Powdered poly(ethylene terephthalate)

The influence of the conditions of preparation on the properties of powdered poly(ethylene terephthalate) was followed from the point of view of its specific surface. The powdered poly(ethylene terephthalate) prepared by reprecipitation from the melt of 6-caprolactam has a porous and structured surface, and consequently, also a large specific surface in comparison with the powedered poly(ethylene terephthalate) prepared by mechanical milling. The specific surface value is influenced by the cooling rate of the initial homogeneous melt of poly(ethylene terephthalate)-6-caprolactam, by the concentration of poly(ethylene terephthalate) in this melt and by its molecular weight, by the water temperature at the extraction of 6-caprolactam from the tough mixed melt, by the drying temperature of the powdered poly(ethylene terephthalate), and by the content of residual 6-caprolactam in the powdered product. In the examined area, the specific surface value of the powdered poly(ethylene terephthalate) prepared by reprecipitation from the melt of 6-caprolactam ranged from 10 to 110 m²·g^?1.     

Modification of polyamide 6 with hycar ATBN

The preparation of block copolymers from 6-caprolactam and a liquid amine terminated butadiene-acrylonitrile copolymer Hycar ATBN 1300X21 having higher notched impact strength than ordinary poly(6-caprolactam) was studied. In the polymerization of 6-caprolactam initiated by an adduct of phosphoric acid with 6-caprolactam the influence of initiator concentration (0– 50 mol-%) and Hycar ATBN 1300X21 concentration (0–5 wt.-%) in the polymerization charge, of polymerization time (4 – 72 h) and of temperature (200–280°C) on the 6-caprolactam conversion and on the properties of the copolymers formed were followed. Notched impact strength of the block copolymers prepared under optimized conditions was as high as 13.5 kJ·m^?2.     

Controlled synthesis of crosslinked polyamide 6 using a bis-monomer derived from cyclized lysine

The controlled synthesis of polyamide 6 chemical networks by anionic ring-opening copolymerization of ε-caprolactam (CL) with synthesized bis-ε-caprolactam derived from α-amino-ε-caprolactam, i.e. N-functionalized α-amino-ε-caprolactam bis-monomers, using sodium ε-caprolactamate as an initiator and hexamethylene-1,6-dicarbamoylcaprolactam as di-functional fast activator was examined in bulk at 140 °C. An urea-based bis-monomer and CL were first shown to copolymerize with a decreasing polymerization rate due to side reactions. On the contrary, quantitative copolymerization of CL with various amounts of bis-N(2-oxo-3-azepanyl)-1,6-tetramethylenediamide, an amide-based bis-monomer, leads to fast kinetics similar to the homopolymerization of CL. Crosslinked PA6 with network exhibiting elastic or viscoelastic behaviors, depending on the amount of crosslinker, were observed and characterized by swelling in hexafluoroisopropanol, dynamic mechanical analysis and rheology measurements. Crystallinity and swelling were shown to decrease with the increasing content of the crosslinking agent.     

Vapour phase beckmann rearrangement of cyclohexanone oxime over MEL type zeolites

The vapour phase Beckmann rearrangement of cyclohexanone oxime to -caprolactam is reported over different MEL zeolites viz., silicalite-2, titanium silicate-2 (TS-2), ZSM-11 and alumino-titanium-silicate (Al-TS-2) and fumed silica. TS-2 exhibits 100% conversions with lactam selectivities close to 90%. The titanium containing analogs are also more resistant to deactivation than the parent zeolites. The conversion of cyclohexanone oxime and selectivity for -caprolactam increase with temperature. The selectivity for -caprolactam increases with the duration of run at all the temperatures.     

On the polymerization of 1-substituted 2-azabutadienes

Summary Three 2-aza-1,3-butadienes carrying substituants at the 1-position have been synthesized by flash vacuum pyrolysis of precursor cyclopentadiene cycloadducts. 1-Phenyl-2-aza-1,3-butadiene led to low molecular weight polymer when exposed to anionic and radical initiators. 1-(2,4,6-Trimethylphenyl)-2-aza-1,3-butadiene and 1-t-butyl-2-aza-1,3-butadiene were synthesized similarly, but they did not polymerize.     

Polymerization of lactams, 49. Hydrolytic polymerization of 6-caprolactam in the presence of its cyclic dimer

The hydrolytic polymerization of 6-caprolactam has been studied at 260–280°C in the presence of 5, 10 and 15 mol-% of cyclic dimer of 6-caprolactam and 2 mol-% of 6-aminocaproic acid as an initiator. The content of monomer and cyclic oligomers, including pentamer, was determined by HPLC. It has been proved that the rate of polymerization decreases with increasing content of cyclic dimer in the initial mixture and the time required to attain the equilibrium content of polymer increases as much as by an order of magnitude. The cyclic dimer is incorporated into the polymer above all in the final reaction stage.     

Synthesis by reactive processing of block copolymers of Nylon 6 / Poly (ether-esteramide)

Summary Block copolymers of nylon 6 with 10, 15 and 20% of poly (ether-esteramide) as elastomeric phase were synthesized by reactive processing. These materials are obtained by the anionic polymerization of -caprolactam in the presence of a linear prepolymer of poly (ether-esteramide) with a Grignard reagent. Differential Scanning Calorimetry (DSC), torque rheometry and formic acid test were used to characterize the obtained copolymers. The results showed that block copolymers of Nylon 6 were formed. The melting temperature and the crystallinity of the copolymer decreased when the elastomer phase content increased. Two Tgs appeared; the blocks of the copolymers were not miscible. We calculate the size of nylon 6 blocks for each composition. The physical-mechanical behavior was also studied. More flexible materials were obtained when the soft phase content in the copolymer was increased. The results of this work provide an important information for the synthesis of this kind of materials by reactive extrusion.     

The effect of hydrogenation in the presence of raney nickel on the content of microimpurities of unsaturated compounds in ε-caprolactam

Conclusions 1. It has been confirmed that the qualitative indices of -caprolactam are improved after hydrogenation in the presence of Raney nickel.2. It has been shown that hydrogenation reduces the content of microimpurities of unsaturated compounds in -caprolactam.State Institute for the Nitrogen Industry (GIAP). Translated from Khimicheskie Volokna, No. 5, pp. 5–6, September–October, 1969.     

Flammability and thermal behavior of phosphorus-containing polyamide-6

An investigation is reported on the flammability and thermal behavior of polyamide-6, obtained by anionic polymerization of ?-caprolactam, carried out in bulk, in the presence of the following N-substituted phosphorus-containing lactam derivatives: diethyl-(N-caprolactam)-phosphonite (PL₁), diethyl-(N-caprolactam)-phosphonate (PL₂), and 2,5-dichlorophenyl-bis(N-caprolactam)-phosphinate (PL₃). Phosphorus-containing lactam derivatives PL,₁ and PL₃ are used as activators of the anionic polymerization of ?-caprolactam, and PL₂, as a modifying additive. The phosphorus-containing polyamide-6 possesses improved flame retardancy, as well as improved thermo- and thermooxidative resistance. Destruction kinetics were studied in nitrogen and air atmospheres, and the activation energy for thermal and thermooxidative destruction have been determined. The effect of PL₁ PL₂, and PL₃ on the melting temperature (T_m) and glass-transition temperature (T_g) of polyamide-6 was established. © 1993 John Wiley & Sons, Inc.     

Improving the pore structure and adsorption properties of industrial active carbons

The paper describes the possibility of improving the pore structure and adsorption properties of industrial active carbons (AC) by means of their modification with ɛ-caprolactam (CL). Application of ɛ-caprolactam (a product of large-scale organic synthesis) as a modifying substance allows the targeted regulation of the specific surface area and volume of AC mesopores, while the conditions of modification change the chemical composition of the surface of carbon adsorbents and, as a result, their adsorption properties. The process of modification includes three stages. The first is the adsorption of CL from aqueous solution and heating at 300°C in the presence of atmospheric oxygen. The second is carbonization in an argon flow at 900°C, and the third is the vapor-gas activation of the resultant adsorbents at 900°C. Each stage is followed by determining the parameters of the pore structure by N₂ adsorption and the adsorption parameters with respect to benzene, iodine, aqueous solutions of ɛ-caprolactam, and copper sulfate (CuSO₄). When modifying the carbonized samples with an initial ɛ-caprolactam content of 2%, we observe the growth of mesopores over 100% of volume, relative to AG-OV-1 original industrial activated carbon. Depending on the stage of modification, an increase in adsorption is observed, relative to the AG-OV-1 original carbon: benzene adsorption rises by 50%, the adsorption of iodine from aqueous solution rises by 20%, the adsorption of ɛ-caprolactam from aqueous solution grows by more than 30%, and the adsorption of copper(II) ions rises by more than 70%. The procedure for the production of the described modified adsorbent has no rivals abroad; it is protected by a patent and can be used in industry. It is possible to use inexpensive industrial carbons as the original material. The procedure allows the production of carbon adsorbents with predetermined structural and adsorption properties.     

Six- and seven-membered 1-oxa-4-aza-2-silacyclanes as possible correctors of adaptational mechanisms

The biological activity of eight 1-oxa-4-aza-2-silacyclanes with the OSiCH(2)N fragment including 6-membered 2-sila-5-morpholinones (1-3) and 4-acyl-2-silamorpholines (4-6)and previously unknown 7-membered derivatives of salicylic acid (7, 8) was studied. Compounds 1 and 3-6 show the certain antihypoxic action. Compounds 2 (40 mg/kg), 4 (20 mg/kg), 6 (40 mg/kg), 7 (20 mg/kg) and 8 (40 mg/kg) reduce the physical serviceability of intact animals. Compound 1 (20 mg/kg) influences the physical serviceability in a moderate-positive way on the background of chlorophos-poisoning. Compounds 5-8 displayed protective properties against chlorophos-poisoning at the LD(50) dose and compounds 2, 4, 5, 7 at the LD(100) dose. Influence of compounds 1 and 2 on the emotional-research behavior of mice was studied.     

Depolymerization of poly-ϵ-caprolactam catalyzed by sodium hydroxide

Depolymerization of poly-?-caprolactam chips was carried out at low pressures (3–15 mm Hg) and elevated temperature (225°–270°C) in the presence of sodium hydroxide as catalyst. The effects of variation of amount of sodium hydroxide, time, temperature, and pressure on ?-caprolactam yield were studied. With increase in alkali content the yield increases linearly, reaching a maximum at 1% (w/w) NaOH and then falls. The yield increases with time of depolymerization up to 4 1/2 hr and then becomes practically constant. Between 240° and 250°C there is a sudden increase in depolymerization rate. Further increase in temperature has very little effect. Decrease in pressure from 15 to 3 mm Hg shows a nine-fold increase in yield. The optimum conditions for the depolymerization were a temperature of 250°C, a pressure of 3 mm Hg, and a time 4 1/2 hr in the presence of 1% NaOH (w/w), which gave a 90.5% yield of ?-caprolactam. Physical properties, IR spectra, and behavior toward polymerization of the recovered monomer indicated the presence of some impurities.     

Cycloadditions of 1-Aza-2-azoniaallene Salts derived from coumarin and camphor

The 1-aza-2-azoniaallene salt 8 prepared from 3-acetyl coumarin via the hydrazone 6 and the (chloroalkyl)azo derivative 7 reacts with nitriles to afford the 3-(3-chromenyl)-1,2,4-triazolium salts 11a–d . With diisopropylcarbodiimide the triazolium salt 13 and with norborene a tricyclic pyrazolium salt 14 are obtained. Concurrent to these cycloadditions the by-product 12 is formed by intramolecular cyclization of the cumulene 8 . Similarly, the intramolecular cyclization product 18 is isolated as the sole product when the 1-aza-2-azoniaallene salt 17a (prepared from the ethyl carbazone of camphor by chlorination and treatment of the product 16a with SbCl₅) was treated with nitriles, carbodiimides or alkenes. In contrast, 1,2,4-triazolium salts 20a–c , 23c , respectively pyrazolium salts 20d–f , and 1,3,4-thiadiazolium salts 23a,b are obtained by reaction of the 1-aza-2-azoniaallene salt 17b with nitriles, respectively alkenes, alkynes, diisopropylcarbodiimide, and isothiocyanates. The constitutions of two of these products ( 20e, 23a ) were secured by X-ray structural analysis.     

Preparation and characterization of a polyphenylene ether and Nylon-6 block copolymer

Summary A block copolymer of PPO^®(1) and Nylon-6 was prepared through modification of the hydroxyl end group of the polyphenylene ether (PPE) with cyanuric chloride or 4,4-difluorobenzophenone and subsequent anionic polymerization of -caprolactam using the modified PPE as the promoter. The pure copolymer was isolated by selective solvent extraction, using chloroform to remove PPE homopolymer and unreacted -caprolactam, and formic acid to remove Nylon-6 homopolymer. The copolymer has two melting points indicative of the Nylon and PPE segments. Its composition has been determined by carbon-13 NMR and elemental analysis.     

Determination of the residual monomer concentration of ε-caprolactam in polyamide-6 using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy gas analysis

For the anionic polymerization of ε-caprolactam to polyamide-6 the residual monomer concentration in the final polymer is an important characteristic. To determine this residual ε-caprolactam monomer concentration, a fast and fail-safe method was developed, which couples thermogravimetric analysis (TGA) with Fourier transform infrared spectroscopy (FTIR) gas analysis. FTIR allows an identification of the types of gasses released during heat treatment. Calibration of the infrared absorbance of ε-caprolactam and the corresponding mass loss in TGA allows a quantitative evaluation of the ε-caprolactam monomer release. Low-heating rates and powdery samples guarantee high-precision measurements.     

Morphology and Thermal Behavior of MCPA6/SAN Blends Prepared by Anionic Ring-Opening Polymerization of ε-caprolactam

Summary In this article, a series of blends of monomer casting polyamide 6 and styrene-co-acrylonitrile (MCPA6/SAN) were prepared by in situ anionic ring-opening polymerization of ε-caprolactam (CL). Their morphology and thermal behaviors were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD), respectively. The SAN phase had much finer domain in MCPA6/SAN than that in the polyamide6/SAN (PA6/SAN) blends prepared by melt blending of PA6 and SAN. All the melting and crystallization parameters of MCPA6/SAN blends decreased gradually with the increase of SAN content, while the melting temperature was almost unchanged. These results were due to the hydrolysis reaction of SAN occurred during the anionic polymerization of ε-caprolactam (CL). In addition, WAXD results showed that only α crystal forms existed in the MCPA6/SAN blends.     

Die polymerisation der lactame XIV. Einfluß des hexamethylguanidiniumchlorides auf die aktivierte anionische polymerisation der lactame

It was proved that hexamethylguanidiniumchloride (HMGC) exhibited a pronounced accelerating effect on the activated anionic polymerization of 2-pyrrolidone (40°C) and 6-caprolactam initiated by alkali metal salts of the corresponding lactams. The accelerating effect of HMGC was not specific for a certain type of alkali metal salt of lactams as initiator, it was proved that the effect is operative for polymerization of 6-caprolactam when using sodium or cesium salt of 6-caprolactam. It was proved that HMGC does not form growing centers under reaction conditions studied. The initial polymerization rate in the homogeneous phase is a linear function of square root of HMGC concentration at constant concentrations of initiator and activator. On the basis of this finding it was possible to suggest a plausible mechanism of HMGC influence on the polymerization process.     

Polymerization of lactams, 87. Block copolymers of poly(ϵ-caprolactam) and polybutadiene prepared by anionic polymerization. Part I: Preparation and properties

The effect of the polymerization conditions on the properties of poly(?-caprolactam)-polybutadiene block copolymers prepared by polymerization casting through anionic polymerization of ?-caprolactam initiated with potassium salt of ?-caprolactam in the presence of α,ω-dihydroxy-polybutadiene and isocyanates or their blocked derivatives as functionalizing agents was investigated. The influence of the content of telechelic polybutadiene, its molecular weight, type of diisocyanate, and polymerization temperature on the fundamental mechanical properties of the prepared materials and on the polymerization rate was evaluated.     

Mapping Resistance to Argentinean Fusarium (Graminearum) Head Blight Isolates in Wheat

Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum (Schwabe), is a destructive disease worldwide, reducing wheat yield and quality. To accelerate the improvement of scab tolerance in wheat, we assessed the International Triticeae Mapping Initiative mapping population (ITMI/MP) for Type I and II resistance against a wide population of Argentinean isolates of F. graminearum. We discovered a total of 27 additive QTLs on ten different (2A, 2D, 3B, 3D, 4B, 4D, 5A, 5B, 5D and 6D) wheat chromosomes for Type I and Type II resistances explaining a maximum of 15.99% variation. Another four and two QTLs for thousand kernel weight in control and for Type II resistance, respectively, involved five different chromosomes (1B, 2D, 6A, 6D and 7D). Furthermore, three, three and five QTLs for kernel weight per spike in control, for Type I resistance and for Type II resistance, correspondingly, involved ten chromosomes (2A, 2D, 3B, 4A, 5A, 5B, 6B, 7A, 7B, 7D). We were also able to detect five and two epistasis pairs of QTLs for Type I and Type II resistance, respectively, in addition to additive QTLs that evidenced that FHB resistance in wheat is controlled by a complex network of additive and epistasis QTLs.     

Polymerization of lactams, 48. Autocopolymerization of 6-caprolactam with 12-dodecanelactam

The homo- and copolymerization of 6-caprolactam and 12-dodecanelactam was studied in the absence of an intentionally added initator. Both the polymerization and the copolymerization of an equimolar mixture of the monomers exhibited an induction period, the length of which was reduced with increasing temperature. Above 260°C, the polymers and copolymers of 6-caprolactam were not stable and their intrinsic viscosities as well as the polymer content decreased during long polymerization periods. On the other hand, insoluble products were formed in the homopolymerization of 12-dodecanelactam at temperatures of 300°C and higher. As much as 35 wt.-% of oligomers, predominantly cyclic ones, were formed in the initial stage of polymerization and copolymerization.