Analysis of Ageing Processes of Semi-Crystalline Materials

The article presents the influence of accelerated UV ageing on the structural properties of selected polymer materials. In this study, 3 types of materials from a group of thermoplastics known as PP30T, PE, POM were used. The test samples were prepared by injection moulding. In turn, an accelerated UV ageing process (600 h) was carried out in the UV Test chamber with fluorescent lamps characterized by a wavelength of 313 nm. Changes in the structure of the tested materials were observed by using an optical microscope. Measurements of gloss on the surface of primary samples that were exposed to UV rays were also taken. In addition, the structure of primary and aged samples was tested by differential scanning calorimetry (DSC). The conducted studies have demonstrated the impact of UV radiation on the changes in the surface layer of tested materials.

Performance Evaluation of Anti-Ultraviolet Ageing Bitumen with Combined Modification Based on Dynamic Rheological Test

Based on the rheological property master curve, a new definition of ageing index was proposed for styrene-butadiene-styrene block copolymer (SBS) modified bitumen. The UV ageing resistance of the combined-modifier modified SBS bitumen was evaluated. Twelve different methods of combined modification were designed with three kinds of modifiers: ultraviolet absorber (Tinuvin 770), organic montmorillonite (OMMT) and layered double hydroxide (LDHs). With modified SBS bitumen, short-term ageing (TFOT) and laboratory ultraviolet ageing (UV) were performed. The dynamic shear rheometer (DSR) was used to perform frequency sweep test on the samples before and after ageing. The rheological property master curve was obtained by fitting the constitutive model equation. Based on the rheological property master curve, a new definition ageing index was proposed for SBS bitumen to evaluate the modified bitumen with different combined-modifier. The results show that the ageing index could effectively evaluate the UV ageing resistance of SBS bitumen. The evaluation results show that the combined-modifier bitumen exhibits better anti-ultraviolet ageing effects than a single modifier. Among them, the combined-modifier modes of 0.3%Tinuvin770+5%OMMT and 0.6%Tinuvin770+2.5%LDHs performed.

Assessment on UV ageing of photopolymerizable resin repaired GFRPs for wind turbine blades

The photopolymerizable resin repair method was investigated for the high altitude location and harsh remediation condition of wind turbine blades, because of its short operation time and low equipment requirement. This paper demonstrates the durability under ultraviolet (UV) irradiation environment of a photo- or thermal-polymerizable resin repaired GFRP, which is the essential material for manufacturing wind turbine blades. During the experiments, the fundamental GFRP specimens fabricated by wet prepreg manufacture technique were pre-damaged, and then repaired by attaching external photo- or thermal-polymerizable resin-impregnated glass fabric patches, followed by UV curing and room temperature (RT) curing, respectively. Long-term UV ageing (over 1300 h) was conducted to repaired specimens by employing a 365 nm wavelength UV lamp. The mechanical properties, thermal properties and surface morphology were evaluated before and after ageing. The results revealed that the UV cured specimens have better mechanical properties and stability compared to RT cured specimens in UV ageing environments.