LIMITATION OF POLYURETHANE FOAMS
Polyurethane are commonly used in a wide variety of applications in modern life. Some of their applications include building insulation, furniture and beddings, footwear, automotive due to their versatile applications ease of implementation. Despite these advantages, polyurethanes also have some disadvantages.
Durability
Short life is a major disadvantage of polyurethane products. Polyurethanes have hydroscopic tendencies, i.e. water absorption characteristics. Mattresses made from polyurethane foams absorb water and gradually disintegrate and lose their quality of support. Polyurethane adhesives and sealants have the same problem. In addition, the durability of polyurethane paints is adversely affected when exposed to direct sunlight or organic solvents.
Odour
Polyurethanes emit odours and fumes, though they are not that highly noticeable. The petroleum-based chemicals and flame retardant fumes cause physical pains, especially in case of mattresses and paints, this becomes irritating. Prolonged exposure to this smell may make people ill. Woodworkers who use polyurethane finish also encounter overwhelming fumes.
Health Problems
Polyurethanes are widely used in many applications like building insulations, footwear and paints. Energy research shows that polyurethanes release toxic fumes that are not healthy to inhale. People who are over-exposed to polyurethane fumes experience health problems including allergic reactions, rashes, difficulty in breathing, loss of consciousness and even blindness. If your eyes or skin come in contact with polyurethane foams, clean and rinse them thoroughly to avoid health problems.
Environmental Issues
Polyurethane foam emits toxic fumes if burned. Some blowing agents in polyurethanes produce greenhouse gases that have negative effects on the atmosphere. Some polyurethane foams contain non-renewable fossil fuels that adversely affects the environment. Though polyurethanes are not toxic as many other chemicals, they still harm the environment.
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APPLICATIONS OF POLYURETHANE FOAMS
The greatest advantage offered by polyurethane foams is their versatility both in finished product properties and ease of production. By proper choice of isocyanate and polyol, products can be made with properties ranging from the downy softness of very low density foams to high strength of elastomeric bubble -free castings.
“Technological” approach was taken in the past in developing processing techniques, but it is also largely due to the complete nature of these materials. Many advances have occurred in the collective knowledge of how morphology develops based on formulation and this has led to a better understanding of how these various structures lead to properties. However, new application continue to develop challenging existing knowledge of structure, property relationship and demanding better explanations. This is particularly true where formulations need to be altered to meet more rigorous performance criteria.(NIS 295 1993)
The major uses of polyester polyurethane foams includes
– Lagging of stem pipes as insulation
– Manufacture of carpet backings
– Building of cold rooms for preservation
– Partitioning of offices and rooms
– Uses as specialized limitation
– Making of acoustic devices dices to its open cell structure
