PSI - Issue 56

Cristina Vălean et al. / Procedia Structural Integrity 56 (2024) 97– 104 Author name / Structural Integrity Procedia 00 (2023) 000 – 000

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Fig. 3. The variation of strength (a), strain (b) and energy (c) properties with the filament type

Figure 3b shows that strain at strength extremes (maximum and minimum values) are represented, such tensile strength, also by the PLA (5.41%) and PLA+BP (3.42%) samples. In this case, differences of over 36% were obtained between PLA and PLA+BP. The same two materials show the biggest difference between strain at strength and strain at break (27.0% for PLA and 22.2% for PLA+BP). At the opposite pole, differences below 3.5% are obtained for PLA+GF and PLA+CF samples. Considering that the fracture energy is given by the area under the stress-strain curves, the PLA samples show significantly higher values than the other configurations. More precisely, PLA absorbs up to 47.9% more energy than the sample in second place and 79.5% more than the sample in last place. The PLA+GF and PLA+CF samples absorb approximately the same amount of energy, the values being slightly favorable (3%) for the PLA+CF material. From tensile results, a clear domination of pure PLA properties is observed. The fillers prove to decrease consistently the mechanical strength and dramatically the fracture energy. This effect can be put on the discontinuity created in the in the PLA matrix, induced by the presence of the filler material. The bond between the filler fiber/particle and the matrix seems to be weaker than the bond inside the polymeric matrix. Also, it can be observed that carbon and glass fillers, which are in almost the same percentage in the mixture, produce similar property loss comparing to pure PLA. Also, the bronze filler in a much higher percentage is further decreasing the properties in a significant manner.