Variation in physical and mechanical properties of hemp stalk fibers along height of stem

Industrial hemp bast fiber is a widely used natural fiber and its stalk is a low-density, soft material and generally considered as waste and by-products. In this study, the physical and mechanical properties of hemp stalk at different locations on the hemp stem were assessed, and the mechanical properties of hemp stalk fiber cell walls were evaluated by nanoindentation. The samples were taken from five locations, from the bottom to the top of a hemp stalk, and labeled a, b, c, d, and e, respectively. The results show that the fiber size, the relative degree of crystallinity, and the mechanical properties of hemp stalk fiber were different in the different parts of the hemp stalk that were sampled. The MFA (micro fibril angle) was almost the same in different parts of the hemp stalk, except for part b. The mechanical properties (elastic modulus and hardness) of the fiber cell wall in the midsection were larger than those of the fiber cell wall at the bottom and top parts of the hemp stalk. The mechanical properties of the hemp stalk fibers cell wall were also found in general to be lower than those of softwood, hardwood and other agriculture crops’ cell walls.

► The different parts have great influence on the properties of hemp stalk fiber. ► No marked relationship between the physical and mechanical properties of hemp fiber. ► The mechanical properties of hemp stalk fiber in middle part are highest. ► Mechanical properties of hemp stalk fiber cell wall are lower than those of other fiber. ► Test the mechanical properties of fiber cell wall, the location of it should be known at first.