Polylactic Acid Plates Research Articles

Investigation of Friction Stir Welding of Additively Manufactured Biocompatible Thermoplastics Using Stationary Shoulder and Assisted Heating.

Additive manufacturing (AM), also known as 3D printing, offers many advantages and, particularly in the medical field, it has stood out for its potential for the manufacture of patient-specific implantable devices. Thus, the unique properties of 3D-printed biocompatible polymers such as Polylactic Acid (PLA) and Polyetheretherketone (PEEK) have made these materials the focus of recent research where new post-processing and joining techniques need to be investigated. This study investigates the weldability of PLA and PEEK 3D-printed plates through stationary shoulder friction stir welding (SS-FSW) with assisted heating. An SS-FSW apparatus was developed to address the challenges of rotating shoulder FSW of thermoplastics, with assisted heating either through the shoulder or through the backing plate, thus minimizing material removal defects in the welds. Successful welds revealed that SS-FSW improves surface quality in both PLA and PEEK welds compared to rotating shoulder tools. Process parameters for PLA welds are investigated using the Taguchi method, emphasizing the importance of lower travel speeds to achieve higher joint efficiencies. In PEEK welds, the heated backing plate proved effective in increasing process heat input and reducing cooldown rates which were associated with higher crystallinity PEEK. Despite these findings, further research is needed to improve the weld strength of SS-FSW with these materials considering aspects like tool design, process stability, and 3D printing parameters. This investigation emphasizes the potential of SS-FSW in the assembly of thermoplastic materials, offering insights into the weldability of additively manufactured biocompatible polymers like PLA and PEEK.

Using the Point Method to estimate failure loads in 3D printed graphene-reinforced PLA notched plates

This work estimates failure loads in Fused Filament Fabrication (FFF) printed graphene-reinforced PLA (polylactic acid) plates containing different types of stress risers. With this aim, firstly, several notched plates are tested and conducted to fracture. Then, linear elastic Finite Element (FE) analyses are completed to define the corresponding stress profiles and, finally, the Point Method (PM) is applied to establish the failure criterion. This approach asserts that fracture conditions are achieved when the stress level equates the inherent strength (σ0) at a distance from the notch tip equal to L/2, so both parameters (related to each other through the material fracture toughness, Kmat) have been defined beforehand. The estimations of fracture loads obtained following this approach agree with the experimental results. Thus, the present work demonstrates the accuracy of the PM to estimate failure loads in this 3D printed material.

Fracture Load Estimations for U-Notched and V-Notched 3D Printed PLA and Graphene-Reinforced PLA plates using the ASED Criterion

This paper addresses the estimation of critical loads in FFF (Fused Filament Fabrication) printed polymers and composites containing notches. Particularly, the analysis is focused on the fracture load estimations of 39 PLA (polylactic acid) and 39 graphene reinforced PLA (PLA-Gr) printed plates containing two different types of notches (U- and V-notches) and combining different plate thicknesses and defect length to plate width (a/W) ratios. The addition of graphene (1 wt.%) increases both the yield stress and the ultimate tensile strength, also reducing the strain at rupture and, thus, generating a material whose behavior is closer to linear elasticity. Among the different assessment tools that may be used to estimate critical loads, this work applies the well-known Averaged Strain Energy Density (ASED) criterion, which compares the averaged strain energy over a certain control volume at the notch tip with the corresponding critical value, the latter being a material property. This approach has a linear-elastic nature, so its application to non-fully linear materials may require the use of specific corrections or calibrations. For the two materials analyzed here, PLA and PLA-Gr, it has been observed that the ordinary linear-elastic ASED criterion provides good estimations for the PLA-Gr material, whereas the pristine PLA, with more evident non-linear behavior, the obtainment of accurate results requires a previous specific calibration of the ASED material parameters

Influence of Counterpart Material on Fretting Wear of FDM Printed Polylactic Acid Plates

Influence of Counterpart Material on Fretting Wear of FDM Printed Polylactic Acid Plates

New Transparent Flame-Retardant (FR) Coatings Based on Epoxy-Aluminum Hypophosphite Nanocomposites

The present study investigated the flame-retardant (FR) effect of transparent epoxy coating containing aluminum hypophosphite (AHP) nanoparticles (NPs) on polylactic acid (PLA) sheets used as a typical model of combustible polymeric material. First, AHP NPs (≤60 nm) were prepared by a specific two-stage wet milling process and deeply analyzed (morphology, thermal/mechanisms of degradation under nitrogen and air). The thermal properties of epoxy–AHP nanocomposites were compared with the pristine epoxy resin. The addition of AHP NPs into epoxy resin accelerated thermal degradation of the coating, thereby increasing the amount of char residue. The application of blank epoxy coating on the surface of PLA plate slightly made PLA more ignitable, without any reduction in the peak of heat release rate (pHRR). The decrease of time to ignition (TTI) was more important in the presence of AHP NPs due to their reactivity toward epoxy resin. Epoxy coating containing 15 wt.% AHP NPs showed the most significant reduction in pHRR as the result of the formation of a homogenous char layer. Further increase of AHP NPs content up to 20 wt.% did not end in any further enhancement, as a consequence of structural cracks observed in the coating that prevent the formation of an effective char. The coated samples remained transparent, promisingly paving the way to appropriate decorative flame-retardant coatings.

Material extrusion 3D printing and friction stir welding: an insight into the weldability of polylactic acid plates based on a full factorial design

Material extrusion 3D printing and friction stir welding: an insight into the weldability of polylactic acid plates based on a full factorial design

3D Printing of Abdominal Immobilization Masks for Therapeutics: Dosimetric, Mechanical and Financial Analysis.

Molding immobilization masks is a time-consuming process, strongly dependent on the healthcare professional, and potentially uncomfortable for the patient. Thus, an alternative sustainable automated production process is proposed for abdominal masks, using fused deposition modelling (FDM) 3D printing with polylactic acid (PLA). Radiological properties of PLA were evaluated by submitting a set of PLA plates to photon beam radiation, while estimations of their mechanical characteristics were assessed through numerical simulation. Based on the obtained results, the abdominal mask was 3D printed and process costs and times were analyzed. The plates revealed dose transmissions similar to the conventional mask at all energies, and mechanical deformation guarantees the required immobilization, with a 66% final cost reduction. PLA proved to be an excellent material for this purpose. Despite the increase in labour costs, a significant reduction in material costs is observed with the proposed process. However, the time results are not favorable, mainly due to the printing technique used in this study.

Mechanical strength of 3D-printed open hole polymer plates

Fused Deposition Modeling (FDM) as one of the most popular processes of Additive Manufacturing (AM), offers flexibility in manufacturing of parts with complex geometries. Although three-dimensional (3D) printing was initially used for rapid prototyping, currently it is being utilized in manufacturing of final products. Since some 3D-printed plates with open-holes might be subjected to the tensile loads during their operation, study the mechanical strength of these parts is a necessity. In the current study, the specimens have been fabricated by means of the FDM technique using Polylactic Acid (PLA) material. As ratio of the specimen width to the hole diameter has influence on the structural integrity of the part, we have fabricated specimens with different hole diameters. A series of tensile tests under static loading conditions was conducted to determine strength and effect of the the ratio of the specimen width to the hole diameter on the structural integrity of the 3D-printed PLA plate. Moreover, parallel to experimental tests, numerical simulations are performed and a good agreement between experimental finding and simulation results is obtained. The outcome of this study can be used for design of 3D-printed polymer plates with open-hole and improvement of their mechanical strength and structural integrity.

Oriented homo-epitaxial crystallization of polylactic acid displaying a biomimetic structure and improved blood compatibility.

Epitaxial crystallization and solid hot-drawing technology were employed to fabricate oriented homo-epitaxial crystallization of polylactic acid (PLA) with nano-topography to enhance its blood compatibility and mechanical characteristics as blood-contacting medical devices. The process involved solid hot stretching the PLA plates. A PLA nutrient solution was then used to immerse the oriented plates to dissolve some of the PLA solutes, ensuring plate integrity. Consequently, the drawing process exponentially enhanced the modulus and tensile strength of the PLA. Orientation and epitaxial crystallization could substantially enhance blood compatibility of PLA by prolonging clotting time and decreasing hemolysis rate, protein adsorption, and platelet activation. The oriented homo-epitaxial crystallization of PLA exhibited a nano-topography and fibrous structure similar to the intimal layer of a blood vessel, and this biomimetic structure was advantageous in decreasing the activation and/or adhesion of platelets.

Enhancement of bone to polylactic acid plate bonding by carbonate apatite coating

Polylactic acid (PLA) has no osteoconductivity, causing the early failure of PLA implants. For obviating this problem, coating, rather than incorporation, of PLA with calcium phosphate is considered to be effective. In this study, PLA plates were coated with granular carbonate apatite (CAp), the inorganic component of bone, using the thermal fusion bonding method. The water contact angles of the CAp-coated PLA (CAp/PLA) plates and PLA were 0.7° ± 0.1° and 90.3° ± 3.9°, respectively. Thus, CAp coating significantly improved the wettability of the PLA surface. Furthermore, the roughness (Ra) of CAp/PLA and PLA was 11.7 ± 2.2 μm and 1.8 ± 0.2 μm, respectively. CAp coating involved two types of micropores (~30–80 μm and ~2 μm). Thus, CAp coating provided a rough surface and micropores to the PLA plate. The CAp/PLA and uncoated PLA plates were fixed onto a rabbit tibial surface to evaluate their bone formation and adhesion abilities. Four weeks after implantation, new bone formed on the surface of the CAp/PLA plates. In contrast, no tissue was present in most of the regions between the uncoated PLA plate and the tibia. The tensile bond strengths of the CAp/PLA and PLA plates to the tibia were 4.0 ± 2.5 and 0 N, respectively. Thus, CAp coating of PLA promoted new bone formation on the plate surface and increased the ability to bond to the bone surface at an early stage. CAp coating of PLA is an effective strategy for achieving rapid and robust bone fixation.

An investigation of surface quality characteristics of 3D printed PLA plates cut by CO2 laser using experimental design

ABSTRACT In this work, two typical surface characteristics, i.e., mean surface roughness and angle of the kerf during laser processing of 3D-printed Polylactic Acid (PLA) plates with 4.00 mm in thickness, are investigated. A carbon dioxide laser was utilized to separate 27 work pieces of rectangular shape. The governing laser parameters, speed of cutting and laser power, were varied according to full factorial experimental methodology. An orthogonal array (OA) having nine combinations was implemented, and nine specimens were cut with the same set-up and the same parameters three times (27 replicates in total). The experimental results were analyzed using descriptive statistical analysis, i.e., histograms, box plots, interaction charts and optimized using analysis of means (ANOM) plots as well as ANOVA analysis. The data analysis indicated that laser speed is the dominant parameter for the kerf angle, whilst both the laser velocity and power are important for mean surface roughness of the cut surface for PLA 3D-printed parts. The spread of the data is smaller in Y direction, which indicates that the weaving phenomenon affects the laser cut performance.

Security of 3D-printed polylactide acid piece sterilization in the operating room: a sterility test.

3D-printing technology has become very popular the last 10years, and their advantages have been widely proved. However, its safety in the operating room after sterilization has not been evaluated. Thus, the use of 3D printing is still questioned. The aim of this work is to evaluate the security of polylactic acid (PLA) to print surgical models after its sterilization. One hundred and eighty-six PLA plates and 6 negative controls without microorganisms were seeded. After 10days of culture, the PLA plates were randomized into three groups: A, B, and C. Group A underwent a sterilization process using an autoclave program at 134°C. Group B was seeded in different culture media and group C was used to make crystal violet stains on the biofilms formed on the PLA. Mechanical properties of PLA after autoclave sterilization including, the breaking load, deformation and breaking load per surface were calculated. Hundred percent of the group B showed monomicrobial growth. Stains performed on group C PLA showed biofilms in all PLA pieces. After sterilization, no pathogen growth was observed in group A during the culture observation period showing 100% sterilization effectiveness. A filling percentage of 5% obtained a breaking load of 6.36MPa, and its elastic limit occurred after an elongation of 167.4%. A 10% infill was mechanically safe. Autoclave sterilization of PLA-printed pieces is safe for the patient and mechanically strong for the surgeon. This is the first 3D-printing protocol described and evaluated to implement 3D-printing technology safely in the operating room. This is the first 3D-printing protocol described to print and sterilize 3D biomodels using an autoclave showing its biological safety and its mechanical resistance.

Potential effects of biodegradable single-use items in the sea: Polylactic acid (PLA) and solitary ascidians

With conventional plastics posing a great threat to marine organisms, and potentially also to humans, bio-based, biodegradable plastics are being offered as an ecological solution by which to reduce the environmental impact. Inside compost facilities, bioplastics that comply with the EN 13432:2000 international standard biodegrade almost completely within 180 days. However, outside compost facilities, and specifically in marine environments, these bioplastics may have a similar effect to that of fossil-fuel based plastics. Here we investigated the effects of polyethylene terephthalate (PET) and polylactic acid (PLA) single-use cups and plates on a solitary ascidian’s biological and ecological features. Both PET and PLA microparticles reduced the fertilization rate of Microcosmus exasperatus, with no significant difference between materials. Accumulation rates in adult M. exasperatus exposed to micronized PET and PLA particles at two concentrations were similar for both the bioplastic material and the conventional plastic particles, with no significant difference between the two materials. A microbial-based digestive protocol was developed in order to recover the bioplastic material from ascidian tissue and reduce any material-loss caused by the known digestion protocols. Finally, PET plates submerged for three months in the Red Sea exhibited a significantly higher community richness and cover area in comparison to PLA plates, which did not provide a firm substrate for settlers. Indeed, coverage by the solitary ascidian Herdmania momus was significantly higher on PET plates. The current study demonstrates that discarded bioplastic products may have similar effects to those of conventional plastics on marine organism fertilization and biological accumulation, emphasizing the need to revise both the production and marketing of “biodegradable” and “compostable” plastics in order to prevent a further negative impact on ecosystems due to the mismanagement of bioplastic products.

Improving the quality of polycaprolactone nanofibres using glass ionomer label 1

In this study, the electrospinning of polycaprolactone (PCL) nanofibres with different solvents and various ratios as well as electrospinning on the poly lactic acid plate are investigated for use on the wounds. Utilising several materials at various concentrations, including dimethylformamide–methylene chloride solvent and methylene chloride and methanol solvent, electrospinning of PCL nanofibres are performed. The results show that the obtained fibres have a large number of beaded fibres when using the dimethylformamide–methylene solvent. However, the beaded fibres reduced for methylene chloride and methanol solvent. After adding the glass ionomer label 1 and ciprofloxacin, the beaded fibres intensively decline and also Young's modulus reaches a maximum value (5.2 MPa). Therefore, the combination of glass ionomer label 1 and ciprofloxacin with the methylene chloride and methanol solvent can provide very interesting results to reduce the number of beaded fibres, which show the combination is very suitable for use in wounds.

Mechanical Behaviour of PLA and PHBV Based Lignocellulosic Composite Plates

The knowledge of 3D printing material used in 3D printing technique is so abundant. Even though there are many critical issues in practical applications. This paper reports the comparison study of the Tensile, Flexural and Impact properties of Environmental friendly composites. This composite material is intended to be used as a replacement for the current 3D printing material. The composite was prepared in compression molding/Injection molding technique under 150 kg/cm2 pressure. This work consists of three specimens. One specimen is Poly Hydroxy Butyrate co Valerate (PHBV) and Sansevieria Roxburghiana. Second specimen is Poly Lactic Acid (PLA) and Sansevieria Roxburghiana and the last specimen is Pure PLA plate. The tensile, impact, flexural strength of pure PLA is comparatively better than the other two composite mixture plates. When comparing the fiber mixture of PLA and PHBV plates the PLA mixture possess greater mechanical properties. The research is further extended by changing the proportion of fiber and also improving the fiber lengths.

Anti-ultraviolet and microwave transmission property of ZnO coating on PLA plate

The ZnO coated on the PLA (Polylactic acid) plate with the anti-ultraviolet and high microwave transmission property was fabricated. The particle morphology was measured by the scanning electron microscopy (SEM). The UV-spectrum was measured by the UV Spectrometer. The complex permittivity was measured using a vector network analyzer in 2-18 GHz and the transmission rate (S12) was calculated for the two materials respectively. In order to get the high transmittance property, the genetic algorithm was used to optimize the thickness of the composite and the weight content of the ZnO absorbent. The results showed that the ZnO coating had the good UV protection property, UPF could be estimated 45∼50 as the wavelength was 200∼400 nm, and as the weight content increased, the transmittance value decreased. The composites with thickness 0.1 mm ZnO coating and 1 mm PLA plate had the high transmission rate (larger than 0.95).

Feasibility Test of Three Dimensional Intermittent Oro-Esophageal Tube Guide for Dysphagia; Biocompatibility and Pilot Case Study

Background: In our previous study, oropharyngeal airway was beneficially tested as insertion guide of intermittent oro-esophageal (IOE) tube for feeding of dysphagia patients. As advanced investigation, patient-customized tube guide was designed based on a soft neck radiography image of the patient, and fabricated using three-dimensional printer with polylactic acid (PLA).Methods: Before clinical trial of the 3D-printed tube-guide, biocompatibility of the 3D-printed PLA plate is tested. The biocompatible tube-guide was tried on three consenting subjects.Results: Despite its small cohort size, the customized tube-guide group spent less time in the insertion of the IOE tube than the only IOE tube group.Conclusion: This tendency increases feasibility of the customized IOE tube. We are still recruiting subjects for statistical significance of our trial.

Fabrication of Bioactive Apatite Nuclei Precipitated Polylactic Acid by Using Sandblasting Process

Micropores were formed on the surface of polylactic acid (PLA) plate by doubled sandblasting process using alumina particles with 14.0 μm for average particle size as first process, then using the particles with 3.0 μm for average particle size as second process. Apatite Nucleus (AN) was precipitated in the pores. By these treatments, bioactive AN precipitated PLA was fabricated. Bioactivity of the AN precipitated PLA was examined by soaking in SBF and it was observed that hydroxyapatite was induced on the surface of the PLA within 1 d. High adhesive strength of hydroxyapatite layer was achieved due to a mechanical interlocking effect between hydroxyapatite formed in the micropores and the PLA plate.

The Fixation Effect of a Silk Fibroin–Bacterial Cellulose Composite Plate in Segmental Defects of the Zygomatic Arch<subtitle>An Experimental Study</subtitle><alt-title>Silk Fibroin–Bacterial Cellulose Composite Plate</alt-title>

Bioresorbable fixation systems have been popular for the treatment of facial fractures. However, their mechanical properties are uncertain and complications have been reported. To overcome these problems, we developed a bioresorbable fixation plate using a composite of silk fibroin and bacterial cellulose (SF-BC) with biodegradability and increased biocompatibility. To investigate the regenerative effect of the bioresorbable SF-BC fixation plate on zygomatic arch defects in rats. In vivo animal study. The SF-BC composite plate had a tensile strength similar to that of a polylactic acid plate and a tight, pore-free microstructure. Bilateral segmental bone defects (2 mm in length) were created in the zygomatic arches of adult rats. One side was fixed with the SF-BC composite plate, and the other side was left without fixation. Academic research laboratory. Fifteen adult Sprague-Dawley rats. Fixation of the zygomatic arch defect with the SF-BC composite plate. Micro-computed tomography and histological evaluation of bone samples. Gross inspection revealed no specific complication. At 1, 2, 4, and 8 postoperative weeks, the zygomatic arches were explored by micro-computed tomography and histological examination. Control sides did not heal completely and showed bony degeneration and necrosis during the 8-week follow-up. However, we observed new bone formation in sides treated with the SF-BC composite plate, and bony defects were completely healed within 8 weeks. The SF-BC composite plate is a potential candidate for a new bioresorbable fixation system. Our composite material could considerably shorten bone regeneration time. Additional study of the control of biodegradability and mechanical properties of SF-BC composite plates and a comparative study with the resorbable plates currently in use should be undertaken.

G040021 ガソリン浸漬によるポリ乳酸樹脂の劣化評価([G04002]機械材料・材料加工部門一般セッション(2))

Recently, from the viewpoint that decreases the load to the global environment, the bio-plastics, which are derived from the reusable resources from the biomass, attract much attention as new polymeric materials instead of the polymers derived from exhaustible resources such as petroleum. Poly lactic acid (PLA) is considered to be one of the most promising bio-plastics because its strength and modulus are as high as that of the existing plastic, and it has also biodegradability. In this study, we investigated the effect of immersion in gasoline on mechanical properties of injection-molded PLA plates in the case of assuming that PLA will be applied to severe environment such as in contact with gasoline.