Structure-Property Relationships of Nanocomposites

Rameshwaram, J. K., Yang, Y.-S., and Jeon, H. S. 2005. Structure-property relationships of nanocomposite-like polymer blends with ultrahigh viscosity ratios. Polymer 46 5569-5579. 

A morphological characteristic, which is of fundamental importance to the understanding of the structure-property relationship of nanocomposites, is the surface area/volume ratio of the fillers [37]. As illustrated in Fig. 1, the change in particle diameter, layer thickness, or fibrous material diameter from micrometer to nanometer changes the surface area/volume ratio by three orders of magnitude. At this scale, there often is a distinct size dependence of the material properties. In addition, the properties of the composite became dominated by the properties of the interface or interphase when the interfacial area drastically increased. 

Table 10.2 presents a summary of the properties reviewed in this chapter according to the type of carbon nanofillers used. The enhancements provided by these nanomaterials are diverse indicating that there are still many challenges for explaning the structure-property relationships of carbon-based polymer nanocomposites. 

In the case of polymer nanocomposites, measurements of melt rheological properties are not only important to understand the processability of these materials but are also helpful in determining the strength of polymer-filler interfacial interactions and the structure-property relationships in nanocomposites. This is because rheological behaviors are strongly influenced by the nanoscale structure and interfacial characteristics. 

C. Manzi-Nshuti, D. Chen, S. P. Su, and C. A. Wilkie, Structure-property relationships of new polystyrene nanocomposites prepared from initiator-containing layered double hydroxides of zinc aluminum and magnesium aluminum. Polymer Degradation and Stability, 94 (2009), 1290-97. 

Structure-Property Relationship of Polymer Nanocomposite Foams.101... 

STRUCTURE-PROPERTY RELATIONSHIP OF POLYMER NANOCOMPOSITE FOAMS... 

A well-accepted definition of nanocomposite material is that one of the phases has dimensions in the order of nanometers [51]. Roy et al. [52] present in their paper on alternative perspectives on nanocomposites a summary of features of particle properties when particle size decreases beyond a critical size. As dimensions reach nanoranges, interactions improve dramatically at the interfaces of phases, as do the effect of surface area/volume on the structure-property relationship of the material [53]. There is definite increase in the modulus of the material reinforced with composites, higher dimensional stability to thermal treatment, as well as enhanced barrier, membrane (conductive properties) and flame resistance. Thus, as Paul and Robeson [54] rightly put it, the synergistic advantage of nanoscale dimensions ( nano effect ) relative to larger-scale modifications is an important consideration ... 

Little further activity is found in the literature until the advent of the importance of exfoliated layered clays in the dramatic enhancement of polymer mechanical performance at low concentrations was reported [2]. Subsequent systematic evaluations of the thermal stability of polymer-clay nanocomposites were initiated by Jeff Gilman s group at NIST and Emmanuel Giannelis group at Cornell, with remarkable results. This work led to a dramatic increase in scientific investigations focused on the structure-property relationships of polymer-clay nanocomposites to thermal stability and flame retardancy. 

The results of work on PO/clay nanocomposites are summarized in Table 13.1. The preparation and properties of and issues underlining the structure-property relationships in nanocomposites based on various POs and clays have been systematically reviewed. It was observed that the non-polar nature of POs necessitates the usage of a compatibilizer such as an anhydride or the presence of acidic or ionic groups to improve the matrix polarity. Incorporation... 

Structure-property relationships of polypropylene nanocomposite fibres... 

The unexpected beneficial behavior of nanocomposites is due to filler/matrix and filler/filler interactions. Owing to the huge specific surface of well dispersed nanoparticles, it is often quoted that the properties of nanocomposites are controlled by interface/interphase characteristics. The distinction between interface and interphase depends on whether or not this region has a finite thickness. Polymer nanocomposites are already commercialized, e.g., films of improved barrier properties and low-density injection moldable resins with high heat distortion temperature. Although the structure-property relationships in nanocomposites are poorly understood, the... 

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