EFFECT OF ULTRAVIOLET RADIATION ON THERMAL INSULATION OF NATURAL COMPOSITE MATERIALS

الملخص

Thermal conductivity and performance of the natural composite materials as thermal insulators after exposure to ultraviolet radiation effect are investigated. An accelerated weathering chamber has been manufactured to investigate the ultraviolet radiation effect on composite materials. The composite materials were prepared of polyester resin which was reinforced with fiberglass, jute, and eggshell powder. The experimental work has been divided into two parts. The first part studies the effect of ultraviolet radiation on the thermal conductivity of the composite materials with different volume fractions (20%, 40%, and 60%) using Lee's disc method. The second part deals with manufacturing three test chambers (reference chamber, unaffected chamber, and affected chamber) with dimensions of (50×50×50cm). These chambers are used to investigate the performance of composite materials, with specimens dimensions of (50×50cm) and 4mm thickness for volume fractions of (30% and 60%), as thermal insulators after weathering with ultraviolet radiation. Experimental results indicate that cladding the external wall of the chamber with affected or unaffected composite materials gives lower temperature distribution inside the chamber throughout the day than without cladding. The thermal conductivity of fiberglass and eggshell composite materials with ultraviolet radiation effect is higher than that without ultraviolet radiation effect. While the thermal conductivity of jute composite material decreases after exposure to ultraviolet effect Jute composite material gives a higher temperature reduction of (19%) compared with fiberglass composite material (10%) and eggshell composite material (9%).