Biodegradable nanocomposites based on modified bentonite and polycaprolactone

Abstract

The main objective of this work was to obtain biodegradable nancomposites from polycaprolactone and bentonite with optimized mechanical properties by the chemical modification of the clay (cation exchange reactions). First the CEC (cation exchange capability) of the original and saturated clays was determined. Ammonium and phosphonium salts were used as modifiers at different concentrations (with respect to the CEC) and times of reactions. The modified bentonites were characterized by X-Ray and TGA (thermogravimetric analysis). No important differences were found between the original and saturated bentonites. On the other hand, for both modifiers, the interlaminar spacing increased as a function of the salt amount whereas not important changes were observed by changing the reaction time. In addition, phosphonium salt was more effective than the ammonium one. Nancomposites with PCL and 5 wt.% of original and several optimized bentonites were prepared via exfoliation-absorption using a 50% v/v mixture of dimethtylformamide and dichloromethane as solvents and the optimal preparation conditions determined in a previous work. Tensile and permeability tests were carried out and the mechanical properties were correlated with the results of the chemical modifications.