Effect of the Degree of Filling on Mechanical Properties of Polymeric Specimens from Polyethylene Terephthalate Glycol and Polylactic Acid Produced by 3D Printing

Abstract

Based 3D printing has become very popular in recent years due to the emergence of projects for low-cost machines, making the technology very accessible. In view of this, some polymers, in general, in thermoplastic filaments, are placed on the market for application in this type of printing technique, making it increasingly necessary to develop research for the characterization of materials to provide information on physical, thermal and mechanical properties. For the development of this work, the polymer poly(ethylene glycol terephthalate) (PETG) was used for a comparative study in relation to poly(lactic acid) (PLA). PETG is obtained by adding modified glycol to the material composition during the polymerization process. It consists of a polymer with a glass transition temperature close to 80°C, with mechanical properties similar to those of PET, with the advantages of notable tenacity, flexibility, and high processing capacity, and PLA is a polymer synthesized from corn sugar, potatoes, and sugar cane, through bioconversion and polymerization. PLA presents biocompatibility, biodegradability, and biological absorption, presenting good mechanical properties, processability, thermal stability and low environmental impact. Mechanical tests of compressive strength and flexural strength were carried out. In the compressive strength test, the specimen with 100% filling presented a deformation 76% greater than the specimen with 50% filling. This can be attributed to the mechanical property of the PETG polymer, as it is very ductile, thus facilitating the processability of this artifact. The mechanical flexural strength tests carried out with the PLA polymer with the highest filling percentages (100% and 50%) showed less deformation until failure, characterizing them as more ductile materials. On the other hand, specimens with 30% filling showed ~215% greater deformation than specimens with 100% filling. With this, it can be seen that PLA has greater flexibility and tenacity for fillings of low percentages, due to the internal spacing absorbing the impact of loads. The PLA polymer showed better mechanical properties, such as Young's modulus, ductility and more satisfactory resistance when compared to the PETG polymer. As well as the synthesis of PLA, it characterizes the process in a more sustainable way, as it is a biopolymer, in addition to its excellent processability.