INFRARED PHYSICS AND TECHNOLOGY, cilt.150, sa.105979, ss.1-13, 2025 (SCI-Expanded)
This study investigates the changes in mechanical properties (yellowing index and impact resistance) of different
polycarbonate (PC) greenhouse covering materials under natural aging conditions over 21 months. Materials
studied include UV additive PC (UV PC), UV and infrared additive PC (UV + IR PC), and Polyethylene (PE) with
CO-EX technology. A sloped roof structure with a 26.5◦ angle was used, and measurements were taken every
three months using a thermal camera to monitor aging, crystalline region changes, and reflectivity. The initial
yellowing index values were − 1.46 for UV PC, 4.41 for UV + IR PC and − 1.28 for PE. At completion of study,
yellowing index values were 18.4, 14.5 and 18.7, respectively. Initial impact resistance was 1203.4 g for UV PC
and 1162.5 g for UV + IR PC. After 21 months, UV PC showed a 20.3 % decrease in impact resistance, while UV
+ IR PC showed a 6.3 % increase. The results suggest that PE underwent aging, whereas UV PC and UV + IR PC
did not show significant aging. Thermal images revealed an inverse relationship between crystalline regions and
reflectivity. Overall, UV + IR PC exhibited the best performance, which is especially important for greenhouse
cultivation in regions like Antalya. The UV PC material completed 40.6 % of its expected service life.