Influence of Multiple Thermomechanical Processing of 3D Filaments Based on Polylactic Acid and Polyhydroxybutyrate on Their Rheological and Utility Properties

Plavec, Roderik; Horváth, Vojtech; Hlaváčiková, Slávka; Omaníková, Leona; Repiská, Martina; Medlenová, Elena; Feranc, Jozef; Kruželák, Ján; Přikryl, Radovan; Figalla, Silvestr; Kontárová, Soňa; Baco, Andrej; Danišová, Lucia; Vanovčanová, Zuzana; Alexy, Pavol

doi:10.3390/polym14101947

Cited by 7 publications

(2 citation statements)

References 84 publications

(91 reference statements)

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“…Relatively fewer reports have been presented on the application of PLA in dentistry, and most reports focus on its applications in provisional crowns. However, the glass transition temperature of PLA is known to be 50–80 °C [ 62 , 63 ]. PLA improves crystallinity and increases heat resistance.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of Dental Models Fabricated Using Recycled Poly-Lactic Acid

et al. 2023

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Based on the hypothesis that the fabrication of dental models using fused deposition modeling and poly-lactic acid (PLA), followed by recycling and reusing, would reduce industrial waste, we aimed to compare the accuracies of virgin and recycled PLA models. The PLA models were recycled using a crusher and a filament-manufacturing machine. Virgin PLA was labeled R, and the first, second, and third recycles were labeled R1, R2, and R3, respectively. To determine the accuracies of the virgin and reused PLA models, identical provisional crowns were fitted, and marginal fits were obtained using micro-computed tomography. A marginal fit of 120 µm was deemed acceptable based on previous literature. The mesial, distal, buccal, and palatal centers were set at M, D, B, and P, respectively. The mean value of each measurement point was considered as the result. When comparing the accuracies of R and R1, R2, and R3, significant differences were noted between R and R3 at B, R and R2, R3 at P, and R and R3 at D (p < 0.05). No significant difference was observed at M. This study demonstrates that PLA can be recycled only once owing to accuracy limitations.

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Section: Discussionmentioning

confidence: 99%

Accuracy of Dental Models Fabricated Using Recycled Poly-Lactic Acid

et al. 2023

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“…There have been a few works concentrating on the recyclability of PHAs. The studies range from recycling of the pure polymers PHB, poly(3-hydroxybutyrate-co-3hydroxyvalerate) PHBV and P(3HB-co-4HB) [27][28][29][30] to recycling via blend design of PLA/PHB, PHBV/PLA, PHBV/poly (butylene adipate-co-terephthalate) PBAT and PP/PHB and the composite synthesis of PHBV/Sisal [31][32][33][34][35][36][37][38]. Since PHBs are expensive and circulate only in small quantities, there are few studies on their mechanical recycling and chemical recycling potential.…”

Section: Introductionmentioning

confidence: 99%

Impact of Multiple Reprocessing on Properties of Polyhydroxybutyrate and Polypropylene

Main,

Petersmann,

Wild

et al. 2023

Polymers

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Biobased plastics have the potential to be sustainable, but to explore their circularity further, current end-of-life options need to be broadened. Mechanical recycling is one of the most accepted methods to bring back plastics into the loop. Polyhydroxybutyrates (PHBs) are biobased and biodegradable in nature with promising properties and varied applications in the market. This study focuses on their potential for mechanical recycling by multiple extrusion cycles (E1–E5) and multi-faceted characterization of the virgin (V) and reprocessed materials from E1 to E5. The behavior is compared to polypropylene (PP) as a reference with a similar property profile, which has also been reprocessed five times. The thermal properties of both series showed a stable melting point and thermal decomposition temperature from thermal analyses (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)). However, a steady increase in the degree of crystallinity was observed which could counterbalance the decrease in molecular weight due to repeated extrusion measured by gel permeation chromatography and resulted in similar values of tensile strength across the cycles. The strain at break was impacted after the first extrusion, but no significant change was observed thereafter; the same was observed for impact strength. Even in scanning electron microscopy (SEM) images, virgin and E5 samples appeared similar, showing the stability of morphological characteristics. Fourier transform infrared spectroscopy (FTIR) results revealed that no new groups are being formed even on repeated processing. The deviation between the PHB and PP series was more predominant in the melt mass flow rate (MFR) and rheology studies. There was a drastic drop in the MFR values in PHB from virgin to E5, whereas not much difference was observed for PP throughout the cycles. This observation was corroborated by frequency sweeps conducted with the parallel plate method. The viscosity dropped from virgin to E1 and E2, but from E3 to E5 it presented similar values. This was in contrast to PP, where all the samples from virgin to E5 had the same values of viscosity. This paper highlights the possibilities of mechanical recycling of PHB and explains why future work with the addition of virgin material and other additives is an area to be explored.

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