Polymers Present in a Polyurethane

Polymers can be differentiated readily, in most cases, as urethanes and further as polyester or polyether urethanes by infrared. The presence of the urethane structure can be ascertained by examination of the spectrum for bands at approximately 6 5 fim (amide II (NH deformation)), 5 8 jum (amide I (C=0 stretch)), and 3 0 fim (NH stretch). 

The presence of polyester or polyether linkages in the polymer chain can be established by examining the relative intensity of the rather large diffuse 

Many elastomeric polyurethanes are difficult to microtome because of their high elasticity and tensile strength, but relatively small thin sections can be cut easily with a scalpel. These samples are amenable to analysis using a microbeam condenser. 

Plasticizers and fillers may interfere. Fillers such as titanium dioxide absorb in the 810-650 cm region, silica in the 1100-800 cm region, 

The presence and identity of a plasticizer may be determined by extracting with a Soxhlet extraction apparatus approximately 1-2 g of polyurethane with acetone. The acetone can then be evaporated and a spectrum of the residue can be obtained simply by preparing a salt plate 

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