Degradable materials are substances designed to break down into simpler forms, returning to the environment. This breakdown can occur through various processes, either natural or human-driven. The ability of a material to degrade means its chemical structure changes over time, often weakening it or altering its appearance.
How Materials Break Down
Materials can degrade through several distinct mechanisms. One common process is biodegradation, which involves microorganisms like bacteria and fungi consuming and breaking down organic matter. These microbes secrete enzymes that dismantle complex polymers into smaller, simpler compounds, eventually converting them into substances like water, carbon dioxide, or methane, depending on the presence of oxygen.
Another mechanism is photodegradation, where materials break down due to exposure to light, particularly ultraviolet (UV) radiation from the sun. UV light can initiate chemical reactions, such as oxidation, that alter the material’s structure, causing it to become brittle and fragment into smaller pieces. This process often leads to the incorporation of oxygen molecules into the material, especially in polymers like polystyrene.
Chemical degradation involves reactions with chemical agents in the environment, such as water or oxygen. Hydrolysis, for example, is a chemical reaction where water molecules break down chemical bonds within a material, often seen in the degradation of polyesters or polyamides in moist conditions. Oxidation, another form of chemical degradation, involves reactions with oxygen or other oxidizing agents, leading to changes in the material’s molecular weight and properties, as observed in the rusting of iron or the breakdown of rubber. These chemical reactions can be influenced by factors like temperature and pH.
Clarifying Similar Terms
The terms “degradable,” “biodegradable,” and “compostable” are often used interchangeably, leading to confusion, but they have distinct meanings. “Degradable” is a general term indicating that a material can break down. This breakdown might be due to various factors like UV light or chemical reactions, and it does not specify what the material breaks down into or how long it takes. For example, some degradable plastics might break into smaller fragments but still remain as microplastics.
“Biodegradable” refers specifically to materials that break down through the action of living organisms, such as bacteria and fungi, into natural components like water, carbon dioxide, and biomass. While all biodegradable materials are degradable, not all degradable materials are biodegradable, as some may break down through non-biological processes. The rate of biodegradation can vary greatly and is influenced by environmental conditions.
“Compostable” is a more specific term, indicating that a material will biodegrade under specific composting conditions, typically within a defined timeframe, and without leaving behind toxic residues. Compostable materials break down into natural elements and often contribute nutrients to the soil, producing humus. All compostable materials are biodegradable, but they require a controlled environment with specific temperatures, humidity, and microbial activity to fully break down into beneficial compost. For instance, a certified compostable item is tested to break down completely within 90 days in a commercial composting facility.
Why Degradable Materials Matter
Degradable materials offer environmental advantages by reducing waste accumulation. They break down into natural, basic components such as carbon dioxide, water, and biomass, lessening the burden on landfills. This contrasts with conventional materials that persist in the environment for extended periods, contributing to long-term pollution, particularly plastic pollution. The production of degradable materials often generates fewer carbon emissions compared to traditional manufacturing processes.
These materials also play a role in resource recovery and mitigating environmental impact. By decomposing, they can prevent the saturation of landfills and reduce the release of harmful substances into ecosystems. For instance, biodegradable materials can help reduce methane emissions from landfills when disposed of properly.
Degradable materials are finding increasing applications across various industries. In packaging, they offer alternatives to traditional plastics for items like food containers and films. In agriculture, they are used for products such as films that can degrade in the soil, eliminating the need for removal. The medical field also utilizes biodegradable polymers for temporary implants, surgical sutures, and controlled drug delivery systems, where the material needs to break down safely within the body over time.