| dc.description.abstract | The need for inexpensive, sustainable, and environmentally friendly materials has significantly increased in recent years as a result of rising environmental awareness. Given the widespread usage of petrochemical plastics, which are frequently reinforced with synthetic fibers to improve their functionality, there is a noteworthy potential for natural fibers to be employed as a feasible substitute in reinforcement applications. When incorporated into a thermoplastic matrix, natural fibers present a structural material that possesses not only strength and other mechanical properties but also demonstrates environmental friendliness due to its renewability. Within the wide range of natural fibers, industrial hemp fiber distinguishes itself as a highly robust and rigid alternative. Hemp fibers provide composite materials with distinct characteristics that are comparable to those exhibited by conventional synthetic fiber composites.
This research focused on developing hemp fiber-reinforced polypropylene composite materials. The pelletization of hemp fibers was a crucial step in this research, which aimed to improve their ease of handling, storage, and feeding in extruders along with polypropylene pellets. The present research also extensively investigated the impact of different variables on the mechanical properties of hemp pellets and the subsequent composites. These variables included the use of different particle sizes, the use of additives to enhance fiber dispersion in composites, the application of coupling agents, the alkali treatment of hemp fibers, different composition mixes of bast and hurd fibers, and a comparative analysis of composites prepared with hemp fibers obtained from different suppliers from different countries such as USA, Canada, and Paraguay.
The research revealed a noteworthy correlation between the size of fibers and the overall performance of the composite material. The flexural modulus exhibited a steady upward trend as the size of fibers increased from 1 mm to 3 mm, whereas the tensile modulus reached its highest point with a 1.5 mm fiber size. The use of wax additives did not yield any significant impact on the mechanical properties of the composites. Moreover, by performing NaOH treatment of hemp fibers, the moisture absorbance of fibers was reduced and composites with NaOH-treated fiber demonstrated enhanced mechanical properties in comparison to composites with untreated fibers. However, composites with MAPP coupling agent exhibited better properties than NaOH-treated fiber composites. A comparison of different proportions of bast and hurd fibers in the pellets and composites showed that an increase in bast fiber concentration correlated with an increase in mechanical properties.
These above-mentioned findings function as a guiding principle for customizing polypropylene composites reinforced with hemp fiber to meet specific performance requirements. Lastly, a comparison between glass fiber and hemp fiber reinforced polypropylene composite was made and it was found that composites reinforced with 20% hemp fiber exhibited superior flexural and tensile properties than 10% glass fiber reinforced composites. | en |
