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Cryogenic Mechanical Alloying of Poly(methyl methacrylate) with Polyisoprene and Poly(ethylene-alt-propylene)

Summary: Cryogenic Mechanical Alloying of Poly(methyl methacrylate) with
Polyisoprene and Poly(ethylene-alt-propylene)
Archie P. Smith,, Harald Ade,*, C. Maurice Balik, Carl C. Koch,
Steven D. Smith,| and Richard J. Spontak*,,
Departments of Materials Science & Engineering, Physics, and Chemical Engineering,
North Carolina State University, Raleigh, North Carolina 27695; and Corporate Research Division,
The Procter and Gamble Company, Cincinnati, Ohio 45239
Received August 26, 1999
ABSTRACT: Mechanical alloying is performed at cryogenic temperatures to incorporate polyisoprene
(PI) or its hydrogenated analogue poly(ethylene-alt-propylene) (PEP) into poly(methyl methacrylate)
(PMMA) as an example of high-energy solid-state blending. Morphological characterization of the blends
by X-ray and electron microscopies confirms that the degree of dispersion of the constituent polymers
improves with increasing milling time. Such dispersion in the PEP/PMMA blends is, however, ultimately
compromised by phase coarsening when the materials are postprocessed above the PMMA glass transition
temperature in the melt. Milling-induced PI cross-linking serves to suppress phase coarsening in PI/
PMMA blends, which remain relatively well-dispersed even after postprocessing. These blends are
generally less fracture-resistant than the as-received PMMA due mainly to the accompanying reduction
in PMMA molecular weight. Their optical transparency is observed to decrease dramatically with
increasing PEP or PI concentration until they appear opaque. An overall improvement in blend properties
by mechanical alloying is, however, anticipated upon judicious selection of more degradation-resistant


Source: Ade, Harald W.- Department of Physics, North Carolina State University


Collections: Physics