Characterization of sustainable biocompatible materials based on chitosan: cellulose composites containing sporopollenin exine capsules

Abstract

In this work, photothermal beam deflection spectrometric technique (BDS) is applied for non-contact and non-destructive characterization of chitosan (CS): cellulose (CEL) biocomposites with incorporated sporopollenin exine capsules (SEC). The objective was to determine the structural and thermal properties of synthesized CS:CEL:SEC composites with varying amounts of SEC, and to validate the BDS by photopyroelectric calorimetry (PPE) as an independent technique. It was found that CS:CEL biocomposites without SEC exhibit low porosities, which are on the order of 0.005 %, but can be increased by augmenting the content of CEL in the composite and/or by incorporation of SEC. By increasing the SEC content of CS:CEL composites to 50 % (w/w), the porosity increased up to 0.17 %. SEC also increases the surface roughness of biocomposite by over 2000-times to reach the roughness amplitude of 6 μm in composites with 50 % SEC. The thermal conductivities of investigated biocomposites were in the range of 40-80 mWm^-1 K^-1, while the thermal diffusivities were on the order of fractions of mm²s^-1. With first validation of BDS results for thermal properties of CS:CEL-based composites, which show agreement with PPE results to within 5 %, this study confirms BDS technique as a perspectives tool for non-destructive characterization of CS:CEL:SEC biocomposites.

Keywords: Biocomposite materials; Chitosan:cellulose composites; Photothermal beam deflection spectrometry; Porosity determination; Sporopollenin; Thermal properties.