Stabilization of Dispersed Phase to Static Coarsening:  Polymer Blend Compatibilization via Solid-State Shear Pulverization

Previous work showed that high density polyethylene (HDPE)/exfoliated graphene nanoplatelets (GNP) nanocomposites fabricated with melt extrusion followed by injection molding had a relatively high percolation threshold of between 10 and 15 vol % GNP loading. To lower the percolation threshold of injection molded HDPE/GNP nanocomposites, two special processing methods were investigated: solid state ball milling (SSBM) and solid state shear pulverization (SSSP). Results have confirmed that the percolation threshold of HDPE/GNP nanocomposites could be reduced to between 3 and 5 vol % GNP loading by these two approaches. The mechanism by which SSBM and SSSP are capable of producing lower percolation is to coat the polymer surface with GNP platelets which facilitates the formation of conductive networks during injection molding. However, it was found that HDPE/GNP nanocomposites obtained from these two techniques exhibited lower mechanical properties at high GNP loadings. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: [525][526][527][528][529][530][531][532][533][534][535] 2012

Section: Solid State Shear Pulverization and Injection Moldingmentioning

confidence: 99%

Reduction in percolation threshold of injection molded high‐density polyethylene/exfoliated graphene nanoplatelets composites by solid state ball milling and solid state shear pulverization

Jiang

Drzal

2011

“…1-3). 16,17 As the domain size of blend phases decreases, tensile strength increases as interfacial area between phases increases and the probability of finding a large flaw, resulting stress concentration, in blend structure decreases. 33 Except for 60 wt % PET containing system, ground composites provide higher tensile strength values when compared with conventional composites.…”

Section: Resultsmentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14] Additionally, a new approach, solid-state shear pulverization method has been applied to obtain well dispersed and stable blend microstructure, composed of immiscible polymer phases. [15][16][17] Microstructured or nanostructured blend morphology is important in terms of electrical conductivity and mechanical properties of conductive polymer composites. However, conventional melt mixing methods, e.g., extrusion, have limitations in preparation of microstructured or nanostructured blend systems.…”

Section: Introductionmentioning

confidence: 99%

Effect of solid state grinding on properties of PP/PET blends and their composites with carbon nanotubes

Köysüren

Yeşil

Bayram

2010

In this study, it was aimed to improve electrical conductivity and mechanical properties of conductive polymer composites, composed of polypropylene (PP), poly(ethylene terephthalate) (PET), and carbon nanotubes (CNT). Grinding, a type of solid state processing technique, was applied to PP/PET and PP/PET/CNT systems to reduce average domain size of blend phases and to improve interfacial adhesion between these phases. Surface energy measurements showed that carbon nanotubes might be selectively localized at PET phase of immiscible blend systems. Grinding technique exhibited improvement in electrical conductivity and mechanical properties of PP/ PET/CNT systems at low PET compositions. Ground composites molded below the melting temperature of PET exhibited higher tensile strength and modulus values than those prepared above the melting temperature of PET. According to SEM micrographs, micron-sized domain structures were obtained with ground composite systems in which PET was the minor phase.

“…Another advantage is that there is no need to do any chemical modification on the base materials before their compounding. From this aspect, sonochemical compatibilization is similar to mechano-chemical methods, such as solid-state shear pulverization, [27][28][29] cryogenic mechanical alloying, 30 and CO 2 high-energy ball milling. 31 The outcome of these technologies could be crucial for the efficient recycling of rapidly growing plastic waste.…”

Section: Introductionmentioning

confidence: 99%

“…Although most other studies on compatibilization through radical mechanisms are based on morphological or spectroscopic observations with indirect evidence, some advances in the direct detection of in situ formed copolymers with fluorescence-detection gel permeation chromatography (GPC) have been made recently. 27 However, little information on rheological and mechanical properties is reported in the literature for mechanochemically compatibilized thermoplastic blends. In one case, inferior mechanical properties were reported, 30 despite the achievement of a nanosize dispersion in an immiscible blend obtained by cryogenic mechanical alloying.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic treatment of polypropylene, polyamide 6, and their blends

Lin

Isayev

2006

The mechanical and rheological properties of polypropylene (PP), polyamide 6 (PA6), and their blends treated by high-intensity ultrasound during extrusion were investigated. A lower head pressure was achieved in the extrusion of these thermoplastics. The mechanochemical and sonochemical effects of ultrasound led to simultaneous ionic condensation reactions and degradation in a homogeneous melt of PA6, with a prevailing effect of enhanced polycondensation reactions. The observed improvements in the mechanical properties of ultrasonically treated PA6 were attributed to condensation reactions, which yield a higher molecular weight, a higher crystallinity, and a more uniform crystal size distribution. At high ultrasound amplitudes, for PP, the degradation of polymer chains was observed with little deterioration of the mechanical properties. For ultrasonically treated PP/PA6 blends, a competition between the degradation and partial in situ compatibilization effect was found. At certain blend ratios, the tensile toughness and impact strength of the treated blends were almost double those of the untreated blends. However, full compatibilization was not achieved, possibly because of the low coupling selectivity of highly reactive radicals.