Aug 2026· Materials Science Forum· Vol 1199, pp. 147 - 153· 0 citations· 17 references
Abstract
Processing methods strongly influence the degradation behaviour of semi-crystalline polylactic acid (PLA) by affecting its molecular orientation, crystallinity, and micro-and macrostructural features. In our previous study, we presented the changes in the properties of the electrospun PLA fibers during in vitro degradation. Building on these findings, this study compares the degradation of PLA specimens prepared using two bulk processing methods: (i) fused filament fabrication (FFF) 3D printing and (ii) film extrusion. Specimens were incubated in phosphate-buffered saline (pH 7.4) at 37 °C for 1, 3, 7, 28, and 56 days. At each time point, degradation was assessed by tensile testing, differential scanning calorimetry, and weight retention analysis. PLA films exhibited an initial decrease in Young’s modulus, followed by a temporary increase and subsequent decline, whereas FFF specimens maintained mechanical stability for several days before a gradual deterioration. Both specimens showed reduced crystallinity over time, with FFF samples becoming fully amorphous by day 56. Minimal weight change (<1%) indicated that degradation proceeded primarily through structural and morphological changes rather than bulk erosion. Overall, 3D-printed PLA exhibited more stable mechanical properties than extruded PLA films. These findings highlight the significant impact of the processing route on PLA degradation, guiding the optimization of PLA performance in biomedical, packaging, and sustainable material applications.
In the present work, we developed unique structures from polylactic acid (PLA) by combining electrospinning and fused filament fabrication (FFF). The thin layers of fiber mats were used as interleaves between printed infill layers, and hence, we obtained a multi-level porous structure. Due to the known favorable characteristics of the electrospun mats for cell adhesion and growth, these structures may be used as scaffolds in the future. The aim of this study was to test the processing, the structure, and the hydrolytic degradation at a fundamental level. Samples were immersed into phosphate-buffered saline (PBS) solution and incubated at 37 °C for 1, 3, 7, 15, 30 and 60 days. Our findings show that adding 0.15 wt% electrospun fibers results in a significantly higher degree of crystallinity. We found that the embedded fiber mats promoted heterogeneous nucleation, thus improving mechanical properties significantly. Scanning electron microscopy confirmed that fibers fused with the FFF grid in situ, resulting in increased tensile strength and elongation at break. Additionally, the hierarchical structures exhibit better mechanical performance at the potential application temperature (37 °C) than the neat 3D printed samples.
ABSTRACT This study investigates the structure-property-degradation relationships of melt-spun polyethylene/polylactic acid (PE/PLA) blend-fibers, addressing the knowledge gap regarding the biodegradation mechanisms of oriented fiber morphologies compared with bulk films. PE/PLA fibers with varying compositions (5–50 wt% PLA) were fabricated via melt spinning and subjected to controlled soil burial degradation (ISO 17556:2019) for 85 days. The results reveal a composition-dependent, three-stage biodegradation mechanism characterized by selective PLA hydrolysis, fungal hyphae penetration at phase boundaries, and subsequent structural fragmentation. Mechanical characterization identifies the 90/10 PE/PLA blend as the optimal formulation, achieving a tensile strength of 64.88 ± 3.1 cN/Tex, which exceeds that of pure PE. This enhancement is attributed to effective stress transfer facilitated by weak interfacial dipole – induced dipole interactions and van der Waals forces, evidenced by a 6 cm−1 redshift in carbonyl stretching vibrations observed by FTIR and an interfacial bonding energy (ΔG) of 12.6 kJ/mol. In contrast, blends containing higher PLA contents (≥20 wt%) exhibit pronounced phase separation accompanied by a significant reduction in elastic-modulus, decreasing from 294.3 to 73.28 cN/Tex. Furthermore, degradation kinetics analysis demonstrates that fibers with 40 wt% PLA degrade approximately four times faster than pure PE, corresponding to 12.3 versus 3.2% weight loss. Graphical abstract
Hamze-Ali Hajipasha, P. Valipour, H. Tayebi et al.· Polymer-Plastics Technology...· 0 citations
The obtained results confirm the potential of PLA-based composites modified with hydroxyapatite and gentamicin as functional biodegradable materials for implant applications in regions with moderate mechanical loading, combining mechanical support, bioactivity, and local antimicrobial protection.
A. Khrustaleva, A. Yedrissov, D. Khrustalev et al.· Medicine and ecology· 0 citations
Rotational molding is a shear-free technology to produce hollow plastic parts. Rotomolded poly(lactic acid) (PLA) and its biocomposites remain in a largely amorphous state, which limits their stiffness, toughness, and thermal resistance. Post-processing thermal annealing develops crystallinity without additives, but its combined effect with natural fibers has rarely been quantified. This work evaluates annealing at 100 °C for 1 h on rotomolded PLA biocomposites reinforced with 10, 20, and 30 wt.% of agave, coir, or pine fibers. Crystallinity (DSC, XRD), density and porosity, morphology (SEM), water absorption, mechanical properties (tensile, flexural, Charpy impact, Shore D hardness), and 28-day disintegration under lab-scale composting conditions were measured for treated and untreated samples. Annealing raised the matrix crystallinity from below 21% to 41–56% and produced predominantly α crystals with a nearly constant average size of about 20 nm. The treatment improved the matrix-dominated properties for every formulation: for neat PLA, Charpy impact strength increased by 120% (28.1 to 61.7 J/m), flexural strength by 53% (61.1 to 93.4 MPa), and flexural modulus from 3264 to 4511 MPa. Tensile strength and modulus, in contrast, remained unchanged or decreased. Porosity, set by fiber content, was unaffected by annealing; at 30 wt.%, the matrix barrier nonetheless reversed, and annealed samples absorbed more water and disintegrated faster than untreated ones. Fiber content sets the balance between matrix crystallinity and the interfacial damage caused by crystallization-induced contraction.
E. Cisneros-López, Josué Rivera-Aguilera, R. G. López-Gonzaleznúñez et al.· Polymers· 0 citations
Poly(L-lactide) (PLLA) scaffolds are widely used in tissue engineering because they are biodegradable and have good mechanical properties. Their performance changes during degradation, which is important for the design of biodegradable implants. In this study, we investigated the structural and mechanical stability of 3D-printed PLLA scaffolds during 180 days of in vitro hydrolytic degradation in phosphate-buffered saline (PBS) at 37 °C. Mechanical properties of the material were evaluated by tensile and compression tests. The material during degradation was analyzed for the scaffolds for which the lost mass and chemical and surface changes were analyzed using FTIR-ATR spectroscopy and SEM microscopy. The scaffolds lost more than 8% of their initial mass throughout the study, indicating slow degradation. However, their mechanical properties gradually decreased. Young’s modulus dropped from 2.46 GPa to 2.09 GPa, and tensile strength decreased from 45.5 MPa to 31.1 MPa. The material also became more brittle after about 90 days. FTIR results confirmed progressive hydrolysis of ester bonds, while SEM images showed increasing surface roughness, micropores, and cracks. The results show that PLLA scaffolds maintain their shape and mass during the early stages of degradation. However, their mechanical strength decreases over time. These changes should be considered when designing biodegradable scaffolds for regenerative medicine.
OBJECTIVES
This study aimed to evaluate bio-based, biodegradable polylactic acid (PLA) as a sustainable material for clear aligners by comparing its physicochemical, mechanical, and biological properties with commercial aligner materials (Essix Ace, Essix C+, Zendura FLX, and Zendura).
METHODS
PLA and commercial materials, both neat and aged in artificial saliva for up to 14 days, were examined as sheets. Thermal properties were measured using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical and optical properties were evaluated using a universal testing machine (UTM) and UV-visible spectrophotometry. Degradation behavior was assessed via weight and average molar mass changes, and surface morphology via scanning electron microscopy (SEM). Cytotoxicity was tested using human gingival fibroblasts with an MTT assay.
RESULTS
PLA showed a glass transition temperature of 55.4 °C, melting temperature of 152.1°C, and degradation onset temperature of 362.9 °C, comparable to commercial aligner materials. Its tensile strength and yield stress were similar to those of commercial materials, indicating adequate strength. However, PLA exhibited lower elongation at break and higher Young's modulus, reflecting higher brittleness and stiffness. Aging caused negligible water absorption, minimal weight loss, and minor thermal property change. Mechanical properties remained stable upon aging. Aged PLA was transparent when wet but became hazy when dry, which occurs reversibly. Extracts from PLA were non-cytotoxic, maintaining 90% cell viability in average.
SIGNIFICANCE
PLA demonstrated properties comparable to commercial aligner materials, with the exception of increased stiffness and brittleness. Its stability during aging and favorable biocompatibility supports its potential as a sustainable alternative for clear aligner applications.
Mayuri Parappullil Vellayappan, Sean Johnson, Taylor Stewart et al.· Dental Materials· 0 citations
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