Thermal Properties of Polymer-Clay-Silica Nanocomposites

3 Thermal Properties of Polymer-Clay-Silica Nanocomposites 

A major aim to prepare the polymer-nanofiller composites is to enhance the thermal stability of the materials. The thermal properties of polymer nanocomposites are usually evaluated by differential scanning calorimetry (DSQ and thermogravimetric (TG) analyses. From DSC and TG testing, the glass transition temperature (Tg) and decomposition temperature can be determined, from which the thermal properties of polymer nanocomposites can be evaluated. 

Shim and co-workers used an ultrasonically assisted in situ emulsion polymerization to prepare electrically conducting copolymer poly(aniline-co-/7-phenylenediamine) [poly(Ani-co-pPD)] and silica (Si02) nanocomposites. 

TGA and DSC curves for neat copolymer (a) and poly(Ani-co-pPD)-Si02 nanocomposite (5% Si02) (b) under nitrogen. Reproduced with permission from reference 104. 

The enhanced thermal stability of PAN-Na-MMT-Si02 nanocomposites is believed to be induced by the formation of a network structure, because the strong electronegative -CN groups in the PAN chain can interact with the Si02 particles and the exfoliated Na-MMT layers. In addition, the presence of Na-MMT can prevent the diffusion out of the volatile decomposition products because of its layer structure, which makes a further contribution to the thermal stability. Consequently, the PAN-Na-MMT-Si02 nanocomposites exhibit superior thermal stability to the PAN-Na-MMT and PAN-Si02 systems. 

---

So far, most polymer nanocomposites contain only one type of nanofiller. Recent studies revealed that combination of clay and Si02 has a more enhanced effect on the polymer matrix. In this chapter, we discuss the structure and properties of clay- and silica-based polymer nanocomposites prepared by in situ emulsion polymerization, especially polyacrylonitrile (PAN)-clay-silica ternary nanocomposites. The chapter consists of three parts (1) synthesis and structure of polymer-clay-silica nanocomposites (2) thermal properties of polymer-clay-silica nanocomposites and (3) mechanical properties of polymer-clay-silica nanocomposites. 

---