Impact of Layer Thickness and Storage Time on the Properties of 3D-Printed Dental Dies

Trueness and precision of digital light processing fabricated 3D printed monolithic zirconia crowns

OBJECTIVES

The present study aimed to evaluate the trueness and precision of monolithic zirconia crowns (MZCs) fabricated by 3D printing and milling techniques.

METHODS

A premolar crown was designed after scanning a prepared typodont. Twenty MZCs were fabricated using milling and 3D-printing techniques (n=10). All the specimens were scanned with an industrial scanner, and the scanned data were analyzed using 3D measurement software to evaluate the trueness and precision of each group. Root mean square (RMS) deviations were measured and statistically analyzed (One-way ANOVA, Tukey's, p≤0.05).

RESULTS

The trueness of the printed MZC group (140 ± 14 μm) showed a significantly higher RMS value compared to the milled MZCs (96 ± 27 μm,p<0.001). At the same time, the precision of the milled MZCs (61±17 μm) showed a significantly higher RMS value compared to that of the printed MZCs (31±5 μm,p<0.001).

CONCLUSIONS

The Fabrication techniques had a significant impact on the accuracy of the MZCs. Milled MZCs showed the highest trueness, while printed MZCs showed the highest precision. All the results were within the clinically acceptable error values.

CLINICAL SIGNIFICANCE

Although the trueness of the milled MZCs is higher, the manufacturing accuracy of the 3D-printed MZCs showed clinically acceptable results in terms of trueness and precision. However, additional clinical studies are recommended. Furthermore, the volumetric changes of the material should be considered.

Accuracy of zirconia crown manufactured using stereolithography and digital light processing

OBJECTIVES

The aim of this study is to evaluate the accuracy of zirconia crowns fabricated using stereolithography (SLA) and digital light processing (DLP) and to compare their accuracy with those fabricated using the subtractive manufacturing (SM) method.

METHODS

A typodont model with a prepared maxillary first molar was scanned, and the anatomical contour crown was designed using dental computer-aided-design (CAD) software. The designed file in standard tessellation language (STL) format was used to fabricate 10 crowns per group. The crowns were manufactured using a dental milling machine (Datron D5; MLC group), SLA (CERAMAKER 900; SLAC group), and DLP (ZIPRO; DLPC group) printers. The fabricated crowns were scanned using a dental laboratory scanner and saved in three parts: the external, intaglio, and marginal surfaces. For accuracy assessment, these parts were superimposed to the reference file. Root mean square (RMS) values were evaluated using three-dimensional analysis software (Geomagic Control X). Statistical significance was evaluated using a nonparametric Kruskal-Wallis test (α = 0.05) and a post-hoc Mann-Whitney U test with Bonferroni correction (α = 0.016).

RESULTS

Trueness evaluation revealed the lowest RMS value in all areas in the MLC group, followed by that in the DLPC group. The precision evaluation revealed the lowest RMS value in all areas in the MLC group. Statistically significant differences were observed among the groups in the external, intaglio, and marginal surface (P < 0.05).

CONCLUSIONS

Although the restorations fabricated using SM revealed higher accuracy, the crowns manufactured using SLA and DLP methods were considered clinically acceptable.

CLINICAL SIGNIFICANCE

In the production of zirconia crowns, subtractive manufacturing continues to demonstrate significantly higher accuracy compared to additive manufacturing. However, crowns fabricated using the additive manufacturing method also demonstrated high accuracy.

Effect of storage temperature on the dimensional stability of DLP printed casts

STATEMENT OF PROBLEM

Despite studies focusing on the accuracy and dimensional stability of additive manufacturing, research on the impact of storage conditions on these properties of 3-dimensional (3D) printed objects is lacking.

PURPOSE

The purpose of this in vitro study was to investigate the influence of storage temperature on the dimensional stability of digital light processing (DLP) printed casts and to determine how different locations in printed casts react differently.

MATERIAL AND METHODS

A completely dentate maxillary typodont model was digitized with a desktop laser scanner. The typodont was subsequently modified with a software program by adding cuboids with a side length of 3 mm on both maxillary central incisors, first molars, and second molars. The file was saved in the standard tessellation language (STL) format. The modified digitized typodont was then processed through the DLP technology printing process with a desktop DLP printer and photopolymerizing resin. The casts were printed 32 times and stored in sealed plastic bags, shielded from light, and subjected to 4 different temperature conditions (-20 °C, 4 °C, 20 °C, and 37 °C, n=8 each). The cuboids on the central incisors were labeled as the P1 group, first molars as the P2 group, and second molars as the P3 group. The distance between the cuboids was measured 5 times, with results recorded immediately after cast production and at 1, 2, 3, 5, 7, 14, and 28 days after. Repeated analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) test were used to compare the recorded values among the groups (α=.05).

RESULTS

In the P1 group, the casts stored at -20 °C exhibited the smallest overall size change, with a mean ±standard deviation volume of 99.42 ±0.04% compared with the original casts after 28 days of storage. This was followed by the casts stored at 4 °C, 20 °C, and 37 °C, with remaining volumes of 99.39 ±0.06% (P=.139), 99.14 ±0.08% (P<.001), and 98.96 ±0.03% (P<.001), respectively. For the P2 and P3 groups, casts stored at 4 °C retained the most volume at 99.82 ±0.01%, whereas those stored at -20 °C, 20 °C, and 37 °C underwent greater changes, with remaining volumes of 99.66 ±0.03%, 100.32 ±0.02%, and 100.44 ±0.02%, respectively (P<.001). The P3 group exhibited a similar trend to that of the P2 group, with the casts stored at 4 °C remaining closest to the original dimensions at 99.86 ±0.02%, while casts stored at -20 °C showed 99.73 ±0.03% of the original volume and those stored at 20 °C and 37 °C expanded with volumes of 100.37 ±0.03% and 100.48 ±0.03%, respectively (P<.001).

CONCLUSIONS

DLP printed casts stored at 4 °C exhibited the greatest overall dimensional stability, followed sequentially by those stored at -20 °C, 20 °C, and 37 °C. Additionally, the study confirmed that the posterior and anterior teeth regions of DLP printed casts respond differently to different storage temperatures.

Advancements in Clear Aligner Fabrication: A Comprehensive Review of Direct-3D Printing Technologies

Clear aligners have revolutionized orthodontic treatment by offering an esthetically driven treatment modality to patients of all ages. Over the past two decades, aligners have been used to treat malocclusions in millions of patients worldwide. The inception of aligner therapy goes back to the 1940s, yet the protocols to fabricate aligners have been continuously evolved. CAD/CAM driven protocol was the latest approach which drastically changed the scalability of aligner fabrication-i.e., aligner mass production manufacturing. 3D printing technology has been adopted in various sectors including dentistry mostly because of the ability to create complex geometric structures at high accuracy while reducing labor and material costs-for the most part. The integration of 3D printing in dentistry has been across, starting in orthodontics and oral surgery and expanding in periodontics, prosthodontics, and oral implantology. Continuous progress in material development has led to improved mechanical properties, biocompatibility, and overall quality of aligners. Consequently, aligners have become less invasive, more cost-effective, and deliver outcomes comparable to existing treatment options. The promise of 3D printed aligners lies in their ability to treat malocclusions effectively while providing esthetic benefits to patients by remaining virtually invisible throughout the treatment process. Herein, this review aims to provide a comprehensive summary of studies regarding direct-3D printing of clear aligners up to the present, outlining all essential properties required in 3D-printed clear aligners and the challenges that need to be addressed. Additionally, the review proposes implementation methods to further enhance the effectiveness of the treatment outcome.

Evaluation of the influence of different build angles on the surface characteristics, accuracy, and dimensional stability of the complete denture base printed by digital light processing

Purpose

This study aims to investigate the influence of the build angle on the surface characteristics, accuracy, and dimensional stability of digital light processing (DLP) printed resin bases.

Material and methods

Rectangular and complete denture base samples were fabricated at 0, 45, and 90-degree angles (n = 5 for rectangular samples; n = 10 for maxillary and mandibular denture base samples) using a DLP printer. Surface morphology and roughness were assessed using a profilometer, followed by measuring hydrophilicity with a contact angle meter. Accuracy (trueness and precision) and dimensional stability were evaluated at intervals of 1, 3, 7, 14, 28, and 42 days after base printing using best-fit-alignment and deviation analysis in 3D software. Statistical analysis was performed using one-way ANOVA for surface characteristics (α = 0.05), multi-way ANOVA for accuracy and dimensional stability data, and Tukey's test for post-hoc comparisons.

Results

The 0-degree group exhibited significantly lower mean roughness (1.27 ± 0.19 μm) and contact angle (80.50 ± 3.71°) (P < 0.001) compared to the 90-degree and 45-degree groups. The 0-degree build angle led to superior trueness (maxilla: 77.80 ± 9.35 μm, mandible: 61.67 ± 10.32 μm) and precision (maxilla: 27.51 ± 7.43 μm, mandible: 53.50 ± 15.16 μm) compared to other groups (P < 0.001). Maxillary base precision was superior to mandibular base precision (P < 0.001). The maxillary base exhibited less dimensional deviation than the mandibular base. The 90-degree group showed the highest deviation compared to the other two groups, and all groups' deviations increased over time (P < 0.001).

Conclusions

The build angle significantly influences the surface characteristics, accuracy, and dimensional stability of DLP-printed denture bases. A 0-degree build angle provides the most favorable performance. The maxillary base displayed superior precision and dimensional stability than the mandibular base.

Chairside 3-D printed impression trays: a new approach to increase the accuracy of conventional implant impression taking? An in vitro study

PURPOSE

A high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations persist between the intraoral implant position and the model obtained, even for the benchmark conventional custom implant impressions with polyether. Thus, new approaches using 3-D printed impression trays may increase the transfer accuracy of implant impressions. The ability to adjust parameters such as the thickness of the layers and the influence of the openings in the impression tray could potentially affect accuracy.

METHODS

Four different types of impression trays (n = 10 for each group) for the conventional impression technique were investigated: conventional custom impression tray, customized foil tray, chairside 3-D printed impression tray with the SHERA system, and the Primeprint system using an implant master model with four implants in the posterior region and a reference cube. After plaster model casting, all models were measured using a coordinate measuring machine, and the deviation from the reference dataset was determined. A statistical ANOVA analysis was performed (p < 0.05).

RESULTS

Chairside 3-D printed impression trays showed the best results, followed by conventional custom impression trays. Implant impressions obtained using a customized foil tray exhibited the lowest accuracy. Statistically significant differences were observed between 3-D printed impression trays and conventional custom impression and customized foil trays (p < 0.05). Whereas, the implant position did not have any significant influence on accuracy (p > 0.05).

CONCLUSIONS

Chairside 3-D printed impression trays significantly increase the transfer accuracy for implant impression taking.

Influence of the postpolymerization type and time on the flexural strength and dimensional stability of 3D printed interim resins

STATEMENT OF PROBLEM

The mechanical strength of 3-dimensionally (3D) printed interim resins is unclear but influenced by printing parameters. Evidence regarding standardization of the postpolymerization type and time for 3D printed interim resins is sparse.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of postpolymerization type and time on flexural strength and dimensional stability of 3D printed resins for interim restorations.

MATERIAL AND METHODS

A total of 288 bars were 3D printed (Form 2; Formlabs, stereolithography-SLA, 50 µm, 30 degrees), (25×2×2 mm; International Organization for Standardization-ISO 4049:2019) abraded and randomly divided into 9 groups (n=30) according to postpolymerization (Ultraviolet device-UV; Microwave with water-MWA; Microwave without water-MW) and time (15, 20, and 30 minutes for UV; and 5, 8, and 10 minutes for MW and MWA). Each bar was then measured with digital calipers at 11 points for length, thickness, and width before and after postpolymerization to analyze dimensional stability. The flexural strength was then measured (σ; 980.6 N, 1 mm/minute) and the fractured surfaces were analyzed with scanning electron microscopy. The σ (MPa) data were evaluated by using a 2-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) pairwise comparisons test (α=.05). Dimensional stability data (mm) were analyzed by using the Kruskal-Wallis test and Dwass-Steel-Critchlow-Fligner multiple comparisons. The Weibull analysis was performed with σ data.

RESULTS

The 2-way ANOVA revealed that all factors and their interaction were significant for σ (P<.001). The UV groups presented the highest σ values, being statistically higher than all MW and MWA groups. The Weibull analysis revealed that postpolymerization UV groups found the highest values regarding the characteristic strength, although the MW 8-minute group (13.71) found the highest value for the Weibull modulus. Furthermore, the Kruskal-Wallis test revealed that only the postpolymerization factor was significant for dimensional stability (P<.001). The postpolymerization microwave groups found greater expansion variations at all times, with the MW 8-minute group (0.78 ±0.54) presenting the greatest variation in dimensional stability.

CONCLUSIONS

UV was determined to be the most suitable type of postpolymerization for interim printed resin among the postpolymerization methods, regardless of the application time. The postpolymerization MW groups found greater variations in dimensional stability.

Optimization of Dimensional Accuracy and Surface Roughness of SLA Patterns and SLA-Based IC Components

Rapid investment casting is a casting process in which the sacrificial patterns are fabricated using additive manufacturing techniques, making the creation of advanced designs possible. One of the popular 3D printing methods applied in rapid investment casting is stereolithography because of its high dimensional precision and surface quality. Printing parameters of the used additive manufacturing method can influence the surface quality and accuracy of the rapid investment cast geometries. Hence, this study aims to investigate the effect of stereolithography printing parameters on the dimensional accuracy and surface roughness of printed patterns and investment cast parts. Castable wax material was used to print the sacrificial patterns for casting. A small-scale prosthetic biomedical implant for total hip replacement was selected to be the benchmark model due to its practical significance. The main results indicate that the most significant stereolithography printing parameter affecting surface roughness is build angle, followed by layer thickness. The optimum parameters that minimize the surface roughness are 0.025 mm layer thickness, 0° build angle, 1.0 support density index, and across the front base orientation. As for the dimensional accuracy, the optimum stereolithography parameters are 0.025 mm layer thickness, 30° build angle, 0.6 support density index, and diagonal to the front base orientation. The optimal printing parameters to obtain superior dimensional accuracy of the cast parts are 0.05 mm layer thickness, 45° build angle, 0.8 support density index, and diagonal to the front model base orientation. With respect to the surface roughness, lower values were obtained at 0.025 mm layer thickness, 0° build angle, 1.0 support density index, and parallel to the front base orientation.

Comparison of the marginal and internal fit of PMMA interim crowns printed with different layer thicknesses in 3D-printing technique

OBJECTIVE

The aim of this in vitro study was to compare the effect of printing layer thickness on the marginal and internal fit of interim crowns.

MATERIAL AND METHODS

A maxillary first molar model was prepared for ceramic restoration. Thirty-six crowns were printed with three different layer thicknesses using a digital light processing-based three-dimensional printer (25, 50, and 100 µm [LT 25, LT 50, and LT 100]). The marginal and internal gaps of the crowns were measured with replica technique. An analysis of variance was conducted to determine if there were significant differences between the groups (ɑ = .05).

RESULTS

The marginal gap of LT 100 group was significantly higher than that LT 25 (p = .002) and LT 50 groups (p ≤ .001). The LT 25 group has significantly larger axial gaps than LT 50 group (p = .013); however, there were no statistically significant differences between other groups. The LT 50 group showed the smallest axio-occlusal gap. The mean occlusal gap differed significantly by printing layer thickness (p ≤ .001), with the largest gap occurring for LT 100.

CONCLUSIONS

Provisional crowns printed with 50 µm layer thickness provided the best marginal and internal fit.

CLINICAL SIGNIFICANCE

It is recommended that provisional crowns be printed with a 50 µm layer thickness to ensure optimal marginal and internal fit.

Comparative Analysis between Conventional Acrylic, CAD/CAM Milled, and 3D CAD/CAM Printed Occlusal Splints

The development of digital technologies has allowed for the fabrication of new materials; however, it makes it difficult to choose the best methods to obtain occlusal splints with optimal properties, so it is essential to evaluate the effectiveness of these materials. The aim of the study is to compare the fracture resistance of occlusal splints made of different materials after thermo-mechanical aging.

METHODS

A total of 32 samples were made from 4 materials (two 3D printed polymeric materials, a PMMA disc for CAD/CAM, and a conventional heat-cured acrylic resin); subsequently, the fracture test was performed using the load compression mode applied occlusally on the splint surface.

STATISTICAL ANALYSIS

Four statistical tests were used (Shapiro-Wilk, Levene's test, ANOVA, and Tukey's HSD test).

RESULTS

The following study showed that there are differences in fracture strength among the four materials investigated, where the highest strength was observed in the milled splint, with a mean of 3051.2 N (newton) compared to the strength of the flexible splint with 1943.4 N, the printed splint with 1489.9 N, and the conventional acrylic splint with 1303.9 N.

CONCLUSIONS

The milled splints were the most resistant to fracture. Of the printed splints, the splint made with flexural rigid resin withstood the applied forces in acceptable ranges, so its clinical indication may be viable. Although the results of this research indicated differences in the mechanical properties between the CAD/CAM and conventional fabrication methods, the selection may also be influenced by processing time and cost, since with a CAD/CAM system there is a significant reduction in the production time of the splint material.

3D Printing for Dental Applications

Due to increased life expectancy and greater concern among populations regarding oral health problems and aesthetics, in the last few years, there has been a growing demand for dental structures and devices to replace/restore missing/damaged teeth [...].

The state of additive manufacturing in dental research - A systematic scoping review of 2012-2022

Background/purpose

Additive manufacturing (AM), also known as 3D printing, has the potential to transform the industry. While there have been advancements in using AM for dental restorations, there is still a need for further research to develop functional biomedical and dental materials. It's crucial to understand the current status of AM technology and research trends to advance dental research in this field. The aim of this study is to reveal the current status of international scientific publications in the field of dental research related to AM technologies.

Materials and methods

In this study, a systematic scoping review was conducted using appropriate keywords within the scope of international scientific publishing databases (PubMed and Web of Science). The review included related clinical and laboratory research, including both human and animal studies, case reports, review articles, and questionnaire studies. A total of 187 research studies were evaluated for quantitative synthesis in this review.

Results

The findings highlighted a rising trend in research numbers over the years (From 2012 to 2022). The most publications were produced in 2020 and 2021, with annual percentage increases of 25.7% and 26.2%, respectively. The majority of AM-related publications in dentistry research originate from Korea. The pioneer dental sub-fields with the ost publications in its category are prosthodontics and implantology, respectively.

Conclusion

The final review result clearly stated an expectation for the future that the research in dentistry would concentrate on AM technologies in order to increase the new product and process development in dental materials, tools, implants and new generation modelling strategy related to AM. The results of this work can be used as indicators of trends related to AM research in dentistry and/or as prospects for future publication expectations in this field.

3D Printing of Dental Prostheses: Current and Emerging Applications

Revolutionary fabrication technologies such as three-dimensional (3D) printing to develop dental structures are expected to replace traditional methods due to their ability to establish constructs with the required mechanical properties and detailed structures. Three-dimensional printing, as an additive manufacturing approach, has the potential to rapidly fabricate complex dental prostheses by employing a bottom-up strategy in a layer-by-layer fashion. This new technology allows dentists to extend their degree of freedom in selecting, creating, and performing the required treatments. Three-dimensional printing has been narrowly employed in the fabrication of various kinds of prostheses and implants. There is still an on-demand production procedure that offers a reasonable method with superior efficiency to engineer multifaceted dental constructs. This review article aims to cover the most recent applications of 3D printing techniques in the manufacturing of dental prosthetics. More specifically, after describing various 3D printing techniques and their advantages/disadvantages, the applications of 3D printing in dental prostheses are elaborated in various examples in the literature. Different 3D printing techniques have the capability to use different materials, including thermoplastic polymers, ceramics, and metals with distinctive suitability for dental applications, which are discussed in this article. The relevant limitations and challenges that currently limit the efficacy of 3D printing in this field are also reviewed. This review article has employed five major scientific databases, including Google Scholar, PubMed, ScienceDirect, Web of Science, and Scopus, with appropriate keywords to find the most relevant literature in the subject of dental prostheses 3D printing.

Accuracy of 3D printed models and implant-analog positions according to the implant-analog-holder offset, inner structure, and printing layer thickness: an in-vitro study

PURPOSE

This study aimed to determine how the implant-analog-holder (IAH) offset, inner structure, and printing layer thickness influence the overall accuracy and local implant-analog positional changes of 3D printed dental models.

METHODS

Specimens in 12 experimental groups (8 specimens per group) with different IAH offsets, inner structures, and printing layer thicknesses were printed in three dimensions using an LCD printer (Phrozen Shuffle) and digitized by a laboratory scanner (Identica T500). The trueness and precision of the printed model as well as the angular distortion, depth deviation, and linear distortion of the implant analog were evaluated using three-way ANOVA.

RESULTS

The positional accuracy was significantly higher for IAH offsets of 0.04 mm and 0.06 mm than for one of 0.08 mm, for a hollow than a solid inner structure, and for a printing layer thickness of 100 µm than for one of 50 µm (all P<.001).

CONCLUSIONS

The accuracies of the 3D printed models and the implant-analog positions were significantly affected by the IAH offset, inner structure, and printing layer thickness.

CLINICAL SIGNIFICANCE

Given the observation of this study, premeditating the IAH offset of 0.06 mm, hollow inner structure, and printing layer thickness of 100 µm before printing can help clinicians reach the optimum overall printing accuracy and minimum the local positional changes of the implant-analogs.

Fabrication of Customized dental guide by stereolithography method and evaluation of dimensional accuracy with artificial neural networks

The present study was investigated the production dental guides by using additive manufacturing stereolithography (SLA) technology, and the dimensional aperture values of the dental guides for dental implant treatment using artificial intelligence technology. The aim of this study is to benefit from artificial neural networks (ANNs) to classify the results obtained from the new production freedom of SLA by changing the existing design concept of dental guides. In the study, the Three Dimensional (3D) anatomical model was designed by using Mimics programme the data obtained from the Cone Beam Computed Tomography (CBCT) images of the patient. Three different dental guide designs were performed using the 3-Matic programme for dental implant treatment on the obtained 3D anatomical model. Dental guide designs and mandible model were produced with a SLA 3D printer, and a data set was created using a 3D scanner. The dimensional aperture values were obtained by performing the 3D registration process between the mandible and dental guides. The data set was analyzed both statistically with Jamovi 2.0.0 software and ANNs. The results showed that the minimum and maximum aperture values obtained from the dental guides were very close to each other, indicating that the guides were compatible with the mandible bone. The statistical results showed that the dimensional aperture values decrease in proportion to the values with minimum arithmetic mean value in the data set, and it was determined that the dental guide-3 was the most suitable model for the mandible. When all test data in the confusion matrix obtained from ten different aritificial neural network models created using ANNs were examined, it was been seen that ANN model-5 was the most successful model with an accuracy rate of 99%.

Analysis and Optimization of Dimensional Accuracy and Porosity of High Impact Polystyrene Material Printed by FDM Process: PSO, JAYA, Rao, and Bald Eagle Search Algorithms

High impact polystyrene (HIPS) material is widely used for low-strength structural applications. To ensure proper function, dimensional accuracy and porosity are at the forefront of industrial relevance. The dimensional accuracy cylindricity error (CE) and porosity of printed parts are influenced mainly by the control variables (layer thickness, shell thickness, infill density, print speed of the fused deposition modeling (FDM) process). In this study, a central composite design (CCD) matrix was used to perform experiments and analyze the complete insight information of the process (control variables influence on CE and porosity of FDM parts). Shell thickness for CE and infill density for porosity were identified as the most significant factors. Layer thickness interaction with shell thickness, infill density (except for CE), and print speed were found to be significant for both outputs. The interaction factors, i.e., shell thickness and infill density, were insignificant (negligible effect) for both outputs. The models developed produced a better fit for regression with an R² equal to 94.56% for CE, and 99.10% for porosity, respectively. Four algorithms (bald eagle search optimization (BES), particle swarm optimization (PSO), RAO-3, and JAYA) were applied to determine optimal FDM conditions while examining six case studies (sets of weights assigned for porosity and CE) focused on minimizing both CE and porosity. BES and RAO-3 algorithms determined optimal conditions (layer thickness: 0.22 mm; shell thickness: 2 mm; infill density: 100%; print speed: 30 mm/s) at a reduced computation time equal to 0.007 s, differing from JAYA and PSO, which resulted in an experimental CE of 0.1215 mm and 2.5% of porosity in printed parts. Consequently, BES and RAO-3 algorithms are efficient tools for the optimization of FDM parts.

Dimensional Stability of 3D Printed Objects Made from Plastic Waste Using FDM: Potential Construction Applications

Construction projects are often challenged by tight budgets and limited time and resources. Contractors are, therefore, looking for ways to become competitive by improving efficiency and using cost-effective materials. Using three-dimensional (3D) printing for shaping materials to produce cost-effective construction elements is becoming a feasible option to make contractors more competitive locally and globally. The process capabilities for 3D printers and related devices have been tightened in recent years with the booming of 3D printing industries and applications. Contractors are attempting to improve production skills to satisfy firm specifications and standards, while attempting to have costs within competitive ranges. The aim of this research is to investigate and test the production process capability (Cp) of 3D printers using fused deposition modeling (FDM) to manufacture 3D printed parts made from plastic waste for use in the construction of buildings with different infill structures and internal designs to reduce cost. This was accomplished by calculating the actual requirement capabilities of the 3D printers under consideration. The production capabilities and requirements of FDM printers are first examined to develop instructions and assumptions to assist in deciphering the characteristics of the 3D printers that will be used. Possible applications in construction are then presented. As an essential outcome of this study, it was noticed that the 3D printed parts made from plastic waste using FDM printers are less expensive than using traditional lightweight non-load bearing concrete hollow masonry blocks, hourdi slab hollow bocks, and concrete face bricks.

Self-Healing and Highly Stretchable Hydrogel for Interfacial Compatible Flexible Paper-Based Micro-Supercapacitor

Most reported wearable electronic devices lack self-healing chemistry and flexible function to maintain stable energy output while irreversible damages and complex deformations. In this work, we report a dual-dynamic network electrolyte synthesized by micellar elastomers introduced into strong hydrogel matrix. The gel electrolyte is fabricated by physically cross-linking the borax-polyvinyl alcohol (B-PVA) network as tough matrix and poly (ethylene oxide) (PEO)-poly (propylene oxide) (PPO)-poly (ethylene oxide) (Pluronic) to frame elastic network, followed by immersion in potassium chloride solution. Under the action of dynamic borate ester bond and multi-network hydrogen bond, the as-prepared electrolyte exhibits high stretchability (1535%) and good self-healing efficiency. Based on the electrolyte, we assemble the interfacial compatible micro-supercapacitor (MSC) by multi-walled carbon nanotubes (MWCNT) interdigital electrode printed on cellulosic paper by direct ink writing (DIW) technique. Thanks to the large specific area and compressive deformation resistance of cellulosic paper, the MSC with tightly interfacial contact achieves high volumetric capacitance of 801.9 mF cm⁻³ at the current density of 20 μA cm⁻². In the absence of stimulation of the external environment, the self-healing MSC demonstrates an ideal capacity retention (90.43%) after five physical damaged/healing cycles. Our research provides a clean and effective strategy to construct wearable MSC.