| 摘要 |
<p>In a laminar extrusion, overlapping layers of an EVOH phase (16) are dispersed into a PP or MAPP matrix phase (15) incompatible with the EVOH phase to form a vapor, gas and/or organic liquids barrier. When the matrix phase is a PP phase, MAPP can be added to improve adhesion between the overlapping layers and the matrix phase. MEPR and/or PE can also be mixed with the EVOH and/or PP phase to adjust the mechanical properties of the extrusion. In order to produce the extrusion, a molten polymer blend including bodies of the EVOH phase dispersed in the PP or MAPP phase is first prepared and then extruded through a die unit (17). In the die unit, a converging extensional flow is produced to lengthen the dispersed bodies (21) of EVOH phase in a first direction while a diverging extensional flow lengthens these bodies in a second direction transversal to the first one. Such lengthening of the bodies produces in the extrusion the overlapping layers of EVOH phase.</p> |
