The aim of this study is to simultaneously improve the mechanical strength and fracture toughness properties of recycled poly(ethylene terephthalate) (r-PET). For this purpose, Joncryl^® was used as chain extender and Lotader^® was used as impact modifier. The combined effect of chain extender and impact modifier on the chemical, fractural, mechanical, and thermal properties of r-PET was investigated. Fourier transformed infrared spectroscopy (FTIR) analysis, EWF analysis, tensile test, and differential scanning calorimetry (DSC) analysis were performed. FTIR analysis revealed that all the epoxy groups in the Joncryl^® were consumed during the compounding. EWF results showed that while toughness of r-PET decreased with the addition of Joncryl^®, toughness was increased with addition of impact modifier Lotader^®. It was found that 2.5% Lotader^® usage at the same time with Joncryl^® increased the tensile strength of r-PET as well as toughness. It was observed from DSC analysis that chain extender and impact modifier addition did not change the thermal transition temperatures of r-PET.

Fused deposition modeling (FDM) method is a commonly used additive manufacturing technique in various industries. It is crucial that the parts produced using this method meet the necessary service conditions. To achieve this, the study employed the ‘print‐pause‐print’ technique to produce laminated composite materials. Mechanical, tribological, and morphological properties of PETG and ABS samples with various layer configurations are investigated in this study. The samples underwent tests for tensile strength, three‐point bending strength, Shore D hardness, and adhesive wear. Scanning electron microscope images were taken of the resulting fractured and worn surfaces. The results obtained were used to determine the suitability of the two materials for simultaneous production. In addition, results were examined to understand the relation of adhesion between the layers, their strength, and tribological properties. In consideration of the tensile and flexural strengths, the group with PETG material in the middle demonstrated the most significant enhancement in comparison with the base materials. In the tensile test results, specimen APA_171 with one layer of ABS on both outer surfaces and seven layers of PETG inside exhibited a strength of 33.6 MPa. The synergistic effect arising from the combination of ABS and PETG during manufacturing resulted in enhanced hardness values and modulus, which exhibited a similar trend. In the wear and hardness tests, the APA_171 sample demonstrated the highest hardness and the lowest coefficient of friction. The results showed that ABS and PETG materials are suitable for simultaneous production in the FDM method, with some composite types exhibiting good adhesion between layers, increased strength, and wear resistance compared to base materials.Highlights: ABS/PETG materials are suitable for simultaneous production in the FDM method. There are types of ABS/PETG composites that show good adhesion between layers. ABS/PETG composites produced by the FDM method can be used for functional applications.

The objective of this study is to improve the properties of polylactic acid (PLA), a biopolymer produced from renewable resources, without compromising its environmentally friendly “natural composite” properties. The aim was to expand the application range of PLA by making it suitable for the production of high performance composites. With this in mind, it was decided to use inorganic and environmentally friendly materials such as basalt fiber (BF) and boric acid (BA) as reinforcements. Adhesive wear and tensile tests were used to investigate the tribological and mechanical performance of the composites. Differential scanning calorimetry (DSC) and dimensional stability analysis (DSA) methods were used to investigate the thermal properties. Scanning electron microscopy analysis was also used to investigate the morphological properties of the samples. In addition, a matrix modification process using Joncryl®, an epoxy‐based chain extender chemical, was applied to enhance the interfacial interaction between the composite components and improve the composite properties by improving the dispersion of reinforcing materials. As a result of the characterization tests, it was observed that a significant improvement in the properties of the material type containing 10 wt% BF, 0.25 wt% BA and 2 wt% Joncryl® was achieved. A 19% increase in tensile strength of this type of material was observed compared with unreinforced PLA, while the sharp peak increase in the coefficient of friction (COF) curve was shifted from 20 m to 60 m. As a result, it has been presented that environmentally friendly and inorganic materials such as BF and BA can be used to produce composite materials that will serve sectors where the need and use of high performance materials is intense, especially in the automotive, aerospace and aviation sectors. Highlights: The properties of PLA matrix composites were improved by the simultaneous use of BF and BA and the addition of Joncryl®. The structural properties of PLA, an environmentally friendly polymer, have been improved without compromising this characteristic. PLA matrix natural composites with performance that can be used in the automotive, aerospace and aviation sectors have been developed.