The structure and properties of layered silicate polypropylene nanocomposites

3 The structure and properties of layered silicate polypropylene nanocomposites 

Generally isotactic polypropylene (iPP) is used for nanofilled materials, although nanocomposites prepared from syndiotactic polypropylene (sPP) have also been reported. The degree of crystallinity in PP depends on the 

A mixed a and P phase was observed in nanocomposites. The relative amount of P phase never exceeded 30%, denoting a rather uniform crystallization in the bulk and on the samples surface. The authors presume that the high P content could be attributed to stearic-acid derivatives which were added as processing aid agent and could act as nucleating agent for p phase. Stearic-acid derivatives are known as promoters of P crystallographic phase.  

X-ray diffraction (XRD), is commonly used to probe the nanocomposite structure. However, XRD can only detect the periodically stacked clay layers, disordered or exfoliated layers are undetected. In general, in layered silicate-filled polymers a coexistence of exfoliated, intercalated and disordered layers is observed. 

Pristine MMT shows a characteristic diffraction peak between 6.94° and 7.3° 20 corresponding to the (001) plane diffraction. It corresponds to 

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