Table 2.

Literature review on hemp fiber reinforced polyethylene composites, based on injection mould production.

Materials	Composite Manufacturing	Research Achievements	Ref.
–Polyethylene: Dow TM 12450N Health, melt flow index, 12 g/10 min (230 °C/2.16 kg) and density, 0.95 g/cm3; –Short hemp fibers; –Coupling agents: (1) Epolene C-26 and (2) DupontTM Fusabond WPC-576D.	–(1) composites were compound in twin-screw extruder; –(2) Cut in small pellets; –(3) The pellets were injection moulded at 190 °C.	–The addition of coupling agent on composites resulted in a decrease of water absorption and reduction of flexural yield strength.	[17]
–Polyethylene: AT 418, melt flow index, 12 g/10 min (230 °C/2.16 kg) and density, 0.916 g/cm3; –Short hemp fibers and other five natural fibers; –Coupling agents: Fusabond MB265D.	–(1) composites were compound in twin-screw extruder; –(2) Cut in small pellets; –(3) The pellets were injection moulded.	–The tensile modulus increased and the strain at failure as well as the impact strength decreased with increasing of hemp fiber content in the composites. –At 40 wt% of hemp fiber, composites had a tensile strength of 12.2 MPa. –Coupling agent was found to significantly increase the mechanical performance and reduce water absorption.	[25]
–Polyethylene: recycled high density polyethylene, melt flow index, 0.45 g/10 min (190 °C/2.16 kg) and density, 0.98 g/cm3; –Alkali treated hemp fibers: 5% NaOH solution	–Composites were manufactured by using a single-screw extruder and injection moulding process.	–Composites with 40 wt% alkali treated hemp fiber had the best mechanical properties: tensile strength, tensile modulus, flexural strength and flexural modulus.	[26]