On the toughness of thermoplastic polymer nanocomposites as assessed by the essential work of fracture (EWF) approach

Abstract

The essential work of fracture (EWF) approach is widely used to determine the plane stress fracture toughness of highly ductile polymers and related systems. To shed light on how the toughness is affected by nanofillers EWF-suited model polymers, viz. amorphous copolyester and polypropylene block copolymer were modified by multiwall carbon nanotube (MWCNT), graphene (GR), boehmite alumina (BA), and organoclay (MMT) in 1 wt% each. EWF tests were performed on deeply double-edge notched tensile-loaded specimens under quasistatic loading conditions. Data reduction occurred by energy partitioning between yielding and necking/tearing. The EWF prerequisites were not met with the nanocomposites containing MWCNT and GR by contrast to those with MMT and BA. Accordingly, the toughness of nanocomposites with homogeneously dispersed and low aspect ratio fillers may be properly determined using the EWF. Results indicated that incorporation of nanofillers may result in an adverse effect between the specific essential and non-essential EWF parameters.

Keywords:

• toughness
• nanocomposite
• thermoplastics
• essential work of fracture

Acknowledgements

This work was performed in the framework of a bilateral cooperation agreement between Italy and Hungary (TéT_10-1-2011-0218). This work is connected to the scientific program of the ‘Development of quality-oriented and harmonized R+D+I strategy and functional model at BME’ and to the New Széchenyi Plan (Projects IDs: TÁMOP-4.2.1/B-09/1/KMR-2010-0002, TÁMOP-4.2.2.B-10/1-2010-0009 and TÁMOP 4.2.4. A/1-11-1-2012-0001).