INVESTIGADORES
FRONTINI patricia Maria
congresos y reuniones científicas
Título:
Deformation, fracture, and tribological behavior of MoS2 filled HMWPE composites
Autor/es:
MARIA JOSE CHURRUCA; VALERIA PETTARIN; LAURA FASCE; PATRICIA M. FRONTINI
Lugar:
Salerno, Italia
Reunión:
Conferencia; Polymer Processing Society 24th Annual Meeting PPS-24; 2008
Resumen:
Trough this work composites based on high density polyethylene of high molecular weight (PE-HMW) modified with molybdenum bisulphide (MoS2) were prepared. Stress-strain, fracture and tribological behavior of composites was studied. The addition of MoS2 practically did not influence the coefficient of friction of PE-HMW. However, the wear rate of PE-HMW decreased with the increase in MoS2 content with an optimum content of 10% for minimum wear rate. Our results suggest that the MoS2 improved the inherent ability of PE-HMW to form a uniform transfer film, and that there was also an improved adhesion between the transfer film and the counterface. The detriment of wear resistance with large amounts of MoS2 could be attributed to the deterioration of the mechanical properties of the polymer due to a lack of physical continuity of PE-HMW matrix, which has a deleterious effect on the wear behavior of composites. Regarding stress-strain behavior the introduction of MoS2 particles into PE-HMW resulted in a sharp decrease in high strain properties (% elongation) while low strain properties (yield strength and modulus of elasticity) remained almost unaltered. These results expose that stresses are not efficiently transferred via the interface between matrix and filler. Depending on recorded load-displacement traces and the degree of plasticity developed at a crack tip (as judged from fracture surfaces), different data reduction approaches from Fracture Mechanics Theory were applied to obtain fracture toughness. The introduction of MoS2 particles into PE-HMW resulted not only in an abrupt change of fracture behavior from stable to unstable, but also in a 3 times toughness reduction under quasi-static loading conditions. Similar results were found under dynamic conditions, with fracture behavior changing from semi-ductile to brittle. Our results indicate that the usefulness of this type of composites will depend on its final application.