Functionalization of LDPE by melt grafting with glycidyl methacrylate and reactive blending with polyamide-6

Qian Wei, Donatella Chionna, Elena Galoppini, Mariano Pracella

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82 Scopus citations

Abstract

Low-density polyethylene (LDPE) was functionalized by melt radical grafting with glycidyl 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 analyzed as a function of the concentration of GMA monomer, radical initiator (BTP), and addition of styrene as co-monomer. Optimized 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 (80/20, 67/33, 50/50 wt.-%) were prepared in an 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 average diameter of dispersed polyolefin particles was about 0.4 μm for LDPE-g-GMA contents < 50 wt.-%. A marked increase of melt viscosity was observed for the compatibilized blends depending on the concentration of grafted polyolefin, and it was accounted for by the reaction between the epoxy groups of GMA and the carboxyl/amine end-groups of PA6. The variation of torque was thus related to the molar ratio of reactive group concentration. The analysis of crystallization and melting behavior pointed out marked differences in the phase structure of the blends due to the presence of the functionalized polyolefin. Finally, 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 FT-IR and DSC analyses.

Original languageEnglish (US)
Pages (from-to)1123-1133
Number of pages11
JournalMacromolecular Chemistry and Physics
Volume204
Issue number8
DOIs
StatePublished - May 30 2003

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Materials Chemistry
  • Polymers and Plastics
  • Physical and Theoretical Chemistry
  • Organic Chemistry

Keywords

  • Compatibilization
  • Low-density polyethylene
  • Polyamide 6
  • Radical grafting
  • Reactive blending

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