Polyurethane Foam
Polyurethane Foam is a versatile material that can be used in a wide range of applications. It can be made to have almost any physical property imaginable through the use of additives and chemical reactions.
However, it’s important to understand the health and environmental concerns associated with this popular insulation material. This article will discuss some of the main ones.
Benzene
Polyurethane foam is a highly durable material that lasts for the entire lifetime of the product it’s contained within. Because of its longevity, it can help reduce fossil fuel consumption and greenhouse gas emissions by replacing disposable materials that need to be replaced frequently. When a consumer disposes of their foam mattress or car seat, the waste typically ends up landfilled or incinerated. If this material is collected and processed in a responsible manner, however, it can be recycled into new, high-quality foam products.
The production of polyurethane foam requires a variety of chemicals, including blowing agents, surfactants, additives, and catalysts. The primary compounds are polyols and diisocyanates, which react to form the polyurethane chain. A blowing agent generates gas to produce the foam’s cellular structure, while surfactants and additives provide additional properties that vary depending on the intended application.
In the past, polyurethane manufacturers used hydrochlorofluorocarbons such as CFC-11 (trichlorofluoromethane) as a blowing agent, but these chemicals were banned by the Montreal Protocol due to their ozone depletion potential. Today, manufacturers use water, pentane, methylene chloride hydrocarbons, and other zero-ozone depletion potential blends to produce polyurethane foam.
Rigid polyurethane foam is often installed in residential homes as insulation for doors, windows, and walls. Its superior thermal insulating qualities result from Polyurethane Foam the combination of its closed-cell foam structure and cell gases, which resist heat transfer. In addition, builders use a similar process to install rigid polyurethane foam in refrigerator and freezer thermal insulation systems.
Chemicals
Polyurethane Foam uses a wide variety of chemicals. This foam is sprayed by trained professionals, who take the necessary safety measures to ensure that they are not exposed to high concentrations of these chemicals. This is because when these liquid chemical components are mixed together, they can release dangerous vapors. This is why workers use protective clothing, masks, and air-driven systems to protect themselves from exposure.
The main chemicals used in the production of polyurethane are amines and isocyanates. These react to make long-chained polymers through a process called polyaddition polymerization, which creates a molecule with alcohol functional groups on one end and isocyanate functional groups on the other. This molecule then further reacts with other isocyanates and polyols to form the polyurethane. The process is made safer through the addition of surfactants and catalysts.
In order to form the cellular structure of the foam, it is treated with blowing agents that generate gas to make it expand and grow in size. Historically, CFC-11 or trichlorofluoromethane was the blowing agent of choice due to its low cost, appropriate boiling point, compatibility with polyurethane, and non-toxicity. However, since the 1987 international agreement to stop ozone depletion led to the ban of CFCs, other blowing agents are now used such as water, pentane, methylene chloride hydrocarbons, and halogen-free azeotropes.
Other auxiliary materials used in the manufacture of polyurethane include chain extenders and cross-linkers. These are low molecular weight hydroxyl and amine terminated compounds that help to control the properties of the polymer by adding functionality. They can be added in various proportions to the polyisocyanate and polyols in order to produce different densities and hardnesses of the polyurethane.
Health & Environmental Concerns
The chemicals used to make polyurethane foam are toxic and can have serious health effects. Exposure to these chemicals can lead to respiratory problems, headaches, skin rash and even cancer. Polyurethane foam can also release dangerous chemicals that cause damage to the environment. These chemicals are also a fire hazard and can pose risks to people and animals when burned. The flame retardant HBCD released by the foam can affect the survival and reproductive health of fish and algae. It can also harm the liver enzymes of birds and a variety of other animals.
Foam manufacturing plants often produce harmful vapors, aerosols and dusts. Workers need to wear chemical resistant gloves and eye protection. The Occupational Safety and Health Administration has safety guidelines for working with polyurethane. Workers should avoid cutting or trimming the foam until it has cured. Attempting to do this will generate dust that may contain unreacted isocyanates and other chemicals.
While polyurethane is not as environmentally friendly as some other materials, it does have one of the best recycling records in the industry. This is largely due to the fact that it can be recycled into the exact same product that it was originally made for. In addition, it does not require the use of new raw materials when recycled. This helps to limit waste in production.
Applications
Polyurethane foam is found in many different applications in our everyday lives. Its flexibility, resilience, durability and insulating characteristics are just some of the reasons it is used in such a variety of products. In our homes, flexible foam padding cushions carpeting, while reflective plastic coverings over rigid polyurethane foam in roofing can bounce sunlight and heat away from the house, keeping it cooler and cutting energy costs.
Rigid polyurethane foam is commonly installed in doors and garages to insulate them, as well as in walk-in refrigerators and SIPS (Structural Insulated Panels). It’s also commonly used to insulate appliances such as hot water heaters and ice machines.
The cellular structure of polyurethane foam is created by using blowing agents that generate gas to expand and create the foam. The first blowing agents were hydrochlorofluorocarbons such as CFC-11 and trichlorofluoromethane, which are now being Polyurethane Foam replaced with water, pentane, methylene chloride hydrocarbons, halogen free azeotropes and other zero ozone depletion potential blends.
The sprayed polyurethane foam is generally bonded to a nonwoven substrate or netting, or to a fabric. This is typically done through a process such as flame bonding, hot film or powder adhesive. The sprayed polyurethane foam has excellent resistance to atmospheric conditions such as rain, extreme temperatures and wind. It’s only attacked over time by long-term exposure to sunlight, which causes a dusty appearance on the surface of the foam.