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Enhancing the water permeation while maintaining high salt rejection of existing reverse osmosis (RO) membranes remains a considerable challenge. Herein, we proposed to introduce polymer of intrinsic microporosity, PIM-1, into the selective layer of reverse osmosis membranes to break the trade-off effect between permeability and selectivity. A water-soluble a-LPIM-1 of low-molecular-weight and hydroxyl terminals was synthesized. These designed characteristics endowed it with high solubility and reactivity. Then it was mixed with m-phenylenediamine and together served as aqueous monomer to react with organic monomer of trimesoyl chloride via interfacial polymerization. The characterization results exhibited that more “nodule” rather than “leaf” structure formed on RO membrane surface, which indicated that the introduction of the high free-volume of a-LPIM-1 with three dimensional twisted and folded structure into the selective layer effectively caused the frustrated packing between polymer chains. In virtue of this effect, even with reduced surface roughness and unchanged layer thickness, the water permeability of prepared reverse osmosis membranes increased 2.1 times to 62.8 L∙m–2∙h–1 with acceptable NaCl rejection of 97.6%. This attempt developed a new strategy to break the trade-off effect faced by traditional polyamide reverse osmosis membranes.

Nafion, a perfluoro-sulfonic acid (PFSA)-based polymer, is a promising material that will help realize the commercialization of proton exchange membrane-based fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs). However, Nafion also exhibits reduced mechanical and dimensional stability and increased hydrogen crossover under cell operating conditions in real operational settings, that is, in a hydrated state or in water at 60–80 °C. These factors may negatively affect cell efficiency and durability and thus must be addressed. To overcome these limitations, polyamide-coated Nafion composite membranes were developed for the first time via interfacial polymerization. 3,5-Diaminobenzoic acid (DABA), which contains carboxyl functional groups, was used as a monomer to add hydrophilicity to the membrane, and the coating layer thickness was controlled by adjusting the DABA content. A nanoscale polyamide (PA) layer was coated on the surface of Nafion-212 to fabricate a membrane, PA-c3-Nafion. PA-c3-Nafion was found to show ion conductivity 13.6% higher than that of a pristine Nafion-212 membrane at 80 °C, while providing improved mechanical performance and dimensional stability. In particular, at 95% RH, the hydrogen permeability of PA-c3-Nafion was 16.4% lower than that of Nafion-212 while, in a fully hydrated state, the hydrogen permeability of PA-c3-Nafion was 21.2% lower than that of Nafion-212. The LSV test results also showed that the degree of hydrogen crossover was significantly lower in PA-c3-Nafion than in Nafion-212.

Polymers have gained the attention of manufacturers due to their significant advantages such as low density, high corrosion resistance, and high humidity resistance. Producing high-precision polymeric components is one the most challenging issues especially in fabricating complex or micro-scale systems. Some of the machining techniques such as electro discharge machining (EDM) and electrochemical machining (ECM) cannot be employed for machining the non-conductive parts. Using abrasive particles is one of the best options for machining these types of materials. In this work, the capability of the acoustic energy for machining polyamide (PA) workpieces is studied. To this end, an experimental setup is installed and design of experiment (DoE) algorithm is employed to survey the effect of process parameters on surface roughness. Three parameters at three levels are considered as the effective factors of the process and the sensitivity of the surface roughness on the process factors is investigated. In the next step, a hybrid finite element/boundary element approach was used to discuss the relation of process parameters to the vibrational characteristics of the container, then the mechanism of the process was investigated employing the discrete element method. Finally, the surface topology of the optimal workpiece before and after the process was presented and compared. It was observed that acoustic energy can be considered as a vibration source of the container’s floor to provide kinetic energy for machining PA parts on the nano-metric scale. Moreover, it was found that the initial roughness of the workpiece and the chosen parameters play a crucial role in the machining process. Experimental results show that in this technique by selecting appropriate process factors the surface roughness can be reduced up to 50%.

Injection molded direct joining (IMDJ) is one type of metal-plastic direct joining methods. IMDJ first treats the metal surface and then injects melted polymer onto the surface via injection molding technology. IMDJ method is excellently suitable for a mass production environment for the injection molding technology characteristics of high-speed production. However, one of the factors limiting the application of IMDJ is its low joining strength. In this study, we improved joining performance by mixing a flow modifier (flow modifier OSGOL MF-11) in the engineering polymer polyamide 6 (PA6). We studied the influence of the additive amount on the joining strength. It was found that mixing OSGOL MF-11 in PA6 is a feasible method to improve the joining strength, with maximum improvement by up to 75%. The mechanical interlocking improvement by higher fluidity was confirmed by cross-sectional analysis. FTIR spectra analysis results showed the possibility of chemical interaction occurrence, which causes the joint to be more robust. Materials modification by additives is much easier to apply compared to modification processing technology. The results provide new ideas for IMDJ development.

The metal-organic framework (MOF)-based polyamide (PA) membranes applied for desalination with high permeability and selectivity are attracting more and more attention. However, the design and fabrication of high-quality and stable MOF-based PA nanocomposite reverse osmosis (RO) membrane still remain a big challenge. Herein, Fe3+-polyphenolic complex coating via interfacial coordination was first explored as an interlayer of an in situ assembled stable and high-quality Fe(BTC)-based PA nanocomposite RO membranes for desalination. Although depositing the Fe3+-polyphenolic complex on the polymer support, sufficient heterogeneous nucleation sites for the in situ synthesizing Fe(BTC) are provided. Using this strategy, we can not only facilely prepare continuous MOF-based PA nanocomposite RO membranes, ignoring the complicated and time-consuming co-blending process and the MOF-particle aggregation, but also restrict the formation of PA matrix inside the pores of the support membrane and increase the rigidity of the polyamide chain. The method also gives a proper level of generality for the fabrication of versatile stable MOF-based PA RO membranes on various supports. The prepared PA/Fe(BTC) composite membrane exhibited excellent separation performance with a large permeate flux of 2.93 L m-2 h-1 bar-1 and a high NaCl rejection of 96.8%.

Purpose: To compare the effects of three surface treatments on bond strength between acrylic teeth and polyamide denture base. Material and Methods: 60 specimens, each composed of maxillary central acrylic cross-linked incisor tooth processed onto thermoplastic polyamide denture base according to the Japanese Standards Association 6506. Test specimens were divided according to the experimental design: Surface treatments (sandblasting, T-shape diatoric holes, or both). The specimens were then subjected to shear load with the Universal Testing Machine. Load was applied till denture teeth separated from the base resin. The resulting debonding forces were recorded and statistically analyzed by using T student-test and ANOVA test followed by Tukey HSD test. The interface where failure occurred was inspected to determine the type of failure whether adhesive or cohesive. Results: Statistical significant differences were found in bond strength among the different surface treatment groups (P

Magnetic nanoparticles were creatively selected as stable, inexpensive, biodegradable, facile recoverable, and functionalizable supports for a variety of synthetic and natural polymers. Herein, for the first time, aromatic polyamide was synthesized on the magnetic core of zinc iron oxide (ZnFe2O4). Terephthaloyl chloride and derivations of phenylenediamine were employed as monomers in this polymerization process. The toxicity of the synthesized hybrid at the highest concentration (1000 μg/ml) is 13.65% and on the other hand, the cell viability percentage is 86.35%. So, the prepared hybrid is biocompatible and non-toxic to Hu02 cells. Also, it has antibacterial ability against gram-positive and gram-negative bacteria. Because the results show that the minimum inhibitory concentration (MIC) of the synthesized polymer for bacteria such as Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853 is in the range of 500–1000 µg/ml. Moreover, the hemolytic effect of ZnFe2O4 based hybrid was below 9% at the concentration of 1000 μg/ml. Therefore, it is compatible with red blood cells.

The behavior of colloidal silicon dioxide in a composition with a styrene/butyl acrylate oligomer grafted onto a thermoplastic polyamide adhesive to obtain a branched binder structure with penetration of branches into a capillary-pore system of a reinforcing fiber component is studied. The modifications of disaggregation of SiO2 using ultrasonic treatment and mechanical activation with the impact of high shear stresses, ultrasound, and cavitation are compared. The methods of dynamic light scattering, IR spectroscopy, thermal analysis, and the textile material science are used in experiments to evaluate the elastic-deformation characteristics of fused packets. The set of complementary results confirms that the combined mechanical activation of an aqueous dispersion of oligoacrylate and silica causes destruction of silica nanospheres and the formation of a hybrid oligolymer-inorganic adduct. In contrast to the short-term effects of ultrasonic dispersion of SiO2, consolidated mechanical activation of components solves the problems of preventing aggregation of nanoparticles and providing a uniform distribution of the reinforcing filler in the composite. The efficiency of using the method for regulating the characteristics of the forming units and parts of sewing products has been shown. By selecting oligoacrylate, the separation of the stages of preliminary bonding of the material packets specific to sewing production using a thermoplastic adhesive, the design of a form of a finished product, and its fixing during wet-heat treatment is taken into account. The preparation of a hybrid adduct of mechanical activation provides an optimal ratio of the particle size for the efficient distribution of fractions in interfacial, interfiber, and intrafiber spaces of the textile web. The shift of the peaks of the phase transitions and chemical transformations in a system with nanodispersed SiO2 controlled on the DSC thermograms is consistent with the temperature conditions of successive stages of the engineering process. The possibilities of a controlled change in the characteristics of the forming composite materials and a decrease in the material consumption of sewing products due to grafting modified oligoacrylate with a variable content of silicon dioxide are demonstrated.

This study revealed that the synthesis of effective flow modifiers using diamine monomers and fatty acid reduces the melt viscosity of polyamide 66 (PA66) composites. Moreover, the study provided insights into the rheological and mechanical properties of these reinforced polymers. In particular, the oligomers hexamethylenediamide, dodecamethylene diamide, 4,4′-methylenebis(cyclohexylamide) (i.e., HMDA, DMDA, MCHA) to modify the PA66 were prepared from hexamethylenediamine, dodecamethylene diamine, 4,4′-methylenebis(cyclohexylamine). The synthesized modifiers showed thermal stability in the PA66 processing temperature. Further, the chemical similarity increased due to amide bonds in the backbone of the flow modifiers, showing good compatibility with PA66. Additionally, PA66/glass fiber (GF) composites containing the flow modifier showed enhanced rheological and mechanical properties. The flow modifiers significantly improved the tensile strength and flexural modulus of the PA66/GF composites. The proposed synthetic method is straightforward, opening up a new strategy for reducing the melt viscosity of PA66 without degradation of the mechanical properties. The method improves the compatibility of the PA66/GF composites even in high amounts of GF, achieving effective polymer processing for practical applications.

The urgency of improving the performance properties of concrete, as the most common building materials, is noted. The reasons for the increased demand for products made of high-strength gas-filled concrete are stated. It is shown that the current volume of polymer fibers production makes it possible to predict the possibility of their widespread use in construction. The information on the physical and mechanical properties of synthetic fiber, which is important for its successful use as dispersed reinforcement of foam concrete mixtures, is presented. The technology of manufacturing experimental samples and methods of their testing are described. It has been established that the introduction of any synthetic fiber into the foam mixture formulation improves the structural properties of foam concrete, however, the measure of efficiency depends on the ratio between the concrete moduli of elasticity and fiber. The greater the value of the elastic modulus of the fiber used, the higher the technical effect of its use in fiber-reinforced concrete for structural purposes can be.

Ductility and tensile strength are among the basic mechanical properties of polymers. Generally, it is difficult to enhance the ductility without significantly reducing the tensile strength. In this study, thermoplastic polyurethane (TPU) is mixed with 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% polyamide 6 (PA6). The results show that the sample containing 100% TPU has the largest elongation of 690.5%. When PA6 is added, the elongation decreases gradually to 635.0%, 623.1%, 529.5%, 476.0%, 391.3%, and 242.8%, corresponding to 2.5%, 5%, 7.5%, 10%, 12.5%, and 100% PA6, respectively. The tensile strengths are 36.7, 33.8, 29.4, 26.5, 23.1, and 24.9 MPa, corresponding to 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% PA6 samples, respectively. The tensile strength decreases gradually when the PA6 content is increased. Notably, the tensile strength of the 12.5% PA6 sample increases compared to the 10% PA6 sample. In addition, the hardness of the TPU/PA blend increases slightly as the PA6 ratio is increased. Finally, scanning electron microscope images demonstrate that PA6 particles act as particles dispersed or dissolved in TPU/PA blends.

A highly permselective nanofiltration membrane was engineered via zwitterionic copolymer assembly regulated interfacial polymerization (IP). The copolymer was molecularly synthesized using single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA) (P[MPC-co-AEMA]). The dynamic network of P[MPC-co-AEMA] served as a regulator to precisely control the kinetics of the reaction by decelerating the transport of piperazine toward the water/hexane interface, forming a polyamide (PA) membrane with ultralow thickness of 70 nm, compared to that of the pristine PA (230 nm). Concomitantly, manipulating the phosphate moieties of P[MPC-co-AEMA] integrated into the PA matrix enabled the formation of ridge-shaped nanofilms with loose internal architecture exhibiting enhanced inner-pore interconnectivity. The resultant P[MPC-co-AEMA]-incorporated PA membrane exhibited a high water permeance of 15.7 L·m-2·h-1·bar-1 (more than 3-fold higher than that of the pristine PA [4.4 L·m-2·h-1·bar-1]), high divalent salt rejection of 98.3%, and competitive mono-/divalent ion selectivity of 52.9 among the state-of-the-art desalination membranes.

Polymer gears have become more established and consequently implemented in various drive train applications. To perform a precise calculation of power train application, a completed database for polymer materials must be known. In the field of polymer database, there is a lack of fatigue and thermal data which are not accessible from suppliers. In the present study, durability testing of POM/PA combination is observed. In the research, different poliamide gears (also reinforced with glass fibers) were characterized to obtain meshing temperatures and fatigue data — Woehler lines. Reinforced polyamide gears show better durability performance at higher loading — torque conditions with lower temperature dispersion in contact compared to generic polyamide when melting failure occurs. When excessive fatigue is observed, resulting in more than 1 million cycles, PA gears have longer lifetime compared to composite gears.

Particulate matter of 0.3 μm in diameter (PM0.3) poses a serious threat to the environment and human beings. Ultrathin and -light nanofibrous filters with excellent filtration properties can significantly prevent the detrimental effects of these particles. Here, we develop free-standing polyamide PA-66 ultrafine nanofiber papers for PM0.3 filtration using effective and scalable blow and electro-blow spinning techniques. The smallest average fiber diameter is 61.7 nm, which is 2-3 orders of magnitude smaller than that of conventional textiles. Poly(ethylene terephthalate) nonwovens are selected to fabricate free-standing nanofiber papers of various polymers, including polyamide, poly(methyl methacrylate), poly(vinylpyrrolidone), and poly(ethylene oxide) owing to the smooth surfaces of the nonwovens. This underlying principle can be used to create similar free-standing nanofiber papers from other commodity polymers in the future. Mechanisms of capturing particulate matter with different nanofiber morphologies are discussed. Salt and oil particulates are used to characterize the filtration properties. PA-66 papers are promising reusable filters owing to their mechanical particle-capture mechanism. The blow-spun PA-66 papers show filtration performance of 98.75% efficiency and a pressure drop of 125.44 Pa owing to the "slip" effect caused by the ultrasmall diameter. In the electro-blow spinning process, a supplementary voltage supply is conducive to separating nanofiber bundles into random-oriented nanofibers. Electro-blown spun papers possess an ultrahigh efficiency of 99.99% with a reduced areal density of 0.9 g m-2. These PA-66 papers can be used in a variety of applications, such as reusable personal protective equipment, industrial waste gas treatment, and central ventilation purification systems.

Polyoxymethylene/thermoplastic polyamide elastomer composites were prepared by using maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer as interfacial compatibilizer via melt extrusion. The compatibility and the properties of blends were studied by the mechanical testing and various physical chemical methods. The notched impact strength and elongation at break of blends were increased significantly after adding of compatibilizer. Simultaneously, the phase structure and crystal shape of the blends were changed. Finally, the elastomer particles were more uniform, and more amorphous regions were produced in the blends.

Since recycling of polymers is a preferred means of reducing unwanted wastes and land-filling activity, and recovering monomers or other materials of economic value, tertiary methods of recycling (chemical recycling) have been critically reviewed, giving special attention, in each case, to the chemical basis of the particular recycling pathway and its potential applicability. Recycling issues of each of the widely used commodity polymers � polyesters, polyamides, polyurethanes, epoxies, poly(vinyl chloride), polystyrene, and polyolefins � have been discussed individually, giving attention to both conventional and unconventional methods of perceived high potential, such as enzymatic degradation, ionic liquids mediation, microwave irradiation, and treatment in super critical liquids as well as super fluids. In addition, novel emerging methods undergoing greater study at present, such as cross-alkane metathesis (CAM), tandem hydrogenolysis/aromatization, vitrimer-based recycling, and dynamic covalent bonding are also highlighted. © 2021 Kingfa Scientific and Technological Co. Ltd.

The potential for replacing the fossil-based Polyoxymethylene (POM) and Polyamide 66 (PA 66) in polymer gear applications with a bio-based Polyamide 6.10 (PA 6.10) was studied and is presented in the article. The use of bio-based plastics is increasing but mostly in undemanding applications like packaging. High-performance plastics are needed in polymer gear transmissions since their operational conditions are far more severe. The potential of bio-based PA 6.10 was studied by means of gear lifespan testing. Additional insights into the process of polymer gear meshing were garnered by simulating all the tested cases with a FEM model of meshing gears. Test gears were manufactured from commercially available materials, making the results useful for gear designers. Encouraging results were observed since the PA 6.10 gears exhibited a 3.5-times longer lifespan than POM gears and a 10-times longer lifespan than PA 66 gears when tested under identical test conditions. The results indicate great potential for replacing fossil-based plastics in polymer gear applications with bio-based polymer materials. The fatigue strength, coefficient of friction, and wear coefficient were determined and compared for the tested materials, facilitating the reliable design of polymer gears.

The classical AlCl3/imidazole-chloride-salt ionic liquid electrolytes are expensive, corrosive, and environmentally sensitive, which limit the large-scale application of aluminum-ion batteries. Herein, a gel polymer electrolyte is prepared through a facile process using a low-cost AlCl3/Et3NHCl ionic liquid as the plasticizer and polyamide as the polymer matrix. The gel polymer electrolyte achieves a decent ionic conductivity of 3.86 × 10-3 S cm-1, a wide electrochemical stability window of 2.6 V (vs Al), and long-term interfacial stability at room temperature. The assembled Al//graphite battery delivers considerable rate capability and excellent cycling performance. Besides, the gel polymer electrolyte can alleviate both moisture sensitivity and leakage corrosion issues owing to the full encapsulation of the ionic liquid by polyamide polymeric matrix. The gel polymer electrolyte should offer great potential for aluminum-ion battery applications.

Since its addition to additive manufacturing (AM), polyamide 12 has dominated the selective laser sintering (SLS) market, thanks to its stable thermal property and high mechanical quality. However, substantial un-sintered residue powders lead to economic losses and are burdensome to the environment. Though several works have reported the aging mechanism and reusability of the polyamide 12 residues in SLS, the quantitative degradation and decomposition changes of differently reused polyamide 12 are not available. This work experiments successive reuse of polyamide 12 residues and quantitatively monitors the thermal decomposition, molecular evolution, and compositional changes of the material in SLS AM. To understand the characteristics of such changes, we reused the same bucket of polyamide 12 powders up to 8 times, collected powder samples, and printed 3- and 32-layer part samples. Our tests revealed that the basic flowability energies per reuse are reduced by 9.90, 15.59, and 12.74 mJ in the 2-, 5-, and 8-time reused powders, respectively. These values are essential to control the flowability of polyamide 12. Laser and heat lower the material onset decomposition temperatures, making the material more labile at a decreased temperature after reuse. On the other hand, the nitrogen atmosphere delays the onset of thermal decomposition to a higher temperature. The 1H NMR spectra reveal the degradation of polyamide 12 with reuse: in polyamide 12 parts 3D-printed using 8-time reused powders, the relative area of the peak on C-H bonds adjacent to nitrogen has a 50% reduction compared to parts using new powders. The carbon deposit and degradation raise the atomic percentages of C and O by 72.49% and 7.13%, respectively, from new powders to the part printed using 8-time reused powders. This study further reveals the surface carbon deposit of polyamide 12 during successive reuse of SLS and explains the effect of laser in inducing polymer decomposition apart from high temperatures.

The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have been established. The ability has been demonstrated for resorbable fibers of natural origin to more actively adsorb AgNPs with sizes from 1 to 10 nm during the first hour and stronger hold them on the surface during the first day of exposure to argogel. During the first hour of incubation of these polymers in a gel composition containing AgNPs obtained by the method of cavitation-diffusion photochemical reduction, their higher sorption activity was revealed in the size range from 1 to 10 nm in relation to the polyfilament synthetic material. After 24 h of exposure, a significant increase in the fraction of small AgNPs already on collagen fibers was observed, which was also accompanied by a significantly lower (19 times) content of AgNPs with a diameter above 40 nm on the catgut.

Background The world today is faced with the humongous challenge of removing the numerous plastic wastes in our environment. Efforts in the removal or remediation of these materials from the ecosystem are presently at the budding stage. Some researchers have shown that certain bacterial enzymes have the ability to hydrolyze and further degrade these plastic compounds. In this study, the ability of PET hydrolase enzyme to hydrolyze polyvinylchloride, polyurethane, polymethyl methacrylate, polyamide, polyethylene terephthalate, and polycarbonate was investigated in silico. Results The binding affinity values of polycarbonate (− 5.7 kcal/mol) and polyethylene terephthalate (− 5.2 kcal/mol) on the enzyme targets were the highest and showed that they are likely to be efficiently hydrolyzed by this bacteria in the environment. The binding affinity of polyvinylchloride was the lowest (− 2.2 kcal/mol) and suggested that it would show resistance to hydrolysis by the PET hydrolase enzyme. Conclusion The findings from this study showed that PET hydrolase enzyme from Ideonella sakaiensis could be efficient in the hydrolysis of plastic wastes composed mainly of polycarbonate and polyethylene terephthalate.

The uniaxial elongational flow of a polymer solution in the electrospinning process was investigated numerically and experimentally. The numerical model was constructed taking into account the viscoelasticity of the material. Therefore, governing equations were supported by a finite extensible non-linear elastic constitutive model and for the first time a FENE-CR model was used. This version of FENE model allows a good description of the rheology of extensional flows. For validation purposes, experimental studies were conducted using polymeric solutions of polyamide 6 (PA6). The main emphasis was made in determining the final fiber diameter and how initial polymer concentration acts on it. Further, the effect of the different concentration regimes on thinning dynamics was also examined. The comparative results of the numerical and experimental outcomes are sufficient to prove the predictive ability of the simulations. It can also be observed that the numerical approach adopted in this study captures not only the viscoelastic behavior of the material but also solidification of nanofibers due to solvent evaporation. As predictive quantitative models for electrospinning are lacking, this study gives good insights into the simulation of this process.

This research was conducted to investigate the bond strength between artificial teeth and a thermoplastic denture base resin for injection molding with different surface preparations for use in flexible resin removable partial dentures. Composite resin denture teeth and acrylic denture resin teeth were bonded to three types of thermoplastic denture base resins for injection molding (polyamide, polyester, and polycarbonate) and a conventional heat-polymerized polymethyl methacrylate (PMMA) resin (control). The ridge lap surfaces of the artificial teeth were classified into four groups based on the type of ridge lap surface treatment applied (n=10): no treatment, ethyl acetate, small T-shaped tunnel, and large T-shaped tunnel. The specimens were tested for bond strength. The results showed that the ethyl acetate treatment was ineffective for enhancing the bond strength (p>0.05) between the artificial teeth and thermoplastic denture base resin for injection molding, whereas the T-shaped tunnel was quite effective in this regard (p

Graphene (G) was produced and melt-blended with polyamide 6 (PA6) to study the mechanical, electrical, and flame-hindrance characteristics of PA6-G compounds. It resulted that G is well dispersed in PA6 up to 2.0 wt owing to electrostatic contact. A clear increment in degradation temperature and a drop in extreme degradation degree is detected from the thermogravimetric experiment for PA6-G compounds. The G inclusion to PA6 amended flame-protection of PA6-G compounds by delaying smoke density and reduction of flammable gas. This work proved an appropriate formulation of polymer/G compounds applied to engineering materials; develop the types of compounds with nano-additives. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

The use of polymer matrix composite materials in the armor industry has rapidly increased. In the present work, the ballistic efficiency of body armor manufactured using a polymer-based composite, with a laminar configuration, was tested. For the composite, a synthesized polyamide 6 reinforced with 37 % weight of fiberglass (GF) and an aramid fabric, were used. The laminar configuration of the composite, like a sandwich form with a size of 30 cm x 30 cm, was made with two panels of composite material (PA6 + 37 wt % GF) and an intermediate aramid fabric layer. It was tested in ballistic environments with available firearms. The results showed that the manufactured body armor prevents the penetration of a 9 mm bullet enabling its potential use as an urban armor level III-A, according to NIJ-Standard-0101.04. However, after testing with weapons larger than 9 mm in caliber, it was permanently deformed (5.56 mm and 7.62 mm weapons), which is why the level IV is not recommended.

In this work, we investigated the morphology, crystallization, and mechanical properties of the polyoxymethylene/thermoplastic polyamide elastomer (POM/TPAE) blends. It was found that POM and TPAE are partially compatible. By blending with TPAE, the toughness and low-temperature performance of POM can be improved significantly. However, there is a maximum value for the improvement of POM toughness, which is related to the amount of TPAE. We found that TPAE is dispersed in the POM matrix as spherical particles, and the particle size of these varies with the content of TPAE. Another interesting finding is that adding TPAE can change the crystalline properties of POM. For example, after adding TPAE, the crystallization particles of POM become smaller, part of the crystal area disappears, and the crystallization temperature decreases. All these results suggest that TPAE improves the toughness and low-temperature performance of POM by improving the crystallization, morphological structure, and morphology of the POM blends.

Polyoxymethylene/thermoplastic polyamide elastomer (POM/TPAE) blends were prepared through melt extrusion in an attempt to improve the toughness and electrical properties of POM. The TPAE used in the study had the permanent antistatic effect, and its brand was MV2080. Acrylonitrile-butadiene-styrene copolymer grafted maleic anhydride (ABS-g-MAH) was added while preparing the POM/TPAE blends to improve the compatibility between TPAE and POM. The effects of TPAE and ABS-g-MAH on the morphologies, melting crystallization, dynamic mechanical analysis, surface resistivity and mechanical properties were examined in detail with various techniques. It was found that after adding 15 phr MV2080 as the modifier, the distribution of MV2080 in the blends was presented as many continuous long strips, which can be called “antistatic networks.” When using ABS-g-MAH as a compatibilizer, the surface resistivity of the samples 5#, 6#, and 7# which all containing 15 phr MV2080 with the best antistatic properties reached 107 Ω, and the impact strength of the above samples was all increased by more than 66%.

The material of the mating gear influences the fatigue life of polymer gears. The bending fatigue characteristics of polyamide 66 asymmetric gears (34°/20° and 20°/34°) corresponding to steel–polymer and polymer–polymer material combinations were investigated. The performance of symmetric gear pairs (20°/20°) was determined to serve as a comparison. Quasi-static numerical simulations were performed in a finite element analysis tool to predict root bending stress, load sharing ratio, and tooth deflection. The bending fatigue strength of steel–polymer and polymer–polymer pairs of each test configuration was determined using bending fatigue tests. The load sharing ratio and root bending stress of polymer–polymer pairs decreased substantially compared to steel–polymer pairs. The extent of deflection-induced load sharing was greater in polymer–polymer pairs. The bending fatigue life of polymer–polymer pairs was lower than that of steel–polymer pairs owing to the higher operating temperature. In polymer–polymer pairs, polymer driving and driven gears increased the heat generated and diminished the heat dissipation to the environment. In steel–polymer and polymer–polymer pairs, the configuration with the highest bending fatigue strength was 34°/20° and 20°/34°, respectively. This divergence was caused by the increase in temperature difference between the two configurations for polymer–polymer pairs. Analysis of hysteresis loops indicated that the loop area was higher for polymer–polymer pairs, signifying the increased amount of dissipated energy. No noticeable variation was observed between the failure modes of steel–polymer and polymer–polymer pairs despite the significant difference in the operating temperatures. The bending stress and operating temperature were the dominant factors affecting the performance of steel–polymer and polymer–polymer gear pairs, respectively.

The introduction of dynamic covalent bonds into chemically cross-linked networks is an effective strategy to solve intrinsic problems of inability to be reprocessed or recycled for thermosetting polymers. Imine bonds (also known as Schiff bases) are promising candidates for constructing covalent adaptable networks (CANs) because of their easily triggered exchange reactions. However, it remains a challenge for polyimine vitrimers to improve the creep resistance and thermal stability due to their unstable imine-based networks. In this work, we report a green strategy to prepare a series of partially bio-based, malleable, recyclable, and robust poly(amide–imine) vitrimers by bulk polymerization for the first time. The amide bonds are introduced into polyimine vitrimers for the improvement of mechanical property, thermal stability, and creep resistance. A series of H₂N-terminated prepolymers with tunable structures were first synthesized, which combined the amide and imine groups together. Then, a bio-based trimethyl citrate was selected as the curing agent to react with H₂N-terminated prepolymers for the construction of CANs with amide bonds as cross-linking points. The imine groups accompanied by a dynamic exchange nature endowed the poly(amide–imine) vitrimers with reprocessability, self-healing property, and degradability. Meanwhile, the amide groups with inherent intermolecular hydrogen bonding enhanced the mechanical properties, thermal stability, and creep resistance of poly(amide–imine) thermosets.

Tribological properties of polyamide 6 were improved synergistically using aramid pulp and irradiated polytetrafluoroethylene (IR-PTFE) hybrid additives. Tribological properties, i.e., coefficient of friction (COF) and wear rate (WR), were measured on a metallic plate using an in-house tribometer testing machine. Aramid pulp improved WR of the neat polyamide 6 by 75%, and IR-PTFE improved COF of the neat polymer by 47%, separately. However, the composite containing hybrid additives improved WR by 82% and COF by 56%, simultaneously. The analysis of COF curves during the test showed improved stability and smoothness of the friction test for the hybrid composite compared to neat polymer or composites containing individual additives. This suggests a synergistic mechanism for the hybrid composite due to some interactions between aramid pulp and IR-PTFE at the interface. However, no synergy was observed in some bulk properties of the hybrid composite, such as yield stress, tensile modulus, and heat distortion temperature. In order to explain the source of synergy just in the tribological properties of the hybrid composite, optical microscopic images of the metallic surface and Fourier transform infrared analysis of transfer films formed on the metallic surface were carried out. A mechanism explaining the formation of a uniform and stable transfer film containing the aramid pulp was proposed for the synergy observed in the hybrid composite.

Purpose: To evaluate Candida albicans adhesion and the surface roughness of polyamide denture base material coated with various concentrations of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. Materials and Methods: A total of 80 disks polyamide resin specimens were fabricated and divided into 4 groups (n = 20/group). Surfaces of the specimens in three groups were coated with MPC in different concentrations (0.25 mol/L; 0.50 mol/L and 0.75 mol/L), while uncoated specimens were used as control. Surface roughness (SR) was evaluated using a profilometer. Specimens were incubated with C. albicans for 18 h and the number of adhered cells was determined. Statistically, the following tests were done: analysis of variance, Pearson correlation coefficient test, post hoc Tukey test. Results: Upon PMPC coating, surface roughness values were decreased, with a significant difference between different groups. A statistically significant decrease was observed in C. albicans adhesion in parallel with the increase in the MPC polymer concentration. There was no significant difference between 0.50 mol/L and 0.75 mol/L groups in terms of adhesion. These findings indicated that graft polymerization of MPC on polyamide denture base material reduces the adhesion of C. albicans, and may be evaluated as a coating for prevention of denture stomatitis. Conclusion: Coating of removable prosthesis with 0.75 mol/L MPC is suitable to reduce C. albicans adhesion on polyamide denture base.

The analysis of antifriction polymer compositions on the basis of polyamide, epoxy, phenol-formaldehyde, furan resins, and also on the basis of fluoroplastic with various fillers working in friction knots is made. The influence of fillers on the mechanisms of friction is little studied, so when creating antifriction compositions capable of working in conditions of lubrication in water, the following tasks were set: to justify the number and type of fillers; to investigate the influence of fillers on the process of wear of material and counterbody; determine the optimal composition of the antifriction composition that provides minimal wear of the coating and the counterbody. The object of study were: compositions based on phenol-formaldehyde resin and fluoroplastic, modified with antifriction fillers; details of submersible pumps. The basis of the study was the study of tribotechnical and technological properties of polymer compositions. Based on the analysis of literature data, the target fillers for the creation of antifriction compositions for radial plain bearings and thrust bearings of submersible pumps are selected, their number and composition are substantiated. The criterion for optimization was the mass wear of the polymer coating and the counterbody. The optimal composition of the antifriction composition for radial plain bearings, which contains: a mixture of colloidal graphite Cl and carbon fabric "TGN-2M"; molybdenum disulfide DM-1; powder polyamide 12 APN-B; crushed prepreg comprising a fiberglass filler impregnated with a modified phenol-formaldehyde resin P2M. For thrust bearings, the optimal composition of the fluoroplastic composition is determined, which includes: fluoroplastic F4; molybdenum disulfide; carbon fabric; powdered copper. The physical and mechanical properties of the optimal composition are presented. Technological equipment has been developed for the restoration and manufacture of plain bearings and submersible pump bearings. Molds are made for industrial implementation.

While the solvating power of ionic liquids (ILs) for a variety of solute types including polymers is well-known, the use of ILs as solvents for ionenes—charged polymers with cationic moieties withi...

It is a challenge to identify each phase in a multi-component polymer system and uniquely determine the interfacial properties between the different phases. Using atomic force microscopy nanomechanical mapping (AFM-NM) and AFM-based infrared spectroscopy (AFM-IR), we identify each phase, visualize structural developments, and determine the interfacial properties in a blend of three polymers: high-density polyethylene (HDPE), polyamide (PA6) and poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS). Each phase can be identified from the Young’s modulus, along with the structural development within the phases before and after compatibilization. The interfacial widths between HDPE/PA6, HDPE/SEBS and SEBS/PA6 were determined independently in one measurement from a Young’s modulus map. The structural, mechanical property development and identity of the phases were determined by AFM-NM, while AFM-IR, providing complementary chemical information, identified interfacial reactions, showed the chemical affinity of a compatibilizer with the component phases, and mapped the distribution of the compatibilizer in the ternary polymer blends. The chemical, structural and interfacial information obtained by these measurements provide information that is essential for producing mechanically robust materials from incompatible mixtures of polymers.

This work explores a novel blend of recycled polyethylene terephthalate/polyamide 11 (rPET/PA11). The blend of rPET/PA11 was introduced to enhance the mechanical properties of rPET at various ratios. The work’s main advantage was to utilize rPET in thermoplastic form for various applications. Three different ratios, i.e. 10, 20 and 30 wt.% of PA11 blend samples, were prepared using a twin-screw extruder and injection moulding machine. The mechanical properties were examined in terms of tensile, flexural and impact strength. The tensile strength of rPET was improved more than 50%, while the increase in tensile strain was observed 42.5% with the addition of 20 wt.% of PA11. The improved properties of the blend were also confirmed by the flexural strength of the blends. The flexural strength was increased from 27.9 MPa to 48 MPa with the addition of 30 wt.% PA11. The flexural strain of rPET was found to be 1.1%. However, with the addition of 10, 20 and 30 wt.% of PA11, the flexural strain was noticed as 1.7, 2.1, and 3.9% respectively. The impact strength of rPET/PA11 at 20 wt.% PA11 was upsurged from 110.53 to 147.12 J/m. Scanning electron microscopy analysis revealed a dispersed PA11 domain in a continuous rPET matrix morphology of the blends. This work practical implication would lead to utilization of rPET in automobile, packaging, and various industries.

Thermally stable and organo-soluble polyamides synthesized by polycondensation reaction of novel diacid monomer, 2,2'-[pyridine-2,6-diylbis(oxy-4,1-phenylene)]diacetic acid with various commerciall...

Polyvinyl butyral is used in safety glass interlayers, mainly in car windshields. Legislative regulations require a recycling of cars after their lifetime and therefore also their safety glass. This causes the availability of recycled polyvinyl butyrate (r-PVB) originated from safety glass interlayers. Due to deteriorated optical properties, such as the transparency, and unknown amounts of plasticizers, it is challenging to reuse the recycled material in new windshields. Therefore, it is of particular interest to find new fields of application for r-PVB, such as the usage as a textile coating. In this research, r-PVB was investigated as a material for yarn coating. Polyester and polyamide mono- and multifilament yarns were coated continuously with solely a polymer dispersion and with mixtures of crosslinking agent and polymer dispersion. Crosslinked r-PVB coatings showed enhanced properties toward abrasion and chemical resistance. Coatings without the crosslinking agent showed a diminished abrasion resistance and could be washed off with ethanol. Mechanical properties of the monofilaments were influenced by the r-PVB coating in general. However, varying concentrations of the crosslinking agent did not affect the mechanical properties.

The synthesis of polyamides containing lateral sulfonyl chloride groups is proposed. The presented polymers can serve as macroinitiators for preparing thermosensitive polyoxazolines. It is proved that polymerization with multisulfochloride initiators proceeds without irreversible termination reaction and makes it possible to obtain polymers with a fairly narrow molecular weight distribution.

The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries. However, the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery. In this study, a composite electrolyte combining the electrospun polyamide 6 (PA6) nanofiber membrane with hierarchical structure and the polyethylene oxide (PEO) polymer is investigated. The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer, so that the ionic conductivity of the electrolyte can be enhanced. Moreover, it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups (C=O and N−H bonds) to be fully exposed, which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal. Moreover, the hierarchical structure can enhance the mechanical strength (9.2 MPa) of the electrolyte, thereby effectively improving the safety and cycle stability of the battery. The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm−2 and 60 °C. This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.

The growing demand for safer lithium-ion batteries draws researchers' attention to solid-state electrolytes. In general, a desired electrolyte should be flexible, mechanically strong, and with high ionic conductivity. A solid-state electrolyte with a polymer as a matrix seems to be able to meet these demands. However, a pure polymer electrolyte lacks sufficient strength to suppress Li dendrites, and hybrids with ceramic components often lead to poor flexibility, both far from satisfactory. Herein, a solid-state electrolyte is designed by employing a mass-produced porous polyamide (PA) film infiltrated with polyethylene oxide (PEO)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The PA/PEO/LiTFSI electrolyte is flexible but robust with a Young's modulus of up to 1030 MPa, ensuring steady Li//Li cycling without short circuit for more than 400 h. Also, the porous structure of the PA film decreases the crystalline regions and effectively enhances the ionic conductivity (2.05 × 10-4 S cm-1 at 30 °C). When cycled at 1C, solid-state LiFePO4//Li batteries assembled with the PA/PEO/LiTFSI electrolyte retain 82% capacity after 300 cycles (60 °C). In addition, a flexible LiFePO4//PA/PEO/LiTFSI//Li pouch cell can also work well in harsh operating environments, such as being folded, crimped, and pierced.

Recycling of poly(ethylene terephthalate) (PET) is considered to be a promising way to reduce environmental pollution. In this work, the valuable monomer bis(6-aminohexyl) terephthalamide (BAHT) co...

Polymer pipes are being widely used by many industrial segments. Although not affected by corrosion, the mechanical performance of these pipes can be reduced due to exposure to temperature, UV radiation and by contact with various fluids. Depending on the deterioration process, embrittlement or plasticization may occur, and the service life of the pipe can be severely reduced. In this work, the combined action of temperature and water upon the mechanical performance of polyamide 12 and high-density polyethylene pipes is evaluated. Destructive and non-destructive techniques were used and the performance of both materials was compared. Both polymers were platicized by the effect of water. However, for high density polyethylene the effect of temperature was more relevant than for polyamide. This behavior was attributed to the dependence of the free volume with the markedly different glass transition temperature of the polymers and the temperatures of testing.

During the abrasive machining of hard steels by the belt grinding, the finished surface texture is greatly influenced by the pressure between the abrasive belt and the belt ground workpiece; this pressure is the force applied by the contacting roller on the part. Therefore, the contacting roller has an important role and a direct impact on process efficiency. The purpose of this paper is to study and compare the influence of seven different polymer contact rollers on the belt ground surface texture (PS-R, POM C-R, PA 6-R, PPC-R, PPH-R, HDPE-R, and LDPE-R). The surface texture quality is characterized by eight roughness parameters (Ra, Rz, Rp, Rv, Rsk, Rku, Rsm, and Rdq) and five parameters of the bearing area curve (Rpk, Rk, Rvk, Mr1, and Mr2). The experimental test results indicate a better surface texture obtained by polyamide roller PA 6 (hardness = 60 Shore D) compared to that obtained with other rollers of the same hardness or of different hardness. Simultaneously, an optimal average pressure between the abrasive belt and the workpiece allows the removal of chips without fracturing the abrasive grains; this generates a good surface texture.

Renewable polymers with excellent stretchability and self-healing ability are interesting for a wide range of applications. A novel type of wholly biobased, self-healing, polyamide-based thermoplastic elastomer was synthesized using a fatty dimer acid and a fatty dimer amine, both containing multiple alkyl chains, through facile one-pot condensation polymerization under different polymerization times. The resulting elastomer shows superior stretchability (up to 2286%), high toughness, and excellent shape recovery after being stretched to different strains. This elastomer also displays high room-temperature autonomous self-healing efficiency after fracture and zero water uptake during water immersion. The highly entangled main chain, the multiple dangling chains, the abundant reversible physical bonds, the intermolecular diffusion, and the low ratio of amide to methylene group within the elastomer are responsible for these extraordinary properties. The polymerization time influences the properties of the elastomer. The use of the optimal self-healing thermoplastic elastomer in anticorrosion coating, piezoresistive sensing, and highly stretchable fibers is also demonstrated. The elastomer coating prevents stainless-steel products from corrosion in a salty environment due to its superhydrophobicity. The elastomer serves as a robust flexible substrate for creating self-healing piezoresistive sensors with excellent repeatability and self-healing efficiency. The elastomer fiber yarn can be stretched to 950% of its original length confirming its outstanding stretchability.

Limiting the generation of polymers waste and maximizing their recyclability and recovery have been the main focus of the research and industry in recent years. Recycling of polyamides leads to the loss in mechanical and thermal properties, therefore, in order to reuse recycled nylons, an enhancement in their properties is desired. Enhancing the properties of recycled polyamides by the addition of functionalised graphene nanoparticles (GNPs) was the goal of this study. Recycled PA6/PA6,6 blends and functionalised graphene nanocomposites were prepared using hot-melt extrusion process. Two types of functionalised graphene were used: O2-GNPs and Amine-GNPs. The nanofillers didn’t affect the crystallinity of the recycled nylon, while the presence of functionalised graphene increased the thermal conductivity by enabling better heat transfer routes within the polymer. The microstructure of the materials was characterised confirming the successful dispersion but with a slight variation in GNPs/Polymer bonding depending on the functionalisation type. The strong nylon-to-graphene interfacial hydrogen bonding increased the mechanical properties of the recycled nylon nanocomposites. The functionalised nanoparticles slowed down the segmental motion of the polymer chain and decreased the ductility with increasing GNPs contents up to 10 wt%. The overall behaviour of recycled nylon nanocomposites showed dependency on the type of functionalisation and concentration of GNPs with better improvement in the overall properties using 2 wt% Amine-GNPs. These enhanced properties make functionalised graphene/recycled nylon nanocomposites a promising new class of advanced materials.

Development of facile polymerization routes and new monomers is attractive for the development of polymer chemistry and materials. This study integrates the dual concepts in one work. Design and synthesis of Meldrum's acid (MA)-amine compounds as monomers and their corresponding self-polymerization based on ketene-mediated chemistry have been reported. An effective synthetic route to polyamides under a melt process in 20 minutes is demonstrated. Self-polymerization of the MA-amine compounds results in both linear and hyperbranched polyamides with high molecular weights, good film formability, and high mechanical strength. Flexible polyamide films prepared through a solution casting method show a high tensile strength of 122 MPa and an elongation at break of 6.7%. The designed monomers and synthetic route open a new window to both polymer chemistry and high-performance polymer materials.

A polymer based bag filter with high temperature resistance plays a key role in dust and acid gas treatment in the power industry. Currently, the polymers used for preparing filters with improved heat resistance include those with a high content of aromatic units. But the aromatic structure inevitably leads to a high melting point, which is disadvantageous for melt spinning. Here, we report a polyamide 66 and polyamide 6T copolymer (PA66-co-PA6T) fiber with both high thermal stability and good spinnability. The retention rates of heat resistance of fibers after heat treatment at 185 °C and 200 °C were higher than 97.8% and 88.4%, respectively. This high thermal stability is ascribed to the high thermal degradation activation energy (E), which was confirmed by DSC, TG, and XRD characterization studies and fitting of kinetic data. PA66-co-PA6T with good melt spinnability, high heat resistance strength and low cost is expected to be applied in high-temperature resistance filtration equipment such as bag filters, expanding the application range of PA66 materials.