The Evaluation of Rheological Properties of Composites Reinforced with Hemp, Subjected to Photo and Thermal Degradation

Abstract

The cars of the future are designed so that to replace partial or total the fossil fuels. For this reason, the structural modifications of the materials used in the cars structure are researched being studied the lightweight materials, ecological and environmentally friendly, reusable and with improved performance in terms of mechanical strength (static and dynamic), thermal insulation and acoustic, with interface aesthetic. The paper aims to assess the structural modifications and visco-elastic properties of the composites reinforced with hemp mat subjected to artificial aging by exposure to UV radiation. Thus, samples having a percentage of reinforcing fiber hemp about 50 % were subjected to a dynamic mechanical analysis (DMA), being determined visco-elastic behavior at different frequencies loading. Then, samples were exposed for 168 h at the UV-A radiations, after that their rheological behavior was re-evaluated. In terms of structural and morphological changes, the samples were analyzed with the atomic force microscope (AFM) and method of contact angle both before and after accelerated aging. It was found that after UV radiation, on the surface of the composite structure reinforced with hemp mat occurred rearrangements of chemical chains and increases of the surface roughness.