Functionalization of PP with Sulfonyl Azide through Reactive Processing

Abstract

Abstract The functionalization of polypropylene (PP) by 4-carboxybenzene sulfonyl azide (CBSA) was investigated in a batch mixer and the reaction was monitored through FTIR, 1H-NMR and XPS spectroscopy. The degree of grafting was found to increase initially with azide feed content and subsequently to level off at azide concentrations of 2 wt.%. Experiments performed at different reaction temperatures showed that a maximum degree of grafting was obtained around 190°C. The linear viscoelastic properties the functionalized PPs were also evaluated by oscillatory shear measurements and were found to correlate with the grafting degree results. Finally, the adhesive properties of the functionalized PPs were evaluated through peel tests on aluminum substrates. The peel strength increased with the degree of grafting and it was found to be significantly higher for purified samples than for non-purified ones. Finally, it was demonstrated that the cooling rate of the PP/aluminum laminate specimens had a major effect on the peel strength.