Poly(ethylene-graft-ethylene oxide) (PE-PEO) and poly(ethylene-co-acrylic acid) (PEAA) as compatibilizers in blends of LDPE and polyamide-6

✍ Scribed by Åsa Halldén; Bertil Ohlsson; Bengt Wesslén

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 366 KB
• Volume: 78
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/1097-4628(20001220)78:13<2416::aid-app190>3.0.co;2-t

✦ Synopsis

In a blend of two immiscible polymers a controlled morphology can be obtained by adding a block or graft copolymer as compatibilizer. In the present work blends of low-density polyethylene (PE) and polyamide-6 (PA-6) were prepared by melt mixing the polymers in a co-rotating, intermeshing twin-screw extruder. Poly(ethylenegraft-polyethylene oxide) (PE-PEO), synthesized from poly(ethylene-co-acrylic acid) (PEAA) (backbone) and poly(ethylene oxide) monomethyl ether (MPEO) (grafts), was added as compatibilizer. As a comparison, the unmodified backbone polymer, PEAA, was used. The morphology of the blends was studied by scanning electron microscopy (SEM). Melting and crystallization behavior of the blends was investigated by differential scanning calorimetry (DSC) and mechanical properties by tensile testing. The compatibilizing mechanisms were different for the two copolymers, and generated two different blend morphologies. Addition of PE-PEO gave a material with small, welldispersed PA-spheres having good adhesion to the PE matrix, whereas PEAA generated a morphology characterized by small PA-spheres agglomerated to larger structures. Both compatibilized PE/PA blends had much improved mechanical properties compared with the uncompatibilized blend, with elongation at break ( b ) increasing up to 200%. Addition of compatibilizer to the PE/PA blends stabilized the morphology towards coalescence and significantly reduced the size of the dispersed phase domains, from an average diameter of 20 m in the unmodified PE/PA blend to approximately 1 m in the compatibilized blends.