Effect of Drying Methods on the Physical and Structural Changes in Oil-Seed Flax Fiber

With the growing environmental concerns, biodegradable materials are gaining more importance. Biocomposites which are made from a combination of biological fiber such as flax and hemp together with plastics are finding a good number of applications in day to day life. Flax has good physical and mechanical properties that can be utilized in areas like construction, biomedical & bioproducts and electronics applications. The quality of fiber depends upon various unit operations used in the processing. Drying is one of the most important unit operations which significantly affect the quality of the fiber. The method of drying for removal of moisture from the fiber significantly affects the drying time and quality. In the present study the raw flax fiber was subjected to drying before and after chemical treatment. The physical properties such as; tensile strength, color and structural changes were measured for raw and chemically treated flax fibers. The diameter range was in-between 30-300 μm the tensile strength recorded for the entire range and was found to vary between 16 to 667 MPa and the elastic modulus values in the range of 2 GPa up to 63 GPa. The tensile strength and elastic modulus of untreated and treated fiber did not show any significant change. High power levels for longer period indicated some black spots due to localized heating. Differential scanning calorimetric data indicated that the degradation temperature of cellulose was found 350(± 10)°C for the treated and dried flax fiber. Among the drying methods microwave-vacuum took more time compared to microwave but could remove the moisture to less than 1%. The maximum moisture removal using microwave-vacuum was achievable because fibers were dried for a longer period of time at comparatively low temperature.