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

• Published in: Macromolecules 2000-04, Vol.33 (7), p.2595-2604
• Main Authors: Smith, Archie P, Ade, Harald, Balik, C. Maurice, Koch, Carl C, Smith, Steven D, Spontak, Richard J
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Machinery and processing; Moulding compound preparation. Mixing; Plastics; Polymer industry, paints, wood; Technology of polymers
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma991453v

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 polymers.