An Improved Test Machine for Mechanical Characterization of Linen Fibers: the Turin Shroud Dating

A recent cyclic-loads machine has been improved to better fix fibers under test by using a special support designed for the purpose. The mechanical behavior of linen fibers of three different ages are measured and compared discussing these results in reference to the complex structure of aged linen fibers; the three samples are: a linen fiber from an Egyptian mummy of 27th Century B.C.; a linen fiber coming from the TS, and a recent linen fiber. This machine allowed to confirm the previous results regarding the TS (Turin Shroud) dating, and showed that the complex non-linear behavior of the fibers is also due to the packing effect of the SCW (Secondary Cell Wall) of the linen fibers, mostly composed of micro fibrils. The stiffening of the linen fibers with the loading increasing is a property detected for all the tested fibers that must not be forgotten also in the construction of linen based composites.