Content Of Nylon Research Articles

Selective recovery of caprolactam from the thermo-catalytic conversion of textile waste over γ-Al2O3 supported metal catalysts

The massive generation of synthetic textile waste has drawn considerable attention. Landfilling/incineration of textile waste has been widely made. To abate the environmental burdensome from the conventional management processes, a thermo-catalytic conversion was used for rapid volume reduction of textile waste and simultaneous valorization by recovering textile monomer in this study. Stockings were chosen as a model feedstock. Because stockings consisted of nylon with other contents, different products (caprolactam (nylon monomer), imines, cyclic dimers, and azepines) were recovered. The yield of caprolactam from the thermal conversion at 500 °C was 53.6 wt%. To selectively enhance the caprolactam yield, catalytic pyrolysis was done using γ-Al2O3 supported metal catalysts (Ni, Cu, Fe, or Co). γ-Al2O3 itself increased the caprolactam yield up to 69.0 wt% via a based-catalyzed reaction of nylon depolymerization and intramolecular cyclization. Under the presence of metal catalysts, the caprolactam yield increased up to 73.3 wt%. To offer desired feature of green chemistry, CO2 was adopted as reactive gas. Under the CO2-mediated catalytic pyrolysis, caprolactam yield was enhanced up to 77.1 wt% over Cu/Al2O3 (basis: stocking mass). Based on the net content of nylon in the stockings, the yield of caprolactam was deemed 95.3 wt%. This study proves that textile waste (stocking) and CO2 are useful resources for recovery of nylon monomer, which can reduce the waste generation with simultaneous recovery of value-added product.

Preparation of Hydrophobic Nylon Fabric

Surface roughness and surface energy are two important factors affecting the hydrophobicity of nylon fabric. In this study, nylon fabric was treated for hydrophobicity with tetrabutyltitanate (TBT) and octadecylamine (OA) which were respectively responsible for increasing surface roughness and reducing surface energy. In order to enhance the hydrophobicity, In order to further enhance hydrophobicity by increasing available reactive sites, 1,2,3,4–butanetetracarboxylic acid (BTCA) was applied as a pretreatment to the nylon fabric It was found that the carboxyl content of nylon was increased by the BTCA pretreatment. SEM images showed that the TBT treatment produced small particles on nylon fabric which made surface rough. The water contact angle of nylon fabric treated with BTCA, TBT and OA was measured to be 134°, which was much greater than the water contact angle of nylon fabric treated only with OA. This indicated that the surface roughness resulting from the TBT treatment played an important role in improving hydrophobicity of the treated nylon fabric. The resistance to water penetration and the repellency of water spray of nylon fabric treated with BTCA, TBT and OA were respectively measured to be 27.64 mbar and 85 out of 100.

<i>In Situ</i> Reinforcement of PLA Using Nylon 6 in PLA/Nylon 6 Extrudate Blend via Twin-Screw Extrusion

This research was aimed to study the possibility of in-situ reinforcement of PLA by elongated Nylon 6 in PLA/Nylon 6 blend during elongating of PLA/Nylon extrusion. PLA was melt blending with Nylon 6 in a twin screw extruder with various compositions i.e. 5, 10, 15 and 20 % of Nylon 6. The extrudate was drawn after leaving extrusion orifice die of 3 mm in diameter, with the pulling speed of 12 cycles per minute. The extrudate gauge length 15 cm were used to perform tension test in order to investigate tensile properties. The blending between PLA and Nylon 6 with 11 phr of benzene sulfonamide (BSA), based on Nylon 6, as a plasticizer was also investigated at the same PLA/Nylon 6 blend ratios. The extrusion used conditions were also the same. Tension was also performed onto the extrudates with the gauge length 15 cm. Thermal degradation was also investigated. The SEM micrographs of blends in the longitudinal direction of PLA/Nylon 6 extrudate showed elongated of Nylon 6 in PLA matrix phase. The elongated of Nylon 6 phase in PLA matrix phase was found very clear in the plasticized blends. This phenomenon clearly occurred for the blends composition of both 95/5 and 90/10, with and without plasticizer. The results also showed that Young’s modulus of the blends with 5 % Nylon 6 was increased about 10 % whereas at 10 % nylon 6, the modulus was not significantly different from neat PLA. With the addition of plasticizer, nylon 6 was elongated more than that in the blend with un-plasticized Nylon 6. Due to the lack in interfacial adhesion, shown by SEM micrograph, tensile strength was found to be decreased. As expected, the elongation at break under tension was increased with the content of nylon 6. This was due to the toughening effect of elongated Nylon 6. Thermal stability, notified by degradation temperature of PLA, Td, was found to be improved. This was due to the high thermal stability of nylon 6. The results from the research can inform that the elongated nylon 6 phase in PLA matrix can perform as fibrous reinforcement. At high content of nylon 6, i.e. 15 and 20 %, the elongation of nylon 6 was rather difficult due to the less matrix phase and low shearing between PLA and nylon 6. Phase compatibility improvement could be the factor to improve the in-situ reinforcement.

Mechanical and thermal properties of dimer acid based nylon 636/Nylon 66 copolymers

ABSTRACTDimer acid (DA)‐based nylon 636/nylon 66 copolymers were synthesized by in situ polymerization. The effects of incorporating nylon 66 on the mechanical and thermal properties were characterized by means of intrinsic viscosity determination, attenuated total reflection (ATR)–Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry, thermogravimetric analysis, and mechanical testing. The results show that the intrinsic viscosity of the copolymers ranged from 1.0 to 2.1 dL/g, depending on the content of nylon 66. The incorporation of nylon 66 into DA‐based nylon 636 had no significant effect on the values of the glass‐transition temperature, melting temperature, temperature at 50% weight loss, or temperature at the maximum rate of decomposition, but the crystallization temperature, crystallinity degree, and extrapolated onset temperature increased. ATR–FTIR spectroscopy and XRD demonstrated that with increasing nylon 66 mass, the content of α‐ and β‐crystal forms would increase accordingly. The mechanical test data revealed that with increasing nylon 66 concentration, the tensile strength of the copolymers increased, and the flexural strength and flexural modulus first increased and then decreased. However, the notched Izod impact strength decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39845.

Polyamides based on the renewable monomer, 1,13-tridecane diamine I: synthesis and characterization of nylon 13,T

Nylon 13,T was successfully synthesized, and its chemical composition, thermal properties, crystal structure and moisture absorption were characterized. Melting temperature and glass transition temperature were deter-mined to be 263 and 90°C, respectively, while the equilibrium melting temperature was determined to be 289°C. Characterization of the crystallization kinetics showed that nylon 13,T exhibits very fast crystallization compared with the industrially important nylons, nylon 6 and nylon 6,6. In addition, the moisture absorption of nylon 13,T was dramatically lower than nylon 6 and nylon 6,6, which is consistent with the much lower amide content of nylon 13,T. The crystal structure was determined to be pseudohexagonal.

Polyamides based on the renewable monomer, 1,13-tridecane diamine II: Synthesis and characterization of nylon 13,6

Nylon 13,6 was successfully synthesized and its chemical composition, thermal properties, crystal structure, and moisture absorption characterized. Melting temperature and glass transition temperature were determined to be 206 °C and 60 °C, respectively, while the equilibrium melting temperature was determined to be 248 °C. Characterization of the crystallization kinetics showed that nylon 13,6 exhibits very fast crystallization compared to the industrially important nylons, nylon 6 and nylon 6,6. In addition, the moisture absorption of nylon 13,6 was dramatically lower than nylon 6 and nylon 6,6 which is consistent with the much lower amide content of nylon 13,6. The crystal structure was determined to be different from the expected γ-form, which possess a pseudohexagonal unit cell. Instead, the x-ray scattering pattern was more similar to the α-form. A similar result has been obtained for other odd–even nylons including nylon 5,6, nylon 5,10, nylon 9,2, nylon 11,10, and nylon 11,12.

나일론 4 공중합물 소재의 구조와 물성(III) -나일론 4 함량의 영향-

The effects of annealing on the fine structure and moisture regain of nylon 4 copolymer films were investigated in terms of the content of nylon 4. Nylon 6-ran-nylon 4 (50/50), (30/70), and (0/100) films were prepared using melt pressing and solution casting methods, respectively. The (N6-ran-N4) copolymer films were annealed in a silicon oil bath at 50, 75, 100, 125 and , and the properties of resultant film were examined by WAXD, DSC, DMTA and moisture regain. The crystal structure in (N6-ran-N4)(50/50) and (30/70) films with increasing annealing temperature was very similar to the gamma phase of nylon 6. The thermal property of (N6-ran-N4)(50/50) and (30/70) films annealed under high temperature exhibit an increase in melting temperature and enthlapy. The result of the tan behavior of (N6-ran-N4)(0/100) film was confirmed to the appearance of two transition peaks. The moisture regain of (N6-ran-N4) copolymer films, except in the case of (N6-ranN4)(30/70) films, decreased when the annealing temperature was increased.

The influence of hybridization on impact damage behavior and residual compression strength of intraply basalt/nylon hybrid composites

Low-velocity impact and compression after impact (CAI) tests were performed to investigate the impact behavior of hybrid composite laminates reinforced by basalt-nylon intraply fabrics. The purpose of using this hybrid composite is to combine the good mechanical property of basalt fiber as a brittle fiber with the excellent impact resistance of nylon fiber as a ductile fiber. Five different types of woven fabric with different contents of nylon (0%, 25%, 33.3%, 50% and 100%) were used as reinforcement. The effect of nylon/basalt fiber content on impact parameters, impact damage behavior and CAI strength was studied at different nominal impact energy levels (16, 30 and 40J). The results indicate that at low impact energy, hybridization and variation in basalt/nylon fiber content cannot improve the impact performance of composite plates. With increasing impact energy, the impact performance becomes more and more dependent on the content of nylon and basalt.

Synthesis and characterization of nylon 18 18 and nylon 18 adamantane

AbstractNylon 18 18 and nylon 18 1,3‐adamantanedicarboxylic acid (ADA) have been synthesized via melt polycondensation and characterized by thermal and spectroscopic techniques. Good film forming behavior combined with film toughness and flexibility indicate reasonable molecular weights for both. The higher aliphatic content of nylon 18 18 leads to increased resistance to common organic solvents over commercial nylons. Crystallization of nylon 18 18 combines hydrogen bonding of the amide units with a more significant contribution from van der Waals forces than possible for lower aliphatic content nylons due to the greater aliphatic chain lengths. Solid state 15N CP/MAS NMR indicates a mostly amorphous polymer, with crystalline regions comprised of the thermodynamically stable α‐form generally adopted by even–even nylons. Nylon 18 ADA as‐produced is completely amorphous as determined by differential scanning calorimetry. However, solution cast samples of nylon 18 ADA shows some ordered structures that can grow into more stable crystals with annealing. These crystals, once melted, do not recrystallize possibly due to chain rearrangement inhibited by bulky adamantly‐groups. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4409–4419, 2009

Nanohybrids of Nylon 6 with Multi-Walled Carbon Nanotubes: Solvent-Free Polymerization of ε-Caprolactam Under Variable Experimental Conditions

The solvent-free polymerization of epsilon-caprolactam on 1,8-diaminooctane-functionalized multi-walled carbon nanotubes (DA-MWNTs) is proposed as a simple and ecologically friendly approach to the preparation of carbon nanotubes/nylon 6 hybrid materials. The main goal of the present study was to find a minimum temperature resulting in an efficient epsilon-caprolactam polymerization, along with the optimization of the weight ratio of DA-MWNTs to epsilon-caprolactam and reaction time. The effect of temperature was studied in the range of 170 degrees C to 210 degrees C. After the reaction at 170 degrees C, the nanotubes functionalized contained a large amount of unreacted monomer along with ca. 14% of polyamide. Increasing the reaction temperature dramatically reduced the content of epsilon-caprolactam impurity and increased the nylon 6 content to ca. 20%. The reaction time tested was 1, 2, 4, 6 and 8 h. Exposures at less than 4 h were insufficient, where the infrared spectral bands of nylon 6 were barely seen. The reaction time of 6 h was found to be optimal since a more prolonged heating for 8 h did not provide an evident further increase in polyamide content. The effect of stoichiometry was studied by varying the weight ratio of DA-MWNTs to epsilon-caprolactam from 1:0.1 to 1:1. The ratios 1:0.1 and 1:0.2 were too high, since they did not provide the amount of epsilon-caprolactam necessary to form the composites with at least 20% content of nylon 6. Starting with the ratio of 1:0.3, the infrared band intensities qualitatively stabilized and did not show dramatic variations. The use of reagent ratios of 1:0.3 to 1:0.7 might be especially appropriate for preparing the composites targeted to biomedical applications, whereas higher weight ratios are expected to increase the content of undesirable monomer impurities.

Factors affecting the apparent intestinal (small and large) disappearance of dry matter and crude protein from rumen undegradable residues of various feeds determined using the mobile bag technique for cattle

This study evaluated the effects of retention time in the post-abomasal digestive tract, washing time (15, 50, 75, 100 s), bag size (3.5 × 5.5 vs. 2.5 × 4.0 cm), sample size to surface area ratio (3.9 vs. 7.5 mg cm-2), pepsin treatment (untreated vs. pepsin-HCl) and bag material (nylon vs. polyester) on apparent dry matter (DM) and crude protein (CP) disappearance from rumen undegradable residues (RUDR) of canola meal, soybean meal, barley straw, barley silage and dehydrated alfalfa using the mobile bag technique. RUDR were placed into 44 or 48 µm mesh size bags and inserted into the duodenum of cannulated steers, with bags recovered in feces. Retention time of bags was not influenced by substrate. Small bags took slightly longer (P < 0.05) to pass through the post-abomasal digestive tract. Retention time in the post-abomasal digestive tract did not affect CP disappearance but had a minor impact on DM disappearance (P < 0.05). Interactions (P < 0.05) were noted between bag size, washing time and substrate. Bag material (nylon vs. polyester) influenced (P < 0.05) CP but not DM disappearance. No effects of pepsin HCl pre-incubation or SS:SA ratio were observed. Polyester may be preferred due to the high N content of nylon. Key words: Cattle, mobile bag technique, nutrient disappearance

Effect of nylon 6 on fracture behavior and morphology of tough blends of poly(2, 6‐dimethyl‐1,4‐phenylene oxide) and maleated styrene‐ethylene‐butadiene‐styrene block copolymer

AbstractTernary blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO), nylon 6, and styrene‐ethylene‐butadiene‐styrene block copolymer grafted with maleic anhydride (SEBS‐g‐MA) were prepared via a melt extrusion, and the fracture behavior, morphology, mechanical properties, and rheology were studied. The compatibilization of the blended components was confirmed by differential scanning calorimetry (DSC) analysis. Mechanical properties evaluation demonstrated that incorporation of nylon 6 resulted in an improvement of the tensile strength, but reduction of both the notched Izod impact strength and elongation at break. Transmission electron microscopy (TEM) observation revealed that the network structure of SEBS‐g‐MA domain was gradually destroyed by incorporating the nylon 6. A conversion of SEBS‐g‐MA domain from the network to the irregular dispersed phase took place when the nylon 6 content reached 20 wt %, which resulted in a reduction of the impact strength. Fracture morphology implied that increase of the tensile strength was caused by the plastic deformation of matrix. Rheology investigation indicated that the melt viscosities could be reduced significantly with increasing the content of nylon 6; thus, the processability was improved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3336–3343, 2006

Determination of moisture content in nylon 6,6 by near‐infrared spectroscopy and chemometrics

AbstractThe effects of moisture on the morphology and mechanical properties of polyamides have been extensively studied by a number of researchers. However, the assessment of water content in the resins has been carried out by thermal or thermogravimetric methods, which are destructive. In the present work partial least‐squares (PLS) calibration models based on near‐infrared (NIR) spectroscopy were produced in order to predict the moisture content of nylon 6,6. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the loss‐on‐drying (LOD) method were used as reference methods. TGA, LOD, DSC, and NIR analysis were performed in parallel, and the obtained data were used for multivariate calibration purposes. Data pretreatment techniques such as derivation and multiplicative scattering correction (MSC) successfully eliminated the baseline offset present in the raw spectra and compensated for differences in thickness and light scattering of the analyzed samples. Calibration models were validated by full cross validation with the help of a test set. A comparison of the prediction ability of PLS models based on pretreated data was also done. NIR spectroscopy is a rapid and nondestructive method for the determination of moisture in recycled nylon. The moisture content can be predicted with a RMSEP = 0.05 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2165–2170, 2003

Crystallization and Melting of Binary Mixtures of Nylon 6 and Nylon 66. A Study by DSC

The crystallization and melting behavior of binary mixtures of nylon 6 and nylon 66 was investigated by differential scanning calorimetry (DSC). Mixture samples prepared from solution were carefully arranged so as to attain a well-mixed state prior to the measurement of DSC. In the mixtures nylon 6 and nylon 66 crystallize separately; nylon 66 crystallizes preferably, while the crystallization of nylon 6 was restricted remarkably, especially in the region where the content of nylon 6 was small. In melting temperature diagram, considerable reduction of melting temperature of nylon 66 was observed, probably due to the diluent effect caused by nylon 6. Analysis of this reduction in terms of the Nishi–Wang equation made it possible to estimate the polymer–polymer interaction parameter for the present mixture system. Obtained parameter is a relatively large negative value and the contribution from the entropy term is significant. Melting temperature of nylon 6 in the mixtures was observed in the narrow range of composition where the content of nylon 66 is small. In the crystallization temperature diagram, the crystallization temperature read from the peak position of the crystallization profile starts from nylon 66, decreased in the mixtures and leveled off. Total crystallinity including both nylon components evaluated from the area under the profile decreased appreciably in the intermediate region of composition. The slope of increasing curve of each profile on cooling process was evaluated as a relative measure for the rate of crystal growth. The composition dependence of the slope thus obtained is discussed qualitatively from the viewpoint of crystallization kinetics concerning crystal growth of both nylon components in the mixtures.

Nylon 6 as a modifier for maleated ethylene–propylene elastomers

Blends of nylon 6 and ethylene–propylene rubber, grafted with maleic anhydride, (EPR-g-MA) were prepared using a melt blending process. For certain compositions, nylon 6 forms finely dispersed particles due to the reaction of the polyamide amine end groups with the grafted maleic anhydride, that have the potential to reinforce the elastomer matrix. This study focuses on the effects of the content of nylon 6 on the rheological, morphological and mechanical properties of such blends where nylon 6 is the dispersed phase. Transmission electron microscopy was used to determine blend morphology. Mechanical properties were examined by stress–strain measurements and dynamic mechanical thermal measurements; the modulus is compared to values calculated from theory. The addition of magnesium oxide causes significant improvement in tensile properties of these blends.

The effects of diluent molecular weight on the structure of thermally-induced phase separation membrane

The effects of molecular weight of a homologous series of diluent on the droplet size of the thermally-induced phase separation membranes were investigated for the mixtures of poly(ethylene glycol) used as a diluent and nylon 12 as a matrix. All the phase diagrams obtained for different molecular weights of the diluent ranging from 200 to 600 showed the upper critical solution temperature type phase boundaries. When molecular weight of PEG was higher than 1000, nylon 12 did not form miscible blends with PEG below the thermal degradation temperature. Interaction energy denssty for each pair was evaluated from the phase separation temperature by the Flory-Huggins theory. The chain end group effects on the interaction energy were also considered using a binary interaction model and a Massa plot. The equilibrium domain size increased as the molecular weight of the diluent increased and then approached an asymptotic value. The increase of the average domain size with the increase of the diluent molecular weight was suppressed to a great extent for a higher content of nylon 12 in the mixture suggesting that there exist specific interactions between PEG and nylon 12.

Crystallization Kinetics of Nylon 6

We have studied the nonisothermal crystallization of nylon 6 polymers using a differential scanning calorimetry technique. Our nylon 6 samples had molecular weights in the range of 11,000-43,000 g/mol (weight average) and polydispersities ( Mw /Mn ) of 1.8-3.0. We evaluated the effects of molecular weight, polydispersity, and moisture content of nylon 6 on the kinetic crystallizability Gc. Because Gc was sensitive to these variables, we concluded that it is an important parameter for understanding the non isothermal crystallization kinetics involved in the solidification of the polymer melt, which takes place in the polymer processing.

Blends of polypropylene and nylon 6: Influence of the compatibilizer, molecular weight, and processing conditions

AbstractThe aim of this work is to study the influence of different types of compatibilizing agents, different processing conditions, and the molecular weight of the two components on the properties of immiscible blends of polypropylene and nylon 6. Increasing the content of the functional group of the modified polypropylene and the content of nylon in the blend, the effectiveness of the compatibilization improves. The same effect is observed by decreasing the molecular weight of the two components, in particular, that of the polyamide. The influence of the processing conditions is slight provided no degradation takes place during processing. © 1993 John Wiley & Sons, Inc.

Friction and wear of polyethylene-nylon blends

The objective of this work was to investigate how the mechanical properties of a high density polyethylene (HDPE) could be increased by adding nylon 6 to it while keeping its good frictional and wear resistance characteristics. Nine blends of 5%–30% nylon in HDPE were prepared with 5% of an ionomer as a linking agent. ASTM D638 traction specimens were injection moulded to control the mechanical properties of the blends, and friction and wear specimens were cut in the runners of the injection mouldings. Traction tests showed between −13% and + 16% variations in tensile yield strength compared to pure polyethylene. Friction tests conducted on a reciprocating machine showed an increase of about 15% in the coefficient of friction over that of pure polyethylene, but it still remained only about 60% that of pure nylon 6. The tests also showed a certain deterioration of the wear resistance for the blends compared to pure HDPE, especially for those blends having the highest content of nylon.

Mechanical properties-structure relationships for immiscible blends of low density polyethylene with nylon-6

Data on mechanical properties of blends of low density polyethylene with nylon-6 as a function of the composition are presented. They suggest that these blends are immiscible in the solid state. However both a theoretical model and scanning electron microscopy seem to indicate some degree of interaction at high content of nylon.