Why is fiber glass good material for a Thermos?

Fiberglass is an Excellent material for a Thermos because it has low thermal conductivity, which helps to maintain temperature by minimizing heat transfer. Additionally, it is lightweight yet durable, making it easy to carry while providing resistance to impacts. Fiberglass also does not corrode or react with beverages, ensuring that the contents remain safe and untainted. These properties make it an ideal choice for efficient thermal insulation in portable containers.