Surface modification of LDPE with PE‐PEO graft copolymer

Films of LDPE containing 1–10 wt % of various polymeric additives were prepared by different techniques. Three poly(ethylene‐graft‐ethylene oxide)s synthesized by grafting poly(ethylene‐co‐acrylic acid) with poly(ethylene oxide) monomethyl ether (MPEO), and two pure MPEOs having molecular weights 750 and 2000 were used as additives. The additives were mixed with LDPE both by blending in a common solvent and by melt mixing. The blends were then solvent cast from xylene onto glass Petri dishes or compression molded between glass plates. The film surfaces were studied by water contact angle measurements and by X‐ray photoelectron spectroscopy (XPS), and melting points and heats of melting were recorded by differential scanning calorimetry (DSC). The blends had a two‐phase morphology, with enrichment of the graft copolymers at the glass–polymer interface, as shown by contact angle values and XPS spectra. Large differences in the interface accumulation between the different film samples were observed. Films prepared by compression molding of solution‐mixed blends exhibited much lower surface accumulation of graft copolymer at the glass–polymer interface than did the solvent cast or melt‐mixed/compression‐molded samples. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 316–326, 2000