Internal mixer dispersion effect

Favis [1994] and Willis andFavis [1988] prepared compatibilized PA blends with PP and carboxylic acid-functionalized EMAA ionomer. Blends containing 90-10 parts PA-6, 0-30 parts EMAA ionomer, and 10-90 parts PP were combined in an internal mixer at 250°C and characterized by torque rheometry and SEM. Dispersed phase particle size vs. interfacial modifier concentration was determined. Emulsification curves were constructed. Effects of mixing protocol on blend properties were studied. Blends were also prepared containing HOPE in place of PP. 

B-AN-AA (20) / S-IPO (80) or combined with unfunctionalized PS internal mixer at 185°C torque vs. functionalization concentration / morphology / mechanical properties / detrimental effect of >5% IPO (too small dispersed phase particle size) Fowler and Baker, 1988... 

Use of internal mixers offers a direct and environment friendly technique for preparation of nanocomposites. A two-step mixing in an internal mixer followed by addition of curative on a two roll mill for preparation of elastomer-layered silicate nanocomposites [51]. In the study on the effect of processing conditions (mixer type, mixing temperature) and formulations on the properties of EPDM nanocomposites, it has been shown that open two roll mill mixing results in inadequate dispersion of the nanofiller in the elastomer matrix compared to compounding in an internal mixer. Melt compounding with layered silicates has been reported for NR [52], ENR [46], SBR [53], NBR [54], EPDM [55] and PU [56] systems. 

Charman M, Leonard E, Dominguez S, Bissuel C, Derail C (2011) Dispersion of multiwalled carbon nanotubes in a rubber matrix using an internal mixer effects on rheological and electrical properties. J Polym Sci B Polym Phys 49 1597-1604... 

Batch Mixing Equipment. Melt mixing can be carried out in a variety of heated mixing equipment. In order of increasing effectiveness, these include vessels stirred with propellers, vessels with high shear (Cowles-type) dispersers, planetary mixers (Hobart-type), internal mixers (Sigma-blade or Banbury type), and modifications of these. 

The conditions for dispersing clay nanolayers into both cis-1,4-polyisoprene (IR) and epoxidized natural rubber (ENR) have been reported. The incorporation of the clays into these elastomers was achieved by mixing the components in a standard internal mixer/mixing mill (melt compounding) or by mixing their dispersions produced in toluene or methyl ethyl ketone solvents (solution Intercalation). X-ray diffraction studies indicated the intercalation of IR and ENR into the silicate interlayers, followed by exfoliation (delamination) of the silicate layers. The reinforcing effect strongly depended on the extent of dispersion of the silicate layers. 

The effects of mixing temperature, mixer and processing technology on the dispersivity of zinc oxide nanoparticles in BR were investigated. It was foimd that dispersivity was improved at elevated temperature in an internal mixer and that blending the zinc oxide nanoparticles with stearic acid before mixing improved both aggregation and dispersivity. 3 refs. 

The paddle ridge width of a batch mixer was varied between 0.2-20 mm and the effects on the rubber mixing process were studied photographically. The distribution of carbon black in the mix was uniform with a width below 11 mm, while a width below 15 mm was required for efficient dispersion. 9 refs. Artieles from this journal can be requested for translation by subseribers to the Rapra produced International Polymer Science and Technology. 

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