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In past one decade, polyamide (PA)6 feedstock filaments has proved its capabilities for fused deposition modeling (FDM) based functional prototypes requiring wear and impact resistance. The almond skin powder (ASP) is organic kitchen waste material, which has highest strength to weight ratio. Some researchers have developed PA6 based composite feedstock filament reinforced with ASP. But hitherto little has been reported on use of ASP reinforced PA6 based composite filament for 3D printing (using FDM) and its printing capabilities. In this research work an effort has been made to 3D print, 10% (by weight) ASP reinforced PA6 composite filament with open source FDM setup as a pilot study. The results are supported with mechanical testing, optical photo-micro graphical analysis. The functional prototype can be very useful in meta-material printing (requiring high modulus of toughness) and rapid tooling applications.

The effect of hybrid micro fillers on two body abrasive wear of PA66/PA6 blend based composites was investigated. Three composites: Blend (PA66/PA6) (80/20 wt%), Blend/10 wt% PTFE and Blend/10 wt% PTFE/5 wt% MoS2 were considered for the investigation. These micro composites were prepared by using melt mix method using twin screw extrusion technique. The two-body abrasion wear behavior of these micro composites was investigated using 180 grit SiC abrasion paper in a multipass condition as per ASTM G99 standard under the influence of variable abrasion load at a constant velocity of 0.5 m/s. It is found from the experimentation that the volumetric wear loss is totally dependent on abrading load. Further, it is found that Blend/PTFE composites exhibited good abrasion wear behaviour due to excellent Ratner-Lancaster (σe) factor. Micro ploughing and micro cutting were noticed during the morphological study through SEM images. Among the micro composites studied, Blend/10 wt% PTFE exhibited better abrasive wear resistance compared to other composites.

Bicomponent spunbond hydroentanglement technology can break the interface between the two components by physical extrusion and shearing, thereby realizing the green and efficient production of high-strength microfiber nonwoven materials. Herein, we report a soft and fluffy bicomponent spunbond hydroentanglement nonwoven material using high-shrinkage polyester/polyamide 6 (HSPET/PA6) as the bicomponent. HSPET/PA6 hollow segmented pie composite fibers with different volume ratios were prepared by spunbond technology, the HSPET and PA6 segments were alternately arranged, and the interface was flat. The composite fibers were split by heat treatment. The dry heat shrinkage rates of the composite fibers were 8.45% (50/50) and 10.57% (70/30), and the boiling water shrinkage rates were 10.02% (50/50) and 12.27% (70/30). HSPET/PA6 hollow segmented pie microfiber nonwovens were prepared by hydroentanglement technology. After heat treatment, the fibers of nonwovens were further split and the HSPET fibers curled, giving the nonwovens a fluffy characteristic. By comparing the properties of HSPET/PA6 after heat treatment, the shrinkage effect of the water bath was obviously better than that of dry heat, and the split degree of fibers reached 81.97% (50/50) and 84.65% (70/30). Compared with polyester/PA6 nonwovens, the softness of HSPET/PA6 nonwovens increased by 45.1% (50/50) and 49.3% (70/30) after boiling water shrinkage. At the same time, the mechanical properties of HSPET/PA6 nonwovens were also improved. The successful fabrication of HSPET/PA6 microfiber nonwovens provides a new method for enhancing the softness of bicomponent spunbond hydroentanglement nonwovens.

This study will contribute to the identification and understanding of the reinforcement mechanisms of thermoplastic matrices by nanofillers. This aspect is addressed through the investigation of the thermal and mechanical properties of nanocomposites consisting of a polyamide 12 (PA12) matrix crammed with organically modified clay nanoparticles. An efficient approach to the synthesis of polyamide 12 (PA12) nanocomposites was investigated; Maghnite may be a processed Algerian mineral clay which will act both as a catalyst and as an inorganic reinforcement. Two sorts of organic substances were used, labeled CTA-Mag (1CEC) and CTA-Mag (2CEC), modified by cetyltrimethylammonium (CTA) ions. However, PA12/CTA-Mag nanocomposites are characterized by various physico-chemical techniques, XRD, FTIR, TGA, scanning and transmission electron microscopy (SEM and TEM). Measurements of tensile modulus, yield strength, lastingness, elongation at break and toughness were done to assess the behavior of the mechanical properties. Furthermore, we have analyzed the consequences of the mass fraction of the fillers on the structural, thermal and mechanical properties of those nanocomposites. Specific attention has been paid to the study of relationships between the macroscopic properties and therefore the structure of nanocomposites. Thermomechanical tests showed a big improvement within the properties of the nanocomposites compared to neat PA12.

Using polylactic acid (PLA), polyamide (PA) and glass fiber–reinforced polyamide (GF/PA) as raw materials, samples with different printing temperature and speed were prepared. PLA samples were prepared by fused deposition modeling, and PA and PA/GF samples were prepared by selective laser sintering. The fracture toughness of 3D printed engineering plastics was characterized by three-point bending test. The results show that the process parameters have little effect on the fracture toughness of the specimen. With the change of printing temperature or speed, the fracture toughness of the specimen decreases by 4.9%. The raw materials have great influence on the fracture toughness of the specimens. The fracture toughness of PLA increases by 27.95% compared with PA and 58.71% with GF/PA. The results show that the fracture toughness of PLA is the highest among the three materials. Finally, the fracture surface of the specimen was scanned by scanning electron microscope, and the fracture microstructure was analyzed to reveal the influence of process parameters and raw materials on the fracture toughness of 3D printed engineering plastics.

The effect of filler amount and kind on the crystalline structure, thermal stability, and mechanical, rheological, and morphological properties of polyamide 6 (PA6) was studied in this research. Glass bead and glass fiber were chosen as mineral fillers. They were incorporated to PA6 solely or in mixed formulations at different proportions (hybrid composites). Tensile strain, tensile strength, impact strength, flexural strain, flexural strength, melt flow index, crystallite size, and thermal degradation parameters were determined for all composites. The addition of glass bead or glass fiber increased the brittleness of pure PA6. The incorporation of glass fiber to pure PA6 improved flexural, impact, and tensile strengths, and mixing of glass bead with pure PA6 polymer caused deterioration of both (tensile and flexural) strengths, but enhanced impact strength. Among hybrid composites, the highest flexural, tensile, and impact strength values were achieved with 15 wt% glass bead and 15 wt% glass fiber content. The addition of glass bead and/or glass fiber to PA6 polymer caused a decrement in melt flow index value. X-ray diffraction results indicated that pure PA6 polymer had α- and γ-crystalline forms, and the reinforcement of glass bead or glass fiber would induce the crystallization into γ-form. It was also found that the incorporation of glass bead or glass fiber influenced the lamellar thickness, and pure PA6 gave thicker lamellar crystal than that of glass bead/fiber-reinforced PA6 and its hybrid composites. Higher thermal stability with glass bead or glass fiber incorporation was found as compared to pure PA6 polymer.

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%.

Self-pumping wound dressings with directional water transport ability have been widely studied for their function of directional extraction of excessive biofluid from wounds while keeping the wound in a moderately humid environment to realize rapid wound healing. However, the existing solutions have not paid close attention to the fabrication of a nonirritating hydrophobic layer facing the wounds, which may cause irritation to wounds and thereby further worsen inflammation. Herein, a flexible and elastic thermoplastic polyurethane (TPU) hydrophobic microfiber mesh (TPU-HMM) produced by melt electrospinning (MES) is reported. The TPU-HMM was compounded to a hydrophilic nanofiber membrane, which was fabricated by blending with polyamide 6 and poly(ethylene glycol) (PA6-PEG) to form a composite self-pumping dressing, for which the breakthrough pressure in a reverse direction was 12.8 times than that in a positive direction and the forward water transmission rate was increased by 700%. It shows good directional water transport ability and is expected to absorb excessive biofluid of the wounds. This solvent-free and easy-process TPU-HMM provides a new strategy for the development of functional self-pumping textiles, and the solvent-free fabrication method for fibers, which eliminates the potential toxicity brought by solvent residues, offers more possibilities for its applications in biomedicine.

To study the compatibility of PA12 with oil and gas medium, the exposure test was carried out by the HTHP autoclave under the simulated medium environment of oil and gas fields. At different exposure periods (test period is 0/1/3/5/7 week(s)) in different temperatures (60 and 90 °C), the physical properties of the samples before and after the test, such as weight and tensile strength were investigated. And then the applicability of the pipes in the simulated medium environment was evaluated comprehensively by analyzing the changes of the micro-morphology and composition of the samples. Compared with the original samples, the weight of samples after test did not change significantly with the average rate of 1.1 to 2.4% at 60 °C, while 1.3 to 3.0% at 90 °C. The yield strength showed a downward trend during the exposure test. In the early stage of exposure (0–3 weeks), the temperature had little effect on the tensile properties, but with the increase of exposure time (3–7 weeks), the effect became more obvious. When the exposure time reaches 7 weeks, the corresponding yield strength at 60 °C is 27.65 MPa, while 27.29 MPa at 90 °C, which is 27.01 and 27.96% lower than the yield strength of the original sample (37.88 MPa), respectively. According to the microscopic morphology analysis, there are cracks on the surface of the specimen under the simulated working conditions. The infrared analysis shows no change in the composition of the sample after immersion compared with the original one, and no damage to the composition and structure of the sample after the exposure test. The above analyses show that the service performance of PA12 pipes is reduced due to penetration and swelling.

Selective laser sintering (SLS) process is the most perfect seven three-dimensional printing processes that produces three-dimensional parts from a polyamide or metal powders in stratified, the need of this process is in all different fields, the medical field, art, aerospace and other industries. The thermal phenomena generated by SLS is essential to analysis the microstructure, mechanical properties, residual stress, and all deformation of produced parts. This study applied three-dimensional element finite (EF) method by COMSOL Multiphysics software to investigate the temperature evolution in SLS. The surface heat source and the dependence of material properties on temperature are considered. It is found that the developed element finite (EF) method is able to capture the high gradients of temperature in the center of the spot laser of polyamide powder 12 (heat affected zoon). The effects of physical proprieties and laser parameters are also investigated, it was observed in the polyamide 12 powder bed, the temperature increase with the increase of pre-heating temperature and also with increasing the power laser which sintered the polyamide powder bed, the temperature increases. Also, this simulation helps us to control all the parameters and optimize the SLS process of polyamide 12, to make a perfect polyamide part manufactured by this machine with excellent quality.

Additive manufacturing is traditionally used to manufacture either prototypes or very small-scale demonstrators. In recent years though, it is being increasingly used to make low volume parts for the aeronautical and defence industry. One concern with laser sintered parts is that their relatively porous nature, means that they may be more susceptible to ageing than injection moulded parts. Parts were aged for 6 months in at different temperatures (18°C, 40°C, 50°C, 60°C, 80°C and 100°C) and in a humidity chamber at 60°C and 80% relative humidity. Each month samples were removed for characterisation. The testing included tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and gas pycnometry. During ageing the samples displayed visible discolouration and embrittlement over the 6-month test period. This embrittlement was not observed in those samples aged at room temperature or an elevated humidity. The observed yellowing in the samples aged above ambient temperature is likely a result of the build-up unsaturated degradation products. No significant differences as a result of ageing were observed via DSC, TGA, SEM or gas pycnometry.

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.

Fused Filament Fabrication is a very common additive manufacturing technology and several manufacturers have developed commercial 3D-printers that enable the use of fibre-reinforced filaments in order to improve the mechanical properties of the printed parts. The obtained material is a composite that exhibits complex mechanical properties. The aim of this study is to characterize the mechanical behaviour of 3D-printed continuous glass fibre-reinforced polyamide composites. In a first step, we focus on the reinforced filament: the heterogeneity of its microstructure is evidenced as well as its brittle elastic tensile behaviour. In a second step, parts of different fibre orientations and fibre volume contents are manufactured using a Mark Two 3D-printer (MarkForged®), their microstructure is analysed and tensile, flexural and short beam bending tests are performed. As expected, the results show a significant influence of fibre volume content and fibre orientation. Standard homogenization methods are used to compare the predicted mechanical behaviour to the experimental results. Regarding the elastic stiffness, a good correlation is observed when the material is loaded in the direction of the fibres. Regarding the tensile strength, the results show that no benefit is obtained above a fibre volume content of about 11%. These results highlight the importance of choosing an optimised stacking sequence prior to the printing process, in order to obtain composites with the desired mechanical properties. The mechanical results are analysed in the light of Scanning Electron Microscopy observations of specimen cross-sections before and after testing.

Formaldehyde-based resins are widely used in the field of wood adhesives. However, high formaldehyde emission is still a serious problem. Therefore, a low-toxic wood adhesive was successfully synth...

Effect of exfoliation of MoS2 on the wear characteristics of the MoS2/PA-6,6 composite is investigated. Exfoliation of MoS2 is identified using X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Wear loss of composites is done using Taber abrasion tester with CS-17 abrasive wheel and atomic force microscope is used to characterize the worn surface. It is observed that wear loss of MoS2/PA-6,6 composite is strongly affected by content and exfoliation of MoS2. Wear loss of composites is decreased by the addition of MoS2 irrespective of exfoliation and it is improved with increasing filler content. Exfoliated MoS2/PA-6,6 composites show improved wear characteristic, that is, reduced wear loss, compared to the pristine MoS2/PA-6,6 composite. Addition of MoS2 induces less plastic deformation of the worn surface of composites, and it is more distinct for exfoliated MoS2.

Over the years, various types of techniques have been used for the synthesis of nanocomposites. In this work, melamine-based polyamide (PA) was synthesized using a one-pot polycondensation method under mild conditions. carboxyl graphene (CG)/PA nanocomposites (CGMPA) were prepared by CG nanofiller loadings of 1, 3, and 5 wt.% via delamination/adsorption approach. The prepared CGMPA nanocomposites were characterized using different analyses, such as Fourier transform infrared techniques (FTIR), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA). The effects of the CG on the thermal properties of the CGMPA nanocomposites were significant. The results showed that the melting temperature (Tm) of neat PA and CGMPA were increased from 378°C to 393°C suggested better dispersion of CG in PA matrix. The decomposition temperature of PA was increased from 451°C to 463°C in CGMPA nanocomposites indicates the better thermal stability of PA matrix by addition of CG.

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

Statement of problem Xerostomia refers to the decrease in the quality and quantity of saliva. In denture wearers, xerostomia affects the retention of the denture because of lack of wettability of the denture base. However, which denture base resin materials are best wetted by artificial salivary substitutes is unclear. Purpose The purpose of this in vitro study was to determine the wetting properties of 3 different commercially available denture base resin materials with artificial salivary substitute by using contact angle measurements and to compare these properties before and after thermocycling. Material and methods A total 120 specimens were fabricated with 3 different denture base materials (n=40): heat-polymerized polymethylmethacrylate (DenTek), injection-molded nylon polyamide (Valplast), and microwave polymerized (VIPI WAVE). The advancing and receding contact angles were measured with a goniometer by using the WinDrop++ software program. The contact angle hysteresis was calculated from the advancing and receding contact angles values. The same specimens were subjected to thermocycling to measure the advancing and receding contact angles values. The comparative evaluation was carried out before and after thermocycling. Results The mean ±standard deviation contact angles of the microwave-polymerized material were (62.40 ±1.21 degrees) advancing contact angle, (32.12 ±0.66 degrees) receding contact angle, and (30.28 ±1.40 degrees) contact angle of hysteresis. It was followed by the injection-molded nylon polyamide material, whose mean ±standard deviation contact angle values were (68.57 ±1.72 degrees) advancing contact angle, (43.02 ±1.39 degrees) receding contact angle, (26.27 ±2.05 degrees) contact angle hysteresis and high impact strength heat-polymerized polymethylmethacrylate material, whose mean ±standard deviation contact angle values were (69.81 ±0.16 degrees) advancing contact angle, (41.90 ±1.02 degrees) receding contact angle, and (27.91 ±0.97 degrees) contact angle hysteresis. The statistical analysis showed significant differences among contact angle values of the microwave-polymerized material as compared with the heat-polymerized polymethylmethacrylate and injection-molded nylon polyamide materials (P Conclusions The microwave-polymerized material showed better wettability with artificial saliva substitute than heat-polymerized polymethylmethacrylate and injection-molded nylon polyamide.

Polyamide resin is widely used in dentistry as a denture base material. Cinnamon burmanii has been proven to have antibacterial and antifungal substances. Therefore, it is the potential to be used as a nature denture cleanser. This study aimed to examine the effect of soaking 50% cinnamon extract solution on the surface roughness of polyamide resin. This study used 16 polyamide resin samples soaked in 50% cinnamon extract solution and 16 samples soaked in distilled water as the control group. It examined the surface roughness before and after immersion for four days and seven days. Data were analyzed using paired T-test and independent T-test. The results showed a significant difference in the surface roughness of polyamide resin before and after immersion in cinnamon solution for four days and seven days. The surface roughness change is due to the polyphenol's reaction on the polyamide resin surface, which has destroyed the polymer chain of polyamide resin.

HIPS-g-MAH compatibilizer and the other three compatibilizers were prepared and added to the polyamide 66/polyphenylene oxide (PA66/PPO) alloy. The FT-IR spectra showed that the maleic anhydride (MAH) had successfully undergone grafting on the high impact polystyrene (HIPS). The effect of the MAH ratio in the HIPS-g-MAH compatibilizer, the HIPS-g-MAH compatibilizer weight ratio, and the PA66/PPO ratio on the mechanical properties of PA66/PPO alloy was systematically studied. The results showed that the PA66/PPO alloy possessed the optimal mechanical properties when the HIPS-g-MAH compatibilizer weight ratio was 7% and the MAH ratio in HIPS-g-MAH compatibilizer ranged 4% ~ 8%. The fracture morphologies of PA66/PPO alloy with different HIPS-g-MAH compatibilizer weight ratios were characterized by scanning electron microscope (SEM). The PA66/PPO alloy without HIPS-g-MAH compatibilizer showed a typical brittle fracture. The mechanical properties of PA66/PPO alloys with the HIPS-g-MAH compatibilizer were improved. In addition, the crystallization temperature of PA66/PPO alloy decreased with the increase in the HIPS-g-MAH compatibilizer weight ratio. The PA66/PPO ratio also played an essential role in the PA66/PPO alloy properties. The coefficient of friction and wear rate both increased with the increase in the PPO ratio.

This paper is devoted to obtaining and investigating polymer composites based on polyamide-6 and carbon nanotubes. Polyamide 6, type 210/310, was used as a polymer matrix, and carbon nanotubes manufactured by OcSiAl were used as a modifier. The components were compounded in a co-rotating twin-screw extruder HAAKE Rheomex OS PTW 16 to obtain granulate. The granulate was processed by injection molding on a Babyplast 6/10V machine to obtain test samples as double-sided blades (ISO-527-2, type 5A). Elastic strength tests were carried out on a Gotech UAI-7000M universal tensile-testing machine. It has been shown that introduction of 0.15% CNT promotes an increase in the yield point and the initial modulus of elasticity with a significant decrease in the ultimate strength. The maximum value of the tensile strength (161 MPa) has been obtained for the specified composition at an injection rate of 12.9 ml/s.

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 aimed to explore the safety and efficacy of using nano-hydroxyapatite/polyamide (N-HA/PA) composite in anterior cervical vertebral body subtotal corpectomy and interbody fusion. Total 50 patients with cervical spondylotic myelopathy were enrolled to undergo anterior cervical spondylectomy. Bone graft pedicles were compounded with N-HA/PA and intervertebral body fusion was performed. Study outcomes included surgical efficacy and the degree of fusion. Patients in whom vertebral body fusion was performed with N-HA/PA composite pedicles had significantly improved symptoms. The postoperative Japanese Orthopaedic Association scores increased to 18.56±4.37 from 11.37±3.52, reflecting an improvement rate of 87.3%. The composite pedicle fusion rate was 96.4%. Therefore, N-HA/PA composite pedicle as a bone graft material in fusion surgery provides significant therapeutic efficacy. Moreover, the composite pedicle fusion rate is high, making it ideal for anterior cervical vertebral body subtotal corpectomy and fusion.

In this research work, a metallization strategy for the fabrication of core-shell polymer-metal composite filaments has been presented for the development of strain sensors. The polyamide filaments were etched by carefully controlling the etching parameters and observing the surface functionality which allowed metallization of the filaments. The Differential Scanning Calorimetry (DSC) analysis revealed that the etching treatment did not result in substantial loss in crystallinity. The Attenuated Total Reflectance – Fourier Transformation Infrared (ATR-FTIR) Spectroscopy showed intensification of amide peaks. This was accompanied by the preservation of methyl peaks indicating an absence of chain scission. Etching of the filaments was followed by surface activation and acceleration prior to plating. The metallization of etched filaments comprised of electroless plating followed by electroplating with copper which resulted in the formation of a porous spongy metal network on the substrate filaments as revealed by the morphological analysis carried out using optical and electronic microscopes. The spongy network of copper gave the sensors high sensitivity to strain due to the presence of metallic percolation network at low initial resistance. The metallized polyamide filaments with strain sensing ability showed bilinear behavior under monotonic static tensile loading with an initial gauge factor of 7.6 increasing to a value of just over 31 in the 2nd linear region. The hysteresis error also settled to a low value of ~0.01 after a few initial cycles during cyclic loading tests. The metallized polyamide filaments hold promise for structural health monitoring, proprioceptive testing, soft robotics and smart textiles etc.

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.

Glass fiber-reinforced polyamide 66 composite with red phosphorus flame retardant (PA66-GF FR (RP)) has excellent strength and flame retardant properties, and is widely used in electrical engineering. In order to further improve the mechanical and crystallization properties of PA66 composites, post-treatment of the composites is necessary. In this paper, the crystallization behavior and melting behavior of PA66-GF25 FR (RP) untreated and treated by three different post-treatment routes were studied by differential scanning calorimetry. The Jeziorny-modified Avrami’s model, Ozawa’s model, and Mo’s model were applied to analysis the non-isothermal kinetics, and Kissinger theory was used to calculate the activation energies of non-isothermal crystallization. The results showed that the Mo’s model can successfully describe the non-isothermal crystallization kinetics of PA66-GF25 FR (RP) untreated and treated by three different post-treatment routes, while the other two models are not applicable. In addition, it is identified that post-treatment processes can improve the crystallinity and crystallization rates of PA66-GF25 FR (RP).

In this study, polyamide 66 (PA 66) filaments were prepared for fused filament fabrication (FFF). The effects of the process parameters on the mechanical properties, initial microstructures, dynamic mechanical behavior, and crystallinity of the samples were investigated. The samples obtained at high processing temperatures exhibited high crystallinity, high tensile strength, and low porosity. Almost fully dense samples with excellent mechanical properties were obtained under optimal conditions. The tensile strength of the samples improved by 29.5% (from 68.07 to 88.17 MPa) with an increase in the nozzle temperature from 270 to 290 °C. The elongation at break abruptly increased (from 2.38 to 13.17%), because of the plastic behavior of the material and strain hardening. X-ray diffraction results demonstrated that the crystallinity of PA 66, significantly improved (from 47.3 to 65.6%). In addition, the dynamic mechanical performance of the samples was significantly related to the raster angle. The samples fabricated at a raster angle of 0° exhibited the best dynamic mechanical properties, followed by the 45° and 90° samples. The successful fabrication of PA 66 samples demonstrates the potential use of PA 66 for producing parts using FFF, and provides options for utilizing materials with improved performance for additive manufacturing applications in engineering.

Aiming the sustainability of 3D-printed objects, in this study, pine bark particles were used as filler reinforcement for polyamide 6 (PA). In order to enhance the performance of the produced composites, the biomass was chemically modified via a two-step procedure. In the first step, the OH groups present on the particles surface were reacted with ethylenediamine, which were subsequently reacted with a polyol. Fourier-transform infrared spectroscopy (FTIR), 13C solid-state cross polarization–magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) and scanning electron microscopy coupled with energy-dispersive X-ray analysis confirmed the chemical modification of biomass. The masterbatch was prepared from modified pine bark particles and polymeric matrix (PA) being processed into test specimens. The ensuing composites revealed a significant increase in Young's modulus and maximum stress. Thus, the introduction of 10% modified biomass increases the Young's modulus by 87% and the maximum stress by 15%. Furthermore, analyzing the glass transition temperature (Tg), melting flow index and thermogravimetric analysis results, the modified biomass ensuing composites proved to be suitable for 3D printing. This was attributed to better compatibility between chemically modified biomass and matrix and, further, easier processing.

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.

The development of adhesive technology is gaining increasing attention in machinery, electronics, aviation, and other fields. However, traditional adhesives are difficult to be peeled and removed after cross-linking and curing due to the limited solubility in common solvents, which causes pollution and damage to the surface of the adherend. In this work, we synthesized random hyperbranched polyamide-amine hot melt adhesives through Michael addition of 1,8-octanediamine and N,N'-methylene diacrylamide (ODA-RHP HMA). Owing to the presence of various polar groups, ODA-RHP HMA exhibited robust lap shear strength to different substrates, including glass (6.6 MPa), ceramics (10.3 MPa), steel (11.5 MPa), and aluminum (11.8 MPa). Due to the hydrogen bonds in ODA-RHP, the HMA demonstrated intrinsic self-healing ability, which can be used repeatedly when being subjected to cyclic heating and cooling. Since ODA-RHP HMA can be swollen or dissolved in ethanol, the adhesives can be easily removed through erasing. In addition, ODA-RHP exhibited aggregation-induced luminescence due to the tertiary amine structure in the molecular structure of ODA-RHP, which can be used in the field of cultural relics restoration.

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.