A one‐point intrinsic viscosity method for polyethylene and polypropylene

A statistical analysis of dilute solution viscosity data for a wide range of polyethylene and polypropylene samples in Decalin at 135°C has shown that the Martin equation\documentclass{article}\pagestyle{empty}\begin{document}$ {{\eta _{sp} } \mathord{\left/ {\vphantom {{\eta _{sp} } c}} \right. \kern-\nulldelimiterspace} c} = [\eta ] + k'[\eta ]^2 c $\end{document}fits the experimental data better than the Huggins equation\documentclass{article}\pagestyle{empty}\begin{document}$ \log \left( {{{\eta _{sp} } \mathord{\left/ {\vphantom {{\eta _{sp} } c}} \right. \kern-\nulldelimiterspace} c}} \right) = \log [\eta ] + k[\eta ]c $\end{document}at higher values of [η] c . A grand average k of 0.139 is applicable to both polymers. Based upon this, tables have been calculated permitting the ready determination of [η] from a single relative viscosity measurement at a known concentration. The Martin equation has been put into a universal form, permitting [η] to be calculated from a measured η sp if k and c are known. Graphs relating η sp to [η] are included for use of the Martin equation over wide ranges of both k and c . It was found that the Solomon and Ciuta equation\documentclass{article}\pagestyle{empty}\begin{document}$ [\eta ]c = \left( {2\eta _{sp} - 2\ln \eta _{rel} } \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document}fits the experimental polyethylene and polypropylene data, and the reasons for this are discussed.