Luciana A. Castillo

Thermoplastic starch films reinforced with talc nanoparticles

Nanocomposite films of thermoplastic corn starch (TPS) with talc particles were obtained by thermo-compression in order to study the effect of filler on structure, optical, and thermal properties. Talc increased the films rigid phase, thus their cross-sections resulted more irregular. Talc preferential orientation within matrix and good compatibility between particles and TPS was observed by SEM. Slight crystalline structure changes in TPS matrix were measured by XRD and DSC, due to talc nucleating effect. Randomly dispersed talc nanoagglomerates and individual platelets were assessed by TEM. Laminar morphology and nano-sized particles allowed that nanocomposite films were optically transparent. TPS-talc films resulted heterogeneous materials, presenting domains rich in glycerol and others rich in starch. Talc incorporation higher than 3%, w/w increased softening resistance of the nanocomposites as stated by DMA. Relaxation temperatures of glycerol-rich phase shifted to higher values since talc reduces the mobility of starch chains.

Use of talc as low-cost clarifier for wastewater

Talc is proposed as a low-cost mineral for wastewater clarification. In this sense, adsorption of methylene blue (MB) from aqueous solutions was studied comparatively by using sepiolite (qualified as very good adsorbent) and two talc samples with different particle size and purity degree. The MB adsorption was assessed by determining remnant dye in the supernatant using UV-vis spectroscopy and by detecting dye adsorbed on mineral samples through thermogravimetric analysis and infrared spectroscopy. Both isothermal curves and kinetic studies demonstrate that talc is a good dye adsorbent. Particularly, with dye concentrations similar to those of textile wastewater, talc was demonstrated to adsorb the same dye content of sepiolite at similar times. Natural talc could be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes.

Polypropylene/talc nanocomposites films as low-cost barrier materials for food packaging

Abstract Over the past few decades, materials based on polymers and silicate minerals have become one of the most promising nanocomposites, having suitable characteristics and properties which could be satisfactorily used in packaging development. However, the processing of these materials to obtain films for flexible packaging is a challenge and the key to their success. In this work, polypropylene/talc nanocomposite films up to 5% w/w of talc were obtained by blown extrusion. A detailed analysis of structure and final properties of films were performed, focusing mainly on their application on food packaging. Tensile tests, tear resistance, and thermosealing capacity were determined. Important issues in the packaging field, such as color, UV-barrier capacity, and gas permeability were examined. Packaging bags made from nanocomposite films were obtained by thermosealing the package and storing several fruits under controlled temperatures and relative humidity to demonstrate the feasibility of using them in food packaging.