A comparison of blends of linear with branched polyethylenes prepared by melt mixing and by solution blending

• Published in: Polymer (Guilford) 1994-01, Vol.35 (11), p.2452-2457
• Main Authors: Puig, Cristian C., Odell, Jeffrey A., Hill, Mary J., Barham, Peter J., Folkes, Michael J.
• Format: Article
• Language: English
• Subjects: liquid-liquid phase separation; melt mixing; polyethylene blends
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(94)90788-9

Blends of a linear and a lightly branched polyethylene were prepared by solution blending and in the melt, by mixing in a screw extruder, and the phase morphologies were compared. First, the melt phase behaviour of the solution-blended system was studied by differential scanning calorimetry and transmission electron microscopy. A loop of liquid-liquid phase separation was found at low linear-polyethylene content. Three melt-mixed blends were then prepared and characterized, again by differential scanning calorimetry and transmission electron microscopy. The general pattern of phase behaviour of these melt-mixed blends was similar to that obtained by solution blending the same pair of polymers (i.e. a region of phase separation was again found at low linear-polyethylene content). Where the phase behaviour allowed mixing, the screw extruder produced blends with uniform composition throughout the sample. The morphologies of the melt-mixed materials showed enhanced nucleation, compared with the solution-blended materials, and orientation effects, particularly at low linear-polyethylene content.