Biodegradable polymer which, edible films have gained more attention due to their environmentally-friendly characteristics, vast variety and availability, non-toxicity, and low cost. Biodegradable polymers have a long history, and since many are natural products, the precise timeline of their discovery and use cannot be accurately traced. One of the first medicinal uses of a biodegradable polymer was the catgut suture, which dates back to at least 100 AD. The first catgut sutures were made from the intestines of sheep, but modern catgut sutures are made from purified collagen extracted from the small intestines of cattle, sheep, or goats. The concept of synthetic
Catgut as withstanding high tension within low alto, tenor, and high-bass ranges. Many acoustic guitarists moved away from gut strings in the early 1900s when the C. F. Martin & Company introduced steel strings, which gave greater volume to the guitar. "The demand for steel came from ensemble players, who couldn't make themselves heard clearly without it." Within a few years the majority of Martin guitars were made with steel strings to accommodate the demand. After World War II, most classical and flamenco guitarists switched from catgut to the new nylon strings for their greater smoothness, durability, and stability of intonation.