The modern construction market is ready to offer its consumers both materials with long-term use and a stable reputation, as well as a whole list of polymers that have come to the market not so long ago and are still gaining recognition from buyers. Polyurethane foam belongs to this group.
What is polyurethane foam?
This modern building material belongs to the group of gas-filled plastics. Polyurethane foam (PPU) consists of an inert gas phase by more than 85%. The scope of this material is wide and varied. However, the fierce debate over whether polyurethane foam is harmful to he alth has not subsided for many years. The most discussed from this point of view include the behavior of the material during combustion and the release of toxic components when heated.
History of appearance of the material
The date of birth of polyurethane foam can be safely called 1937, when a small group of scientists from a laboratory in Levenkusen synthesized a material with unusual properties. ATdepending on what was the mixing ratio of the components of the new material and how quickly the reaction took place, the properties of polyurethane foam were radically different. On the one hand, the material was elastic and flexible, but rather fragile to breaking loads. On the other hand, strength, hardness, density, but brittleness in bending. The material had extremely wide prospects, but the Second World War significantly slowed down their execution. However, since the 60s of the last century, the manufacture of PPU began to develop at a rapid pace.
Component composition of PPU
The main components that make up polyurethane foam and are necessary for the formation and attachment of polymer chains are polyol (component A) and polyisocyanate (component B). Sometimes domestic producers can add one more component to the polyol - a catalyst. The main components of polyurethane foam have a specific smell and are a liquid of a fairly thick consistency with shades from light yellow to dark brown.
Polyol tends to flake during long-term storage, so it is recommended to mix it before use. Polyisocyanate interacts with water - upon contact, crystallization begins. During long-term storage in the open air, a film forms on the surface of the material. According to its component composition, PPU can be of two types - for spraying and for pouring.
Biogenic properties
Polyols and polyisocyanates used in the production of PU foam areoil products. However, it is known that polyurethane foam components can also be produced from vegetable oils. The best option for this purpose is castor oil. The polyol component can also be obtained from sunflower, soybean, and rapeseed oils. However, the cost of this raw material is quite high and the production is not economically feasible. Biogenic PU foam materials are produced in small volumes and are used to solve very narrow specific tasks.
Properties of PPU
Polyurethane foam produced by domestic and foreign manufacturers has a number of both positive and negative characteristics.
Low thermal conductivity of the material (0.019 - 0.03 W/m), almost complete vapor permeability, water resistance make polyurethane foam an excellent heat and water insulator. The same can be said about soundproofing. The high adhesion coefficient makes it possible to apply PPU on almost any surface.
However, not only positive qualities are characterized by polyurethane foam. Harm to human he alth can be caused during the combustion of PPU (in the presence of a direct source of fire, the material burns). In addition, polyurethane foam releases toxic substances into the atmosphere - formaldehyde. Polyurethane foam, the components of which interact with air and water, is not resistant to sunlight. Over time, it darkens and falls off.
Scope of PPU
This modern building polymer has foundwide application in various fields of human activity. Its widest scope is in construction: thermal insulation, acoustic and waterproofing of civil and industrial facilities for any purpose (residential, country houses, workshops, warehouses, hangars, etc.). Due to the low thermal conductivity, polyurethane foam is used to insulate not only roofs, but also walls, both inside and outside buildings. PPU sandwich panels are indispensable in the construction of prefabricated construction projects.
PPU with a density of 30-86 kg/m³ (rigid polyurethane foams) are used as sound and heat insulating material. Material with a density of 70 kg / m³ has a dense structure, does not let water through and is successfully used for waterproofing work.
In the production of refrigeration equipment, PPU is used as a cold insulator. The shoe industry uses the material to make various elements of shoes and arch supports.
However, there are areas where the use of a material such as polyurethane foam is very doubtful. Lining material and fillers for upholstered furniture, mattresses, pillows, etc. can cause harm to he alth. (polyurethane foam with a density of 5-40 g / m³ - soft foam blocks). Although PU foam manufacturers claim that the material is environmentally and biologically neutral, its use as filler for children's toys can also make parents think about the he alth of their children.
Sleeping in the arms of a PPU…
It will be about such items of bedding aspolyurethane foam mattresses. Harm, and quite serious, can be caused by inhalation of fumes of complex volatile chemical compounds (about 30 types), the most dangerous of which are phenol and 2-ethylhexanoic acid. Moreover, new mattresses filled with polyurethane foam emit 5-6 times more hazardous substances into the atmosphere than old ones. The vapor concentration of these substances is comparable to the emissions from a new laminate flooring.
Assurances of the safety of mattresses filled with polyurethane foam are doubtful for the simple reason that resins, catalysts, solvents, active chemical components (phenol!) are used at the stage of their manufacture.
Is phenol a big threat?
Phenol is considered a toxic substance for the reason that it emits toxic fumes, and this process can continue for years without reducing or losing toxicity. This chemical element can cause disruption of the most important systems of the human body: respiratory, nervous, cardiovascular. The result may be headaches, loss of consciousness, impaired coordination of movements. Kidney and liver function may also be impaired. Constant contact with phenol and its fumes can cause such formidable diseases as asthma, infectious pulmonary pathologies, and allergies.
According to scientists involved in research in this area, the use of polyurethane foam for the manufacture of children's furniture, mattresses, toys is unreasonable. PPU may well be replaced with safer materials. If parents are concerned about the he alth of theirchildren, they need to be very careful when choosing toys and mattresses for them, in which polyurethane foam can be used as a filler. The bulk of civilized countries have banned the use of phenol for the manufacture of everyday goods.
What else is bad?
Polyurethane foam products are widely used in many areas of human life. Polyurethane foam and foam board based on polyurethane foam adversely affect the lungs, skin, and eyes. Thermal insulation boards made of polyurethane foam release toxic polyisocoanate compounds into the air that can cause allergies or asthma. When PPU boards are heated by heating batteries or sunlight, the release of polyisocyanate increases.
When a fire occurs, PPU burns and releases toxic gases, which is an additional source of danger and threat to life. However, it is worth noting that recently non-combustible types of polyurethane foam, obtained by introducing special additives into their composition, have been increasingly used. Such polyurethane foam practically does not cause harm to he alth.
So where is the truth?
Polyurethane foam - what is it? Harm from it or benefit? A huge number of places where polyurethane foam is used in various areas of human life does not allow us to give an unambiguous answer to this question. For the construction industry, this is certainly a benefit, and a huge one. The ability to prepare a mixture and apply polyurethane foam on the surface to be insulated directly on the construction site reduces the associated costs and allows you to createmonolithic PPU-surface without gaps during installation and cold bridges. Thermal insulation of main pipelines, insulation of low-temperature pipelines of the chemical industry is also currently hardly possible with the same efficiency provided by polyurethane foam.
However, the use of this material in the production of goods for people (and for children in particular) is seen by many specialists in this field as not entirely justified. The release of toxic substances can have a negative impact on human he alth. Even before 2003, the technology for manufacturing domestic components for the production of polyurethane foam provided for the use of highly volatile ether compounds. Today, manufacturers claim that this technology has been abandoned. Within 3 days after application, the material is released from a small amount of gases remaining after the reaction of the components, and after that the polyurethane foam is environmentally friendly.
In general, in each specific case, before using PPU products, one must sensibly evaluate all the pros and cons of using this material in a particular area of life.
