Increasing concern for reducing the weight of aircraft and aerospace components has led to the use of environmentally friendly composite materials. These materials can be recycled as they are manufactured using either natural fibers reinforcement or natural matrix, or sometimes both. However, synthetic materials cannot be recycled. This transition to sustainable materials is essential to reduce the carbon footprint in the world. Environmentally friendly materials are known to have less negative impact on the atmosphere and the environment. Thus, the study of their durability is of great interest, especially under environmental conditions (moisture, UV, thermal oxidation, etc.) and mechanical loads. This chapter is dedicated to the study of next generation polymer composites for aerospace applications. The aim is to propose a comprehensive experimental approach with the aim of understanding all the physical phenomena induced by aging and involved in damage and fracture mechanisms. To fully utilize these materials, it is essential to understand the relationships between microstructure(s) and macroscopic properties. Therefore, this study focuses primarily on the mastery of scale transitions. Subsequently, multi-scale experimental approaches are proposed with the aim of developing micromechanical models that can be used to predict the life-cycle behavior and damage of composite materials. The influence of aging phenomena on the deformation and damage mechanisms of materials will also be addressed.