Polyurethane Products
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| polyurethane products |
Any class of synthetic, fiber, or elastic resin compounds belonging to the family of organic polymers that reacts with other active compounds, such as polyurethane and dissociate (organic compounds that have two functional groups in the NCO structure) glycol Made of The most popular of these are flexible
polyurethane foams - used as apostrophes, mattresses, and similar rigid foams - used for lightweight structural elements such as aircraft wing coverings.
Foamed polyurethane is formed due to the reaction of separation with organic compounds, usually polyesters consisting of carboxyl groups. These reactions emit carbon dioxide bubbles, which spread throughout the product. The use of polyurethane or polyesters containing hydroxyl groups in the manufacture of polyurethane leads to the formation of elastic fibers or rubbers, which are highly resistant to ozone attack but sensitive to the effects of acids or alkalis.
Synthetic fibers known as spandex in fabrics weigh at least 85% polyurethane. These fibers are usually used for their highly elastic properties. Brand fibers in this group are Lycra, Noma, Spindle, and Vernon. These fibers have widely replaced natural and synthetic rubber fibers for many fabric purposes.
Although the spandex is somewhat weak in comfort, it can stretch to about 500-610% of its original length without breaking and quickly return to its actual size. The fibers, usually white with a matte sheen, can be easily dyed. It absorbs some moisture. It dissolves at about 250 ° C (480 ° F) and turns yellow on prolonged exposure to heat or light. The spandex material can be machine washed and dried over medium heat. The use of chlorine bleach can cause yellowing. Spandex is often covered with other fibers such as nylon.
Spandex is used in base wear, support socks, and swimwear. It is light and cool. It is resistant to the breakdown of body acids. It is easily washed off and quickly dries.
Use of Polyurethane
. The properties of a polymer - the relative molecular mass, the number of photoactive active groups in each molecule, and the molecular structure - affect the final polymer property and, therefore, how it is used.
There is a fundamental difference between polyurethane and many other types of plastics. Polymers such as polyethylene and polypropylene are produced in chemical plants and sold as granules, powders, or films. The polymer is then heated, pressed, and cooled to form a product. The properties of these manufactured products depend almost entirely on the original polymer.
On the other hand, polyurethane is usually formed directly into the final product. Most are made in large blocks of polyurethane foam, which are used for pillows or thermal insulation. Chemical reactions can also occur in molds, for example, car bumpers, computer cases, or building boards. It can happen
when the liquid reactant is sprayed on the roof of the building or covered with a cloth.
Polyurethane can be hard or rubber, having a density between 10 kg m3 and 100 kg m3. The general range of features for the designer and manufacturer is very wide, and this is reflected in the many and very different uses in which polyurethane is used.
Polyurethane production and processing
Polyurethane is formed in the reaction between diol and diocyanate, and the production process can be divided into three parts:
1. Diols production
2. Ocean production
3. Production of polyurethane from these components.
The polyol used in the manufacture of polyurethane is usually a polymer (90% in polyurethane) or a polyester with terminal hydroxyl groups. In addition, there are many aromatic and aliphatic polysaccharides; However, the two most important, Toluene dissociate (TDI) and methylene dissociate (MDI), make up about 95% of all polyurethanes. TDI is commonly used in the manufacture of soft, flexible foams for cushioning, while MDI is used to manufacture highly interactive and hard polyurethane.
If the diol reacts with TDI or MDI, it forms a linear thermoplastic polymer by a condensation polymerization reaction. If the alcohol contains more than two hydroxyl groups, the result will be a solid, heat-hardening molecule.
Compounds are usually added to enhance specific properties such as cross-linking agents, chain extension agents, paralyzing agents, surfactants, fillers, plasticizers, paints, and radiation resistors. The paralyzing agents will form a polyurethane foam, and the surfactant will control the structure of the bubbles, thus controlling the structure of the foam cells. Fillers increase hardness, plasticizers reduce hardness and add color to paint materials.
Polyurethane properties
Polyurethanes are formed in a polymerization reaction between diols (or polyols: alcohols with two or more hydroxyl-OH-reactive groups) and diisocyanates (polyisocyanates: isocyanates with two or more NCO-reactive isocyanate groups). The result is a molecule that binds to urethane bonds (COONH).
There are many substitutes for alcohol molecules and related oocyte molecules, each group producing new polyurethane with new properties. Polyurethane properties depend on the structure of the polymer spine and may be designed for greater strength and rigidity or greater flexibility and durability.
Thermoplastic Polyurethane vs. Thermoplastic Polyurethane
The selected polyols molecule has a significant effect on the cross-linking properties and grade of the polyurethane product. Specifically, the number of hydroxyl groups in each molecule and the size and elasticity of the hydrocarbon spine can be optimized to extend to the resulting mechanical properties of the polyurethane.
polyurethane foam
When two liquids interact, a solid polymer is formed. Polymers can be flexible or rigid. However, it can also contain gas bubbles, a cellular foam.
When preparing foamed polyurethane, there are two possible ways to produce gas inside the reaction liquid mixture. Water is used to wash away these so-called chemicals, which may have been added to the polyol, which reacts with some polysaccharides to form carbon dioxide.
Alternatively (physical beating), a liquid with a low boiling point, such as pentane, is added to the polyol. This reaction is external heat, so as it continues, the mixture heats up, and the pentane evaporates.
A small amount of air is released through a mixture of polyisocyanates and polyols. It provides the nucleation seed for the many gas bubbles throughout the polymer. Heat causes the bubbles to break apart without the chemical reaction turning the liquid into a solid polymer, and the presence of gas pressure cannot cause further expansion.
For example, a shoe unit can be "passed" to double the production of a hard polymer. The process is so extensive that it can be further expanded low-density foam for apocalyptic or thermal insulation with less than 3% of total polyurethane volume. The gas captured by the liquid is 30 to 40 times larger than the original volume. In the case of cushions, we all need a strong polymer so that you can sit comfortably.
In hot springs, gas trapped in the atmosphere is what cools. The polymer that fills the space is reduced so that logical gains are obtained as little as possible.
Polyurethane applications
Since there are many polyurethane and polyurethane materials for polyurethane production, different materials can be created to meet the needs of specific applications. Its relatively low weight and durability make it an ideal material for construction, automotive, marine, and even clothing.
Flexible polyurethane foam
Flexible polyurethane foam is lightweight, durable, supportive, and comfortable. It is commonly used for bedding, furniture, car interior, carpet lining, and packing lining. It accounts for 30% of the Polyurethane market due to its consumer goods.
Hard polyurethane foam
Hard polyurethane foam is highly economical and energy-efficient insulation, significantly reducing energy costs. When used in the insulation of ceilings, walls, windows, and doors, it helps maintain a constant temperature and reduce noise. Hard polyurethane foam is also commonly used as a heat insulator in refrigerators and freezers.
Covers, adhesives, sealants, and elastomers
Polyurethane coatings can improve the shape of the product and prolong its life. Polyurethane paint can add shine to the surface of objects, which offers relatively better properties than traditional lines, lacquers, and varnishes.
Polyurethane or Wip of Polyurethane Paint is usually an oil-based polyurethane paint that is applied to wood or concrete surfaces to add color and increase durability, as it is usually so dirty that it cannot be sprayed. However, water-based polyurethane is becoming more popular because it is less toxic and takes less time to dry than its oil-based counterpart.
Polyurethane adhesives offer strong bonding benefits, especially immediately after their production, and polyurethane sealants provide a stronger seal than their traditional counterparts. Polyurethane elastomers can be made in any desired shape; they are lighter than metal, increase pressure, and are more resistant to the environment.
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