Fracture toughness and creep performance of PMMA composites containing micro and nanosized carbon filaments

Chopped carbon fiber (CCF), multiwall carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) were introduced to polymethylmethacrylate (PMMA) via melt compounding. Fracture toughness and creep performance of these composites are presented. A constant volume concentration of 1 vol.% was used. Dispersion was evaluated on both micro- and nano-scales. Flexural modulus was also measured.Composite behavior was found to differ both between fillers and studied property; fracture toughness or creep resistance. While MWCNTs and CNFs did not increase fracture toughness, they did improve creep resistance. Here, MWCNTs had a more significant effect. CCFs were the only fillers that improved fracture toughness. Their effect on creep was less significant than MWCNTs. Analysis of the data in this study suggests that carbon nanofilaments function mainly to resist crack initiation rather than propagation in the PMMA matrix.