CHANGES IN ROW STRUCTURE OF EXTRUDED POLYETHYLENE FILM IN GRAFTING WITH STYRENE - 2. COPOLYMER MORPHOLOGY.

In the reported experiments, the morphology of extruded high-density polyethylene film grafted with styrene was studied by transmission electron microscopy of thin stained sections. Near the film surface grafted polystyrene was confined to amorphous layers between lamellar crystals of polyethylene. In the film interior separate polystyrene domains were also formed and became predominant in grafting in diluted styrene. The deciding factor for the location of grafted polystyrene is the chain length because only long chains can coalesce in large separate zones. The polystyrene zones expand by cracking the stacks of lamellae along the lamellar normals. Straightening of the twisted crystalline lamellae of polyethylene occurred in grafting. ″Bubbles″ of styrene homopolymer were formed under conditions of high monomer concentration. The effect of staining the graft by the Kaning method was also discussed.