STRUCTURAL MODEL OF EFFICIENCY OF COVALENT FUNCTIONALIZATION OF CARBON NANOTUBES
Abstract
Functionalization of carbon nanotubes (covalent and noncovalent ones) is effective and often applied method of enhancement of their interaction with polymer matrix of nanocomposites. In present work the treatment is proposed, for the first time allowing quantitative estimation of efficiency (quality) of this nanofiller functionalization. For this purpose proposed earlier generalized model was used, taking into consideration characteristics of matrix polymer and nanofiller and also type of the last. Application of the indicated model allows to obtain quantitative characteristic of functionalization efficiency and also elucidation of interconnection of the indicated efficiency with structure of carbon nanotubes in polymer matrix of nanocomposite, namely, with radius of their annular structures. It has been found that the same method of functionalization from the chemical point of view can be changed its efficiency in 20 times that is dependent upon structure (radius) of annular formations of carbon nanotubes. Their specific surface is the more precise characteristic of these formations. This surface serves as indicator of intensity of contact of polymer matrix and surface of nanotubes, which in the end forms mechanical and other properties of the considered nanocomposites. The equation has been obtained, showing the dependence of functionalization efficiency on two parameters: effective specific surface and content of carbon nanotubes. The sharp discrete reduction of functionalization occurs at reaching of percolation threshold of nanofiller. This means that functionalization of local structures of carbon nanotubes is more effective than functionalization of uninterrupted structures of this nanofiller. The most important mechanical property of polymer nanocomposites, namely, the reinforcement degree, is defined unequivocally by efficiency of functionalization. This approach allows making structural prediction of mechanical properties of nanocomposites polymer/carbon nanotube depending of efficiency of nanofiller functionalization.
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