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Microplastics (MPs) in the air are one of the major concerns due to their possible health risks. In addition, airborne microplastics act as a carrier for several toxic air pollutants and cause carcinogenic, mutagenic and teratogenic effects. Nylon 66 is one of the most abundant MPs in the microenvironments. In this study, we report an optimized method for the quantification of nylon 66 MPs present in the fine particulate matter (PM2.5) using high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The optimized method exhibited excellent linearity, recovery rates, intraday and interday precision and sensitivity. The optimized method was deployed to carry out a pilot study to measure the mass concentrations of nylon 66 microplastics present in the inhalable fraction of particulate matter collected in a shopping complex. The observed mass concentrations of nylon 66 MPs in this study are in the range from 0.30 ng m−3 to 4.37 ng m−3. This study demonstrates the presence of inhalable fraction of nylon 66 MPs in the indoor environment and their mass concentrations were determined using HPLC-MS/MS. [ABSTRACT FROM AUTHOR]

This study presents the feasibility of improving some selected mechanical strengths and the inner-structural analyses of cement matrix by electrospun nanofibers containing nylon 66, nanosilica, and carbon nanotube. The hybrid electrospun nanofibers were fabricated and mixed into ordinary Portland cement. From the mechanical strength test results, the hybrid nanofibers have shown their role in improving the tensile, compressive, and toughness behavior of the mixed cement material. The improvements of 62%, 38%, and 69%, respectively, were observed compared to those of the control paste. The novelty of the surface and inner structure of the hybrid fibers, as well as the modified cement matrix, were observed by the scanned images from electron microscopes. Besides, the additional pozzolanic reaction between the generated calcium hydroxide and the attached silica was clarified thanks to the results of energy dispersive spectroscopy, X-ray diffraction, and thermal gravimetric analysis. Finally, the consistency between mechanical strength results and inner-structure analyses showed the potential of the proposed fiber to improve cement-based materials. [ABSTRACT FROM AUTHOR]

Tough conductive carbon black/nylon66 (CCB/PA66) antistatic composites modified by maleic anhydridegrafted ethylene-vinyl acetate copolymer (EVA-g-MAH) were prepared by twin-screw extrusion and injection molding. The mechanical, melt flow, and antistatic properties of the composites were tested, and the fracture surface morphologies and crystallization behavior of the composites were observed and studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The results showed that EVA-g-MAH has good compatibility with PA66. The antistatic properties of PA66 increased with the addition of CCB, however the toughness and processing ability of the composites decreased significantly. The addition of 10% EVA-g-MAH in the 8% CCB/PA66 blend resulted in a 75.4% and 45.1% increase in impact strength and elongation at break, respectively, while maintaining relatively higher tensile strength (50.5 MPa). When the mass fraction of EVA-g-MAH was 20%, the volume resistivity and surface resistance and of 8% CCB/PA66 decreased by 2 to 3 orders of magnitude to 4.3 x 107 Ω · cm and 6.5 x 106 Ω, respectively, due to the selective location of CCB particles in 8% CCB/EVA-g-MAH/PA66. 10% EVA-g-MAH enhanced the crystal formation of PA66 in the 8% CCB/EVA-g-MAH/PA6 composites, however 20% EVA-g-MAH inhibited the crystal formation of PA66. [ABSTRACT FROM AUTHOR]

V‐belts are commonly used to transmit power between two distant pulleys. Therefore, a strong reinforcement for dimensional stability and thermomechanical properties are essential in power transmission belts. The influence of resorcinol formaldehyde resin (RFL) treated nylon short fibers in EPDM peroxide‐cured formulations was investigated, with concentrations ranging from 0 to 30 parts per hundred rubber (phr) in increments of five. The incorporation of nylon short fibers resulted in improved tensile and mechanical properties in EPDM vulcanizates. Specifically, the tensile stress at 100% elongation increased by 177% to (10.8 MPa), and the improvement in tear strength to 16.2% (75.7 N/mm) was observed. Among other functional requirements in a weak rubber like EPDM, enhanced tear strength is significant for its application in power transmission. Substantial reinforcement between the fiber‐elastomer matrix was confirmed via scanning electron microscopy, as evidenced by increased storage modulus (E′). Notably, there were no considerable effects on the curing rate or low‐temperature properties. Significant improvement in heat stability is observed through thermogravimetric analysis. These enhancements in mechanical and thermal properties might play a role in increased durability and performance in actual V‐ribbed belt applications. Highlights: This manuscript describes the effect of treated nylon 66 short fiber on EPDM V‐belt compound.A significant increase in storage modulus, tear strength, and thermal stability.A belt is made using the experimental formulation and it meets the performance requirement.Low fiber content (<15 phr) compounds are unsuitable for dimensional stability.High fiber content (>25 phr) compounds pose processing challenges. [ABSTRACT FROM AUTHOR]

The mechanical properties of engineering plastics can be enhanced through effective surface mechanical treatment (SMT), which can be applied to various types of engineering plastics, eliminating the limitations of conventional polymer processing and could potentially extend their applications and improve their performance and reliability as structural-functional materials. Inspired by metal forging, this work proposes a simple and effective SMT strategy to enhance the mechanical properties of polyamide 66 (PA66). Tensile tests have shown that SMTed PA66 samples exhibit significant improvements in both Young's modulus and ultimate tensile strength (UTS), with a 2104 MPa Young's modulus, almost double that of the pristine samples, and a 35.56% increase in UTS, reaching 183 MPa. Additionally, the modulus within the localized SMTed surface layer could reach up to 14 GPa, which is approximately 14 times higher than that of the pristine sample. The Vickers hardness within the localized SMTed surface layer can be doubled, reaching 10.72 Hv, and the crystallinity can increase by approximately 20% compared to the untreated region. Furthermore, force field molecular dynamics (FFMD) simulations were conducted to investigate the ternary relationship between the SMT method, PA66's molecular structure, and its properties. The combination of MD simulations and versatile structural characterizations provides evidence that the SMT method's mechanism, under heat induction, results in a chain-combing procedure that changes the polymer's molecular morphology microscopically and enhances its mechanical properties macroscopically. [ABSTRACT FROM AUTHOR]

This study presents the feasibility of improving some selected mechanical strengths and the inner-structural analyses of cement matrix by electrospun nanofibers containing nylon 66, nanosilica, and carbon nanotube. The hybrid electrospun nanofibers were fabricated and mixed into ordinary Portland cement. From the mechanical strength test results, the hybrid nanofibers have shown their role in improving the tensile, compressive, and toughness behavior of the mixed cement material. The improvements of 62%, 38%, and 69%, respectively, were observed compared to those of the control paste. The novelty of the surface and inner structure of the hybrid fibers, as well as the modified cement matrix, were observed by the scanned images from electron microscopes. Besides, the additional pozzolanic reaction between the generated calcium hydroxide and the attached silica was clarified thanks to the results of energy dispersive spectroscopy, X-ray diffraction, and thermal gravimetric analysis. Finally, the consistency between mechanical strength results and inner-structure analyses showed the potential of the proposed fiber to improve cement-based materials.

A semi-crystalline designated nylon 66 polymer is a crucial, high-performance engineering material that is used in wide variety of industrial applications including sensors, electrical insulators, electronic devices, and automotive sector. Using modules based on density functional theory and finite-field approaches, this work explores the optoelectronic and spectroscopic characteristics of this polymer. Absorption, dielectric function, refractive index, and optical conductivity are the principle topics of this study. The effects indicated that nylon 66 is a first-rate insulator and the degree of crystallinity estimated is 46.44%. The simulated bandgap vs. the Tauc relation value is greater than 7.0 eV and has a proportional inaccuracy of 2.36%. Absorption coefficient value, however, suggests that while the refractive index and dielectric function remain stable, the optical conductivity is elevated. In order to determine the advantages appropriate for many applications, this research develops a strong basis and perception of the linear and nonlinear optical properties of nylon 66.

The investigation focused on the separation, through selective dissolution, of polyamide 66 (PA 66) from mixtures with cellulose fibers with calcium chloride‐ethanol‐water (CEW). The dissolved PA 66 was reprecipitated by addition of water. Analysis of the cellulose after separation revealed no change in mechanical strength, suggesting the polymer was undamaged by the treatment. There were residues of the polyamide retained on the cellulose, but a substantial proportion could be removed by carding. About 80–90% of the PA 66 originally present in the mixtures was recovered. Effective removal of calcium residues from the recovered PA 66 is found to be critical, as calcium contents of greater than ca. 0.8 wt% in the polymer is observed to change the melt behavior. These investigations are being conducted in the broad context of fiber‐to‐fiber recycling from textiles, and will be followed up by investigations on the impact and fate of colorants present in the fibers. [ABSTRACT FROM AUTHOR]

In this study, various blended fabrics of modacrylic fibre with flame retardant (FR) viscose, and Nylon 66 have been manufactured and studied for their thermal, mechanical and comfort properties for workers of oil & gas industry. The ring spinning system is used to manufacture three sets of yarns. In the first set, three yarns are produced using only modacrylic, only FR viscose, and only Nylon 66 fibres. The second set of yarns is made using blends of FR viscose and modacrylic. These fibres are blended in three different ratios of 30:70, 50:50 and 70:30 for making yarns. The third set is made out of tertiary blends of FR viscose, nylon 66 and modacrylic. These are blended in two different ratios of 30:20:50 and 50:20:30 respectively. Fabric samples have been produced out of these yarns and evaluated for their flame, thermal and mechanical properties after 5 and 50 washes. The radiant heat transfer index and convective heat transfer index of blends of modacrylic fibre are found in the range 12 - 13.5 s and 5.0 - 5.7 s respectively. Multivariate test analysis has been applied to find out the effect of different fibre blends on various flame and thermal properties. The study shows that flame and thermal resistant properties are influenced by fibre blending ratio. [ABSTRACT FROM AUTHOR]

The radical mechanisms of the thermal degradation of polyamide 66 (PA66) occurring under a vacuum at a temperature range between 80 °C and 240 °C (which includes the temperature of practical applications) were investigated using a spin-trapping electron spin resonance (ST-ESR) technique, as well as FTIR, TG-DTA, and GPC methods. No significant weight loss and no sign of thermal degradation are observed at this temperature range under oxygen-free conditions, but a slight production of secondary amine groups is confirmed by FTIR. GPC analysis shows a small degradation by the main chain scission. ST-ESR analysis reveals two intermediate radicals which are produced in the thermal degradation of PA66: (a) a ●CH2− radical generated by main chain scission and (b) a −●CH− radical generated by hydrogen abstraction from the methylene group of the main chain. The ST-ESR result does not directly confirm that a −NH−●CH− radical is produced, although this reaction has been previously inferred as the initiation reaction of the thermal degradation of PA; however, the presence of −●CH− radicals strongly suggests the occurrence of this initiation reaction, which takes place on the α-carbon next to the NH group. The ST-ESR analysis reveals very small levels of reaction, which cannot be observed by common analytical methods such as FTIR and NMR. [ABSTRACT FROM AUTHOR]

In this study, a modified version of electrospun nylon 66 nanofibers by silica particles were blended into ordinary Portland cement to investigate the microstructure and some mechanical properties of cementitious material. The addition of silica into the nanofibers improved the tensile and compressive properties of the hardened cement pastes. The observations from the mechanical strength tests showed an increase of 41%, 33% and 65% in tensile strength, compressive strength, and toughness, respectively, when modifying the cement pastes with the proposed nanofibers. The observations from scanning electron microscopy and transmission electron microscopy showed the morphology and microstructure of the fibers as well as their behaviors inside the cement matrix. Additionally, X-ray diffraction and thermal gravimetric analysis clarified the occurrence of the extra pozzolanic reaction, as well as the calcium hydroxide consumption by the attached silica inside the cement matrix. Finally, the observations from this study showed the successful fabrication of the modified nanofibers and the feasibility of improving the tensile and compressive behaviors of cement pastes using the proposed electrospun nanofibers. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An overview of recent developments of flame-retardant nylon 6 and nylon 66 is presented in this paper. The research of flame-retardant composites is mainly through adding flame-retardant elements to nylon molecules, which can be divided into physical addition and chemical addition. Each of these two methods has its advantages and disadvantages. In this paper, according to the different addition methods and flame-retardant mechanism of various flame-retardants, the flame-retardant properties of phosphorus flame-retardants, nitrogen flame-retardants, bio based flame-retardants and synergistic systems, as well as their effects on the mechanical properties of flame-retardant composites have been critically reviewed and summarized. This review will objectively explore and give new direction for the development of the flame-retardant nylon materials, which would be more accessible to the emerging field of materials science.

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Poly(hexamethylene adipamide), nylon 66, is a popular plastic that requires high surface wettability and strong adhesive bonds for many applications. However, pristine nylon is difficult to bond due to its hydrophobic nature and poor surface wettability. The objective of this work was to modify the physio-chemical surface properties of nylon 66 via a novel atmospheric plasma surface treatment approach using oxygen (O2) or water vapor (H2O) plasma glow. The surface hydrophilicity of the plasma-treated nylon surface was substantially enhanced immediately after either helium (He)/H2O or He/O2 plasma surface treatment. The average water contact angle was reduced from 65 degrees to ~30 degrees after He/H2O plasma and ~40 degrees after He/O2 plasma treatments. The improved hydrophilicity was also evidenced by the increased intensities of the surface oxygen and hydroxyl bonds in the X-ray photoelectron spectra. The interfacial adhesion strength of nylon surfaces before and after plasma treatment was further evaluated by uniaxial tensile tests of nylon single-joint lap shears bonded with three adhesives, i.e., thermoset epoxy resins EPON 825/ JEFFAMINE D-230 and EPON825/JEFFAMINE D-2000, and the thermoelastic polyurethane adhesive Sikaflex 252. The most significant improvements in bond strengths due to plasma treatment were found for lap shears bonded with the EPON 825/JEFFAMINE D-230 epoxy resin; their shear strengths with maximum loads were more than doubled—from 299–451 to 693–1594 N—after plasma treatment and were further enhanced by a factor of four to 895–1857 N after a subsequent silane treatment. In contrast, the bond strength of lap shears bonded with EPON 825/JEFFAMINE D-2000 and Sikaflex was not significantly improved because of the different a, re-affirming the importance of adhesive bulk properties This work presents the preliminary success of effective surface functionalization leading to enhanced interfacial adhesive bonds for nylon 66 via the development of scalable atmospheric plasma surface treatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mica/nylon 66 composite nanofibers were fabricated by electrospinning process. • The electric field loss was diminished by incorporation of mica into the nylon 66 nanofibers. • Triboelectric nanogenerator with composite nanofibers showed robust performances under harsh environment. The triboelectric nanogenerator (TENG) is a fascinating energy-harvesting device that utilizes the triboelectric effect caused by contact electrification and electrostatic induction. Nylon 66 is used widely in TENG applications because it is a representative tribo-positive polymer with excellent biocompatibility. On the other hand, the generated charges are vulnerable to discharge due to moisture in the air, which impedes the TENG performance in harsh environments. Moreover, the dielectric loss, which generates heat by consuming the considerable electric charge in triboelectric materials, significantly degrades the TENG performances. This study fabricated the composite nanofiber (NF) structure of nylon 66 and mica, which has excellent electrical insulation, low dielectric loss, high thermal conductivity, and enhanced tribo-positive properties, to circumvent these problems. Embedding the mica into the nylon NFs enhanced the TENG performance and prevented performance degradation even in harsh environments at a relative humidity of 70%. Furthermore, after 100,000 cycles of friction, the nylon/mica composite NFs showed smaller temperature increments than the pristine nylon NF because of the low dielectric loss and efficient heat dissipation of the mica. The nylon/mica composite NFs were applied to a sustainable and wearable power generator operating in a humid and hot environment by attaching the device to the forearm and soles of the feet. The generators were efficient enough to turn on 80 light-emitting diodes. [ABSTRACT FROM AUTHOR]

Removal of toxic pollutants such as heavy metals and dyes from water has received great attention due to a significant decline in the clean water level, worldwide. Herein, we attempted to remove both metals and dyes using a single material. Nylon 66 (nylon) films were prepared and then functionalized with nitric acid. The functionalized nylon 66 (F-nylon) was utilized for the adsorption of copper (II) (Cu(II)) ions from an aqueous solution. The adsorption study revealed the efficient adsorption of Cu (II) ions through F-nylon. Moreover, the adsorption data were fitted to Langmuir, Freundlich, and Temkin isotherms, and the values are best fitted to Langmuir isotherm as compared with Freundlich isotherm. The nylon 66, F-nylon, and Cu/F-nylon were characterized through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). SEM of F-nylon samples showed highly porous surface and membrane-like appearance that is suitable for the metal adsorption. The EDX analysis confirmed the overall elemental composition of the adsorbed copper on F-nylon surface. FTIR was helpful to confirm the introduction of new functional groups after modification of nylon, while TGA analysis demonstrated significant thermal stability of all samples. The copper adsorbed F-nylon 66 (Cu/F-nylon) was further utilized as a photocatalyst for the photodegradation of Eriochrome Black T (EBT) dye. Cu/F-nylon and recovered Cu/F-nylon films degraded about 93 and 89.3 % EBT dye within 240 min, respectively. The optimum conditions for EBT photodegradation were pH 6, 0.05 g photocatalyst dosage, and an initial dye concentration of 60 ppm. [ABSTRACT FROM AUTHOR]

Strong acids, such as hydrochloric acid and sulfuric acid, are colorless and are not easily detected when leaked by accident. A chemosensor using halochromic dye can provide a simple and easy detecting method by exhibiting different color when it is exposed to liquid acids. In this study, bromocresol green was used as a pH-indicating dye in detecting liquid acids. Nylon 66 woven fabrics were dyed with bromocresol green and the dyeing properties were investigated. pH sensing property was also investigated by immersing the dyed nylon fabric in acidic solutions. Bromocresol green in an aqueous solution showed maximum absorption at 445 nm with yellow color at a pH of 2–4, whereas the maximum absorption changed to 616 nm showing blue color at a pH above 6. Color yield and exhaustion of bromocresol green on nylon 66 were highly dependent on the dyebath pH. When yellow sample, which was dyed at pH 3 or less, was immersed in a solution of a pH range of 2.0–3.5, its original orange color was maintained, whereas the color turned blue when immersed in a solution of a pH range of 4.0–5.5. On the contrary, blue sample was obtained when dyed at pH 4 or more. When the sample was immersed in a solution of pH 2.0–3.5, the color was markedly changed into yellow and showed a big color difference. Wash fastness of the fabric dyed at pH 4 was good to excellent. The results suggest that nylon 66 fabric dyed with bromocresol green may be used as a textile sensor. [ABSTRACT FROM AUTHOR]

Delamination is the main responsible for structural failure of composites having a laminar structure. In the present work, polyamide (Nylon 66) nanofibers, even impregnated with uncrosslinked nitrile butadiene rubber (NBR), are interleaved into epoxy‐based carbon fiber reinforced polymer (CFRP) laminates with the aim to counteract the delamination phenomenon. The performance of nano‐modified composites using both the nanofibrous mat types, that is, Nylon 66 and NBR‐impregnated Nylon 66 membranes, is investigated. Mode I loading tests show a significant improvement of the interlaminar fracture toughness of rubber‐modified CFRPs, especially in the GI,R (up to +151%). The improvement in the GI,C is less pronounced, but still significant (up to +80%). The achieved results are very encouraging and pave the way to the use of such Nylon–NBR hybrid mats for hindering delamination. [ABSTRACT FROM AUTHOR]

The radical mechanisms of the thermal degradation of polyamide 66 (PA66) occurring under a vacuum at a temperature range between 80 °C and 240 °C (which includes the temperature of practical applications) were investigated using a spin-trapping electron spin resonance (ST-ESR) technique, as well as FTIR, TG-DTA, and GPC methods. No significant weight loss and no sign of thermal degradation are observed at this temperature range under oxygen-free conditions, but a slight production of secondary amine groups is confirmed by FTIR. GPC analysis shows a small degradation by the main chain scission. ST-ESR analysis reveals two intermediate radicals which are produced in the thermal degradation of PA66: (a) a ●CH2− radical generated by main chain scission and (b) a −●CH− radical generated by hydrogen abstraction from the methylene group of the main chain. The ST-ESR result does not directly confirm that a −NH−●CH− radical is produced, although this reaction has been previously inferred as the initiation reaction of the thermal degradation of PA; however, the presence of −●CH− radicals strongly suggests the occurrence of this initiation reaction, which takes place on the α-carbon next to the NH group. The ST-ESR analysis reveals very small levels of reaction, which cannot be observed by common analytical methods such as FTIR and NMR.

In this study, a modified version of electrospun nylon 66 nanofibers by silica particles were blended into ordinary Portland cement to investigate the microstructure and some mechanical properties of cementitious material. The addition of silica into the nanofibers improved the tensile and compressive properties of the hardened cement pastes. The observations from the mechanical strength tests showed an increase of 41%, 33% and 65% in tensile strength, compressive strength, and toughness, respectively, when modifying the cement pastes with the proposed nanofibers. The observations from scanning electron microscopy and transmission electron microscopy showed the morphology and microstructure of the fibers as well as their behaviors inside the cement matrix. Additionally, X-ray diffraction and thermal gravimetric analysis clarified the occurrence of the extra pozzolanic reaction, as well as the calcium hydroxide consumption by the attached silica inside the cement matrix. Finally, the observations from this study showed the successful fabrication of the modified nanofibers and the feasibility of improving the tensile and compressive behaviors of cement pastes using the proposed electrospun nanofibers.

Plasma treatment of nylon fabric was carried out with aim of improving the adhesion properties with polyurethane polymer. The effect of the plasma parameters vis. treatment time and power on adhesion improvement were examined. The force required to separate the coating from the fabric was measured as a peel-off strength of the coated fabric. Significant improvement in the adhesion of the plasma-treated sample was observed as compared to the untreated sample. Surface wettability after plasma treatment was studied by wicking measurements. A change in surface morphology was analysed using a scanning electron microscope (SEM). SEM results reveal the surface roughening after plasma exposure. The mechanical property was also studied by tensile strength measurements. [ABSTRACT FROM AUTHOR]

Solvent-precipitated nylon 66 (SP PA66) is a key material used to fabricate microfiltration membranes. The crystallization kinetics and behavior of SP PA66 were investigated through differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD). The Avrami equation was used to describe the isothermal crystallization of SP PA66. Nonisothermal crystallization behaviors were analyzed using Avrami equations modified by Jeziorny, Ozawa and Mo. The Avrami analysis demonstrated that the k values of SP PA66 were higher than those of neat PA66. The n was between 2 and 3 indicating the presence of two- and three-dimensional mode with thermal nucleation. With an increasing cooling rate, the Jeziorny crystallization rate constant increased for SP PA66; however, the Ozawa model was not satisfactory for all SP PA66 samples. The Mo method suggested that SP PA66 had a faster crystallization rate than neat PA66 during the nonisothermal crystallization process. The solvents dissolved nylon 66, rearranged it and formed a regular hydrogen-bonded region. These regions served as nucleation sites and increased the crystallization rate constant in the subsequent melting process. The crystal morphology of the SP PA66 under the POM investigation exhibited Maltese cross spherulites. The sizes of the spherulites of SP PA66 were significantly smaller than those of neat PA66. Wide-angle XRD revealed that SP PA66 had the same crystal structure and a higher crystal perfection than neat PA66.

Thermomechanical properties of tire cords, which have a considerable influence on tire functions, were investigated in the current research. The nylon and polyester cords are the most commonly used polymers in the tire. Many efforts have been made to produce a new tire cord having the capability of integrating the desired properties of these two polymers into one cord. In this study, a new cord structure was developed using nylon 6,6 and polyester tire yarns. The effect of thermal treatment was studied at the temperatures of 180°C, 200°C, and 220°C under two different loads of 600 and 1800gf on thermomechanical properties of the nylon 6,6/polyester hybrid tire cord. Shrinkage and shrinkage force as thermal properties, as well as static and dynamic mechanical properties, were investigated. The relationship between the aforementioned properties and variation in the crystal structure and fiber orientation obtained from Differential scanning calorimetry (DSC) and Wide‐Angle X‐Ray Scattering (WAXS) analysis were examined too. The results showed that the higher tension leads to the higher initial modulus and storage modulus due to the crystallization of polymers during heat treatment. The shrinkage and shrinkage force also increased, as the tension increased. In addition, a decrease in residual shrinkage and shrinkage force were acquired because of an enhancement in the temperature. [ABSTRACT FROM AUTHOR]

In this study, nylon 66 industrial fabrics (used in the conveyor belts) were exposed artificially to the accelerated ultraviolet rays and the degradation mechanism was evaluated using spectral, thermal, and morphological analyses. The fabric samples were exposed to six different exposure times in a UV chamber and tensile tests were carried out in the main and bias (45°) directions. The results showed that the shear modulus was reduced in the early stages covering 4 h of the UV radiation because of the linkages breakage and the increase in the amorphous regions. However, after this early stage, the shear modulus started to increase. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) analysis, and X-ray photoelectron spectroscopy (XPS) study were also performed to evaluate the surface morphology and the degradation mechanism of the nylon 66 fibers after UV illumination. The results also revealed that the formation of new links by free radicals caused the change in the bond wavelengths. Furthermore, it was found that there was an interesting mechanism for the UV degradation of nylon 66 fabrics at different exposure times, as confirmed by the results obtained regarding the mechanical properties of the samples. The results of this study can be, therefore, helpful for the industrial application of nylon 66 woven conveyor belts exposed to solar UV radiation. [ABSTRACT FROM AUTHOR]

Cellulose acetate (CA)/nylon 66 (NYL66) blend membranes were prepared and tested for the pervaporation separation of isopropanol (IPA) aqueous solution. These membranes were characterized through scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, contact angle measurement, and pervaporation test. The effects of CA/NYL66 ratio were investigated on the pervaporation performance of the membranes with the proportion of the NYL66 ranging from 0 to 20 wt.%. All blend membranes illustrated lower total flux than the pure CA membrane, while the CA/NYL66 (95/5) blend membrane had the highest separation factor and pervaporation separation index in dehydration of 80 wt.% IPA aqueous solution at 30°C. [ABSTRACT FROM AUTHOR]

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE)/Nylon 66 blends have been considered as the potential heat resistant engineering plastics with high mechanical toughness and flame retardancy, suitable for high temperature applications. However, incompatibility between PPE and Nylon 66 and poor thermal stability of Nylon 66 degrade mechanical toughness and flame retardancy. In this work, for the first time, the PPE/Nylon 66 blends with high mechanical toughness and flame retardancy simultaneously have been prepared through newly synthesized compatibilizer of PPE grafted with fumaric acid (PPE-g-FA) and environmental-friendly non-halogen organic phosphinate flame retardant. The PPE/Nylon 66 blend achieved not only V0 grade flame retardancy with the help of improved fire resistance through the solid phase reaction of non-halogenic flame retardant, but also large impact strength larger than 10 kJ/m2 due to the strong compatibility of PPE-g-FA. [ABSTRACT FROM AUTHOR]

Gelatin (GA) is a natural protein widely used in food packaging, but its fabricated fibrous film has the defects of a high tendency to swell and inferior mechanical properties. In this work, a novel spinning technique, solution blow spinning (SBS), was used for the rapid fabrication of nanofiber materials; meanwhile, nylon 66 (PA66) was used to improve the mechanical properties and the ability to resist dissolution of gelatin films. Morphology observations show that GA/PA66 composite films had nano-diameter from 172.3 to 322.1 nm. Fourier transform infrared spectroscopy and X-ray indicate that GA and PA66 had strong interaction by hydrogen bonding. Mechanical tests show the elongation at break of the composite film increased substantially from 7.98% to 30.36%, and the tensile strength of the composite film increased from 0.03 MPa up to 1.42 MPa, which indicate that the composite films had the highest mechanical strength. Water vapor permeability analysis shows lower water vapor permeability of 9.93 g mm/m2 h kPa, indicates that GA/PA66 film’s water vapor barrier performance was improved. Solvent resistance analysis indicates that PA66 could effectively improve the ability of GA to resist dissolution. This work indicates that SBS has great promise for rapid preparation of nanofibrous film for food packaging, and PA66 can be applied to the modification of gelatin film.

In recent years, portable electronic devices have flourished, and the safety of lithium batteries has received increasing attention. In this study, nanofibers were prepared by electrospinning using different ratios of nylon 66/polyacrylonitrile (PAN), and their properties were studied and compared with commercial PP separators. The experimental results show that the addition of PAN in nylon 66/PAN nanofibrous film used as separator of lithium-ion battery can enhance the porosity up to 85%. There is also no significant shrinkage in the shrinkage test, and the thermal dimensional stability is good. When the Li/LiFePO4 lithium battery is prepared by nylon 66/PAN nanofibrous film used as separator, the capacitor can be maintained at 140 mAhg−1 after 20 cycles at 0.1 C, and the coulombic efficiency is still maintained at 99%, which has excellent electrochemical performance.

Abstract To enable intelligent design of fire resistant polymeric materials, it is highly important to have a quantitative understanding of the relation between the composition of these materials and chemical and physical properties that control the process of fire growth. This paper presents a methodology that provides a capability to determine the core subset of these properties including the kinetics and thermodynamics of the thermal decomposition of the condensed-phase constituents and enthalpy of combustion of gaseous pyrolyzates. This methodology is based on three experimental techniques – Thermogravimetric Analysis, Differential Scanning Calorimetry and Microscale Combustion Calorimetry – and inverse numerical modeling of the results of these tests. The material system analyzed in this study is polyamide 66 reinforced with chopped glass fiber and flame retarded with red phosphorous. This system shows a complex decomposition behavior that is highly dependent on the phosphorus concentration. First, a semi-global thermal decomposition mechanism consisting of a set of first- and second-order (two components) reactions was developed using three material specimens containing different phosphorus concentrations. Subsequently, the extrapolative power of the developed reaction model was demonstrated by accurately predicting the experimental measurements obtained for several compositions not used in the model development process. [ABSTRACT FROM AUTHOR]

In this study, the potential usage of the Nylon 66 hydrolysis products (HP) for curing "high ortho" novolac resin (N) was investigated. According to FTIR, DSC and TGA results, it is concluded that HP can be as a curing agent for N without the need for another crosslinking agent and thermal degradation stability of cured N-HP blends increased significantly up to 15% HP content. Furthermore, according to performed surface coating tests, it is shown that all films prepared with HP up to 30-wt % have excellent water resistance, drying and adhesion properties as well as with high hardness values. [ABSTRACT FROM AUTHOR]

In this work, the treatment of oily wastewater was investigated using developed cellulose acetate (CA) membranes blended with Nylon 66. Membrane characterization and permeation results in terms of oil rejection and flux were compared with a commercial CA membrane. The solution casting method was used to fabricate membranes composed of CA and Nylon 66. Scanning Electron Microscopy (SEM) analysis was done to examine the surface morphology of the membrane as well as the influence of solvent on the overall structure of the developed membranes. Mechanical and thermal properties of developed blended membranes and a commercial membrane were examined by thermogravimetric analysis (TGA) and universal (tensile) testing machine (UTM). Membrane characterizations revealed that the thermal and mechanical properties of the fabricated blended membranes better than those of the commercial membrane. Membrane fluxes and rejection of oil as a function of Nylon 66 compositions and transmembrane pressure were measured. Experimental results revealed that the synthetic membrane (composed of 2% Nylon 66 and Dimethyl Sulfoxide (DMSO) as a solvent) gave a permeate flux of 33 L/m2h and an oil rejection of around 90%, whereas the commercial membrane showed a permeate flux of 22 L/m2h and an oil rejection of 70%.

• The initiation reactions on thermo-oxidative degradation of Polyamide 66 under air was investigated using spin-trapping electron spin resonance (ST-ESR). • GPC analysis shows a large degradation by main chain scission when heated up to 240°C. • ST-ESR analysis has newly revealed the presence of two more radical intermediates, −•CH−NH− and •(C=O)NH−, under air, in addition to the two radical intermediates, •CH 2 − and −CH 2 −•CH−CH 2 −, already found under vacuum in the previous report. • The generating temperature of −•CH−NH− coincides with the onset temperature of the large chemiluminescence (CL) by oxidation reaction. • The initial radical of thermo-oxidative degradation of PA66 is determined as −•CH−NH− radical generated by selective oxygen attack on the NH-adjacent methylene group. • The ST-ESR analysis reveals more small levels of reaction than other analytical methods. We succeeded in detecting the radical intermediates produced during the thermo-oxidative degradation of polyamide 66 (PA66) in air between 80°C to 240°C, the temperature range for practical applications, using spin-trapping electron spin resonance (ST-ESR) even in the presence of oxygen, which interferes with ESR measurements. As a result, ST-ESR analysis has newly revealed the presence of two more radical intermediates, −•CH−NH− and •(C=O)NH−, under air in addition to the two radical intermediates, •CH 2 − and −CH 2 −•CH−CH 2 −, already found in the previous report, which was examined under oxygen-free conditions. The formation of those four radicals can be explained by hydrogen abstraction and β-scission in the autoxidation mechanism. The onset temperature of the rapid oxidation reaction observed in chemiluminescence (CL) measurement coincides with the one for generating the −•CH−NH− radical, indicating that the initial radical of thermo-oxidative degradation of PA66 is −•CH−NH− radical generated by selective oxygen attack on the NH-adjacent methylene group. This finding strongly supports previous reports that concluded hydrogen abstraction from the NH-adjacent methylene group is the main reaction under air. [Display omitted] [ABSTRACT FROM AUTHOR]

It is an important approach to prevent the damage mechanisms that cause sudden fractures during fatigue loading in bonding joints by modifying the matrix with nanostructured materials. The aim of this study is to examine the effect of graphene nanoplates (GNPs) doped nylon 66 (N66) nanofiber mats reinforcement on the fatigue life of composite to aluminum single lap joint. For this purpose, 1 wt%, 3 wt% and 5 wt% GNPs doped N66 nanofibers were produced by electrospinning method. The morphological characteristics, chemical bond structures and % crystallinity of these nanofiber mats was investigated by SEM, TEM, FTIR, DSC analysis. The fatigue tests of the bonding joints with single axis periodic cycle loading were performed at five different load levels as 20%, 30%, 40%, 50% and 60% of the maximum shear strength of each samples. Fatigue life of bonding joints was assessed by S-N curves plotted according to the fatigue results. Damage mechanisms of fractured surface in the bonding joints were investigated with the macro and micro images. The results show that, these composite nanofiber mats have increased the fatigue life of bonding joints in all case. [ABSTRACT FROM AUTHOR]

Nylon 66 microcomposites with various weight percentage of titanium dioxide (TiO2) were prepared by a twin screw extruder and investigated for mechanical and tribological properties. Mechanical properties of the composite such as tensile strength/modulus, flexural strength/modulus, impact, and compressive strength first showed an increase up to 6 wt% TiO2 followed by a decrease at higher filler loading. The value of heat deflection temperature increased with the increase in wt% of TiO2. Sliding wear tests were performed on pin‐on‐disk equipment under different loads, sliding velocity, and sliding distance combinations. It was found that micro‐TiO2‐Nylon 66 composite exhibited reduced wear and coefficient of friction up to 6 wt% TiO2. Micro‐TiO2 at 2 wt% was most effective in improving the tribological properties of plain nylon 66. The worn surfaces were examined by scanning electron microscopy to understand the wear mechanism. The optimal combination from 2 wt% to 6 wt% micro‐TiO2‐Nylon 66 can be used depending upon the application requiring improvement in tribological or mechanical properties, respectively. [ABSTRACT FROM AUTHOR]

Blends of bottle-grade post-consumer polyethylene terephthalate (PET) and virgin polyamide 66 (PA66), over the complete composition range, and corresponding short glass fiber (SGF) reinforced composites were investigated. These materials were compounded in a twin-screw extruder and injection molded as standard specimens. Morphological investigation of the composites revealed that the short glass fibers have a good size distribution and are homogenously dispersed within a polymeric matrix. The PET/PA66/SGF composites showed good mechanical performance in flexural, tensile and impact tests demonstrating that the addition of SGFs to PET/PA66 blends is an interesting approach to obtaining new thermoplastic composites. In addition, this represents a potential application for post-consumer PET, an abundant and cheap material, in the well-established market of PA66/SGF composites, which are widely used in technical parts requiring high mechanical and thermal properties.