ABSTRACT
Polymer nanocomposites (PNCs) formed by dispersing a few weight percent or less of nanometer-sized „llers, such as carbon nanotubes and mont morillonite (clay), in either thermoplastic or thermosetting polymers are now commonly available. Compared to “neat” polymers, PNCs tend to have higher tensile and ¥exural moduli, improved barrier properties, and enhanced ¥ame resistance, among other properties. It is for this reason that they are of great research and commercial interest in many „elds (Gupta et al. 2010). This chapter is concerned with the study of molecular diffusion of small molecules through PNCs. This situation is encountered in food packaging where PNCs help to prolong shelf life, by preventing oxygen ingress into foods such as ketchup, beer, and juice; by stopping carbon dioxide loss from carbonated beverages; or by preventing moisture
CONTENTS
14.1 Introduction ................................................................................................ 467 14.2 Diffusion through Polymers .................................................................... 469 14.3 Moisture Diffusion through VE as a Polymer Matrix .......................... 472 14.4 Theories of Diffusion through PNCs ...................................................... 474 14.5 Studies on Diffusion through Polymer/Clay Nanocomposites ..........477 14.6 Literature on Graphene-Based PNCs ......................................................480 14.7 Studies on Diffusion through GPNCs .................................................... 482 14.8 Conclusions and Future Outlook ............................................................ 491 Acknowledgment ................................................................................................ 491 References ............................................................................................................. 491
from reaching baked goods. In addition to food packaging, PNCs are utilized to develop more durable tennis balls, protective gloves, as well as coatings for tubing, fuels, and chemical tanks, and a pressure retention layer for tire applications (Goldberg et al. 2004). Moreover, they are applied in composite bridge decks in order to exclude moisture diffusion into „ber-reinforced polymers, since the presence of moisture can deteriorate the long-term durability and performance of composites (Rana et al. 2005; Ravindran and Gupta 2006; Shah et al. 2002). As a consequence, quantitatively predicting the reduction in diffusion is both fundamentally important and a practical necessity. Indeed, there is now substantial literature on this topic (Azeredo 2009; Beall 2001; Bharadwaj et al. 2002; Bhattacharya et al. 2011; Choudalakis and Gotsis 2009; Dunkerley and Schmidt 2010; Herrera-Alonso et al. 2009; Jacob et al. 2008; Lu and Mai 2007; Maji et al. 2010; Minelli et al. 2011; Petrovicova et al. 2000; Paul and Robeson 2008; Priolo et al. 2010; Sorrentino et al. 2005; Sun et al. 2008; Tortora et al. 2002; Takahashi et al. 2006; Xu et al. 2006; Yano et al. 1993).
