Moisture dependence of the properties of composites made from tung oil based polyurethane and wood flour

MOSIEWICKI, MIRNA A.; U. CASADO; MARCOVICH, NORMA E.; ARANGUREN, MIRTA I.

JOURNAL OF POLYMER RESEARCH

SPRINGER

Lugar: Berlin, Germany; Año: 2012 vol. 19 p. 9776 - 9783

1022-9760

ABSTRACT: Natural composites prepared from a polyurethane (PU) based on tung oil and different percentages of wood flour (WF) or microcellulose (MC) were exposed to humid environments and the resulting changes of their properties were evaluated. The equilibrium moisture content of the composites increased with the wood flour percentage. Dynamic mechanical tests performed during temperature scans revealed the changes resulting from moisture absorption on the main transition temperature of the matrix as well as on the storage modulus.  The tensile mechanical properties of the materials were also strongly affected by moisture.  The different degree of dispersion achieved during the incorporation of WF and MC into the matrix was considered the main reason for the different effect of each filler on the thermal and mechanical properties of the resulting composites.    Keywords:  Natural fibers; composites; mechanical properties; moisture absorption; vegetable oils.