Bio-based plastics are derived from sources such as algae, microbes, and plants, as opposed to conventional plastics which are based on fossil fuels. These bio-based plastics are still chemically identical to regular plastic and don’t necessarily biodegrade at all. It is just that they are using plants as a source of carbon instead of petroleum.
Not necessarily bio-based; a plastic that can be broken down by the action of living organisms into simple chemical constituents, such as carbon dioxide, methane, and water, does not speak to the quality or environmental fitness of the degraded material. There is no time restriction on how long it must take to biodegrade, or what the environmental conditions must be. This is a loose definition. What is known, however, is that biodegradable plastics will not biodegrade in the ocean – it is too cold.
Not necessarily bio-based; breaks down into organic material suitable for plant growth, cannot leave toxic residues. Require very specific conditions (high heat, lots of oxygen, specific microbes) that are only found in industrial composters, not in backyard composts. Most of industrial compost facilities don’t compost long enough for the compostable plastics to actually compost at all. Eventually, these plastics are sent to the landfill, where they definitely won’t compost
Plastics that contain additives known as pro-oxidants, typically metal salts, that are designed to accelerate degradation without any help from microbes. Not allowed in compost bins. Basically just become microplastics faster than regular plastic.