Quantification of the maleic anhydride grafted onto polypropylene by chemical and viscosimetric titrations, and FTIR spectroscopy

• Published in: Polymer (Guilford) 2000-03, Vol.41 (6), p.1989-1999
• Main Authors: Sclavons, M., Franquinet, P., Carlier, V., Verfaillie, G., Fallais, I., Legras, R., Laurent, M., Thyrion, F.C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Maleic anhydride grafted polypropylene; Organic polymers; Physicochemistry of polymers; Properties and characterization; Quantification; Structure, morphology and analysis; Titration
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(99)00377-8

An acid–base titration method for an accurate and reproducible quantification of maleic anhydride grafted onto polyolefins is proposed. The use of an organic base (tetra-butylammonium hydroxide) enhances the base solubility in organic solvents and prevents phenomena like coarcervation. The titration goes on until the visual endpoint of a coloured indicator, corresponding to the neutralisation of the grafted functions. Bromothymol blue is chosen as the coloured indicator to determine this equivalence point. It is critically correlated with a Fourier transform-infrared spectroscopy quantification developed previously by De Roovers et al. [J Polym Sci, Part A: Polym Chem 1995;33:829] and with a viscosimetric titration method here-proposed. Finally, the titration mechanism is confirmed by the titration of some well-defined amount of anhydride model compounds and by FTIR analyses of their products after titration.