Propriedades de compósitos poliéster/juta. Influência da adição de carga mineral nanoparticulada e sistema antichama.

Abstract

The present work deals with the properties of polyester/jute composites; of the systems polyester/bentonite and polyester/jute/bentonite. The mechanical performance (tensile and impact properties) of these composites was investigated as a function of fiber content and orientation; clay content and chemical modification and system composition. The influence of a flame retarding system addition on the mechanical, thermal and burning characteristics of selected composites was also analyzed. The water sorption characteristics of some of these systems were determined. The clay was modifiied with hydrochloric acid (0.3N) and with two different quaternary ammonium salts (Dodigen and Cetremide). Both natural and modified clays were characterized by chemical analysis, FTIR spectroscopy, X ray diffraction and thermogravimetry which indicated that acid activation promoted exfoliation while quaternary ammonium salt modifications promoted organophilization. The results show composite properties to be strongly dependent on fiber orientation, being much higher in composites tested along the jute fiber axis direction. Mechanical properties higher than those of the matrix were achieved at fiber contents as low as 10% in weight. It was shown that composite properties, mainly those of elongation at break and impact strength, were dependent on clay modification. Better toughness was displayed by polyester/bentonite and polyester/jute/bentonite systems with HCI and Dodigen modified clays at 2% w/w clay contents. X ray diffraction data showed that a polyester/bentonite nanocomposite was obtained with the cetremide modified clay incorporation which led to an increase in flame resistance of the system. Only the matrix and the composite Polyester/bentonite 5% w/w with the Cetremide modified clay having 5, 6, 7,5% and 5% w/w bromine in the flame retardant system, respectively, achieved V-0 classification on the UI-94V test. The system polyester/5%bentonite natural and 5% w/w bromine in the flame retardant system achieved V-1 classification. The remainder did not achieve classification. Water sorption increased with jute fiber and with clay addition in the matrix.