Mechanical and Thermal Properties of Rotational Molded PE/Flax and PE/Hemp Composites

The article describes the investigation of the mechanical and thermal properties of polymer composites with flax or hemp fibers and polyethylene matrix (LDPE and LLDPE) with and without the maleic anhydrite as a compatybilizer. Also for increase the flammability resistance the 3 types of special flame retardants (5% by weight) were used as modifiers in the study. The composites with 3 and 5% by weight of flax and hemp fibers in the LDPE matrix have been prepared using a twin screw extruder, pulverizer and rotational molding machine. The influence of the flax and hemp content on mechanical and thermal properties (tensile test, DSC, Vicat softening temperature and UL 94 test) of obtained polymer composites has been presented. Also the structure of the prepared composites has been studied using the scanning electron microscopy - SEM. On the basis of the obtained results, it was found that modification of LDPE with flax or hemp fibers in the analyzed concentration range causes small improvement or does not significantly affect the tested properties of LDPE polymer. The use of flame retardants in the amount of 5% for most composites has a positive effect on flame retardancy. The study shows also that big differences in tested properties compared to unfilled LLDPE are visible for composites based on the LLDPE matrix with maleic anhydride. The presented preparation method and properties of obtained materials confirms the possibility of using this type of composites in production of rotational molded parts.