Polyvinyl alcohol (PVA) fibers, unlike glass fibers or carbon fibers, are water-soluble and typically do not maintain their structural integrity when exposed to water or moisture. This means that PVA fibers can break down and dissolve when mixed with water or immersed in a moist environment.

In contrast, glass fibers and carbon fibers are known for their high strength and resistance to degradation when exposed to water or moisture. They are commonly used as reinforcement materials in various composite applications, including construction, aerospace, and automotive industries, where their mechanical properties are essential.

PVA fibers, on the other hand, are often used in applications where temporary reinforcement is required, such as in concrete mixes to provide initial strength before they dissolve upon exposure to water, leaving behind voids that can improve the concrete's toughness and durability. They are also used in applications like water-soluble packaging and medical products where their ability to dissolve in water is a desirable characteristic.

So, to directly answer your question, yes, PVA fibers will break down and dissolve when mixed with water, unlike glass fibers or carbon fibers which are designed to maintain their structural integrity in such environments.