Switching from brittle to ductile isotactic polypropylene-g-maleic anhydride by crosslinking with capped-end polyether diamine.

Abstract Ductile functionalized polypropylene is of great interest in multi-layer composites development. A capped-end triblock polyether diamine (H 2 N-PO 2 -TMO 9 -PO 3 -NH 2) was used as a linker of two different maleated isotactic polypropylenes (iPP -g- MAH, at 1 and 3 wt%) by twin-screw reactive extrusion. The molecular architecture, the semi-crystalline microstructure and the mechanical properties of the resulting polymers were analysed as a function of the molar ratio of NH 2 :MAH (0:1, 0.33:1, 0.5:1, 0.66:1, 1:1, 1.5:1, 2:1). At the molecular scale, the chemically modified polymers were characterized by FTIR and by the determination of gel content following the ASTM D2765-84 standard method. Differential Scanning Calorimetry, Wide Angle X-rays Scattering and Self Successive Auto-nucleation techniques showed the impact of the crosslinking: a decrease of the melting temperature as compared with the unmodified iPP -g- MAH polymer, as well as a decrease of the crystallinity ratio for the iPP -g- MAH at 3 wt% of MAH. Interestingly, Dynamic Mechanical Analysis and video-controlled uniaxial tensile tests showed that the polymers obtained in stoichiometric NH 2 :MAH molar ratio exhibit the best mechanical properties enlightened by a switch from brittle to ductile mechanical behaviour with few differences between the two iPP -g- MAH. Graphical abstract A slight crosslinking enables maleated isotactic polypropylenes to switch from brittle to ductile mechanical behavior with higher resilience than the most conventional one. Image 1 Highlights • A capped-end triblock polyetherdiamine is used as a linker of different iPP- g -MAH by twin-screw reactive extrusion. • The three-dimensional networks are characterized by FTIR and by the determination of gel content. • The semi-crystalline microstructure is thermally described applying the Self-Successive Auto nucleation technique. • A switch from brittle to ductile mechanical properties is observed studying the intrinsic true mechanical behaviours. [ABSTRACT FROM AUTHOR]