Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds
Аутори
Vorkapić, MilošMladenović, Ivana
Ivanov, Toni
Kovačević, Aleksandar
Mohammad Sakib, Hasan
Aleksandar, Simonović
Trajković, Isaak
Чланак у часопису (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт
Five series of specimens with two different print orientations (−45/45 and 0/90) and two print layer thicknesses (0.1 and 0.2 mm) were made. In total 60 specimens with 100% filament infill were made. One specimen series (20 pieces) was isolated as a reference or thermally untreated. Before the thermal treatment (annealing), two specimen moulding methods were used: NaCl powder (granulation 63 mm: 20 pieces) and Calcium Sulphate (Gypsum: 20 pieces). During the annealing, specimens immersed in NaCl powder were heated in a drying oven to the filament melting point (for PLA: 200°C, with a duration interval of 30 min), while the treatment of the heated specimens in gypsum was performed at a temperature of around 190°C, with duration interval of 3 h with the observed temperature inside the mould of about 100°C. An ultrasonic bath and a drying oven were used in the gypsum treatment. Temperature measurement and control during both annealing treatments were performed using a thermal imaging came...ra, while the temperature control inside the drying oven was performed using a digital thermometer. After treatment, the specimens in the moulds were cooled at room temperature, and the dimensions of annealing and untreated specimens were controlled. Surface morphology was characterised using scanning electron microscopy (SEM). The SEM analysis reveals improved internal structure after heat treatment of the PLA specimens. These results show that the investigated specimens after heat treatments had better structural properties than the referent specimens. Tensile testing on a universal testing machine in compliance with the ASTM D638 standard was also performed. The referent PLA specimen with −45/45 and layer thickness of 0.1 mm had the highest tensile stress value (64.08 MPa) while the specimen with minimal tensile stress value before fracture was 0/90, 0.2 mm (54.81 MPa). Heat treatment in gypsum showed the most significant increase in strength with −45/45 (0.1 mm) being the strongest (71.66 MPa) while the strongest specimen treated in sodium chloride was −45/45 (0.1 mm) with maximum tensile stress of 70.08 MPa. The mechanical characteristics of the PLA were characterised using the Vickers microhardness tester. The PLA microhardness value was calculated according to standards ASTM E384 and ISO 6507. The referent PLA specimen with −45/45 (0.2 mm) orientation shows the maximal microhardness value (125 MPa), and the minimal microhardness value was observed for the 0/90 (0.1 mm) orientation specimens (108 MPa). The heat treatment specimens in gypsum have a better hardness (185 MPa) than those treated in gypsum (165 MPa), with microhardness increasing by about 12%. The essence of the work is reflected in the additional filament processing to achieve a better structural and mechanical performance of the materials and reduce the anisotropy that is characteristic of 3D printing.
Кључне речи:
3D printing / mechanical performance / PLA / polymer remelting / tensile testing / Vickers micro hardnessИзвор:
Advances in Mechanical Engineering, 2022, 14, 8, 1-15Издавач:
- SAGE
Финансирање / пројекти:
- Министарство науке, технолошког развоја и иновација Републике Србије, институционално финансирање - 200105 (Универзитет у Београду, Машински факултет) (RS-200105)
- Министарство науке, технолошког развоја и иновација Републике Србије, институционално финансирање - 200026 (Универзитет у Београду, Институт за хемију, технологију и металургију - ИХТМ) (RS-200026)
DOI: 10.1177/16878132221120737
ISSN: 1687-8132; 1687-8140
WoS: 000846847100001
Scopus: 2-s2.0-85136736328
Институција/група
IHTMTY - JOUR AU - Vorkapić, Miloš AU - Mladenović, Ivana AU - Ivanov, Toni AU - Kovačević, Aleksandar AU - Mohammad Sakib, Hasan AU - Aleksandar, Simonović AU - Trajković, Isaak PY - 2022 UR - https://cer.ihtm.bg.ac.rs/handle/123456789/5363 AB - Five series of specimens with two different print orientations (−45/45 and 0/90) and two print layer thicknesses (0.1 and 0.2 mm) were made. In total 60 specimens with 100% filament infill were made. One specimen series (20 pieces) was isolated as a reference or thermally untreated. Before the thermal treatment (annealing), two specimen moulding methods were used: NaCl powder (granulation 63 mm: 20 pieces) and Calcium Sulphate (Gypsum: 20 pieces). During the annealing, specimens immersed in NaCl powder were heated in a drying oven to the filament melting point (for PLA: 200°C, with a duration interval of 30 min), while the treatment of the heated specimens in gypsum was performed at a temperature of around 190°C, with duration interval of 3 h with the observed temperature inside the mould of about 100°C. An ultrasonic bath and a drying oven were used in the gypsum treatment. Temperature measurement and control during both annealing treatments were performed using a thermal imaging camera, while the temperature control inside the drying oven was performed using a digital thermometer. After treatment, the specimens in the moulds were cooled at room temperature, and the dimensions of annealing and untreated specimens were controlled. Surface morphology was characterised using scanning electron microscopy (SEM). The SEM analysis reveals improved internal structure after heat treatment of the PLA specimens. These results show that the investigated specimens after heat treatments had better structural properties than the referent specimens. Tensile testing on a universal testing machine in compliance with the ASTM D638 standard was also performed. The referent PLA specimen with −45/45 and layer thickness of 0.1 mm had the highest tensile stress value (64.08 MPa) while the specimen with minimal tensile stress value before fracture was 0/90, 0.2 mm (54.81 MPa). Heat treatment in gypsum showed the most significant increase in strength with −45/45 (0.1 mm) being the strongest (71.66 MPa) while the strongest specimen treated in sodium chloride was −45/45 (0.1 mm) with maximum tensile stress of 70.08 MPa. The mechanical characteristics of the PLA were characterised using the Vickers microhardness tester. The PLA microhardness value was calculated according to standards ASTM E384 and ISO 6507. The referent PLA specimen with −45/45 (0.2 mm) orientation shows the maximal microhardness value (125 MPa), and the minimal microhardness value was observed for the 0/90 (0.1 mm) orientation specimens (108 MPa). The heat treatment specimens in gypsum have a better hardness (185 MPa) than those treated in gypsum (165 MPa), with microhardness increasing by about 12%. The essence of the work is reflected in the additional filament processing to achieve a better structural and mechanical performance of the materials and reduce the anisotropy that is characteristic of 3D printing. PB - SAGE T2 - Advances in Mechanical Engineering T1 - Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds VL - 14 IS - 8 SP - 1 EP - 15 DO - 10.1177/16878132221120737 ER -
@article{ author = "Vorkapić, Miloš and Mladenović, Ivana and Ivanov, Toni and Kovačević, Aleksandar and Mohammad Sakib, Hasan and Aleksandar, Simonović and Trajković, Isaak", year = "2022", abstract = "Five series of specimens with two different print orientations (−45/45 and 0/90) and two print layer thicknesses (0.1 and 0.2 mm) were made. In total 60 specimens with 100% filament infill were made. One specimen series (20 pieces) was isolated as a reference or thermally untreated. Before the thermal treatment (annealing), two specimen moulding methods were used: NaCl powder (granulation 63 mm: 20 pieces) and Calcium Sulphate (Gypsum: 20 pieces). During the annealing, specimens immersed in NaCl powder were heated in a drying oven to the filament melting point (for PLA: 200°C, with a duration interval of 30 min), while the treatment of the heated specimens in gypsum was performed at a temperature of around 190°C, with duration interval of 3 h with the observed temperature inside the mould of about 100°C. An ultrasonic bath and a drying oven were used in the gypsum treatment. Temperature measurement and control during both annealing treatments were performed using a thermal imaging camera, while the temperature control inside the drying oven was performed using a digital thermometer. After treatment, the specimens in the moulds were cooled at room temperature, and the dimensions of annealing and untreated specimens were controlled. Surface morphology was characterised using scanning electron microscopy (SEM). The SEM analysis reveals improved internal structure after heat treatment of the PLA specimens. These results show that the investigated specimens after heat treatments had better structural properties than the referent specimens. Tensile testing on a universal testing machine in compliance with the ASTM D638 standard was also performed. The referent PLA specimen with −45/45 and layer thickness of 0.1 mm had the highest tensile stress value (64.08 MPa) while the specimen with minimal tensile stress value before fracture was 0/90, 0.2 mm (54.81 MPa). Heat treatment in gypsum showed the most significant increase in strength with −45/45 (0.1 mm) being the strongest (71.66 MPa) while the strongest specimen treated in sodium chloride was −45/45 (0.1 mm) with maximum tensile stress of 70.08 MPa. The mechanical characteristics of the PLA were characterised using the Vickers microhardness tester. The PLA microhardness value was calculated according to standards ASTM E384 and ISO 6507. The referent PLA specimen with −45/45 (0.2 mm) orientation shows the maximal microhardness value (125 MPa), and the minimal microhardness value was observed for the 0/90 (0.1 mm) orientation specimens (108 MPa). The heat treatment specimens in gypsum have a better hardness (185 MPa) than those treated in gypsum (165 MPa), with microhardness increasing by about 12%. The essence of the work is reflected in the additional filament processing to achieve a better structural and mechanical performance of the materials and reduce the anisotropy that is characteristic of 3D printing.", publisher = "SAGE", journal = "Advances in Mechanical Engineering", title = "Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds", volume = "14", number = "8", pages = "1-15", doi = "10.1177/16878132221120737" }
Vorkapić, M., Mladenović, I., Ivanov, T., Kovačević, A., Mohammad Sakib, H., Aleksandar, S.,& Trajković, I.. (2022). Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds. in Advances in Mechanical Engineering SAGE., 14(8), 1-15. https://doi.org/10.1177/16878132221120737
Vorkapić M, Mladenović I, Ivanov T, Kovačević A, Mohammad Sakib H, Aleksandar S, Trajković I. Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds. in Advances in Mechanical Engineering. 2022;14(8):1-15. doi:10.1177/16878132221120737 .
Vorkapić, Miloš, Mladenović, Ivana, Ivanov, Toni, Kovačević, Aleksandar, Mohammad Sakib, Hasan, Aleksandar, Simonović, Trajković, Isaak, "Enhancing mechanical properties of 3D printed thermoplastic polymers by annealing in moulds" in Advances in Mechanical Engineering, 14, no. 8 (2022):1-15, https://doi.org/10.1177/16878132221120737 . .