A: Compostable biodegradable materials fall into two categories, one being bio-based compostable materials and the other being petroleum-based compostable materials. The bio-based compostable material is further divided into materials directly derived from plants, such as pulp, polylactic acid (PLA), aliphatic polyester (PHA), and blends of natural materials with the above two types of polymers. Petroleum-based compostable materials derived from petroleum, such as polybutylene terephthalate (PBAT), polyethylene glycol (PCL) etc.