for the elevated temperature moisture conditioning of pultruded fiber reinforced polymer composites. The proposed standard was developed through a combination of a robust literature review of the many experimental methodologies that have been employed in the past by researchers while investigating the many effects of environmental factors on fiber reinforced polymer composites in general and performing the elevated temperature moisture conditioning of a pultruded composite with subsequent mechanical testing.;A commercially pultruded fiber reinforced polymer composite was used for the experiments. The composite was machined into recommended shapes and sizes as specified in relevant ASTM standards, depending on what type of test to be carried out after its conditioning. For conditioning, samples were submerged in distilled water held at 100 +/-3°F and mechanically tested after immersion periods of 250, 500, 750, 1000, 1250 and 1500 hours. Both tensile and compression tests were carried out after the conditioning. Samples were also weighed daily for a given time period to establish a moisture gain profile of the composite. A decrease in tensile strength was observed for tensile test samples corresponding to increase in conditioning time following predictions of previous research. Compressive strength of the samples fluctuated after an initial decrease in strength. A regression analysis carried out on the strength data indicated a further decrease is expected in the tensile strength with increased immersion times indicating a progressive degradation while the regression analysis on the compressive strength data showed a poor fit to the available data. The moisture gain profile of the composite followed a Fickian distribution and displayed a saturated phase after 30 days of immersion.;Based on both experimental methodology of this study and an introduction of standard conditioning practices with a few tweaks, a draft standard was proposed for use in the conditioning of pultruded fiber reinforced polymer composites at elevated temperature and moisture exposure, and ensuing testing. It is expected that the proposed standard arising from this study will be presented to the appropriate ASTM committee responsible for the approval of draft standards for pultruded composites.