Nylon Matrix Research Articles

Surface engineering of carbon nanotube-carbon fiber networks for enhanced strength in additive manufacturing of nylon composites

This work quantifies the impact of chemical functionalization of carbon nanotubes and carbon fibres on the interfacial shear strength, tensile and interlaminar shear strength properties of additively manufactured nylon composites. The surface chemistry of functionalized carbon materials was evaluated through infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Single carbon fibre was dip-coated in a suspension of nanotubes and embedded into a nylon matrix. The fibres were pulled out to measure the interfacial shear strength, and the fibres with attached neat, carboxylated, and silanized nanotubes increased it by up to 67 %, 112 %, and 216 %, respectively. Composite samples were manufactured using a novel hybrid additive manufacturing method, which was able to deposit nylon layers and a suspension containing carbon reinforcement. The use of chemically functionalized nanotubes in the suspension led to carbon layers that improved tensile strength by 49 % and tensile modulus by 126 % over neat nylon. Functionalization of carbon reinforcement increased the interlaminar shear strength by up to 63 %. Overall, this paper demonstrates the importance of chemical modification in composite materials containing a large interface area of carbon materials.

Achieving highly-efficient room-temperature phosphorescence with a nylon matrix

Achieving highly-efficient room-temperature phosphorescence with a nylon matrix

In‐situ preparation and performance of cellulose nanocrystals grafted with polyamide 6 composites

AbstractNylon nanocomposites were prepared by in‐situ ring‐opening polymerization to overcome the problem of poor properties due to the uneven dispersion of the nanoparticles by the traditional melt blending. This high‐performance polyamide 6 (PA6) nanocomposites with high dispersion and strong interface was prepared by grafting PA6 onto the surface of cellulose nanocrystals (CNC). The micromorphology, mechanical, crystalline and thermal properties of the composites were also investigated. Firstly, the hydroxyl group on the surface of CNC reacted with the para isocyanate of toluene diisocyanate (TDI), and the remaining ortho isocyanate was blocked by caprolactam to prepare CNC grafted with caprolactam (CNC‐g‐CL). Then CNC‐g‐CL was used as an activator to prepare cellulose nanocrystal grafted with polyamide 6 (CNC‐g‐PA6) composites by the ring‐opening polymerization of caprolactam on the CNC. The effects of different reaction temperatures, solvent amounts and molar ratios on the grafting rate of CNC‐g‐CL were investigated. The results showed that the highest grafting rate of CNC‐g‐CL with 66.7% was achieved at a reaction temperature of 45°C, 0.1 g/mL CNC in toluene, and a molar ratio of 6 for TDI/CNC. Further, different CNC‐g‐PA6 composites prepared from different CNC content and activator content were explored. For CNC‐g‐PA6 composites, CNC was uniformly dispersed in the PA6 matrix and had a good compatibility with the matrix. CNC exhibited significant reinforcement in the composites with a tensile strength of up to 108 MPa. In addition, the glass transition temperature of CNC‐g‐PA6 was increased to 92°C, which significantly improved the heat resistance of the new composites.Highlights Effects of reaction condition of CNC and TDI on DSTDI and DSCL were studied. Effects of CNC and activator content on CNC‐g‐PA6 properties were studied. CNC is uniformly dispersed in PA6 with average particle size less than 1 micron. The nylon matrix was significantly strengthened by the addition of CNC. The addition of CNC significantly improved the heat resistance of the composites.

Nylons with Highly-Bright and Ultralong Organic Room-Temperature Phosphorescence

Endowing the widely-used synthetic polymer nylon with high-performance organic room-temperature phosphorescence would produce advanced materials with a great potential for applications in daily life and industry. One key to achieving this goal is to find a suitable organic luminophore that can access the triplet excited state with the aid of the nylon matrix by controlling the matrix-luminophore interaction. Herein we report highly-efficient room-temperature phosphorescence nylons by doping cyano-substituted benzimidazole derivatives into the nylon 6 matrix. These homogeneously doped materials show ultralong phosphorescence lifetimes of up to 1.5 s and high phosphorescence quantum efficiency of up to 48.3% at the same time. The synergistic effect of the homogeneous dopant distribution via hydrogen bonding interaction, the rigid environment of the matrix polymer, and the potential energy transfer between doped luminophores and nylon is important for achieving the high-performance room-temperature phosphorescence, as supported by combined experimental and theoretical results with control compounds and various polymeric matrices. One-dimensional optical fibers are prepared from these doped room-temperature phosphorescence nylons that can transport both blue fluorescent and green afterglow photonic signals across the millimeter distance without significant optical attenuation. The potential applications of these phosphorescent materials in dual information encryption and rewritable recording are illustrated.

Material testing for injection molded and 3D printed pristine/glass reinforced nylon at various strain rates

With the advent of new polymer material and non-conventional methods of manufacturing, the effect of loading conditions on mechanical properties has now been in huge demand to facilitate their industrial applications. Present paper has been focused on investigating the strain rate effects on mechanical properties of pristine nylon-6 and 20% glass reinforced nylon-6 material fabricated using injection molding and SLS (Selective Laser Sintering) printing manufacturing methods, respectively, at three strain rates of 0.0003, 0.003, and 0.01 per second. Tensile strength of injection molded nylon-6 has shown a positive relationship with strain rate whereas compressive strength has shown a reciprocal effect. At highest strain rate of 0.01 s−1, tensile strength exhibits 10.27% more as compared to lowest strain rate of 0.0003 s−1. Tensile strength at highest strain rate is found 60 MPa whereas at lowest strain rate it exhibits 54.41 MPa. At higher values of strain rate, rising of maximum strain is found very much sensitive than the rise in tensile strength. It also shows high percentage of deformation at higher value of strain rate. On the other hand, SLS printed 20% glass reinforced nylon-6 shows variable tensile strength with respect to strain rate due to uneven distribution of glass particles into nylon matrix created due to manufacturing process of SLS printing. FESEM images shows the cavity formation as observed before loading conditions whereas the glass fracturing phenomenon observed at the after loading conditions. However, compressive strength is found minimal with strain rate with an average value of 175.61 MPa. The findings of this study have contributed in avoiding the improper selection of material and its strain rate application during numerical modeling for industrial application purpose.

Sustainable biocomposites from pyrolyzed lignin and recycled nylon 6 with enhanced flame retardant behavior: Studies on manufacturing and quality performance evaluation

AbstractThe recycled nylon (RN)‐based biocomposites were fabricated by adding 25% lignin biocarbon. Lignin was pyrolyzed at 300, 600, and 900°C to produce Lig300, Lig600, and Lig900 biocarbon (BioC) samples, respectively. Higher functionality of Lig600 (unlike Lig900) allowed for improved interfacial interaction with the polar nylon matrix. Mechanical properties were further enhanced for RN_Lig600 composite with enhanced flexural and tensile strength by 18% and 8%, respectively, compared to neat polymer (RN). RN_Lig900 composite showed enhancement in tensile and flexural modulus by 32.6% and 51.1%, respectively, compared to RN. Incorporation of Lig900 in RN matrix resulted in 77.9% reduction in burning rate compared to RN. These results show the potential of lignin BioC as a filler in RN composites for flame retardant applications and mechanical enhancement, such as in the automotive industry.Highlights Effect of pyrolysis temperatures (300, 600, and 900°C) on lignin biomass. Composites prepared from recycled polyamide 6 from carpet waste and biocarbon. Improved interfacial adhesion of 600°C biocarbon with recycled nylon matrix. Enhanced thermal, mechanical properties, reduced flammability of biocomposites. Sustainable biocomposites with 900°C biocarbon reduced burning rate by 78%.

Solution spun electrically conductive nylon 6/poly(pyrrole) nanotubes-based composite fibers

Wearable electronic device applications require flexible polymer-based conducting fibers. Towards this, various conductive fillers have been used in a polymer matrix. However, it usually requires the addition of a high amount of fillers. In this study, electrically conductive composite fibers of nylon 6 (Ny)-poly(pyrrole) nanotubes (PPyNTs) have been demonstrated using the solution-spinning process. The high aspect ratio of PPyNTs can provide a good electrically conductive network and show a percolation threshold at a low concentration of PPyNTs in a nylon matrix. The composite fibers exhibited good DC electrical conductivity of ∼0.002 S/cm at only 6 wt% of PPyNTs. The influence of PPyNTs concentration on the morphology, physical, chemical, and electrical properties of the fibers have been investigated.

Experimental Investigation on the 3D Printing of Nylon Reinforced by Carbon Fiber through Fused Filament Fabrication Process, Effects of Extruder Temperature, and Printing Speed

This study investigated how the extruder temperature, printing speed, and specimen geometry interact during a tensile test of continuous carbon fiber‐reinforced nylon matrix composites produced by the fused deposition modelling (FDM) process. The investigation utilized statistical techniques. For this purpose, tensile examinations were done on manufactured samples using a testing apparatus. The study’s objective is to identify the most efficient specimen geometry for tensile testing result optimization and to maximize the 3D printing process’s capability for producing complex, freeform patterns in these composites. In this study, the input parameters required for the response surface methodology (RSM) were varying extruder temperature (240‐255°C) and printing speed (60‐80 mm/s), and experimental responses included modulus, elongation at break, and weight. The findings of the regression analysis showed output responses are influenced by both input variables. The results showed that the strength of the samples was significantly influenced by the input parameters. To draw the surface and residual plots, the software of design expert software was used. The interaction between the two input variables suggests raising the extruder temperature and decreasing printing speed, which leads to printing heavier samples. Inversely, the diversity between the forecasted and real responses for the optimal specimens is less than 10% which is assumed to be acceptable for the design of experiments (DOE). The analysis took into account the lower and upper ranges of the input variable with the goal of enhancing both the most modulus and fracture elongation while simultaneously degrading the weight of the specimens. To achieve this objective, the extruder temperature and printing speed are between 240 and 250°C and 65 and 75 mm/s, respectively.

Ultrafast spectroscopic studies on the interaction of reactive oxygen species with a probe impregnated in nanoscopic and microscopic matrix formulation

Reactive oxygen species (ROS) plays important role to maintain homeostasis in living bodies. Here we have studied interaction of ROS generated from hydrogen peroxide (H2O2) with a well-known spectroscopic probe Rose Bengal (RB) encapsulated in nanoscopic sodium dodecyl sulphate (SDS) micelles in aqueous medium and entrapped in microscopic nylon 66 solid matrix generated using electrospinning technique. A detailed spectroscopic characterization of ROS with SDS encapsulated RB (RB-SDS) shows efficient interaction compared to that in bulk medium. The time resolved analysis on the probe based on femtosecond resolved 2D-spectrum time images collected from streak camera reveal the simultaneous existence of an ultrafast electron (∼6 ps) and a hole transfer mechanism (∼93 ps) resulting from generation of hydroxyl radicals through photobleaching of the probe in presence of H2O2. Based on the spectroscopic and time resolved studies of RB in bulk and in restricted (SDS) medium, we have further translated it for the development of an in-field prototype device which utilizes RB as a ROS sensor impregnated in a nylon thin film. The microscopic nylon solid matrix characterized by scanning electron microscope (SEM) shows porous structure for holding sample containing ROS. Our study quantitatively measures the amount of ROS by using RB embedded microfiber membrane. Thus, our developed prototype device based on RB embedded on the nylon matrix would be beneficial for the potential use in quantification of ROS in extracellular fluids and food materials.

Acoustic 4 × 2 encoder based on linear waveguides in two-dimensional solid-solid phononic crystals

The paper proposes a design for an acoustic 4 × 2 encoder that incorporates acoustic waveguides within a two-dimensional square lattice phononic crystal structure. The encoder's structure comprises of a nylon matrix embedded with a 33 × 30 molybdenum rod array, featuring four input ports and two output ports. The simulation results demonstrate that the proposed structure can effectively achieve the acoustic 4 × 2 encoder functionality. To evaluate the performance of the acoustic 4 × 2 encoder, we analyzed the transmission spectrum using the finite element method (FEM).

Four-input acoustic XOR logic gate based on solid-solid phononic crystals

The paper introduces a 2D square lattice phononic crystal structure, with a nylon matrix and molybdenum rods as inclusions. Initially, a new type of resonator, called a triangle resonator, was designed, each of which acts as a two-input acoustic XOR logic gate. Then, a four-input acoustic XOR logic gate is presented by combining these resonators. Simulation results indicate that the realization of two-input and four-input acoustic XOR logic gates is possible using the structures we have proposed. In order to analyze the proposed acoustic XOR logic gates, the transmission spectrum is calculated using the finite element method (FEM).

RETRACTED: Characterization and performance evaluation of nylon-66 composite at various composition of carbon fibers and GNP reinforcement

Recycled reinforcements are being utilized more and more to make sustainable composites for load-bearing structural applications, which now dominate the key transportation industries, because they have lower environmental impact than virgin fiber manufacturing and are also less expensive. In order to improve the mechanical properties of composites, a combination of recycled carbon fibers (rCF) and waste tire-derived graphene nanoplatelets (GNP) with oxygen surface functional groups was used as reinforcement for the nylon-66 matrix. The alignment of the rCF and GNP during the injection molding process was monitored using numerical methods in conjunction with the rheological behavior of the compounds. The effective dispersion of the rCF and GNP was obtained using high shear mixing. In contrast, the flexural modulus and strength of the 20% rCF-0.3% GNP reinforced nylon-66 composites increased by 86% and 35%, respectively, while the tensile strength and modulus improved by 43% and 95%. Further, the addition of 0.3% GNP to the composition resulted in a 7.7% increase in Charpy notched impact energy compared to the 20% rCF composite. Moreover, the flow model developed to study the injection molding process of rCF/GNP reinforced composite using the fiber aspect ratio and distribution in the compounds described fiber alignment and provided insight into mechanical strengthening mechanisms.

Ultra-flexible self-supporting Ag2Se/nylon composite films for wearable thermoelectric devices

Recently, flexible thermoelectric (TE) generators (f-TEGs) have received a lot of attention. Compared with TE films on flexible substrates, self-supporting composite films prepared by combining TE materials with soft fabrics and thus retaining the inherent advantages of fabrics, such as stretchability, breathability, and flexibility, are more practical and may significantly expand the application of f-TEGs in smart wearable devices. Hence, in this work, a facile and rapid method for preparing ultra-flexible self-supporting Ag2Se/nylon composite films is developed. The composite films with both TE properties and flexibility were obtained by fast selenization of commercial Ag/nylon fiber fabrics in a short time (60 s) at room temperature and then hot pressing at 230 °C in a vacuum. The maximum power factor of an optimized composite film at room temperature can reach 73.7 μW m−1 K−2. Meanwhile, the film exhibits excellent flexibility with the Seebeck coefficient and electrical conductivity decreased by only 7.37 and 8.48% after being bent 4000 repetitions around a round bar with a radius of 4 mm, which exceeds most reported flexible TE films. The ultra-high flexibility is mainly attributed to its high content of the nylon matrix (∼85.05 wt%), the tight bonding between Ag2Se grains, and the good combination between the Ag2Se and nylon matrix. In addition, a 3-leg f-TEG assembled with the optimal film produces a maximum power of ∼1.524 μW (corresponding to a power density of ∼0.47 W m−2) at a temperature gradient of 40.6 K, verifying the good TE performance of the composite film. This f-TEG can also be used as a self-powered temperature sensor, showing potential applications in daily life.

In-situ aligning magnetic nanoparticles in thermoplastic adhesives for contactless rapid joining of composite structures

Magnetic nanoparticles of high magnetic susceptibility, such as magnetite (Fe3O4), have been used for wireless heating of adhesives and composites through the magnetic hysteresis loss mechanism, but the high concentrations of nanoparticles needed to meet heating performance targets can degrade mechanical properties. Herein, we present an in-situ aligning method to enhance the heating efficiency of magnetite nanoparticles in a nylon thermoplastic matrix without adversely affecting its mechanical strength. A composite adhesive was made by dispersing Fe3O4 nanoparticles in a nylon matrix followed by hot melting. Experimental results show that by subjecting the adhesive to an alternating magnetic field during the hot-melt process, its heating rate can be improved by 200% compared to that without applying the magnetic field. The improvement in the heating performance has been identified to stem from the alignment of the ease axis of the magnetic nanoparticles. This in-situ aligning technique enables better induction heating performance with the same amount of Fe3O4 nanoparticles, avoiding the agglomeration problem of high nanoparticle concentrations. Moreover, this technique makes it possible to develop high-performance self-heating thermoplastic adhesive for reversible bonding and self-healing solution with a wide range of applications, such as bonding and debonding of composites, temporary attachment of systems, and recyclable bonded structures.

Viscoelastic characterisation of additively manufactured composites with nylon matrix: Effects of type and orientation of fibres

This study investigates the viscoelastic performance of additively manufactured (AM) nylon and nylon-matrix composites reinforced with short and continuous fibres with three different fibre orientations: longitudinal, transverse, and quasi-isotropic. Dynamic mechanical analysis under a frequency sweep of 1–100 Hz along with tensile tests used to determine the Young's modulus and X-ray micro-CT for evaluation of microstructural porosity were employed to fully describe the viscoelastic behaviour of the composites. Generally, the addition of fibres increased the storage modulus of most composites. The composites revealed increased porosity and fractography using a scanning electron microscope on the tensile specimens demonstrated poor fibre-matrix bonding. These factors, along with the fibre orientation, had a complex effect on the loss modulus of the composite structures. Overall, the addition of fibres reduced the damping factor of the composite specimens compared to pure AM nylon samples. The quantified parameters, including those of the Prony series, can be used in numerical simulations supporting the design and optimisation of AM components.

Research on Characterization of Nylon Composites Functional Material Filled with Al2O3 Particle.

This study revolves around the issues raised by the current semiconductor device metal casings (mainly composed of aluminum and its alloys), such as resource and energy consumption, complexity of the production process, and environmental pollution. To address these issues, researchers have proposed an eco-friendly and high-performance alternative material-Al2O3 particle-filled nylon composite functional material. This research conducted detailed characterization and analysis of the composite material through scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results show that the Al2O3 particle-filled nylon composite material has a significantly superior thermal conductivity, about twice as high as that of pure nylon material. Meanwhile, the composite material has good thermal stability, maintaining its performance in high-temperature environments above 240 °C. This performance is attributed to the tight bonding interface between the Al2O3 particles and the nylon matrix, which not only improves the heat transfer efficiency but also significantly enhances the material's mechanical properties, with a strength of up to 53 MPa. This study is of great significance, aiming to provide a high-performance composite material that can alleviate resource consumption and environmental pollution issues, with excellent polishability, thermal conductivity, and moldability, which is expected to play a positive role in reducing resource consumption and environmental pollution problems. In terms of potential applications, Al2O3/PA6 composite material can be widely used in heat dissipation components for LED semiconductor lighting and other high-temperature heat dissipation components, thereby improving product performance and service life, reducing energy consumption and environmental burden, and laying a solid foundation for the development and application of future high-performance eco-friendly materials.

Monotonic crack propagation in a notched polymer matrix composite reinforced with continuous fiber and printed by material extrusion

The study presents the crack mouth opening and propagation of cracks in a composite material printed by material extrusion subjected to monotonic loading. The composite material is made out of a nylon matrix (with embedded short carbon fiber—called Onyx®) and reinforced with continuous Kevlar fibers. Three-point bending tests were performed on notched specimens built according to ASTM-E399. Tests were digitally recorded to extract crack opening displacement (COD) and crack length data through image treatment techniques (using ImageJ), and results were analyzed using linear elastic fracture mechanics parameters through the use of COD. Therefore, the crack mouth opening was established, and fracture toughness was found to be 46 MPa√m. Additionally, microscopy analysis identified fracture zones, crack initiation, transition, and final rupture. The observed failure mechanisms were matrix cracking, fiber pull-out, fiber breakage, and defects such as non-proper fiber-matrix bonding.

Effect of Broken Glass Particle on Stress Transfer of Nylon Matrix Composite

Effect of Broken Glass Particle on Stress Transfer of Nylon Matrix Composite

Effects of recycling and hygrothermal environment on mechanical properties of thermoplastic composites

Recyclability of nine types of composites including natural and mineral fillers in polypropylene and nylon matrix have been studied through injection molding and mechanical grinding. No significant degradation in mechanical properties of natural fiber composites occurred after recycling or water absorption tests. In contrast, glass fiber composites showed decrease in tensile strength and modulus by up to 45% and 40%, respectively after five rounds of recycling mainly due to severe fiber attrition. Glass bubbles breakage occurred after recycling, which diminished its ability to provide lightweighting. Only glass fiber reinforced nylon composites were affected by hygrothermal conditioning, which were characterized as a function of recycling. At saturation point, water absorption for nylon composites was 7.7% by wt. after 45 days of immersion, which significantly affected the mechanical properties. Tensile strength and modulus of glass fiber nylon composites reduced from 88.4 MPa and 5.6 GPa to 36.2 MPa and 1.8 GPa, respectively.

Thermal and thermo-mechanical studies on seashell incorporated Nylon-6 polymer composites

Towards environmental sustainability, recycling and effective usage of sea wastes are encouraged to develop novel materials in engineering applications by sustainable waste management. In this research, impact of seashell (SS) particles (75 μm) of varying weight fractions (0, 3, 6, 9, 12,15 and 18%) reinforced in nylon-6 matrix is investigated experimentally by studying its thermal properties viz., vicat softening temperature (VST), heat deflection temperature (HDT), coefficient of linear thermal expansion (CLTE), and melt flow index (MFI) and thermo-mechanical properties by thermo-gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC) according to ASTM guidelines. The polymer matrix composite (PMC) is prepared by blending the pellets of nylon-6 and seashell particles with the help of twin-screw extruder and fabricated into the required shape and size in an injection moulding machine. Outcomes of the experimental investigation show that CLTE decreases with increase in SS content, whereas VST and HDT deflection temperature increases along with the weight % of SSs due to the reduction in plasticity of the thermoplastic until 15% addition. This makes it more resistance to load and deflection along with heat resistivity whereas MFI decreases with addition of SSs in nylon-6 matrix. From DMA analysis it is observed that with inclusion of SSs the glass transition temperature tends to increase along with loss and storage modulus. Thermal and thermo-mechanical features tend to improve until 15% addition of SS in nylon-6 matrix. With further addition, the properties tend to be lowered because of poor adhesion of SSs with Nylon-6.