Elastomer nanocomposites mechanism

Figure 17.19 shows typical thermal expansion behavior of a PP/PP-g-MA/MMT/ elastomer nanocomposite from the first and second heating the thermal expansion is a nonlinear function of temperature when viewed over the wide range of —40 °C to 125 °C hence, CTE is reported in the temperature range of 0-30 °C so it can be related to the mechanical properties determined at room temperature (Lee et al. 2006a). For both extruder-made and reactor-made TPO nanocomposites, the CTE along the ED and the TD decreases, whereas CTE along the normal direction (ND) increases as the MMT content is increased. The increase in CTE in the ND is... 

The use of a commercial Cloisite 20A organoclay to prepare SBS-based nanocomposites by melt processing was recently reported [63]. In this case, the nanocomposite morphology was characterized by a combination of intercalated and partly exfoliated clay platelets, with occasional clay aggregates present at higher clay content. For this particular thermoplastic elastomer nanocomposite system, well-dispersed nanoclays lead to enhanced stiffness and ductility, suggesting promising improvements in nanocomposite creep performance. The use of stearic acid as a surface modifier of montmorillonite clay to effectively improve the clay dispersion in the SBS matrix and the mechanical properties of the SBS-clay nanocomposites was reported [64]. 

Naderi G, Lafleur PG, Dubois C. The influence of matrix viscosity and composition on the morphology, rheology, and mechanical properties of thermoplastic elastomer nanocomposites based on EPDM/PP. Polym Compos 2008 29 1301-9. 

This mbber is very tacky in nature and contains acrylic group, which makes it polar in nature. Nanocomposites have been prepared based on this elastomer with a wide range of nanohllers. Layered silicates [53-55] have been used for this preparation. Sol-gel method [56,57], in situ polymerization [58], and nanocomposites based on different clays like bentonite [59] and mica [60] have been described. The mechanical, rheological, and morphological behaviors have been investigated thoroughly. 

Keywords Clay Elastomer Mechanical properties Morphology Nanocomposite Nanofiller Rubber... 

Historically, polysiloxane elastomers have been reinforced with micron scale particles such as amorphous inorganic silica to form polysiloxane microcomposites. However, with the continued growth of new fields such as soft nanolithography, flexible polymer electronics and biomedical implant technology, there is an ever increasing demand for polysiloxane materials with better defined, improved and novel physical, chemical and mechanical properties. In line with these trends, researchers have turned towards the development of polysiloxane nanocomposites systems which incorporate a heterogeneous second phase on the nanometer scale. Over the last decade, there has been much interest in polymeric nanocomposite materials and the reader is directed towards the reviews by Alexandre and Dubois (4) or Joshi and Bhupendra (5) on the subject. 

A series of five nanocomposite elastomer systems were prepared for this study incorporating 0, 1, 2, 4 and 8% (on total resin mass) of the organically modified montmorillonite clay Cloisite 6A. The appropriate level of Cloisite was dispersed in a starting resin blend of OH terminated PDMS (M -77,000 and Mn -550 g mol in a 3 1 ratio) by a combination of mechanical mixing and ultrasonic processing to give a nano-dispersion of clay platelets. The blend was subsequently crosslinked with a stoichiometric level of tetrapropoxysilane (TPOS) in the presence of 5% diphenylmethylsilanol (DPMS) chain terminator and 5% tin(II) 2-ethylhexanoate catalyst, cured in an open mould at 65°C for twenty minutes, then removed from the mould and post cured for a further fifteen hours at 65°C to give an elastomeric mat. 

IV. The Mix A Nanocomposite of Elastomer and Filler V. Mechanical Properties of Filled Rubbers... 

Coupling agents have also been used in ternary nanocomposites, for example, in a paper by Hui et al. [67] who used a silane-coupling agent on LDPE/EVA elastomer (40/60)/3 wt% silica composites. They observed dramatic improvements in the mechanical properties (increase of 41% for the tensile strength) that were attributed to the reduced agglomeration tendency of the particles, as proved by AFM. 

Xiaoyan, M., Guozheng, L., Haijun, L., Hailin, L., and Yun, H. 2005. Novel intercalated nanocomposites of polypropylene, organic rectorite, and poly(ethylene octene) elastomer Morphology and mechanical properties. Journal of Applied Polymer Science 97 1907-1914. 

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