نسترن رحيمي دولت ابادي

In recent years, the use of glass fiber reinforced polymer composites has increased across various industries such as construction, marine, and oil and petrochemicals due to their lightweight nature and high strength. These materials encounter diverse environmental conditions, including ultraviolet (UV) radiation and humidity, throughout their lifespan, which can significantly impact their mechanical properties and durability. While the individual effects of UV radiation and humidity have been studied, the combined effects of these two factors require further investigation. This research examines the combined impacts of UV radiation and humidity on the mechanical and structural properties of E-glass fiber reinforced polyester composites. Composites were fabricated using the pultrusion method and tested under three conditions over two time intervals: one group was exposed solely to UV radiation, another group underwent salt mist exposure only, and a third group was subjected to both conditions. Mechanical tests, including flexural and impact tests, as well as changes in weight and colorimetric analysis, were conducted. Data analysis and significance eva‎luation of environmental conditions' effects were performed using two-way ANOVA. Scanning electron microscopy and optical microscopy images were employed to investigate structural and surface changes. The results indicate that UV exposure increases moisture absorption. Mechanical tests revealed that samples subjected to UV radiation followed by salt mist exposure experienced the most significant reduction in both flexural and impact strength compared to the other groups. Additionally, mechanical properties notably decreased over time. Microscopic analyses demonstrated the degradation of the interfacial bonding between the fibers and resin after being subjected to combined environmental conditions, directly affecting mechanical properties. Furthermore, the results of the ANOVA confirmed the significant impact of time and combined environmental conditions on the reduction of flexural strength. Moreover, by correlating the exposure duration of the samples in the UV radiation apparatus to an approximate duration of one year in natural environmental conditions in the humid coastal areas of northern and southern Iran, the findings of this study could be applied to predict the properties of E-glass fiber reinforced polyester composites in the humid and coastal climates of Iran.

كامپوزيت‌هاي پليمري , خواص مكانيكي , تابش فرابنفش , رطوبت , شرايط محيطي

Polymer composites , Mechanical properties , UV radiation , Moisture , Environmental conditions

nastaran rahimi

alireza khavandi- seyed hossein seyedein