Microlayer coextrusion

Mueller, C., Topolkaraev, V., Soerens, D., Hiltner, A., and Baer, E., Breathable Polymer Films Produced by the Microlayer Coextrusion Process, J. Appl. Polym. Sci. 78, 816 (2000). 

Morawetz H (1995) Polymers the origins and growth of a science. Dover Publications, New York Mueller CD, Nazarenko S, Ebeling T, Schuman TL, Hiltner A, Baer E (1997) Novel structures by microlayer coextrusion - Talc filled PP, PC/SAN and HDPE/LLDPE. Polymer Eng. Sci 37 355-362. DOI 10.1002/pen. 11678... 

The technique of multilayer coextrusion can he used to produce two-dimensional continuous layers of different polymers via the process of forced assembly [1]. Microlayer coextrusion combines two or more polymeric materials into layered configurations that can be used to produce new architectures with improved mechanical, electrical, barrier, and adhesive properties. Layered composites comprising up to 8000 continuous layers can be successfully produced, with the thicknesses of individual layers ranging from several microns down to a few nanometers [1,8]. Multilayered materials with such small layer thicknesses in the range of a few tens of nanometers can be otherwise only obtained by the copolymerization of polymers into block copolymers (see Chapter 3, Block Copolymers ). 

A special application of the coextrusion technique is the production of polymeric foamed materials with a high strength-to-weight ratio and good acoustic and thermal insulation. Control of the foam cell size is very critical in obtaining these key performance properties. The control of cell size in the thin layers by the microlayer coextrusion technology makes the creation of microcellular foam possible [8]. 

Multilayered films can be formed by various processes to create a structure with specific mechanical and physical properties. Microlayers of foam/film were formed by microlayer coextrusion technology [176], resulting in unique mechanical properties studied by optical microscopy. Cohen et al. [177] studied... 

This coextrusion techniqne has been applied to the fabrication of breathable films, using polyethylene oxide and polyolefin fiUed with CaC03. As the layer thickness decreased, the water vapor transmission rate changed dramatically due to changes from a continuous to discontinuous layer structure. Microlayer extrusion of a number of polymers has been accomphshed, including combinations of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), ethylene-styrene copolymers and low-den-... 

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