S.P. Bao

Structure and Mechanical Behavior of Isotactic Polypropylene Composites Filled with Silver Nanoparticles

Abstract Isotactic polypropylene (PP) nanocomposites containing 0.1, 0.3, 0.5 and 1.0 wt % silver (Ag) nanoparticles were prepared via melt compounding in a twin-screw extruder followed by injection molding The effects of the Ag nanoparticle additions on the structure and mechanical behavior of PP were studied using DSC, WXRD, optical microscopy, tensile and Izod impact techniques. DSC and WXRD measurements showed that the addition of only 0.1 wt% Ag nanoparticles promote the formation of β-form PP. Further increasing Ag content would not lead to additional increase of the β-PP phase content. The induced β- form PP phase is beneficial to enhance the impact strength and tensile ductility of the PP/Ag nanocomposites.

Fabrication and electrical conducting behavior of carbon nanofiber reinforced high-density polyethylene/ polystyrene nanocomposites with low percolation threshold

Abstract Ternary high-density polyethylene/polystyrene/carbon nanofiber nano composites were fabricated by melt-compounding. The effect of melt compounding sequences on electrical conducting behavior of such composites was examined. Two compounding sequences were adopted in this study. Route I consisted of an initial melt mixing of HDPE and PS, followed by blending with CNFs. Route II involved an initial formation of the PS/CNF master batch, followed by blending with HDPE. The results showed that CNFs were dispersed in HDPE phase of Route I prepared HDPE/PS/CNF nanocomposites whilst they resided in PS phase of Route II formed nanocomposites. Electrical measurement showed that Route II prepared nanocomposites had a low percolation concentration of 1.1 vol% CNF.

Fracture Characterization of High Density Polyethylene/Organoclay Nanocomposites Toughened with SEBS-g-MA

High density polyethylene (HDPE)/organoclay nanocomposites toughened with maleated styrene-ethylene-butylene-styrene elastomer (SEBS-g-MA) were prepared by melt compounding. The structure and mechanical properties of such nanocomposites were investigated by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), tensile and impact techiniques. XRD measurements showed that meleic anhydride group of SEBS elastomer was beneficial in forming an intercalated or partially exfoliated structure. The essential work of fracture (EWF) approach under tensile condition was used to characterize the fracture toughness of nanocomposites. The results indicated that the addition of SEBS-g-MA to the HDPE/organoclay nanocomposites greatly enhanced their fracture toughness.

Crystallization behavior of semicrystalline polymer–clay nanocomposites

Abstract: The presence of nanoclay platelets in semicrystalline polymers leads to significant changes in their crystallization behavior and polymorphic structure. Therefore, basic understanding of the effect of clay addition on the structural and crystallization behavior of semicrystalline polymers is needed. The semicrystalline polymers studied include polar PA6 and PVDF as well as nonpolar polyolefins. The chapter begins with a brief description of the general properties and dispersion of nanoclays in polymers. Then the influence of clay addition on the polymorphic structure, crystallite morphology, isothermal and nonisothermal crystallization of semicrystalline polymers is discussed in detail. Particular attention is paid to the use of X-ray diffraction, optical microscopy, fourier transform infrared spectroscopy and differential scanning calorimetry techniques for characterizing the crystallization behavior of polymer–clay nanocomposites.