Comparison of wood fiber reinforced PLA matrix bio-composites produced by Injection Molding and Fused Filament Fabrication (FFF) methods

Abstract

Plastic materials have a variety of chemical and mechanical properties that will be useful for a wide variety of applications. However, plastic waste creates pollution and poses a great threat due to the problem of non-degradability affecting ecological environments. Thermoset polymers, which are used extensively in the polymer industry today, have recycling problems. This situation creates serious environmental problems. The most important feature of thermoplastic materials is that they can be recycled. The use of thermoplastic polymers creates significant advantages in recycling and environmental issues. The rapid evolution in additive manufacturing provides a new path to the circular economy using recycling. Thermoplastic or thermoset materials can be processed in additive manufacturing. Additive Manufacturing Methods (AM) are used today in different industries to produce prototypes and even final products. The polymer material is used in 51% of the parts produced with AM. The Fused Filament Fabrication (FFF) method is the most popular method preferred for shaping polymers with AM. The FFF method is a method of extruding a spool of thermoplastic filament through a heated nozzle and melting the material. Also, FFF is known to have low cost and high printing speeds compared to other AM techniques. PLA material, which is a completely bio-based thermoplastic polymer with many desirable properties, including easy processing ability, strength, hardness, and biodegradability, is widely used in material processing by the FFF method. In this study, the PLA matrix was reinforced with natural fibers to increase the mechanical properties and contribute to recycling. Bio-composite compounds with 15% wood fiber reinforced PLA matrix by weight were prepared. Specimens’ productions were carried out using bio-composite materials, the FFF method, and injection molding methods. Thermal analyzes of the prepared compounds, filaments, and produced specimens were carried out. A decrease in the Tg value of the compound reinforced with natural fiber was observed, while an increase in the Tm value was observed. The Tg value of the specimens produced by the FFF method increased compared to the injection specimens. In addition, the mechanical properties of the specimens produced by FFF, and the injection molding method were compared. It was determined that the stress at break values of the specimens produced by injection were 2 times higher than the specimens produced by FFF. The impact strength of the specimens produced with injection molding is 51.75% higher than the specimens produced with FFF. The bio-composite materials produced in the study were examined under scanning electron microscopy (SEM). Surface interactions and homogeneous fiber distribution between matrix and fiber were investigated.