Scientists at Oxford University and The University of Sheffield have demonstrated that natural silks are a thousand times more efficient than common plastics when it comes to forming fibres. A report of the research is published this week in the journal Advanced Materials.
The finding comes from comparing silk from the Chinese silkworm (Bombyx mori) to molten high density polyethylene (HDPE) – a material from which the strongest synthetic fibres are made. The researchers used polarised light shining through a disk rotating over a plate to study the how fibres are formed as the two materials are spun.
HDPE forms filaments at over 125 C and in addition requires substantial energy input in the form of “shear force” applied to the material in its molten form. Silks, in contrast, in the same set-up forms filaments at ambient temperature and in addition requires only a tenth of the shear force. If the energetic costs of melting HDPE are included for comparison, silks become a thousand times more efficient.
The discovery of low-energy method for fibre formation has led the researchers to view silks as a new class of polymers they call ‘aquamelts’.