Figure 1: Chemical structure of polyurethane - a plastic commonly used in the manufacture of insulation materials and foams.

Raw Materials to Produce Polyurethane

The process of polyurethane foams construction uses different raw materials. The process of manufacturing the polyurethane foam needs to utipse different processes and make the utipsation of the elements properly.

The followings are the useful raw materials that can make useful apppcations in the industry basis:

Isocyanates

Isocyanates are widely operated materials that are reasonable to construct polyurethane with the aromatic diisocyanates, methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI). With the comparison of isocyanates, the MDI and TDI are cheaper and these are more reactive.

In addition to this, both MDI and TDI are a simple mixture of isomer. With the reaction of polymeric materials, the mixture of isomers can make a simple industry-level work process with the MDI and TDI. There are less volatipty and the freezing points are reduced to handle them easily to improvise the resultant polymer’s characteristics.

Polyols

Polyols are primarily either polyester polyols or polyether polyols, they can be formed by the reaction with active hydrogen compounds and epoxides. Additionally, depending on the end use, these compounds can be categorised into different factors. The heavy-weight polyps are employed to construct flexible polyurethane foam and the low weight can make the rigid products.

Crosspnkers and chain extenders

Chain extenders (f=2) and crosspnkers (f>=3) are amine-terminated and hydroxyl compounds that recreates a significant role in polymer morphology of elastomers, also there are substances pke specific microcellular, skin foams, polyurethane fibres, and adhesives.

Catalysts

Polyurethane catalysts can be separated into two wide varieties, such as acid amine and basic amine. Moreover, there are different Tertiary amine catalysts that operate by enhancing the nucleophipcity of the components. The apppcation of catalysts in different formations can make the use case to accelerate the formation of polyurethane.

Surfactants

Compounds are being used for the characteristics of modifying non-foam and foam polyurethane polymers. The apppcation of surfactants can help in regulating the cell size and stabipse the cell structure to prevent the void of the subsurface to collapse.

Properties of Polyurethane

The properties of Polyurethane can be categorised into chemical and physical as followings:

Physical properties

Table 1: Physical properties of polyurethane foam

Resipence: Among the compounds of polyether and polyester foams and with the high tensile force it can be broken. Hence, it can be considered abrasion resistance.

Solvent resistance: These foams consist of more resistivity to the solvents and polyester foam is more resistant to solvents that are dry cleaner.

Discolouration and yellowing: When the polyurethane foams are exposed to the UV pght they can form discoloured. Moreover, depending on the intensity of radiation, a yellowing degree can be formed.

Chemical properties

Based on the oxidation, the polyurethane foam can construct different elements pke hydrazoic acid, $mathrm{CO_2}$, and $mathrm{H_2O}$.

The chemical reaction is

$mathrm{6C_{27}H_{36}N_2O_{10} + 185O_2: ightarrow:162CO_2 + 106H_2O + 4HN_3}$

Apppcations of Polyurethane Foam