An investigation on melt free-radical grafting of GMA onto EPDM backbone: Effect of EPDM-g-GMA on the morphology and mechanical properties of PS/EPDM/PA6 ternary blends

Document Type: Original research


1 Polymer Engineering Department, Amirkabir University of Technology, P.O. Box 5875/4413, Tehran, Iran

2 Chemical, Polymeric and Petrochemical Technology Development Research Division, Research Institute of Petroleum Industry, Tehran, Iran



Melt free-radical grafting reactions between ethylene-propylene-dieneterpolymer (EPDM) and glycidyl methacrylate (GMA) were investigated in a batch mixer (170°C, 60rpm). Effect of dicumylperoxide (DCP) initiator and GMA functionalizing monomer concentrations were studied on the grafted EPDM characteristics. Titration results indicated an increase in the graft degree (GD) and gel content (GC) values with increasing DCP concentration as a result of increasing primary free radical concentration and strengthening cross-linking side reaction. FTIR spectrums confirmed that GMA functionalities have been grafted onto EPDM with appearing carbonyl (C=O) peak. After that, achieved EPDM-g-GMA was used as a compatibilizer in PS(polystyrene)/EPDM/PA6 (polyamide6) ternary blends. The effect of rubbery compatibilizer on the blend morphology and mechanical properties was studied. ATR-FTIR spectra of ternary blends, etched to remove unreacted PA6, emphasized the compatibilizing reactions occurred during melt blending. By investigating SEM micrographs, EPDM-g-GMA compatibilizer (i.e. 5 to 15 wt.%) was shown to change the size and type of the blend morphology from separated dispersed to multicore-shell morphology. The finest morphology was achieved at 7.5 wt.% EPDM-g-GMA. Also, the presence of compatibilizer up to 7.5 wt.% could improve the tensile modulus, yield stress and impact strength, but a decreasing trend was observed in higher compatibilizer content.


Articles in Press, Accepted Manuscript
Available Online from 29 July 2020
  • Receive Date: 05 June 2020
  • Revise Date: 14 July 2020
  • Accept Date: 28 July 2020