Monomer Of Nylon Research Articles

In situ polymerization approach to multiwalled carbon nanotubes-reinforced nylon 1010 composites: Mechanical properties and crystallization behavior

A series of polyamide 1010 (PA1010 or nylon 1010) and multiwalled carbon nanotubes (MWNTs) composites were prepared by in situ polymerization of carboxylic acid-functionalized MWNTs (MWNT–COOH) and nylon monomer salts. Mechanical tensile tests and dynamic mechanical analysis (DMA) show that the Young modulus increases as the content of the nanotubes increases. Compared with pure PA1010, the Young's modulus and the storage modulus of MWNTs/PA1010 in situ composites are significantly improved by ca. 87.3% and 197% (at 0 °C), respectively, when the content of MWNTs is 30.0 wt%. The elongation at break of MWNTs/PA1010 composites decreases with increasing proportion of MWNTs. For the composites containing 1.0 wt% MWNTs, the Young modulus increases by ca. 27.4%, while the elongation at break only decreases by ca. 5.4% as compared with pure PA1010 prepared under the same experimental conditions. Compared with mechanical blending of MWNTs with pure PA1010, the in situ-prepared composites exhibit a much higher Young's modulus, indicating that the in situ polycondensation method improves mechanical strength of nanocomposites. Scanning electron microscopy (SEM) imaging showed that MWNTs on the fractured surfaces of the composites are uniformly dispersed and exhibit strong interfacial adhesion with the polymer matrix. Moreover, unique crystallization and melting behaviors for MWNTs/PA1010 in situ composites are observed using a combination of differential scanning calorimetry (DSC) and X-ray diffraction methods. It was shown that only the α-form crystals are observed in our MWNTs/PA1010 in situ composites. This result is quite different from PA1010/montmorillonite and PA6-clay composites, where both of α- and γ-form crystals were found.

The discovery of polymer‐clay hybrids

AbstractThe first successful example of a polymer‐clay hybrid was nylon‐clay hybrid (NCH), which is a nano‐meter‐sized composite of nylon‐6 and 1‐nm‐thick exfoliated aluminosilicate layers of the clay mineral. NCH was found and developed at Toyota Central Research and Development Laboratories over 17 years ago. The NCH containing a few weight percentages of clay exhibits superior properties such as high modulus, high strength, and good gas‐barrier properties. The key for the discovery of NCH was the polymerization of a nylon monomer in the interlayer space of the clay. This highlight presents the development of NCH from its discovery to its commercialization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 819–824, 2004

Development and validation of analytical methods for monomeric and oligomeric migrants from nylon 12 packaging materials

Analytical methods for the determination of laurolactam—the monomer of nylon 12—as well as the cyclic dimer and trimer were established. High performance liquid chromatography using ultraviolet (HPLC-UV) and mass spectrometric detection (HPLC-MS) were both found suitable to identify and quantify monomer, cyclic dimer and trimer well below the specific migration limit (SML) of laurolactam, being 5 mg/kg of food (simulant). Gas chromatography with flame ionisation detection (GC-FID) showed to be an appropriate method for the detection of only laurolactam in aqueous and fatty food simulants. Food simulants could be analysed directly by all three methods, or after a change of solvents. For olive oil, a method for sample clean-up by size-exclusion chromatography (SEC) was established.

The γ-Radiolysis of Nylons: Molecular Rearrangement and Gas Production

The γ-radiolysis of nylons 12, 11, 6/12, 6/9, 6/6, and 6 were investigated. The IR spectra of film samples before and after the γ-irradiation show the formation of amines, aldehydes, and ketones, and suggest that the cleavage of amide group is one of the major processes of radiolysis. The yields of gaseous products and their evolution from the bulk were measured with a quadrupole mass spectrometer. Four gases were determined as the major radiolytic products and their yields were found to be in the order H2 > CO > CO2 > CH4 for all the nylons. The relationship between the gas yields and the chemical composition of the monomer unit shows that the H2 yield increases with the relative number of H atoms. The results suggest a random distribution of energy leading to H2 production. It was found that the yields of CO and CO2 decrease with an increase in the relative number of amide groups on the nylon monomer unit. Since these later products must be derived from the amide group, chain scission and fragmentation ...

SEPARATION OF IONIC SPECIES UNDER SUPERCRITICAL WATER CONDITIONS

ABSTRACT The unique characteristics of supercritical water (SCW) offer potentially attractive processing options that can be explored for reaction and separation purposes. While supercritical water oxidation (SCWO) can achieve high organic conversion efficiencies, low and relative solubilities of inorganic species in SCW may be further utilized for in situ separation of potential by-products from the SCWO process effluent. This paper describes a novel method for separating ionic species under SCW conditions. The concept is based on relative solubilities of different ionic species in SCW. Laboratory-scale demonstration tests were conducted with a Nylon monomer manufacturing process wastewater containing sodium hydroxide, sodium borate, carboxylic acids, and water. The process achieved (1) effective destruction (>99%) of organic components in the wastewater; (2) selective precipitation of sodium (>99.5%) as carbonates produced from oxidation of the organic components; and (3) efficient recovery of boron (>9...

SEPARATION OF IONIC SPECIES UNDER SUPERCRITICAL WATER CONDITIONS

ABSTRACT The unique characteristics of supercritical water (SCW) offer potentially attractive processing options that can be explored for reaction and separation purposes. While supercritical water oxidation (SCWO) can achieve high organic conversion efficiencies, low and relative solubilities of inorganic species in SCW may be further utilized for in situ separation of potential by-products from the SCWO process effluent. This paper describes a novel method for separating ionic species under SCW conditions. The concept is based on relative solubilities of different ionic species in SCW. Laboratory-scale demonstration tests were conducted with a Nylon monomer manufacturing process wastewater containing sodium hydroxide, sodium borate, carboxylic acids, and water. The process achieved (1) effective destruction (>99%) of organic components in the wastewater; (2) selective precipitation of sodium (>99.5%) as carbonates produced from oxidation of the organic components; and (3) efficient recovery of boron (>90%) as boric acid in the reactor effluent. The sodium removal efficiency is governed by the solubilities of sodium carbonates in SCW and, therefore, can be directly improved by increasing process temperature. As a result of the temperature increase, both organic destruction and boron recovery efficiencies may be enhanced. This method of selective separation of ionic species in SCW has potential for a wide range of processing applications.

Analysis of the fluorescent and phosphorescent species in nylon-6,6 in relation to aldol condensation products of cyclopentanone

Fluorescence analysis of nylon-6,6 polymer indicates the presence of a number of chromophoric species. One of the main species has excitation maximum at 290 nm with a corresponding emission maximum at 326 nm and is extractable from the polymer by 2-propanol; another has an excitation maximum at 340 nm and corresponding emission maximum at 390 and 420 nm and is virtually non-extractable. The latter, as established by other workers, is associated with the presence of α-ketoimide structures formed by thermal oxidation of the molecular backbone of the polymer. The former, after isolation from cyclic nylon monomer using silica TLC, is shown to possess two excitation maxima at 228 and 284 nm and regenerates on exposure of the extracted polymer to pure oxygen and is attributed to a slow ambient oxidation process and not absorption of naphthalene from the “urban atmosphere”. This is confirmed by hydroperoxide analysis of the polymer before and after regeneration. Despite large scale extraction procedures (∼ 2 kg polymer), only trace amounts of the fluorescent species could be isolated after TLC analysis. However, using GC-mass spectrometry interfaced to a computer library (courtesy of ICI Organics Division plc, Manchester) the presence of cyclic enone dimer and dienone trimer of cyclopentanone amongst other products was confirmed in the 2-propanol extract. The phosphorescence emission from the polymer is shown to correspond to a complex mixture of these products and is little affected by 2-propanol extraction. Both the fluorescent and phosphorescent species in nylon-6,6 polymer are shown to originate from aldol condensation products of cyclopentanone. This is confirmed through a detailed luminescence/GC-mass spectrometry analysis of the products of the latter process. Feasible mechanisms, based on earlier nylon oxidation studies, are discussed.

Lesions of the urinary tract produced in Fischer 344 rats and B6C3F 1 mice after chronic administration of 11-aminoundecanoic acid

11-Aminoundecanoic acid, the monomer of nylon 11, was toxic to the urinary tract of both male and female B6C3F 1 mice and Fischer 344 rats, when administered in the diet at 7500 or 15 000 ppm for 103–104 weeks. Dose-related effects included a decrease in mean body weight gain and in survival for male rats and for mice of each sex; increased incidence of hyperplasia of the transitional epithelium of the kidney in rats of each sex; increased incidence of calcification of the kidney in the female rats; increased incidence of hyperplasia of the urinary bladder in male rats; and mineralization of the kidney in mice of each sex. Transitional cell carcinomas of the urinary bladder of the male rat occurred with increased frequency in the high-dose group (control, 0/48; low-dose, 0/48; high-dose, 7/49). Additional evidence for carcinogenicity in the male rat was seen in the liver, where an increased frequency of neoplastic nodules was found in the treated animals (controls, 1/50; low-dose, 9/50; high-dose, 8/50). Therefore, under the conditions of these studies, 11-aminoundecanoic acid was carcinogenic for male Fischer 344 rats, inducing transitional cell carcinomas in the urinary bladder and neoplastic nodules in the liver. The test chemical was not demonstrated to be carcinogenic for female Fischer 344 rats or for B6C3F 1 mice of either sex.

Perturbations of Granulocyte Counts Induced by Procedural, Chemical and Physiological Events Occurring during Filtration Leukapheresis in Rats

During filtration leukapheresis a factor(s) is produced, released or extracted into rat blood which causes a transient granulocytosis in pheresed animals and in recipients of homologous plasma from these animals. To identify which factors contribute to this granulocytosis, the procedural steps involved in filtration leukapheresis as well as a number of chemical agents which are potentially extracted from of produced by the procedure, were tested for their ability to stimulate granulocytosis. Procedural steps tested included the depth of anesthesia, effect of the anticoagulant and possible interactions of blood cells with the plastic tubing in the system (sham-pheresis). Chemical agents tested included common mediators of inflammation and proteinases released by polymorphonuclear leukocytes (PMNs), extracts of nylon fibers and Tygon tubing, nylon monomers and solvents used in the manufacture of nylon, oxidized and decomplemented plasma and lysates of PMNs or microorganisms. Our findings demonstrate that several of these agents contribute to the granulocytosis seen during filtration leukapheresis of rats.

Perturbations of granulocyte counts induced by procedural, chemical and physiological events occurring during filtration leukapheresis in rats.

During filtration leukapheresis a factor(s) is produced, released or extracted into rat blood which causes a transient granulocytosis in pheresed animals and in recipients of homologous plasma from these animals. To identify which factors contribute to this granulocytosis, the procedural steps involved in filtration leukapheresis as well as a number of chemical agents which are potentially extracted from of produced by the procedure, were tested for their ability to stimulate granulocytosis. Procedural steps tested included the depth of anesthesia, effect of the anticoagulant and possible interactions of blood cells with the plastic tubing in the system (sham-pheresis). Chemical agents tested included common mediators of inflammation and proteinases released by polymorphonuclear leukocytes (PMNs), extracts of nylon fibers and Tygon tubing, nylon monomers and solvents used in the manufacture of nylon, oxidized and decomplemented plasma and lysates of PMNs or microorganisms. Our findings demonstrate that several of these agents contribute to the granulocytosis seen during filtration leukapheresis of rats.

Effects of corona treatment on composite formation. Adhesion between incompatible polymers

AbstractPolypropylene–nylon 6 10 composites were prepared by the in situ polymerization of the nylon monomers on polypropylene films. The adhesion between the nylon and the polypropylene was markedly improved by a brief corona discharge treatment of the films in nitrogen prior to coating. This improvement was demonstrated by an increase in the peel strength of the nylon coating and a decrease in brittleness of photo‐oxidized compesites when corona treatment was used. Adhesive bonding between the nylon and substrate was sufficiently strong to cause cohesive failure in the corona‐treated polypropylene. Only interfacial failure was observed at untreated surfaces. These effects were demonstrated by electron microscopy of the surfaces produced in peel tests. The effects of corona treatment on adhesive bonding characteristics of surfaces are discussed in terms of the chemical and physical changes observed in treated surfaces.

Gel permeation chromatography of the cyclic monomers and oliglmers in nylon 6 and nylon 66

The cyclic monomers and oligomers in nylon 6 and nylon 66 were separated and determined by gel pearmeation chromatography. The gels used in the experiment were Sephadex G-15 and Bio-Gel P-4. The ethanol extracts of nylon 6 and nylon 66 were dissolved in 0.1 N hydrochloric acid which was used as an eluant. The effluent was introduced into a flow cell and the absorbance at 210 mμ was measured continously by means of a spectrophotometer. The method is applicable to 1–5 mg samples or less and the time needed for chromatography is less than 6 h. The presence of linear oligomers does not affect the determination of the cyclic oligomers. Linear relationships between log M and several elution values, vis. V e , V e / V t , V e / V o, K d , and V e /( V o + V i ), have been confirmed for the cyclic monomer and oligomers of nylon 6. Deviation from linearity of the elution values of the cyclic dimer of nylon 66 implies that the dimension of the dimer is contracted in a solution compared with others.

Infrared studies of chain folding in polymers. VI. Polyhexamethylene adipamide and its cyclic oligomers

Abstract The 1224 and 1323 cm−1 infrared bands in nylon 66 have previously been assigned to a unique conformation in a tightly folded chain with adjacent reentry. The unique conformation in the fold giving rise to these bands is a nitrogen-methylene bond that is between cis and trans. Models of the cyclic monomer and dimer of Nylon 66 indicate that this type of nitrogen-methylene bond exists in these compounds also. Since these cyclic oligomers must exhibit “adjacent reentry,” the fact that the 1224 and 1323cm−1 bands appear with greatly enhanced intensity in the infrared spectra of these compounds strongly supports the original assignment of these bands. It should be noted that in the infrared spectra of the linear oligomers these bands are absent.

Interpretation of Infrared Spectra of Nylons in the Straight Chain Conformation

AbstractInfrared spectra of nylons in the straight‐chain conformation were interpreted on the basis of frequency–phase curves of the polymethylene chain and of the theory of interaction of a periodic chain with endgroups. In CH2 rocking‐twisting and twisting‐rocking frequencies, no appreciable interaction of neighboring nylon monomer units takes place; in CH2 wagging frequencies this interaction is fairly strong. The interpretation was confirmed by a normal coordinate calculation of out‐of‐plane frequencies.