New gentle extraction method of hemp bast strips for use as bio-based reinforcing fibers in highly loaded fiber composites

Abstract

Nowadays, fiber composites are among the most important construction materials in lightweight design. Increasingly, attempts are being made to replace fossil raw materials with bio-based materials in order to improve their recyclability and reduce greenhouse gas emissions. While processes suitable for industrial use already exist for the production of biopolymers as matrix materials, there is still a considerable need for research in the production of bio-based reinforcing fibers. For hemp bast strips (HBS), promising utilization options arise due to very good mechanical properties. However, current processes for extracting such raw materials from bast fiber plants result in damage to the fiber structure because they use biochemical decomposition processes and/or squeeze and crush large disordered amounts of stalk along their entire length. This strongly reduces the application potential of the raw materials. A newly developed principle extracts the HBS with minimal impact by dividing single hemp stalks only at one end and then isolating them from the wood core by pulling on the resulting wood fragments. In this manner, the fiber structure and the good mechanical properties are largely retained and the HBS obtained can be stored in parallel alignment for further processing with little effort.