Abstract: The seed fibers or comas of Asclepias Syriaca, also known as milkweed floss, distinguish themselves from other natural fibers due to their gloss, softness, and hollow structure. Their abundance and unique microstructure suggest that these fibers could serve as sustainable and lightweight materials for various applications, including clothing, construction, thermal insulation, polymer reinforcement, water treatment, and oil absorption. With these potential applications in mind, this research study aimed to characterize and understand the properties of milkweed floss, as well as explore its prospective uses as a sustainable material for developing thermo-acoustic insulation systems and lightweight reinforced thermosetting matrices. To fully understand the advantages and potential applications of milkweed floss in insulation and polymer reinforcement, the first part of the project was focused on evaluating the microstructure, thermo-acoustic insulating properties, and mechanical and thermal resistances of the fibers. Additionally, a portion of the fibers was treated with acetone, and their properties were measured to analyze the effect of this treatment. Milkweed floss exhibited an average elastic modulus of 3.0 GPa, a thermal resistance comparable to that of other natural fibers, and superior thermo-acoustic insulation capacity than a traditional insulator such as expanded polystyrene. It was observed that the acetone treatment had no impact on the microstructure or acoustic insulation capacity of the fibers. The acetone treatment improved the thermal resistance and thermal conductivity of the fibers but decreased their elastic modulus. The second part of the project comprised the study of the combined effect of temperature, relative humidity, and fiber content on the specific heat capacity of milkweed floss, as well as the thermal conductivity and thermal diffusivity of nonwoven mats made of milkweed floss. The specific heat capacity of milkweed and thermal conductivity of the nonwovens increased with ...