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Measurements of Tensile Strength and Elongation of 3D Printed Polylactide Solids Produced with Different Temperatures of Extruder Using Coordinate Measuring Technique and Finite Element Method

Gaweł Anna Magdalena, Ostrowska Ksenia, Lisowska Aleksandra

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 6

356--366

EN

In order to determine the largest and smallest deformations during 3D printing, measurements were made for pure polylactide (PLA) using a coordinate measuring technique using a measuring arm. The additive manufacturing process was carried out using four nozzle temperatures: 190℃, 200℃, 210℃ and 220℃. The model was properly selected to check the cylindricity, angles of inclination and dimensional deviations from the nominal value of the cuboid. FEM analysis was used to confirm the obtained results. The cylindricity and shape tolerances were shown to be the best at 190℃. The smallest deviations from the angle of 90 ° have solids made at 200 ℃ and 220 ℃. In the case of dimensional tolerances of the centers of the holes relative to each other, the best deviations were obtained for the temperature of 190 ℃ and 220 ℃. The highest stress values during uniaxial stretching using FEM analysis were obtained for samples made with nozzle temperatures of 200°C and 210°C, which are about 31 MPa. For the temperature of 190°C and 220°C, the deviations are the closest to the reference model and are equal to about 30 MPa. In the case of the FEM analysis for single-point bending, the element made at 190°C had a maximum deformation of 0.203 mm, which was the same for the reference model. The largest deviation is noticeable for the printing temperature of 200°C and is 0.211 mm.

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Strength, Water Absorption, Thermal and Antimicrobial Properties of a Biopolymer Composite Wound Dressing

Odili Cletus Chiosa, Sekunowo Olatunde Israel, Ilomuanya Margaret Okonawan, Gbenebor Oluwashina Philips, Adeosun Samson Oluropo

Journal of Casting & Materials Engineering

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2022

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Vol. 6, no. 1

22--32

EN

Conventional wound material allows bacterial invasions, trauma and discomfort associated with the changing of the dressing material, and the accumulation of body fluid for wounds with high exudate. However, there is a shift from conventional wound dressing materials to polymeric nanofibers due to their high surface area to volume ratio, high porosity, good pore size distribution, which allows for cell adhesion and proliferation. There is an urgent need to synthesis a biodegradable composite that is resistant to bacterial infection. In this study, an electrospun polylactide (PLA) composite suitable for wound dressing, with enhanced antimicrobial and mechanical properties, was produced. The neat PLA, PLA/CH (10 wt.%), PLA/CH (5 wt.%), PLA/CHS (10 wt.%), PLA/CHS (5 wt.%), PLA/CH (2.5 wt.%) /CHS (2.5 wt.%) and PLA/CH (5 wt.%)/CHS (5 wt.%), were electrospun using 0.14 g/ml solution. Results show that crystallinity (67.6%) of neat PLA declined by 3.8% on the addition of 2.5 wt.% chitin/chitosan with improved hydrophilicity of the composite. The tensile strength of neat PLA (0.3 MPa) increased (0.6 MPa) with 2.5 wt.% chitin/chitosan addition. The slight increase in the glass transition temperature from 75°C for neat PLA to 78°C of the composite fibre, showed improved ductility. The fibres showed little beads, hence suitable for wound dressing. The electrospun mats have good water absorption capacity and strong resistance against Staphylococcus aureus. Good performance was attained at 5 wt.% of chitin, chitosan and hybrid reinforcements. Therefore, a PLA/chitin/chitosan composite is recommended as a wound dressing material.

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Long-term mechanical testing of multifunctional composite fixation miniplates

Gryń Karol

Engineering of Biomaterials

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2020

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Vol. 23, no. 157

20--25

EN

This paper presents the analysis and comparison of the results of mechanical testing of dumbbell-shaped specimens and multifunctional fixation miniplates made via injection forming. Three types of materials were used: a) polylactic acid; b) a composite made of a polylactic acid matrix modified with tricalcium phosphate β-TCP; c) a composite made of a polylactic acid matrix modified with a mixture of bioceramic powders of tricalcium phosphate β-TCP and hydroxyapatite HAp. All the samples were stored in normal conditions, no special treatment was applied. Tests were conducted right after samples were prepared and they were repeated two and four years after preparation. The values of basic mechanical parameters and stress-strain curves were recorded and analyzed. The attention was focused on changes in time of tensile strength and stiffness of materials and implants. It was discovered that having been stored for four years in the open air, without sunlight, with no hermetic sealing, and no sterilization, all the materials (PL38, PL38/TCP, PL38/TCP/HAp) showed slight changes in mechanical characteristics when compared to the data of the initial samples tested after fabrication. These changes were not critical and did not adversely affect either tensile strength or Young’s modulus of the implants. All the analyzed miniplates maintained their mechanical properties at an acceptable level, fulfilling requirements for fixation devices for osteosynthesis. Therefore, it was proposed that the expiry date of these implants can be indirectly determined, based on long-term mechanical testing.

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Study of thermo-mechanical degradation of biodegradable polymers using oscillation rheometry

Pavlačková M., Alexy P., Tomanová K., Bugaj P., Hudec I., Bakoš D.

Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją

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2010

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Nr 12

283-286

EN

This work is focused on study of possibilities to determine thermo - mechanical degradation during melt processing of biopolymers. The oscillation rheometry was found as the simple method which is able indicates the first stages of degradation process. Polylactide acid was used as bio-polymer substance in comparison to PE and PCL.

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Kompozytowe włókna polilaktyd/hydroksyapatyt otrzymywane metodą przędzenia ze stopu

Rajzer I., Rom M., Fabia J., Morcinek S., Zima A., Ślósarczyk A., Janicki J.

Engineering of Biomaterials

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2009

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Vol. 12, no. 89-91

149--150

PL

W pracy zaproponowano metodę produkcji nano-kompozytowych włókien na bazie polilaktydu (PLA) i nano-hydroksyapatytu (n-HAp).

EN

In the present work, the method of production of nanocomposite fibers based on polylactide acid (PLA) and nano-hydroxyapatite (n-HAp) is proposed.