Microstructural changes in homopolymers and polymer blends induced by elastic strain pulverization

Abstract

SYNOPSISA novel polymer processing technique known as elastic strain pulverization (ESP) involves the simultaneous effects of high pressure and shear deformation to pulverize polymers. Homopolymers'and blends of commercially important postconsumer plastics, including high-density and low-density polyethylene (HDPE, LDPE), polypropylene (PP), and polystyrene (PS) are studied by several characterization techniques to determine the effects of ESP on the microstructure. Electron spin resonance spectroscopy confirms that free radicals are generated by the mechanical rupture of main chain carbon bonds during pulverization by ESP. The possibility of these free radicals terminating by heterogeneous combination to form compatibilizing block or graft copolymers in coprocessed polymer blends establishes the potential of ESP in commingled plastics recycling. Differential scanning calorimetry (DSC) and polarized light microscopy of homopolymers and blends indicate that crystalline structure is drastically altered by ESP processing. Spherulite size reduction is also observed in both crystalline/crystalline and crystalline/amorphous blends after ESP. These results are consistent with homogenization that may be due to the formation of compatibilizing copolymers by heterogeneous macroradical combination. 0

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

“…The possibility that such agitation may promote mechanical degradation of the constituent polymers has severely limited the commercial viability of solid-state blending. This shortcoming is, however, being surmounted in such emerging polymer processes as solid-state extrusion [5][6][7] and mechanical milling/alloying. [8][9][10][11][12][13] Mechanical alloying refers to the high-energy ball milling of two or more dissimilar materials to produce powders in which the materials are intimately mixed on the molecular or atomic scale.…”

Self‐compatibilization of polymer blends via novel solid‐state shear extrusion pulverization

“…On the contrary, a successful recycling in the mixed form mechanism, breaking of chains or formation of free radicals in different polymers is reported by could handle the entire PCPW stream, provided that one can compatibilize them to improve the Ahn et al,2 where they examined the presence of free radicals with electron spin resonance. density polyethylene (LDPE), and other polymers components of the PCPW stream.…”

“…2 During SSSE, polymer chains rupture, forming free radicals, 2 which are capable of reacting of a polymer increases as a result of chain rupture. gle component PE.…”

Developments in Eu+2‐Doped Strontium Aluminate and Polymer/Strontium Aluminate Composite

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