Evaluation of Thermal Properties of Nanocomposites Based on Ecobras Matrix and Vermiculite Modified with Alkylphosphonium Salt

摘要

The use of biodegradable polymers to produce nanocomposites with mineral fillers leads to the production of new materials with low cost and reduced environmental impact, combined with improvements in mechanical and thermal properties. Nanocomposites based on poly(butylene adipate-co-terephthalate) and starch blend (Ecobras) and vermiculite (VMT) modified with hexadecyltributyl- phosphonium bromide (P-VMT) were prepared by melt intercalation in a mixing chamber at 140 ° C, keeping the amount of clay at 4%wt. The intercalation of P-VMT in Ecobras was characterized by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). VMT organophilization was confirmed by the appearance of FTIR bands characteristic of the long alkyl chain of the phosphonium salt used and also by displacement of the basal peak towards lower 2θ values in the diffractogram compared to pure vermiculite. The thermal properties of Ecobras and its compositions were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of VMT and P-VMT in Ecobras increased the crystallization temperature (T_c) and crystalline melting temperature (T_m), as observed by DSC analysis. The result of the thermogravimetric analysis showed that the addition of P-VMT in Ecobras improved thermal stability of the nanocomposite. The Young's modulus of the composite with 4 wt% of P-VMT indicated an increase in stiffness compared to the pure matrix.