ISO 4901:1985

The residual styrene monomer content in reinforced plastics based on unsaturated polyester (UP) resins is an important criterion in evaluating the degree of cure of UP resins in the polymerized state. The determination is carried out by extraction of the residual monomer styrene from the UP resin in the polymerized state using dichloromethane and subsequent gaschromatographic analysis of the extract with n-butyl-benzene as internal standard. An alternative method of determining the residual styrene monomer by the Wijs method is also specified.