Investigation of the Sorption and Tensile Response of Pultruded E-Glass/Vinylester Composites Subjected to Hygrothermal Exposure and Sustained Strain

Abstract

The aim of the present research is to provide insights into the sorption behavior and degradation mechanisms of a unidirectional pultruded E-glass/vinylester composite subjected to synergistic hygrothermal exposure and sustained bending strain for exposure times of up to 2 years. Composite specimens were found to follow a Langmuir-type diffusion behavior in all environments, with departure from that behavior attributed either to material leaching-out, chemical breakdown, interfacial debonding, or central delamination. The composite tensile strength decreased with increasing immersion time and temperature, with high sustained strain levels having a more detrimental effect at elevated temperatures. The initial strength loss was associated with matrix plasticization, while later reductions were caused by the occurrence of mechanisms of fiber degradation and interfacial debonding. Changes in tensile strength were largely reversible as a result of immersion in deionized water at 22 °C, but the level of regain decreased substantially at higher immersion temperatures. Finally, failure by delamination was observed to occur in the most severe environments at strength retention levels dependent upon the amount of imposed bending strain.

Durability of bonded FRP-to-steel joints: Effects of moisture, de-icing salt solution, temperature and FRP type

“…In addition to the common susceptibility of resins to ageing, glass fibres (unlike carbon fibres) may also degrade in the presence of moisture with prolonged exposure. As a result, while the initial reduction in strength is believed to be a consequence of degrading resin and fibre/resin interface [35], its further reduction after 840 days can also be attributed to damaged glass fibres [36].…”

Moisture diffusion and hygrothermal aging of pultruded glass fiber reinforced polymer laminates in bridge application

“…For example, Helbling and Karbhari [15] investigated the degradation mechanisms of a unidirectional pultruded E-glass/vinylester composite subjected to synergistic hygrothermal exposure and sustained flexural strain for different exposure duration up to two years. Study results indicated that the hygrothermal behavior of the pultruded composite specimens evaluated followed a Langmuir-type diffusion behavior in different exposure environments.…”

Reliability Study on FRP Composites Exposed to Wet-Dry Cycles

“…When a sustained loading was applied simultaneously, the creep deformation increased the molecular spacing which makes water molecules and NaCl molecules more easily invaded adhesive, thus causing greater deterioration of the reliability and durability of the structural elements [19]. Helbling et al [20,21] reported that sustained bending strain had no influence on moisture uptake, but could cause severe fiber/matrix interfacial debonding, in addition to fiber pitting and cracking.…”