5. Conclusions
This paper has demonstrated that the EWF method can be
applied to pre-notched miniature specimens, because the basic
principles for the application of the method, the most important
being self-similar load–displacement curves, are met. Besides that,
upper and lower limits for the ligament length of P-SPT specimens
have been established. Although the P-SPT specimen failure mode
is not achieved purely in uniaxial traction, the specific essential
work of fracture term can be compared with that obtained in
DDEN-T specimens we. As a main conclusion, it has been found that
the weP-SPT value in pre-notch SPT specimen is approximately three
times that of the we value for the polypropylene polymer analyzed.
Obviously, this conclusion cannot be extended to other polymers,
and more research is needed to know the behavior of other types
of polymers, but this paper represents a first step in the determination
of the specific essential work of fracture from miniature specimens
when there is not enough material to perform standard
tests.