Structure Property Correlation of Thermally Treated Hemp Fiber

Summary: Hemp (Cannabis sativa L.) is an important ligno‐cellulosic raw material for the manufacture of cost‐effective environmentally friendly composite materials. Hemp plant samples of different initial condition (stem and bast fibers) were subjected to heating varying the temperature (from 160 to 260 °C) and the ambient heating environment (air and inert atmosphere). Weight measurements showed that all heat treatment resulted in a reduced weight of hemp. Those treated in air showed drastic decline in weight compared with those treated under nitrogen, especially at a temperature higher than 220 °C. Observation using optical and scanning microscope showed the possibilities of opening up of the fiber bundles in both heating environments. However, higher temperature and presence of air had a more severe effect on fibers and associated tissues compared to effects under nitrogen. Heat treatment at 220 °C under nitrogen seemed to provide enough fiber opening without affecting tissues of the fibers. SEM micrograph of the cross‐section of hemp fiber heat treated in air environment. magnified image SEM micrograph of the cross‐section of hemp fiber heat treated in air environment.