دراسة الخواص الحرارية والميكانيكية للمادة المركبة (قش القمح _ بولي استر غير المشبع) لاستخدامها كعازل حراري في المنشآت الزراعية

Abstract

In this research the thermal and mechanical properties such as (thermal conductivity, compressive strength, impact resistance, density, moisture absorption) of wheat straw pieces prepared by compressing dried straw and adding a binding material (unsaturated polyester), and pressing them with a press at different pressures to reach the final shape of the pieces, then wrapping hem with a packaging rolls (polyolefin bags) to increase the safety factor from external factors, then two samples were taken with different thicknesses, the first sample with a thickness of (4cm), and the second sample with a thickness of (2cm), and there properties were studied as a good insulating material in maintaining the appropriate conditions inside agricultural facilities. Experiments showed that the prepared sample with thickness (4cm) gave the lowest thermal conductivity value of (0.347 w\m.cͦ) the highest compressive strength in both horizontal and vertical directions, the highest impact resistance, a moisture content lower by (42.24%),  and lower density compared to the sample with thickness (2cm). This is due to the increased  in straw fibers, the density and cohesion of the material,and the homogeneous distribution of the material, which hinders the growth and spread of cracks and leads to the tight filling of the interstitial spaces. It was also observed that the resistance of the sample subjected to vertical pressure decreases more than that of the horizontal sample. As the sample cross-section is smaller and more responsive to the cracking boundaries and propagation, due to the reduced number of load-bearing fibers and the reduced bonding forces between them.