Negative Poisson ratio of crystalline cellulose in kraft cooked Norway spruce.

The tensile properties of kraft cooked Norway spruce were studied by tensile testing with in situ X-ray diffraction (XRD). Samples were of earlywood, cooked for varying times. The total lignin content of the samples was between 21.

Mechanical properties of cellulose fibres and wood. Orientational aspects in situ investigated with synchrotron radiation.

Highly oriented native cellulose fibres (flax) and softwood (pine) have been investigated by means of X-ray diffraction. Local structural information was obtained by using X-ray microbeams. Tensile tests were performed in situ, revealing a change of orientation of cellulose microfibrils in materials with tensile strain.