Probing the Confining Effect of Clay Particles On an Amorphous Intercalated Dendritic Polyester

Document Type

Article

Publication Date

3-10-2017

Department

Polymers and High Performance Materials

Abstract

The fourth generation of a hydroxylated dendritic hyperbranched polyester (HBP) was combined with sodium montmorillonite clay (Na+MMT) using water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. Analysis with differential scanning calorimetry (DSC) showed a deviation in heat capacity, ΔCp, with clay content at the Tg from a two-phase trend which was attributed to the formation of an immobilized rigid amorphous fraction (RAF) in the interlayer spacing of the intercalated system. This deviation occurred in a step-like fashion which we attributed to 0.5 nm incremental changes in the interlayer spacing, previously observed through X-ray diffraction analysis. A simple series model was utilized to quantify these interlayer spacings based on the ΔCp values and showed good correspondence with the X-ray results. The RAF was quantified from changes in heat capacity with clay content and was verified by an alternative novel positron annihilation lifetime spectroscopy (PALS) approach. The PALS quantification of the RAF was possible through an analysis of changes in the hole size thermal expansivity of the nanocomposites as a function of clay composition. Results indicated that as much as 32% by weight of the system is made up of the RAF at its maximum.

Publication Title

Polymer

Volume

112

First Page

76

Last Page

86

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