Permeability polypropylene nanocomposites

Incorporation of silicate nanolayers in semi-crystalline polymers like polypropylene ean have a two-fold effect on the barrier properties, (1) well oriented large aspeet ratio platelets will increase the tortuosity of the diffusion path and (2) the nanolayers will affect the crystalline order (size and interlamellar spacing) and possibly affect the barrier properties. The extent of orientation is greater in blown film than in extmsion cast film and this leads to similar trends in barrier properties of polypropylene nanocomposites with 7wt.% 1.3 IPS (silated) clay as reported by Qian et al. With cast films, the nanoeomposite had a lower permeability to oxygen by a faetor of 1.5 compared to neat polypropylene. With blown films, the nanocomposite permeability to oxygen was lower by a factor of 2.5 compared to neat polypropylene. However, Ellis and D Angelo were able to prepare only intercalated polypropylene nanocomposites with the same 1.31 PS and obtained no improvement in permeability to a solvent over that for neat polypropylene. This underlines the greater sensitivity of barrier performanee to the level of dispersion and orientation. 

This section describes the mechanical characteristics, dynamic viscoelasticity characteristics, and gas permeability characteristics of a modified polypropylene-clay nanocomposite [35]. C18-Mt was used as the organophihc clay, and P01015 was used as the maleic anhydride-modified polypropylene. 

C18-Mt was used as the organophihc clay. Table 11 shows the composition of this nanocomposite. Figure 34 shows the X-ray diffraction patterns of the materials. The clay was uniformly dispersed, as shown. Tables 12 and 13 show the mechanical characteristics and the nitrogen gas permeability characteristics, respectively [37]. Materials with high rigidity and high gas barrier characteristics were obtained, as in the case of polypropylene. 

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