Functionalization of LDPE by Melt Grafting with Glycidyl Methacrylate and Reactive Blending with Polyamide-6

Low-density polyethylene (LDPE) was functionalized by melt radical grafting with glycydyl methacrylate (GMA) and employed for reactive blending with polyamide 6 (PA6). The effect of the reaction procedure on the grafting degree of LDPE-g-GMA samples (0.5-12.5 wt.-% GMA) was analysed as a function of the concentration of GMA monomer, radical initiator (BTP) and addition of styrene as co-monomer. Optimised grafting conditions were obtained when the amount of the monomer is below 10 wt.-% and that of peroxide in the range 0.2-0.4 wt.-%. Binary blends of PA6 with LDPE-g-GMA (3.5 wt.-% GMA) and with LDPE at various compositions were prepared in internal mixer and their properties were evaluated by torque, SEM and DSC analyses. Morphological examination by SEM showed a large improvement of phase dispersion and interfacial adhesion in PA6/LDPE-g-GMA blends as compared with PA6/LDPE blends. The in situ formation of a graft copolymer between LDPE-g-GMA and PA6 was investigated by means of a selective dissolution method (Molau test) and by FTIR and DSC analyses.