Polyolefins, i.e. mainly polyethylene (PE) and polypropylene (PP) are commercially the most important family of polymers with millions tons produced each year. Although they are interesting inert and non-polar materials, some adhesion on their surfaces or their blending with other polar matrixes are desired. Polyolefins functionalized with maleic anhydride (MA) as polar co-monomer is a commercially available product that exhibit enhanced adhesion to polar materials like polyamide, metals, and glass. They are also used as compatibilizing agents that lead to an improvement of impact properties upon blending with polyamide-6 as an example. These products are classically produced by the melt extrusion of the polyolefin and MA in presence of alkyl peroxides as radical initiators Peroxides are the conventional radical-initiators used in all of the reactive extrusion systems. Ideally, the melt modification of a polyolefin should be performed without any drastic modification of the polymer backbone. Nevertheless side reactions such as coupling, chain scission and homopolymer formation occurred. We recently developed acyloxyimides as new H-abstracting agent for the melt radical grafting of maleic anhydride (MA) onto polyethylene. The reaction was conducted in the temperature range 190 - 250 °C in a mini-extruder and the hydrogen abstraction ability of N-acyloxyphthalimide (NAP)-, N-acyloxynaphthalimide (NANP)- and N-acyloxysuccinimide (NAS)-based derivatives was demonstrated and compared to reference peroxides. Optimal experimental conditions were defined by varying the initial MA content and the degree of grafting of MA was determined by infra-red spectroscopy. The MA grafting degree was as high as 2.98 wt% when using tBu-NAP as H-abstracting agent at 230°C with only a slight modification of the PE chains structures as proved by rheological experiments while the use of a peroxide (L101) lead to a lower grafting degree (1.9 wt%) and a cross-linking of the polymer chains confirmed by the three – five fold higher complex viscosity.

Acyloxyimide derivatives as peroxides alternatives for the melt grafting of maleic anhydride onto polyethylene

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.