Polymer Powder Research Articles

Towards the Reuse of Fire Retarded Polyamide 12 for Laser Sintering.

The control of powder aging during Selective Laser Sintering (SLS) processing is one of the challenges to be overcome for the implementation of this technique in serial production. Aging phenomena, because of the elevated temperatures and long processing times, need to be considered when a fraction of the polymer powders present in the build chamber and not used to manufacture the parts are reused at various times. The aim of this study was to investigate the influence of successive reuse of blends of pure Polyamide 12 and its blends with two types of flame retardants (FR): ammonium polyphosphate (APP) and zinc borate (ZB). The composition of the blends was 70/30 (wt/wt) PA 12/FR. Four successive processing stages have been carried out by collecting the remaining powder blend each time. The powders were re-used using the same processing parameters after sieving. DSC measurements showed that the incorporation of FRs entailed a reduction in the processing window up to 4 °C; nevertheless, no further reduction was noted after aging. The TGA curves of aged blends of powders were also similar for pure PA 12 and PA 12 with FR. In addition, initial and reused powders presented a higher degree of crystallinity than the specimens processed from the powders. The heterogeneous character of the PA 12 after LS processing or reprocessing was shown through Pyrolysis Combustion Flow Calorimetry (PCFC) and cone calorimeter (CC) tests. FTIR analysis also showed that post-condensation reactions have occurred. The mode of action of the flame retardants was clearly seen on HRR curves at both tests. The first reuses of PA 12 powders entailed a significant reduction in time to ignition at the cone calorimeter (150 for the initial material to around 90 s for the reused material), indicating the formation of short polymer chains. Only in the case of zinc borate was it noticed that re-used powder was detrimental to the fire performance because of a strong increase in the value of pHRR (between 163 and 220 kW/m2 for reused material instead of 125 kW/m2 for the initial one).

Enhanced PMMA Denture Bases Using Functionalized MWCNT Fused g-C3N4 Nanocomposites

This study presents the development and analysis of a new metal-free nanocomposite that incorporates functionalized multi-walled carbon nanotubes (f-MWCNTs) with graphitic carbon nitride (g-C3N4) for reinforcing polymethyl methacrylate (PMMA) denture bases. The f-MWCNTs were integrated with g-C3N4 nanoparticles, and their structural and morphological features were examined using various techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. A mechanical blending process was employed to synthesize the nanocomposite by mixing 2 wt% of the f-MWCNT/g-C3N4 with PMMA polymer powder, followed by heat curing to form the composite material. Specimens for mechanical testing were crafted to measure flexural strength, impact resistance, compressive performance, and hardness. The findings revealed that the f-MWCNT/g-C3N4-reinforced PMMA composites outperformed standard PMMA in mechanical robustness. Surface examination of the tested samples through SEM showed distinctive dimpling and roughness, indicating a toughened fracture surface in comparison to pure PMMA and g-C3N4 samples. The study concludes that this innovative f-MWCNT/g-C3N4 composite is a promising reinforcement for PMMA denture bases, enhancing both their mechanical and physical attributes.Keywords: PMMA, functionalization, MWCNTs, Graphitic Carbide Nitride, Mechanical Properties and Denture Base

Effect of Basalt Size and Composition on Mechanical Properties of Wood Powder Polymer Biocomposite Material and Basalt as Reinforcement

Utilization of waste for raw materials for new materials is very potential for research. Wood waste from door and window craftsmen is widely available as the property business develops. Wood waste mixed with polyester resin is modified by adding basalt to produce a biocomposite material with better mechanical properties. This research on the effect of adding the composition and size of basalt to the wood-polyester biocomposite material was studied to see changes in hardness values according to the ASTM E384 standard, compressive strength according to ASTM D695 standard, and its effect on density according to ASTM D1622 standard. The results showed that the higher the composition and the smaller the basalt hardness value, the compressive strength and density increased. The highest values of hardness, compressive strength and density were 36.6 HV0.5, 151.14 MPa, and 0.1420 kg/m3, an increase compared to that without the addition of basalt 26.7 HV0.5, 95.97 MPa, and 0.1288 kg/m3. Changes in the properties of hardness, compressive strength and density are taken into consideration in the formulation of using basalt to obtain new materials according to the desired specifications by utilizing wood waste.

Patents as an indicator of sustainability of domestic products in the Russian market on the example of redispersible polymer powders

The article provides information regarding patenting statistics in the field of compositions and methods of production of redispersible polymer powders. It is demonstrated that a patent is primarily a profit-making tool, and patent research is a mechanism for making long-term forecasts in a technological niche. The main mistakes of Russian patent holders when protecting their developments are discussed and ways to prevent them are proposed. Comparative examples of claim writing are offered, and issues of comprehensive patent protection are also discussed.

Predicting the impermeability and mechanical properties of manufactured sand polymer waterproof mortar using an optimised back-propagation neural network

Owing to its complex composition, accurately predicting the performance of polymer waterproof mortar (PWM) using ordinary equations is difficult. To quickly and accurately obtain the proportions of various components of high-performing PWM, in this study, we designed a back-propagation neural network (BPNN) model with a topology structure of 5–12–2 and optimised it using the particle swarm optimisation (PSO) algorithm, whale optimisation algorithm (WOA), and genetic algorithm (GA). The input layer of the model included cement (OPC), a waterproofing additive (WPA), dispersible polymer powder (DPP), tuff stone powder (SP), and fly ash (FA), whereas the output layer included the chloride-ion electric flux and compressive strength of PWM. The model dataset comprised 378 samples, of which 228 were used for model establishment and 150 were used for model validation. Correlation analysis was conducted to determine the relationship between the raw materials and the impermeability and mechanical properties of PWM; further, principal component analysis was performed on the PWM dataset. At 7 and 28 d, the dosages of WPA and DPP in the PWM were negatively correlated with the chloride-ion electric flux and positively correlated with the compressive strength. In addition, at 28 d, the OPC dosage was positively correlated with the chloride-ion electric flux and negatively correlated with the compressive strength; the SP and FA dosages were correlated negatively and positively with the chloride-ion electric flux and compressive strength, respectively. Group B4 performed the best in this study, and group E4 had the optimal ratio of mineral admixtures. The WOA-BPNN achieved the highest prediction accuracy for both the PWM chloride-ion electric flux and compressive strength, with prediction evaluation parameters of R2 = 0.98, MAE = 17.4, MAPE = 0.09, and RMSE = 21.2 and R2 = 0.98, MAE = 15.4, MAPE = 0.07, and RMSE = 21.0, respectively. Using the WOA-BPNN to predict the impermeability and mechanical properties of PWM is viable, and the WOA-BPNN can offer scientific guidance for the proportionate design of PWM.

Antibacterial Food Packaging Containing Stably Dispersed Cu Nanoparticles Synthesized by Novel Physical Vapor Deposition Process

Polymeric materials were modified by nanoparticles on powder (NPP) facility in which metal nanoparticles (Cu, Cu/Zn alloy etc.) are formed on the surface of rotating carrier powder by using physical vapor deposition process untile the metal content reached 0.3wt.%. The polymer material with metal nanoparticles deposited on their surface through the NPP process was then added to the raw polymer material at a ratio of 1 to 9. The mixture of modified polymer powder and raw polymer powder were then processd into a film by conventional processes such as hot melting, extrusion, T-die, and antibacterial characteristics of the film were investigated. We ultimately manufactured antibacterial food package using the film and conducted preservation test for two weeks at room temperature. Since food package containing 0.03wt.% Cu nanoparticles showed over 99.9% bacteria reduction rate, it slowed down the progress of deterioration significantly compared to conventional packages. For safety evaluation, the amount of copper released out was analyzed and a cytotoxicity test was also conducted.

TECHNOLOGY OF STRUCTURAL REPAIR OF CONCRETE AND REINFORCED CONCRETE STRUCTURES OF WATERWORKS

The assessment of the current state of the water and land reclamation engineering infrastructure facilities, which was carried out on the basis of the analysis of technical documentation, visual, and instrumental examination of the structures' technical condition, confirms that as a result of long-term operation of the waterworks without proper reparation and restoration measures, their technical condition has significantly deteriorated. The most promising for the repair of concrete and reinforced concrete structures are cement-based materials modified with polymers (polymer concrete), which are dry mixtures of cement, sand, re-dispersible polymer powder (RPP) and other modifying additives. The research results of the redispersing polymer powders influence on the adhesive properties of repair composites are presented. It is shown that the modification of cement-sand solutions of RPP leads to a significant increase in the adhesive properties of repair composites. The optimally effective concentration of RPP in repair compositions has been found. The article highlights the technology of structural repair of concrete and reinforced concrete structures of the waterworks with the use of modern composite materials, which makes it possible to restore the design geometric indicators and the load-bearing capacity of the structures. The proposed technology and effective repair compositions help to carry out repair and restoration work on hydrotechnical structures of the water management and reclamation complex, in particular those destroyed or damaged as a result of the military aggression of the Russian Federation against Ukraine. The main principles of choosing the optimal technology for the structural repair of concrete and reinforced concrete structures of the waterworks, depending on the nature and degree of damage, the influence of technological and operational conditions on the structures' geometric indicators restoration during the modernization and reconstruction of reclamation systems in the post-war period, are revealed.

Ray tracing heat source model for polymer powder bed fusion considering laser energy absorption and multiple reflection

Powder bed fusion is considered one of the most promising additive manufacturing technologies, but the generation and evolution of volumetric heat source involved in the powder bed fusion process remain unclear as laser-powder bed interactions has not been fully developed. In this work, a ray tracing model is established to simulate the laser-powder bed interaction during the powder bed fusion process. Five types of powder beds with homogeneous and non-homogeneous particle radius distributions are generated using the discrete element method, and then the energy distributions in the ray tracing heat source are explored by considering laser energy absorption and multiple reflection. The results indicate that the energy distribution in the ray tracing heat source basically exhibits a Gaussian-like trend in the horizontal plane and an exponential decay in the vertical direction. The fitting coefficients Z0 (related to laser power) and η2 (related to laser radius) of the ray tracing heat source for different powder beds show maximum differences of 21.87 % and 72.22 %, respectively, compared to conventional Gaussian volumetric heat sources. The deviation between the fitting coefficient η3 (related to laser energy attenuation) and the corresponding fitted attenuation coefficient of the powder bed is related to the overall uniformity of the powder bed. Due to multiple reflections of the laser within the powder bed, the ray tracing heat source has larger width and depth as compared to Gaussian volumetric heat source. This study is significant because it provides a more accurate heat source model for the reliable prediction and safe operation of powder bed fusion process.

Water Condenser Bed to Reduce Trichloroethylene Gas Emission and Air Quality

Purpose: The purpose of this research is how to reduce trichloroethylene emissions using a condenser and the efficiency of reducing trichloroethylene emissions before and after using a condenser. Theoretical Framework: Air quality is influenced by trichloroethylene emissions, condenser and efficiency, trichloroethylene emissions, and condenser. Method: The research carried out was quantitative descriptive research. Data Source: Literature Study; Field observation; Trichlorethylene gas recovery process in existing systems in the field such as dryer units, carbon bed units and added condenser units. Sampling method with Trichlorethylene, Gas Emission, Concentration Measurement. Results and Discussion: The efficiency value of reducing the trichloroethylene gas emission load before and after adding the condenser reached 68.16%. The emission load on the chimney before adding the condenser was an average of 223 kg/day and after adding the condenser an average of 71 kg/day. Research Implications: The efficiency of reducing the trichloroethylene gas emission load is influenced by several supporting factors, namely the temperature of the condenser cooling water and the surface area of the cooling water tube pipe. Originality/Value: The Electric Accumulator Component Industry with products in the form of sheet-shaped Electric Accumulator Separators made from polymer powder, silica powder, oil, and other supporting materials with the production capacity will affect the formation of the solution.

Quality assessment of soybean seeds submitted to industrial seed treatment and stored in a natural and controlled environment

Seed quality is a limiting factor in the search for high soybean yields. However, fungi and insect pests can negatively interfere with their performance, and industrial seed treatment (IST) is a tool used to minimize the attack of pathogens and pests. The treated seeds are often stored until sowing, which can lead to a reduction in their quality. This work aimed to evaluate the physical and physiological quality of soybean seeds submitted to IST, with subsequent storage in a natural and controlled environment. The experiment was conducted in a split-split-plot design in a completely randomized scheme (time x storage systems x IST) with four replications. Soybean cultivar 55I57RSF IPRO was subjected to IST with fungicide (metalaxyl-M, thiabendazole, and fludioxonil) and insecticide (thiamethoxam and cyantraniliprole), combined or not with polymer and dry powder, with subsequent storage in a controlled and natural environment. The moisture content, thousand-seed weights, germination, first germination count, germination speed index, accelerated aging, seedling length, dry matter transfer, and emergence sand test were evaluated. IST did not affect the moisture content and weight of a thousand seeds. However, storage in a controlled environment provided a greater reduction in moisture content and a smaller reduction in the weight of a thousand seeds. IST negatively affected germination, first germination count, germination speed index, and accelerated aging test. IST negatively affected plant length, except in the treatment where only insecticide was applied. The dry mass transfer was negatively affected but with less intensity in seeds subjected only to the application of insecticide or fungicide and the combination of insecticide, fungicide, and polymer. Seed emergence in the sand was negatively affected by all treatments. Regardless of the treatments, all responses evaluated showed a reduction throughout storage, with greater intensity in seeds stored in the natural environment.

Advanced Dentistry Biomaterials Containing Graphene Oxide.

The aim of this study was to obtain three experimental resin-based cements containing GO and HA-Ag for posterior restorations. The samples (S0, S1, and S2) shared the same polymer matrix (BisGMA, TEGDMA) and powder mixture (bioglass (La2O3 and Sr-Zr), quartz, GO, and HA-Ag), with different percentages of graphene oxide (0%, 0.1%, 0.2% GO) and silver-doped hydroxyapatite (10%, 9.9%, 9.8% HA-Ag). The physical-chemical properties (water absorption, degree of conversion), mechanical properties (DTS, CS, FS), structural properties (SEM, AFM), and antibacterial properties (Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Porphyromonas gingivalis, and Escherichia coli) were investigated. The results showed that the mechanical properties, except for the diametral tensile test, increased with the rise in the %GO. After 28 days, water absorption increased with the rise in the %GO. The surface structure of the samples did not show major changes after water absorption for 28 days. The antibacterial effects varied depending on the samples and bacterial strains tested. After increasing the %GO and decreasing the %HA-Ag, we observed a more pronounced antibacterial effect. The presence of GO, even in very small percentages, improved the properties of the tested experimental cements.

Wet tissue adhesive polymeric powder hydrogels for skeletal muscle regeneration

Volumetric muscle loss (VML) frequently results from traumatic incidents and can lead to severe functional disabilities. Hydrogels have been widely employed for VML tissue regeneration, which are unfortunately ineffective because of the lack of intimate contact with injured tissue for structural and mechanical support. Adhesive hydrogels allow for strong tissue connections for wound closure. Nevertheless, conventional adhesive hydrogels exhibit poor tissue adhesion in moist, bleeding wounds due to the hydration layer at the tissue–hydrogel interfaces, resulting in insufficient performance. In this study, we developed a novel, biocompatible, wet tissue adhesive powder hydrogel consisting of dextran-aldehyde (dex-ald) and gelatin for the regeneration of VML. This powder absorbs the interfacial tissue fluid and buffer solution on the tissue, spontaneously forms a hydrogel, and strongly adheres to the tissue via various molecular interactions, including the Schiff base reaction. In particular, the powder composition with a 1:4 ratio of dex-ald to gelatin exhibited optimal characteristics with an appropriate gelation time (258 s), strong tissue adhesion (14.5 kPa), and stability. Dex-ald/gelatin powder hydrogels presented strong adhesion to various organs and excellent hemostasis compared to other wet hydrogels and fibrin glue. A mouse VML injury model revealed that the dex-ald/gelatin powder hydrogel significantly improved muscle regeneration, reduced fibrosis, enhanced vascularization, and decreased inflammation. Consequently, our wet-adhesive powder hydrogel can serve as an effective platform for repairing various tissues, including the heart, muscle, and nerve tissues.

Spherical polystyrene/zinc oxide nanocomposite powder fabricated by continuous process chain of melt mixing and indirect heating

Polymer powders are limited by particle size, shape, and properties in various applications. Preserving the chemical properties of the material throughout the process is a critical part of developing consistently shaped nanocomposite powders across diverse polymer types. The goal of this study is to demonstrate continuous methods to produce spherical Polystyrene (PS) and zinc oxide (ZnO) nanocomposites. A single-screw extruder is used to melt mix PS pellets with ZnO nanoparticles, followed by pelletization, dry grinding, and spheroidization in a Downer Tower to form spherical polymers. To minimize agglomeration, the process incorporates an ethanol treatment and a final sieving step. The resulting nanocomposite powder exhibits exceptional flowability and well-defined spherical morphology. Additionally, incorporating ZnO nanoparticles enhanced the thermal stability and glass transition temperature of the nanocomposite while reducing particle size distribution. Thermogravimetric analysis and X-ray diffraction confirm the preservation of the chemical structure of the spherical nanocomposite specimens throughout processing.

The friction pair composed of polymers and Bi12TiO20 facilitates the tribocatalytic degradation of organic pollutants

In recent years, friction-induced tribocatalysis has garnered significant attention in the fields of environmental pollution and clean energy utilization. Despite its efficacy in converting mechanical energy into chemical energy, the degradation process is time-consuming, which limits its practical applications. In this study, we optimized the morphology of Bi12TiO20 catalyst and employed the most active Bi12TiO20 combined with four kinds of triboelectric polymer powders to form an efficient friction pair that enhances the tribocatalytic efficiency for organic pollutant degradation. The amount of polymer added, stirring rate, number and shape of stirring bars, as well as the materials of stirring bars and beakers were investigated. The recycled tribocatalyst exhibited recyclability and stability in degrading organic pollutants. The hydroxyl and superoxide radicals were quantitatively determined, and the generation and mechanism of positive and negative charges in the process of tribocatalysis were analysed. The potential mechanisms underlying charge generation during tribocatalysis were investigated, while also exploring the degradation pathway of Rhodamine B through high-efficiency tribocatalysis.

Study on the evolutionary mechanism of shrinkage stress-strain behavior of EVA-modified cement mortar at an early age

Understanding the early deformation characteristics is important to predict early cracks in cementitious materials and to serve structural engineering. Incorporation of polyethylene-vinyl acetate (EVA) dispersible polymer powder can improve the early cracking of cementitious materials. In this paper, the homogeneity, shrinkage stress-strain behavior and the evolutionary mechanism of EVA-modified cement mortar (EMCM) with different polymer-to-cement ratios (p/c) were investigated at an early age. The homogeneity and shrinkage stress-strain behavior of EMCM were characterized by a self-designed test setup. Isothermal calorimetric analysis, scanning electron microscopy and X-ray diffraction were used for the evolutionary mechanism analysis. The results show that the homogeneity of shrinkage of EMCM can be improved by adding EVA and prolonging the mixing time. The shrinkage stress of EMCM can be reduced by 83 % when p/c is 10 % and 15 %. Meanwhile, the elastic modulus of mortar can be reduced by 45 % when the EVA content is 15 %. Isothermal calorimetric analysis and characterization of microscopic properties show that EVA can inhibit both the generation and conversion of C4AH13, as well as the generation of AFt and CH, and retard the hydration of cement mortar. Within 3 h of hydration, the change in shrinkage stress of EMCM is only affected by the amount of AFt generated, while the change in shrinkage strain is affected by both CH and AFt generation, and the correlation with CH is greater. Finally, the interpenetrating network structure between the EVA and the cementitious matrix increases the interaction and bond between them, giving good deformability and thus reducing shrinkage. Therefore, the reduction in shrinkage stress-strain of EMCM is a result of the combined effect of the polymer on delaying cement hydration and increasing internal interaction and bonding.

Experimental and numerical mechanical characterisation of additively manufactured polymeric lattice structures under uniaxial tensile load

AbstractAdditive manufacturing enables the production of lighter, more robust components with intricate features like lattice structures. However, since the mechanical behaviour of lattice structures is not fully characterized, the application of such potential is limited today. The challenge with lattice structures tensile tests is defining a suitable design that fits the standard requirements and process characteristics. In the polymeric powder bed fusion process, the problem is to produce powder-free geometries and to avoid stress concentrations zones, adapting the specimen accordingly. In this regard, numerical simulation may provide insightful information and support the analysis of the deformation mechanisms. This paper analyses a new tensile sample for lattice structures using finite element analysis. The sample is designed following the EN ISO 527 standard prescriptions. An area with a controlled gradation of the lattice relative density is designed to ensure both powder-free voids and fracture localization within the lattice specimen gauge length. Experimental tests are performed to validate the numerical results using a modified body cubic centred topology with two different strut diameters. The specimens are produced in polyamide by powder bed AM process. Due to the complexity of the lattice design, a digital image correlation is used to compute the full range of strains at the macroscopic level. Experimental and numerical strain maps results showed a good agreement. The recorded deviation was attributed to the process-induced defect, such as the geometrical accuracy that, if compensated, boosted the capability of the numerical model to predict the mechanical behaviour of the lattice structure.

Recovery of residual polyamide (PA12) from polymer powder bed fusion additive manufacturing process through a binder jetting process

PurposeThis study aims to propose the reuse of PA12 (powder) in another AM process, binder jettiinng, which is less sensitive to the chemical and mechanical degradation of the powder after multiple cycles in the laser system.Design/methodology/approachThe experimental process for evaluating the reuse of SLS powders in a subsequent binder jetting process consists of four phases: powder characterization, bonding analysis, mixture testing and mixture characteristics. Analyses were carried out using techniques such as Fourier Transform Infrared Spectroscopy, scanning electron microscopy, thermogravimetric analysis and stress–strain tests for tension and compression. The surface roughness, color, hardness and density of the new mixture were also determined to find physical characteristics. A Taguchi design L8 was used to search for a mixture with the best mechanical strength.FindingsThe results indicated that the integration of waste powder PA12 with calcium sulfate hemihydrate (CSH) generates appropriate particle distribution with rounded particles of PA12 that improve powder flowability. The micropores observed with less than 60 µm, facilitated binder and infiltrant penetration on 3D parts. The 60/40 (CSH-PA12) mixture with epoxy resin postprocessing was found to be the best-bonded mixture in mechanical testing, rugosity and hardness results. The new CSH-PA12 mixture resulted lighter and stronger than the CSH powder commonly used in binder jetting technology.Originality/valueThis study adds value to the polymer powder bed fusion process by using its waste in a circular process. The novel reuse of PA12 waste in an established process was achieved in an accessible and economical manner.

Poly(dl-lactide) Polymer Blended with Mineral Phases for Extrusion 3D Printing-Studies on Degradation and Biocompatibility.

A promising therapeutic option for the treatment of critical-size mandibular defects is the implantation of biodegradable, porous structures that are produced patient-specifically by using additive manufacturing techniques. In this work, degradable poly(DL-lactide) polymer (PDLLA) was blended with different mineral phases with the aim of buffering its acidic degradation products, which can cause inflammation and stimulate bone regeneration. Microparticles of CaCO3, SrCO3, tricalcium phosphates (α-TCP, β-TCP), or strontium-modified hydroxyapatite (SrHAp) were mixed with the polymer powder following processing the blends into scaffolds with the Arburg Plastic Freeforming 3D-printing method. An in vitro degradation study over 24 weeks revealed a buffer effect for all mineral phases, with the buffering capacity of CaCO3 and SrCO3 being the highest. Analysis of conductivity, swelling, microstructure, viscosity, and glass transition temperature evidenced that the mineral phases influence the degradation behavior of the scaffolds. Cytocompatibility of all polymer blends was proven in cell experiments with SaOS-2 cells. Patient-specific implants consisting of PDLLA + CaCO3, which were tested in a pilot in vivo study in a segmental mandibular defect in minipigs, exhibited strong swelling. Based on these results, an in vitro swelling prediction model was developed that simulates the conditions of anisotropic swelling after implantation.

Research and implementation of large-area sintering technology based on image-shaped laser

PurposeSelective laser sintering (SLS) is an essential technology in the field of additive manufacturing. However, SLS technology is limited by the traditional point-laser sintering method and has reached the bottleneck of efficiency improvement. This study aims to develop an image-shaped laser sintering (ISLS) system based on a digital micromirror device (DMD) to address this problem. The ISLS system uses an image-shaped laser light source with a size of 16 mm × 25.6 mm instead of the traditional SLS point-laser light source.Design/methodology/approachThe ISLS system achieves large-area image-shaped sintering of polymer powder materials by moving the laser light source continuously in the x-direction and updating the sintering pattern synchronously, as well as by overlapping the splicing of adjacent sintering areas in the y-direction. A low-cost composite powder suitable for the ISLS system was prepared using polyether sulfone (PES), pinewood and carbon black (CB) powders as raw materials. Large-sized samples were fabricated using composite powder, and the microstructure, dimensional accuracy, geometric deviation, density, mechanical properties and feasible feature sizes were evaluated.FindingsThe experimental results demonstrate that the ISLS system is feasible and can print large-sized parts with good dimensional accuracy, acceptable geometric deviations, specific small-scale features and certain density and mechanical properties.Originality/valueThis study has achieved the transition from traditional point sintering mode to image-shaped surface sintering mode. It has provided a new approach to enhance the system performance of traditional SLS.

A facile one step route that introduces functionality to polymer powders for laser sintering

Laser Sintering (LS) is a type of Additive Manufacturing (AM) exploiting laser processing of polymeric particles to produce 3D objects. Because of its ease of processability and thermo-physical properties, polyamide-12 (PA-12) represents ~95% of the polymeric materials used in LS. This constrains the functionality of the items produced, including limited available colours. Moreover, PA-12 objects tend to biofoul in wet environments. Therefore, a key challenge is to develop an inexpensive route to introduce desirable functionality to PA-12. We report a facile, clean, and scalable approach to modification of PA-12, exploiting supercritical carbon dioxide (scCO2) and free radical polymerizations to yield functionalised PA-12 materials. These can be easily printed using commercial apparatus. We demonstrate the potential by creating coloured PA-12 materials and show that the same approach can be utilized to create anti-biofouling objects. Our approach to functionalise materials could open significant new applications for AM.