Polyurethanes are a highly variable family of polymers, materials that result from the linking of a chain of simple, repetitive molecules. These materials can be seen in many forms and can be put to numerous uses, depending upon how their properties are manipulated. Polyurethane resin, which is a synthetically produced sticky substance, is one of those forms.
Polyurethane resin is an industrial product that is used in the production of many other products, such as rubbers and medicines. To understand this material, it is best to have a basic understanding of how polyurethanes are made.
An isocyanate is a compound composed of nitrogen, carbon, and oxygen. When it's exposured to a hydroxyl, a compound that contains hydrogen, it will form a urethane linkage. A diisocyanate is a compound that contains two isocyanates, so these are, therefore, also reactive to hydrogen. They are mostly produced for the role they play in making polyurethane, which is a reaction that involves more than one urethane linkage.
Polyols are basically alcohols that contain more than one hydrogen atom. Producing polyurethane resin generally involves allowing a reaction between a polyol, such as polyether polyol, and a diisocyanate, such as toluene diisocyanate. Heat or catalysts are also necessary to complete the process, and when they are added, the resin will generally take a final and irreversible form. This means it may be impossible to reform them even if heat is added again.
Polyurethane resin is considered versatile because it can be used to produce an array of items, from inks to plastics. This is possible because the material can be manipulated to great extremes, which can change properties such as the hardness and elasticity. In many cases, it's produced in a liquid form and can be poured into molds. When used for this purpose, the material is highly impressionable, which means that the slightest detail, such as a small crack, can be seen in the finished product.
There are many advantages to these resins. They are commonly noted for their chemical, oil, and grease resistance, and they are typically very good at resisting abrasion and, as such, are not easily torn. This can explain why they are often used to produce synthetic rubbers. Additionally, they can be used to create strong adhesives.
There are also some disadvantages to using polyurethane materials. Such items can be adversely affected by direct sunlight, for example, and they also generally do not hold up well when exposed to organic solvents.