Polyurethane is a versatile polymer that can be synthesized with a wide range of properties by altering the ratio of diisocyanate and polyol used in its synthesis. Diisocyanates are highly reactive compounds with two isocyanate groups, while polyols are compounds with multiple hydroxyl groups. The reaction between diisocyanates and polyols forms urethane linkages, which are the building blocks of polyurethane.By changing the ratio of diisocyanate and polyol, the properties of the resulting polyurethane can be tailored to specific applications. Some of the properties that can be altered include:1. Hardness: The hardness of polyurethane can be controlled by varying the ratio of diisocyanate and polyol. A higher ratio of diisocyanate to polyol will result in a harder, more rigid material, while a lower ratio will produce a softer, more flexible material.2. Density: The density of polyurethane can also be affected by the diisocyanate-to-polyol ratio. A higher ratio will generally result in a denser material, while a lower ratio will produce a less dense, more porous material.3. Tensile strength: The tensile strength of polyurethane can be influenced by the diisocyanate-to-polyol ratio. A higher ratio will typically result in a material with greater tensile strength, while a lower ratio will produce a material with lower tensile strength.4. Elongation at break: The elongation at break, or the ability of a material to stretch before breaking, can be adjusted by altering the diisocyanate-to-polyol ratio. A higher ratio will generally result in a material with lower elongation at break, while a lower ratio will produce a material with higher elongation at break.5. Thermal stability: The thermal stability of polyurethane can be affected by the diisocyanate-to-polyol ratio. A higher ratio will generally result in a material with better thermal stability, while a lower ratio will produce a material with lower thermal stability.6. Chemical resistance: The chemical resistance of polyurethane can be influenced by the diisocyanate-to-polyol ratio. A higher ratio will typically result in a material with better chemical resistance, while a lower ratio will produce a material with lower chemical resistance.In summary, by adjusting the ratio of diisocyanate and polyol used in the synthesis of polyurethane, it is possible to tailor the properties of the resulting material to suit specific applications. This versatility is one of the reasons why polyurethane is used in a wide range of industries, including automotive, construction, and consumer goods.