Search Results (45)

The amount of non-revenue water, mostly due to leakage, is around 126 billion cubic meters annually worldwide. A more efficient wastewater management strategy would use a parametric design for on-demand, customized pipe fittings, following the principles of distributed manufacturing. To fulfill this need, this study introduces an open-source parametric design of a 3D-printable easy-connect pipe fitting that offers compatibility with different dimensions and materials of pipes available on the market. Custom pipe fittings were 3D printed using a RepRap-class fused filament 3D printer, with polylactic acid (PLA), polyethylene terephthalate glycol (PETG), acrylonitrile styrene acrylate (ASA), and thermoplastic elastomer (TPE) as filament feedstocks for validation. The 3D-printed connectors underwent hydrostatic water pressure tests to ensure that they met the standards for residential, agricultural, and renewable energy production applications. All the printed parts passed numerous hydrostatic pressure tests. PETG couplings can tolerate up to 4.551 ± 0.138 MPa of hydrostatic pressure, which is eight times greater than the highest standard water pressure in the residential sector. Based on the economic analysis, the cost of 3D printing a pipe coupling is from three to seventeen times lower than purchasing a commercially available pipe fitting of a similar size. The new open-source couplings demonstrate particular potential for use in developing countries and remote areas. Full article

In this study, specific additives were incorporated in polyhydroxyalcanoate (PHB) and polylactic acid (PLA) blend to improve its compatibility, and so enhance the cell metabolic activity of scaffolds for tissue engineering. The formulations were manufactured through material extrusion (MEX) additive manufacturing (AM) technology. As additives, petroleum-based poly(ethylene) with glicidyl metacrylate (EGM) and methyl acrylate-co-glycidyl methacrylate (EMAG); poly(styrene-co-maleic anhydride) copolymer (Xibond); and bio-based epoxidized linseed oil (ELO) were used. On one hand, standard geometries manufactured were assessed to evaluate the compatibilizing effect. The additives improved the compatibility of PHB/PLA blend, highlighting the effect of EMAG and ELO in ductile properties. The processability was also enhanced for the decrease in melt temperature as well as the improvement of thermal stability. On the other hand, manufactured scaffolds were evaluated for the purpose of bone regeneration. The mean pore size and porosity exhibited values between 675 and 718 μm and 50 and 53%, respectively. According to the results, the compression stress was higher (11–13 MPa) than the required for trabecular bones (5–10 MPa). The best results in cell metabolic activity were obtained by incorporating ELO and Xibond due to the decrease in water contact angle, showing a stable cell attachment after 7 days of culture as observed in SEM. Full article

Regenerative medicine is an interdisciplinary field aiming at restoring pathologically damaged tissues and whole organs by cell transplantation in combination with proper supporting scaffolds. Gelatine-based ones are very attractive due to their biocompatibility, rapid biodegradability, and lack of immunogenicity. Gelatine-based composite hydrogels, containing strengthening agents to improve their modest mechanical properties, have been demonstrated to act as extracellular matrices (ECMs), thus playing a critical role in “organ manufacturing”. Inspired by the lysyl oxidase (LO)-mediated process of crosslinking, which occurs in nature to reinforce collagen, we have recently developed a versatile protocol to crosslink gelatine B (Gel B) in the presence or absence of LO, using properly synthesized polystyrene- and polyacrylic-based copolymers containing the amine or aldehyde groups needed for crosslinking reactions. Here, following the developed protocol with slight modifications, we have successfully crosslinked Gel B in different conditions, obtaining eight out of nine compounds in high yield (57–99%). The determined crosslinking degree percentage (CP%) evidenced a high CP% for compounds obtained in presence of LO and using the styrenic amine-containing (CP5/DMAA) and acrylic aldehyde-containing (CPMA/DMAA) copolymers as crosslinking agents. ATR-FTIR analyses confirmed the chemical structure of all compounds, while optical microscopy demonstrated cavernous, crater-like, and labyrinth-like morphologies and cavities with a size in the range 15–261 µm. An apparent density in the range 0.10–0.45 g/cm³ confirmed the aerogel-like structure of most samples. Although the best biodegradation profile was observed for the sample obtained using 10% CP5/DMAA (M3), high swelling and absorption properties, high porosity, and good biodegradation profiles were also observed for samples obtained using the 5–10% CP5/DMAA (M4, 5, 6) and 20% CPMA/DMAA (M9) copolymers. Collectively, in this work of synthesis and physicochemical characterization, new aerogel-like composites have been developed and, based on their characteristics, which fit well within the requirements for TE, five candidates (M3, M4, M5, M6, and M9) suitable for future biological experiments on cell adhesion, infiltration and proliferation, to confirm their effective functioning, have been identified. Full article

Poly(styrene-methyl methacrylate-acrylic acid) photonic crystals (PCs), with five different sizes (170, 190, 210, 230 and 250 nm), were applied onto three plain fabrics, namely polyamide, polyester and cotton. The PC-coated fabrics were analyzed using scanning electronic microscopy and two UV/Vis reflectance spectrophotometric techniques (integrating sphere and scatterometry) to evaluate the PCs’ self-assembly along with the obtained spectral and colors characteristics. Results showed that surface roughness of the fabrics had a major influence on the color produced by PCs. Polyamide-coated fabrics were the only samples having an iridescent effect, producing more vivid and brilliant colors than polyester and cotton samples. It was observed that as the angle of incident light increases, a hypsochromic shift in the reflection peak occurs along with the formation of new reflection peaks. Furthermore, color behavior simulations were performed with an illuminant A light source on polyamide samples. The illuminant A simulation showed greener and yellower structural colors than those illuminated with D50. The polyester and cotton samples were analyzed using scatterometry to check for iridescence, which was unseen upon ocular inspection and then proven to be present in these samples. This work allowed a better comprehension of how structural colors and their iridescence are affected by the textile substrate morphology and fiber type. Full article

Most of the experiments on additively manufactured polymers are on a small scale, and it remains uncertain whether findings at a small scale can be extrapolated to their larger-scale counterparts. This uncertainty mainly arises due to the limited studies on the effect of size on three-dimensional (3D)-printed polymers, among many others. Given this background, this preliminary study aims to investigate the effect of geometric dimensions (i.e., the size effect) on the mechanical performance of four representative types of 3D-printable polymers, namely, (1) polycarbonate acrylonitrile butadiene styrene (PC/ABS), (2) acrylonitrile-styrene-acrylate (ASA), (3) polylactic acid (PLA) as a bio biodegradable and sustainable material, and (4) polyamide (PA, nylon), based on compression, modulus of elasticity, tension, and flexural tests. Eight different sizes were investigated for compression, modulus of elasticity, and tension tests, while seven different sizes were tested under flexure as per relevant test standards. A material extrusion technique was used to 3D-print the polymers in a flat build orientation and at an infill orientation angle of 45°. The results have shown that the mechanical properties of the 3D-printed polymers were size-dependent, regardless of the material type, with the most significant being flexure, followed by tension, compression, and modulus of elasticity; however, no clear general trend could be identified in this regard. All the materials except for nylon showed a brittle failure pattern, characterized by interfacial failure rather than filament failure. PLA outperformed the other three polymer specimens in terms of strength, irrespective of the type of loading. Full article

Many studies assess the suitability of fiber-reinforced polymer composites in additive manufacturing. However, the influence of the fiber length distribution on the mechanical and functional properties of printed parts using these technologies has not been addressed so far. Hence, in this work we compare different composites based on Acrylonitrile Styrene Acrylate (ASA) and carbon fiber (CF) suitable for large format additive manufacturing (LFAM) technologies based on fused granular fabrication (FGF). We study in detail the influence of the CF size on the processing and final properties of these materials. Better reinforcements were achieved with longer CF, reaching Young’s modulus and tensile strength values of 7500 MPa and 75 MPa, respectively, for printed specimens. However, the longer CF also worsened the interlayer adhesion of ASA to a greater extent. The composites also exhibited electrical properties characteristic of electrostatic dissipative (ESD) materials (10⁵–10¹⁰ Ω/sq) and low coefficients of thermal expansion below 15 µm/m·°C. These properties are governed by the CF length distribution, so this variable may be used to tune these values. These composites are promising candidates for the design of elements with enhanced mechanical and functional properties for ESD protection elements or molds, so the products can be manufactured on demand. Full article

Wildfires are becoming more intense and more frequent, ravaging the habitations and ecosystems in their path. One solution to reducing the risk of damage to buildings and other structures during a fire event is the use of fire-retardant coatings that can stop or slow down the spread of flames, especially for textile materials. The present study focuses on the preparation and application of halogen-free boron/bentonite-based polymeric fire-retardant (FR) hybrid coating formulations for fabrics such as cotton (CO) and polyester (PE) fibers. For the preparation of FR composites, two types of boron derivatives, disodium octaborate and zinc borate, were used in combination with sodium bentonite. A styrene-acrylic copolymer was specifically synthesized and used as a coating binder for FR components to apply on fabrics. The properties of the synthesized copolymer and FR composites were characterized with a particle size analysis, FTIR spectroscopy, a dynamic mechanical thermal analysis (DMTA), and rheological measurements. The obtained hybrid composites based on styrene-acrylic copolymers and two different inorganic fillers were applied on cotton (CO) and polyester (PE) fabrics with a screen-printing technique, and the flame retardancy performance of the finished textile samples was investigated by means of flame spread and limit oxygen index (LOI) tests. The findings showed that the FR-composite-coated fabrics had higher LOI values and much decreased flame spread rates in comparison with uncoated ones. Among the boron derivatives, the composites prepared with disodium octaborate (FR-A) had much more pronounced LOI values and decreased flame spread behavior in comparison with the composite with zinc borate (FR-B). When compared to a commercial product, the FR-A composite, in conjunction with the specially synthesized polymer, demonstrated commendable fire retardancy performance and emerged as a promising candidate for a halogen-free waterborne fire-retardant coating for fabrics. Full article

To overcome the shortcomings of the temperature sensitivity of exterior flexible facing tiles (EFFIs), a series of crosslinking carboxylic styrene-acrylate (SA) latices were prepared via the semicontinuous seed emulsion polymerization of glycidyl methacrylate (GMA), methacrylic acid (MAA), acrylic acid (AA), butyl acrylate (BA), and styrene (St), and were applied as binders to fabricate EFFTs with mineral powder. The obtained latices exhibited Bragg diffraction because of the narrow particle size distribution. Owing to the low dosage of emulsifiers and the crosslinking reaction between the epoxy group and the carboxyl group, the latex films displayed excellent water resistance, with water adsorption as low as 7.1%. The tensile test, differential scanning calorimeter (DSC) test, and dynamic mechanical analysis (DMA) indicated that at a GMA dosage of 4–6% the latex films had high mechanical strengths, which remained relatively stable in the temperature range of 10 to 40 °C. The optimal AA dosage was found in the range of 2 to 3%, at which the wet mixture exhibited good processability, conducive to forming an EFFT with a compact microstructure. Using the optimal SA latex, the obtained EFFT displayed a series of improved performances, including low water absorption, high mechanical strength, and stable self-supporting ability over a wide temperature range, exhibiting the application potential in the decoration and construction industries. Full article

Polymer micelles are promising drug delivery systems for highly hydrophobic photosensitizers in photodynamic therapy (PDT) applications. We previously developed pH-responsive polymer micelles consisting of poly(styrene-co-2-(N,N-dimethylamino)ethyl acrylate)-block-poly(polyethylene glycol monomethyl ether acrylate) (P(St-co-DMAEA)-b-PPEGA) for zinc phthalocyanine (ZnPc) delivery. In this study, poly(butyl-co-2-(N,N-dimethylamino)ethyl acrylates)-block-poly(polyethylene glycol monomethyl ether acrylate) (P(BA-co-DMAEA)-b-PPEGA) was synthesized via reversible addition and fragmentation chain transfer (RAFT) polymerization to explore the role of neutral hydrophobic units in photosensitizer delivery. The composition of DMAEA units in P(BA-co-DMAEA) was adjusted to 0.46, which is comparable to that of P(St-co-DMAEA)-b-PPEGA. The size distribution of the P(BA-co-DMAEA)-b-PPEGA micelles changed when the pH decreased from 7.4 to 5.0, indicating their pH-responsive ability. The photosensitizers, 5,10,15,20-tetrakis(pentafluorophenyl)chlorin (TFPC), 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TFPP), protoporphyrin IX (PPIX), and ZnPc were examined as payloads for the P(BA-co-DMAEA)-b-PPEGA micelles. The encapsulation efficiency depended on the nature of the photosensitizer. TFPC-loaded P(BA-co-DMAEA)-b-PPEGA micelles exhibited higher photocytotoxicity than free TFPC in the MNNG-induced mutant of the rat murine RGM-1 gastric epithelial cell line (RGK-1), indicating their superiority for photosensitizer delivery. ZnPc-loaded P(BA-co-DMAEA)-b-PPEGA micelles also exhibited superior photocytotoxicity compared to free ZnPc. However, their photocytotoxicity was lower than that of P(St-co-DMAEA)-b-PPEGA. Therefore, neutral hydrophobic units, as well as pH-responsive units, must be designed for the encapsulation of photosensitizers. Full article

Electrophotographic printing and copying processes primarily use toner, which is a mixture of colorant, polymer, and additives. Toner can be made using traditional mechanical milling techniques or more contemporary chemical polymerization techniques. Suspension polymerization provides spherical particles with less stabilizer adsorption, homogeneous monomers, higher purity, and easier control of the reaction temperature. In contrast to these advantages, however, the particle size resulting from suspension polymerization is too large for toner. To overcome this disadvantage, devices such as high-speed stirrers and homogenizers can be used to reduce the size of the droplets. This research investigated the use of carbon nanotubes (CNTs) instead of carbon black as the pigment in toner development. We succeeded in achieving a good dispersion of four different types of CNT, specifically modified with NH₂ and Boron or unmodified with long or short chains in water rather than chloroform, using sodium n-dodecyl sulfate as a stabilizer. We then performed polymerization of the monomers styrene and butyl acrylate in the presence of the different CNT types and found that the best monomer conversion and largest particles (in the micron range) occurred with CNTs modified with boron. The insertion of a charge control agent into the polymerized particles was achieved. Monomer conversion of over 90% was realized with all concentrations of MEP-51, whereas conversion was under 70% with all concentrations of MEC-88. Furthermore, analysis with dynamic light scattering and scanning electron microscopy (SEM) indicated that all polymerized particles were in the micron size range, suggesting that our newly developed toner particles were less harmful and environmentally friendly products than those typically and commercially available. The SEM micrographs clearly showed good dispersion and attachment of the CNTs on the polymerized particles (no CNT aggregation was found), which has never been published before. Full article

As an essential pigment particle in white water-based coatings, light calcium carbonate (CaCO₃) is difficult to disperse in water-based systems. The hard-to-disperse particles agglomerate, causing the viscosity of the coating to rise, which in turn affects the quality of the coating. Therefore, in order to obtain efficient dispersion, the hyperdispersant SSS–MPEGA–DMAEA (SMD) has been prepared in this study using sodium styrene sulfonate (SSS), polyethylene glycol monomethyl ether acrylate (MPEGA), and dimethylaminoethyl acrylate (DMAEA) as monomers through aqueous solution polymerization. Firstly, we utilized the central composite design method to conduct mathematical modeling of the monomer ratios so as to optimize the dispersion performance of the hyperdispersants. Secondly, the structural characteristics and molecular weight distribution of SMD were characterized by ¹H NMR spectroscopy and GPC. Then, the effect of SMD on the dispersion of the CaCO₃ slurry was investigated through particle size distribution and TEM measurements. Finally, we applied the SMD in aqueous white coatings and tested the surface properties of the paint film by SEM as well as the stability of the paint film. The results showed that SMD can significantly reduce the viscosity and particle size of the CaCO₃ slurry. The waterborne coatings prepared by SMD had good storage stability and corrosion resistance, so the materials owned broad application prospects. Full article

The growing amount of waste toner (WT) has posed a significant environmental challenge. Meanwhile, researchers are interested in the feasibility of utilizing waste toner as an asphalt binder modifier because its primary chemical components (Styrene-acrylic copolymer and carbon black) are known to improve asphalt properties. The objective of this study was to evaluate the chemical and rheological properties of the waste-toner-modified asphalt binder and hence determine the suitability of integrating waste toner for asphalt modification. The waste-toner-modified asphalt (TMA) binders were produced by blending base asphalt with two types of waste toners of different gradation sizes. Microscopic tests such as x-ray fluorescence (XRF), attenuated total reflectance transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy with energy dispersive X-ray (SEM-EDS) and fluorescence microscope, as well as rheology tests such as multiple stress creep recovery (MSCR) tests, oscillation tests, and bending beam rheometer tests were performed. The FTIR results showed that there was a chemical reaction between waste toners and base asphalt binder. A fluorescence effect was observed on the binders produced with different toners used in this research. The binder modified with an optimal content of 8%WTs revealed better high and low-temperature properties. Additionally, 8%WTs used in this research could change the PG70-22 binder to PG76-22 binder. The rutting properties of asphalt material were improved for its improved elasticity. In addition, the 200-mesh TMA binders were desirable with respect to waste toner particle size. Overall, there is a benefit to using waste toner in the asphalt industry. Full article

To improve the stability of waterborne epoxy–acrylic emulsions and their comprehensive properties, such as the chemical resistance of coatings, a new research idea is proposed in this paper. First, a series of high-molecular-weight epoxy resins were synthesized with epoxy resin E-51 and bisphenol A (BPA) using benzyl triphenyl phosphine bromide as the catalyst. Then, free-radical graft copolymerization was carried out between the epoxy resin and methacrylic acid (MAA), styrene (ST), and butyl acrylate (BA) using benzoyl peroxide (BPO) as the initiator. This method ensured that the epoxy groups were retained. Finally, the carboxylic acid groups were neutralized with N,N-dimethylethanolamine (DMEA), and a stable aqueous epoxy–acrylic emulsion was obtained by high-speed dispersion in deionized water. The effects of key factors such as temperature, time, the molecular weight and dosage of epoxy resin, the dosage of MAA, the dosage of BPO, and the neutralization degree of the synthesis of emulsions and coating film properties were mainly discussed. The molecular weight and molecular weight distribution of the epoxy resin were determined by gel permeation chromatography (GPC). The epoxy resin and its graft copolymer were analyzed and characterized by Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The particle size and distribution of the emulsions were tested by laser particle size analysis. The morphology of the emulsion particles was observed by transmission electron microscopy. The results showed that the acrylic monomers (MAA, ST, and BA) were grafted onto the epoxy resin. The graft copolymers showed higher glass transition temperatures compared with those of the pure epoxy resin. TGA showed that the graft copolymer started to decompose at a high temperature before the pure epoxy resin did, and the thermal stability was slightly reduced. The prepared emulsions with a particle size of 160 nm had a storage stability of more than one year and showed excellent dilution stability, mechanical stability, and freeze–thaw stability. The emulsions were coated and cured at 150 °C for 1 h with a pencil hardness of 5 H, an adhesion of grade 1, and a flexibility of 1 mm. The water resistance was >60 days, the salt water resistance was >30 days, the acid resistance was >10 days, and the alkali resistance was >5 days. Full article

With the exploration and development of unconventional oil and gas, the use frequency of oil-based drilling fluid (ODF) is increasing gradually. During the use of ODFs, wellbore instability caused by invasion of drilling fluid into formation is a major challenge. To improve the plugging property of ODFs, nano-sized poly(styrene-lauryl acrylate) (PSL) rubber nanogels were synthesized using styrene and lauryl acrylate through soap-free emulsion polymerization method and were characterized using FTIR, NMR, SEM, TEM, particle size analysis and TGA. The results show that, due to good dispersion stability and oil-absorbing expansion ability, the PSL rubber nanogels have a wide range of adaptations for nano-scale pores to deposit a layer of dense filter cake on the surface of filter paper with various pore diameters, reducing the filtration of mineral oil and W/O emulsion significantly. Due to the unique wettability, the PSL rubber nanogels can be adsorbed stably at the oil–water interface and form a dense granular film to prevent droplets coalescing, which improves the emulsification stability of W/O emulsion. Furthermore, the PSL rubber nanogels are soap-free and compatible with ODFs without foaming problems. The PSL rubber nanogels can increase the hole-cleaning performance of ODFs by raising viscosity and yield point. The PSL rubber nanogels outperformed hydrophobic modified nano silica and polystyrene nanospheres in plugging and filtration reduction. Therefore, the PSL rubber nanogels are expected to be used as a new plugging agent in oil-based drilling fluid. This research provide important insights for the use of organic nanogels in ODFs and the optimization of plugging conditions. Full article

Lithium battery separators play a critical role in the performance and safety of lithium batteries. In this work, four kinds of polymer particle adhesives (G1–G4) for lithium battery separators were synthesized via dispersion polymerization, using styrene, butyl acrylate and acrylonitrile as monomers. The particle size/size distributions, particle morphologies and glass transition temperatures (Tg) of polymer particle adhesives were explored using laser particle size analysis, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The adhesion strengths between the battery separators and the poles piece were examined using a tensile machine. The prepared polymer particle adhesive with a uniform distribution of particle size was obtained when the mass ratio of ethanol to water reached 85:15. Compared with the other three polymer particle adhesives, the prepared G3 coated on the surface of the battery separator exhibited a stronger adhesion with the battery pole piece. In addition, the Land battery test system was applied to examine the electrochemical performance of the lithium battery assembled with the battery separator with the prepared polymer particle adhesives. The results suggest that the electrochemical performance of the lithium battery assembled with the battery separator with polymer particle adhesive G3 is the best among the four counterparts. Full article