Graft copolymerization of acrylamide onto nylon 6 using quinquevalent vanadium ion

Nylon 6 has been graft copolymerized with acrylamide using a quinquevalent vanadium ion as an initiator in aqueous media under a variety of conditions. Effects of initiator concentration, monomer concentration, acid concentration, CuSO₄ concentration, temperature, and chain transfer solvents have been studied. The graft yield shows a maxima at 0.005 mole/liter of initiator concentration. Similarly, the graft yield maxima with respect to acid concentration is 0.45 mole/liter. The graft yield increases within the range of the monomer concentration studied. The graft yield is temperature dependent. In addition, the reactions involved in initiation of grafting are elucidated. The work was also extended to study the moisture regain of grafted samples.     

Grafting vinyl monomers onto nylon 6. VI. Graft copolymerization of methyl methacrylate onto nylon 6 using acetylacetonate complex of Mn(III), Co(III), and Fe(III)

The graft copolymerization of methyl methacrylate onto nylon 6 using metal complexes of Mn³⁺, Co³⁺, and Fe³⁺ as initiators was studied. The rate of polymerization, R_p, increased with increasing complex concentrations in the initial stages; but it decreased upon further increase of complex concentrations. With increasing monomer concentrations, the rate of polymerization increased progressively. The graft yield increased with increaing temperature within the range 60–75°C. A suitable kinetic scheme is presented and rate equations are derived.     

Graft copolymerization of polyacrylonitrile (PAN) onto nylon 6/nylon 66 and simultaneous homopolymerization: A comparative study. II

The kinetics of graft copolymerization of polyacrylonitrile (PAN) onto nylon 6/nylon 66 and the simultaneous homopolymerization initiated by potassium peroxomonosulfate (PMS)–ascorbic acid (H₂A) redox systems were studied separately. Various kinetics parameters were evaluated and analyzed to have a comparison among the systems. The occurrence of simultaneous homopolymerization was evident through rate parameters. When the backbone was changed, the following order was observed for grafting efficiency: polyester (PET) > nylon 6 ? nylon 66. © 1995 John Wiley & Sons, Inc.     

Graft polymerization of methyl methacrylate onto nylon 6 using pentavalent vanadium as initiator

Pentavalent vanadium ion (V^v)-induced graft polymerization of methyl methacrylate onto nylon 6 was investigated under a variety of conditions. Increasing the V^v-concentration up to 2 mmol/l was accompanied by an enhancement in grafting; the latter was not affected by further increase in V^v-concentration. Unlike grafting, the homopolymer and total conversion tended to increase by increasing V^v concentration. The graft yield enhanced significantly when the MMA-concentration was increased up to 3% further increase in MMA-concentration had no effect on grafting. Raising the polymerization temperature from 50° up to 70°C caused a significant increase in the rates of grafting, homopolymerization and total conversion. Using a solvent-water mixture as medium for polymerization affected considerably the magnitude of grafting. While using methyl alcohol, ethyl alcohol and acetone at any ratio in the solvent-water mixture resulted in decreased grafting, using an isopropyl alcohol-water mixture up to a ratio of 25 : 75 gave rise to increased grafting.     

Azobisisobutyronitrile-induced vinyl graft polymerization onto nylon 66

The presence of nylon 66 during polymerization of methyl methacrylate (MMA) under the influence of azobisisobutyronitrile (AIBN) produces a nylon-PMMA graft copolymer. The copolymerization reaction is greatly influenced by the reaction medium, temperature and time of the reaction, concentration of MMA, and addition of metallic ions. Polymerization in pure organic solvents brings about little or no grafting. Incorporation of water into the polymerization system enhances grafting significantly. A reaction medium of a water/solvent mixture in a ratio of 75:25 constitutes the most favorable medium for the grafting reaction in question. Of the solvents examined, methanol, ethanol, propanol, isopropanol, and acetone work extremely well. Increase in reaction time is accompanied by an increase in the graft yield. The same holds true for the reaction temperature; the graft yield is much higher at 70 than at 50°C and follows the order 70°C > 60°C > 50°C. Increasing MMA concentration also causes considerable enhancement of the graft yield. The presence of 0.01M cupric sulfate in the polymerization system brings about an eightfold increase in the graft yield, whereas the presence of ferric sulfate at the same concentration causes a sixfold increase. The mode of initiation of grafting seems to be different in the presence of metallic ions than in their absence. A mechanism for the reactions involved in the both cases has been proposed.     

Chemical grafting of 2‐ethyl methacrylate phosphoric acid onto nylon 6 fabric

Graft copolymerization of 2‐ethyl methacrylate phosphoric acid (EMPA) onto nylon 6 fabric is carried out using the K₂S₂O₈/CuSO₄ system as reaction initiators. The most important factors affecting the graft yield are monomer concentration, reaction time and temperature. It was found that the graft yield increased with increasing EMPA concentration, grafting time, and temperature. The grafted nylon 6 fabric shows an increase in moisture regain to reach a maximum of 8.01% with increasing the graft yield to 35.6%. Also, the dyeability with the basic dye was significantly increased due to grafting with EMPA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1357–1361, 2000     

Vibration welding of nylon 6 to nylon 66

Vibration welding of dissimilar nylons is a promising technique for assembling complex components made of different polymers. The effects of pressure and meltdown on the tensile strength of nylon 6 (PA 6) to nylon 66 (PA 66) vibration welds were determined in this study using an experimental design and three weld geometries. Weld strengths were generally improved by increasing meltdown and decreasing weld pressure. The weld strength was also shown to vary with the position of the lower melting material for T‐welds. Using differential scanning calorimentry and fracture surface analyses, it is concluded that for all geometries, higher weld strengths can be achieved when both materials are melted. Polym. Eng. Sci. 44:760–771, 2004. © 2004 Society of Plastics Engineers.     

Free‐radical grafting of 4‐vinyl pyridine onto nylon 6 fiber

The chemistry of free‐radical graft copolymerization initiated with peroxomonosulfate (PMS)–thioglycolic acid (TGA) redox system has been investigated by using 4‐vinyl pyridine (4VP) as a model for nylon 6 fiber in aqueous solution under nitrogen atmosphere. Effects of concentration of 4VP, PMS, TGA, nylon 6, time, and temperature on R_h and graft parameters were studied. The FTIR spectrum of nylon 6‐g‐4VP was reported. Water retention capacity (WRC) of the grafted fiber was tested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3108–3113, 2002     

Studies on melt spinning of nylon 6. I. Cooling and deformation behavior and orientation of nylon 6 threadline

The melt spinning of nylon 6 filament yarns was studied by measuring the filament tensions at the takeup roll, the filament temperatures θ(x), filament diameters d(x), and birefringence Δn(x) as functions of distance x from the spinneret, and by observing how the molecular orientation was affected by these differences in cooling and thinning. Results were as follows: The thinning of the filament line, d(x), is affected little by the spinning temperature or by the degree of polymerization of the yarns taken up; it however depends heavily on the takeup speed V_Tu and the rate Q of production. Trouton viscosity β(T) as a temperature function derived from these experiments on nylon 6 is expressed consistently by the equation β ? 0.34 exp (3250/T), where T is absolute temperature. Nylon 6 filaments exhibit higher Trouton viscosity values than polyester or polypropylene filaments under the same spinning temperature. Filament temperature θ(x) versus distance x agreed well with theoretical values. The speed of molecular orientation was highest in the temperature range from 120°C to 40°C (the latter being the glass transition temperature of nylon 6). Furthermore, the larger the time rate of polymer deformation and the longer the residence time of polymer in the above temperature range, the higher was the orientation of the filament yarns taken up.     

锦纶66与锦纶6帘线的性能对比

对锦纶66与锦纶6帘线的性能进行对比。与锦纶6帘线相比，锦纶66帘线具有良好的基本耐热性能、尺寸稳定性及耐高温性能，在受热状态下的断裂强力保持率较高；用其生产轮胎时可提高硫化温度，缩短硫化时间，提高生产效率，而轮胎使用寿命长，安全性和耐久性较优。     

Polymorphic behavior of nylon 6/saponite and nylon 6/montmorillonite nanocomposites

X‐ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ε‐caprolactam and then exfoliaton of the layered saponite or montmorillonite by subsequent polymerization. Both X‐ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 and in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from melt and the content of saponite or montmorillonite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the γ crystalline form. The addition of clay increases the crystallization rate of the α crystalline form at lower saponite content and promotes the heterophase nucleation of γ crystalline form at higher saponite or montmorillonite content. The effect of thermal treatment on the crystalline structure of nylon 6/clay nanocomposites in the range between Tg and Tm is also discussed.     

Intrinsic birefringence of nylon 6

Different values are reported in the literature for the intrinsic birefringence of the crystalline (Δn) and the amorphous (Δn) phases in nylon 6. Mostly, these values have either been determined by extrapolation (and then it is assumed that Δn = Δn) or calculated theoretically. In this study, intrinsic birefringence values Δn and Δn for nylon 6 were determined using the Samuels two-phase model which correlates sonic modulus with structural parameters. Three series of fiber samples were used: (1) isotropic samples of different degrees of crystallinity for estimation of E and E moduli at two temperatures. The following modulus values were obtained: 1.62 × 10⁹ and 6.66 × 10⁹ N/m² for 28.5°C, and 1.81 × 10⁹ and 6.71 × 10⁹ N/m² for ?20°C; (2) anisotropic, amorphous fiber samples for estimation of Δn = 0.076 and E = 1.63 × 10⁹ N/m² at 28.5°C; (3) semicrystalline samples of various draw ratios for estimations of Δn = 0.089 and Δn = 0.078. All measurements were carried out with carefully dried samples to avoid erroneous results caused by moisture.     

Comparison of nanocomposites based on nylon 6 and nylon 66

Nylon 6 and nylon 6,6 organoclay nanocomposites were prepared by melt processing using a twin screw extruder. The effects of polyamide type and processing temperature on the mechanical properties and the morphology of the nanocomposites were examined. Mechanical properties, transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), percentage crystallinity and isothermal thermo-gravimetric analysis (TGA) data are reported. A particle analysis was performed to quantitatively characterize the morphology; these results are later employed in modeling the modulus of these materials using composite theory. No significant difference was observed in the mechanical properties and morphology of PA-6 nanocomposites processed at two different temperatures. PA-6 nanocomposites had superior mechanical properties than those made from PA-66. The tensile strength of PA-66 nanocomposites deviated from linearity at high levels of MMT. WAXD and TEM results show that the PA-6 nanocomposites are better exfoliated than the PA-66 nanocomposites, which exhibit a mixture of intercalated and exfoliated structures. Mechanical properties were consistent with the morphology. DSC reveals a higher percentage of crystallinity in the PA-66 samples. Isothermal TGA shows only a 5% difference in the degradation of the organic modifier on the organoclay processed at 240 °C versus 270 °C. Particle analysis shows a higher average particle length and thickness, and a lower average particle density and aspect ratio in nanocomposites based on PA-66 versus PA-6. The Halpin-Tsai and Mori-Tanaka composite theories predict satisfactorily the behavior of the PA-6 nanocomposites, while the PA-66 nanocomposites were predicted acceptably up to a certain volume fraction where the non-linear behavior takes effect. All the results indicate that there is a lower degree of exfoliation in the nanocomposites produced with a PA-66 matrix apparently stemming from the chemical differences between PA-6 and PA-66.     

Toughened nylon66/nylon6 ternary nanocomposites by elastomers

The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varying in OMMT content were made by mixing of PA6 and OMMT as a master‐batch and then blending it with PA66 and different elastomers in a twin screw extruder. In this sequence, the OMMT layers were well exfoliated in the nylon alloy matrix. The introduction of silicate layers with PA6 induced the appearance of the γ crystal phase in the nanocomposites, which is unstable and seldom appears in PA66 at room temperature and it further affected the morphology and dispersion of rubber phase resulting in much smaller rubber particles. The incorporation of POE‐g‐MA particles toughened the nanocomposites markedly, but the tensile modulus and strength were both reduced. Conversely, the use of OMMT increased the modulus but decreased the fracture toughness. The nanocomposites exhibited balanced stiffness and toughness. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Drawing and ultimate tensile properties of nylon 6/nylon 6 clay composite fibers

This study systematically investigated the drawing and ultimate tenacity properties of the Nylon 6 (NY6)/nylon 6 clay (NYC) composite fiber specimens prepared at varying NYC contents and drawing temperatures. The achievable draw ratio (D_ra) values of NY6_x(NYC)_y as‐spun fiber specimens initially increase in conjunction with NYC content, and then approach a maximum value, as their NYC contents and drawing temperature approach the 0.5 wt% and 120°C, respectively. The percentage crystallinity (X_c) values of NY6_x(NYC)_y as‐spun fiber specimens increased significantly, as their NYC contents increased from 0 to 2 wt%. As revealed by high power wide angle X‐ray diffraction analysis, α form NY6 crystals grew at the expense of γ form NY6 crystals originally present in NY6_x(NYC)_y as‐spun fiber specimens as their draw ratios increased. The ultimate modulus, tenacity, and orientation factor values of NY6_x(NYC)_y fiber specimens approach a maximum value, as their NYC contents and drawing temperatures approach the 0.5 wt% and 120°C optimum values, respectively. The thermal and melt shear viscosity experiments were performed on NY6_x(NYC)_y resins and/or fiber specimens to determine the optimum NYC content and possible deformation mechanisms accounting for the interesting drawing, orientation, and ultimate tenacity properties found above. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Interaction of nylon 6-clay surface and mechanical properties of nylon 6-clay hybrid

We synthesized nylon 6-clay hybrid materials using four types of clay minerals, montmorillonite, saponite, hectrite, and synthetic mica. The mechanical properties of their injection molded specimens were measured according to ASTM. Nylon 6-clay hybrid using montmorillonite was superior to the other hybrids in mechanical properties. This might result from the difference in the interaction between nylon molecules and silicates in the hybrids. To clarify this hypothesis, we synthesized intercalated compounds of the clay minerals with glycine as the model of the hybrids, and analyzed the interaction using ¹⁵N cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. The ¹⁵N-NMR result reveals that the positive charge density on the nitrogen of the intercalated compound based on montmorillonite was largest in all the intercalated compounds. It was suggested that montmorillonite interacted strongly with nylon 6 by ionic interaction. This ionic interaction was one of the reasons why these hybrid materials had superior mechanical properties. © 1995 John Wiley & Sons, Inc.     

Biodegradation of nylon4 and its blend with nylon6

The nylon4 portion in the blend films composed of nylon4 and nylon6 was degraded and completely disappeared within 4 months in two kinds of composted soils gathered from different university farms as well as pure nylon4 film reported previously, while the nylon6 portion remained even after the burial test for 15 months. Nylon4 powder was also degraded to carbon dioxide in the degradation test in an activated sludge obtained from a sewage disposal institution in Kogakuin University. Three species of microoganisms (i.e., ascomytous fungi) were isolated through the inoculation from the nylon4 film partially degraded in the soil on a medium containing nylon4 powder as a carbon source. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2307–2311, 2002