Efeito de sais quaternários de amônio na organofilização de uma argila bentonita nacional para o desenvolvimento de nanocompósitos de polietileno de alta densidade (PEAD).

Abstract

High density polyethylene (HDPE)/Bentonite clay nanocomposites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary salts of ammonium to obtain the organoclay. Chemical analysis, X-ray fluorescence (XRF), infrared spectroscopy by Fourier Transform (FTIR), X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM) were used to characterize the clays. The unmodified and modified clays with the quaternary salts of ammonium were introduced in several quantities in a HDPE matrix using a twin screw extruder. The thermal stability and the flammability of the systems were investigated by thermogravimetry and UL-94HB standard, respectively. The dispersion analysis and the interlayer distance (dooi) of the clay particles were obtained by XRD and transmission electron microscopy (TEM). Mechanical properties of tensile and impact of the nanocomposites were studied too. The results showed that the salts were incorporated in the clay structure, confirming the organophilization. The organoclay presence in the polymer matrix increased the systems degradation temperature in relation to the pure polymer. In general, the mechanical properties of the systems presented superior values compared to the matrix and the modified clay type affected the properties. The systems showed a reduction on the burning rate, indicating that the flammability resistance of nanocomposites was improved. For comparison, two types of commercial flame retardants were used in HDPE to evaluate the flammability and they showed that the HDPE/organoclay system was more efficient.