A laminar lid-driven cavity flow was constructed to represent the fundamental characteristics of an industrial dynamic mixer. The flow patterns and mixing process in the cavity were measured by using particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) experiments respectively. The refractive indices of the two miscible liquids involved were carefully matched to allow for unhindered optical access. The mixing process was predicted by using computational fluid dynamics (CFD) including models for species transport. The simulated flow and mixing results are in good agreement with the experimental data. The effects of density difference and viscosity of the two miscible fluids on the mixing process were evaluated. Minor variations in the densities of the fluids have significant influence on the mixing process in terms of the coefficient of variation as a function of time. The dimensionless group Ar Re (Archimedes number over Reynolds number) is proposed to characterize the mixing process in the cavity.

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Solid-phase grafting of a soft vinyl monomer, butyl methylacrylate (BMA), onto polypropylene (PP) matrixes with 2,2 0 -azobisisobutyronitrile (AIBN) as initiator was carried out to enhance the polarity of polymer. Soft vinyl monomer was a novel notion in grafting modification of PP. Effects of swell time, BMA concentration, AIBN concentration, grafting reaction time, and temperature on grafting percentage (G p ) and grafting efficiency (G e ) were examined. The optimal conditions of grafting reaction were obtained: swell time of 60 min, BMA concentration of 6 wt %, AIBN concentration of 0.05 wt %, reaction temperature of 85 C, and reaction time of 2 h. The grafting samples were investigated by such characterization techniques as Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscope (SEM) analysis. FTIR results indicated that BMA was actually grafted onto PP backbone. TGA results showed that the decomposition temperature increases with addition of BMA into PP backbone. SEM results indicated that the surfaces of PP-g-BMA had a markedly bumpy texture, whereas the pure PP surface was very smooth. Water contact angle results showed that the polarity and hydrophilicity of PP were improved effectively. Compared with the traditional monomer MAH, G p , and G e , melt flow rate and mechanical property results all indicated that the soft vinyl monomer had a many advantages in the modification of PP. In the end, the mechanism of solid grafting was discussed.

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