Alder Ene functionalization of polypropylene through reactive extrusion

Abstract

A commercial isotactic polypropylene was degraded to increase its terminal vinylidene group concentration, and it was subsequently functionalized with maleic anhydride through the Alder Ene reaction at temperatures above 200°C in a co-rotating twin screw extruder. Characterization of the maleated product by Fourier transform infrared spectroscopy, 1 H NMR, differential scanning calorimetry, and gel permeation chromatography showed the anhydride group to be terminally attached, and the degree of functionalization was determined by infrared analysis. Increased temperature and maleic anhydride concentration, as well as improved mixing in the extruder, were found to improve the extent of the reaction. The catalytic contribution of Lewis acid species was evaluated, and ruthenium chloride was found to increase the extent of the reaction by 16% in comparison with stannous chloride as a catalyst in the Alder Ene reaction.

Interfaces in Cross-Linked and Grafted Bacterial Cellulose/Poly(Lactic Acid) Resin Composites

“…The NMR trace for MAPLA shows a peak positioned at ~2.7 ppm. This peak has been reported to correspond to the formation of succinyl anhydride group formation [35][36][37]. Two other peaks can be seen at approximately 7 and 6.5 ppm.…”

Grafting

“…4,88 The maleation of polypropylene by reactive extrusion via the Alderene reaction produces a terminal functionality of the polymer without significant chain scission. This prevents the maleic anhydride from being grafted onto the backbone of the poly(propylene).…”

Radical grafting of polar monomers onto polypropylene by reactive extrusion

“…It generally improves the adhesion of PP to metals, glass fibers, or other polymers such as polyamides. The grafting of maleic anhydride to PP is usually carried out in the presence of radical initiators in solution,1, 32–34 in the solid state35, 36 or directly in the melt 20, 22, 25, 26, 37–43. Generally, the grafting reaction is accompanied by chain scissions then the grafting degree and efficiency are relatively low.…”