INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
DISTRIBUTION OF MECHANICAL PROPERTIES IN INJECTION MOLDED PARTS OF PP NANOCOMPOSITES AND PP MICROCOMPOSITES BY DEPTH SENSING INDENTATION
Autor/es:
L.A. FASCE; P.M. FRONTINI
Reunión:
Congreso; 11º Congreso Binacional de Metalurgia y Materiales, SAM CONAMET 2011; 2011
Resumen:
In this work the distribution of reduced elastic modulus (Er) and hardness (H) in the skin-core regions of injection molded parts made of PP homopolymer, PP-clay nano-composites, PP-glass fiber micro-composites and ternary PP-clay-glass fiber hybrid-composites were assessed by means of depth sensing indentation technique. The properties of the skin and core regions of the injection molded PP part are similar. Nanocomposites become stiffer and harder than PP due to the expected reinforcement effect of the organoclay. However, enhancement in properties appears to be independent on the PP/organoclay masterbatch concentration. The incorporation of 2wt% PP/organoclay masterbatch is enough to promote the achievable changes in mechanical properties. The incorporation of clay during molding promotes a big differentiation in the properties of the skin and core regions. Remember that hardness is directly related to the yield stress of the material by a constraint factor, so an increase in hardness is related to an increase in yield stress. The enhancement in properties is larger in the core region than in the skin zone of the nanocomposites. PP/GF microcomposites are, as expected, stiffer and harder than PP samples. Elastic modulus and hardness values increase while increasing the glass fiber content. However, taking into account that the reduced elastic modulus of the glass fiber is about 70GPa, GF/PP microcomposites do not exhibit property improvement according to the rule of mixtures. A large differentiation on properties between the skin and core regions develops, being the core stiffer and harder than the skin especially at the highest glass fiber concentration. Hybrid composites show the same distribution pattern and display the highest elastic modulus and hardness values. It appears that the increment in mechanical properties exhibited by the hybrid composites is the addition of PP/clay and GF contributions in the skin as well as in the core regions.