Properties of alpha-methylstyrene–methacrylonitrile copolymer

Physical and mechanical properties of alpha-methylstyrene–methacrylonitrile copolymer have been determined. The effects of copolymer composition and inherent viscosity (molecular weight) on deflection temperature under load, Izod impact strength, tensile, and flexural properties are reported. The azeotropic copolymer of 57 mole-% methacrylonitrile possessed the best overall properties with a DTUL of 129°C and an Izod impact strength of 0.3 ft-lb/in. notch. The impact strength of the copolymer was improved by graft copolymerization upon a butadiene–methacrylonitrile copolymer. The impact-modified copolymer possessed an Izod impact strength of 6 ft-lb/in. notch and a DTUL of 115°C.     

Graft copolymerization of nitrile monomers onto bleached jute fiber using potassium persulfate system and their textile characteristics

Graft copolymerization of nitrile monomers, such as acrylonitrile and methacrylonitrile, onto bleached jute fiber was carried out by using K₂S₂O₈/FeSO₄ redox system in nitrogen atmosphere and their effect on the textile characteristics was also investigated. Percent graft yield increased with the increase of concentrations of monomer, initiator, and catalyst, reaction time, and reaction temperature up to a certain value, and, thereafter, it decreased. The effect of percent grafting efficiency was similar to that of percent graft yield, except for the monomer concentration. The increase of percent graft yield was dependent on the availability of jute‐macroradicals as well as monomer radicals. Sometimes the predominancy of homopolymerization over grafting and the premature termination of growing grafted chains occurred because of the higher monomer radicals and excess primary radicals, SO₄^?? and ^?OH, from K₂S₂O₈ initiator. The percent graft yield of acrylonitrile and methacrylonitrile was 20.5 and 29.1%, respectively. Higher graft yield for methacrylonitrile might be due to the methyl group present in it. Infrared spectra at 2229–2235 cm^?1 of acrylonitrile‐ and methacrylonitrile‐grafted jute strongly supported the graft formation. Grafting of jute fiber improved the thermal stability, protected from photooxidative degradation, and decreased swellability as well as dyeability, etc. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3622–3629, 2004     

An investigation of microstructure of styrene-methacrylonitrile copolymers by FT-IR spectroscopy

Summary The microstructure of styrene-methacrylonitrile copolymers has been investigated by FT-IR spectroscopy. The CN bond stretching frequency was shifted to a higher value with an increase in the methacrylonitrile (MAN) content in the copolymers. There was no linear relationship between the CN frequency and the diad fraction of MAN-MAN linkages in the copolymer chain, as reported previously for styrene-acrylonitrile copolymers. Different methods for the copolymer sample preparation can cause differences in the shifts in the CN frequency. This suggests that the polymer morphology plays an important role. A study of blends of poly(methacrylonitrile) (PMAN) with polystyrene has shown that the CN frequency is shifted to a higher value with an increase of the PMAN composition of the blends.     

Thermally stimulated currents in methacrylonitrile-styrene copolymer films

Summary Measurements are reported on thermally stimulated discharge current in methacrylonitrile — styrene copolymer films. The values of activation energy and relaxation times were calculated.     

Partial oxidation and ammoxidation of isobutane over Bi-Mo-based composite oxide with Nb2O5

Conversion of isobutane to methacrylonitrile via ammoxidation was studied using mixed catalysts composed of Bi---Mo-based composite oxides and various type of Nb₂O₂. The activity for ammoxidation of isobutane on Nb₂O₅ is fairly poor, and that the products were methacrolein without formation of methacylonitriIe. The activity of Bi---Mo-based composite oxides for the ammoxidation of isobutane was also fairly low and that the selectivity to methacylonitrile and methacrolein was 60–80%. The mixed catalyst composed of Bi---Mo-based composite oxides and amorphous Nb₂O₅ and that supported by γ-Al₂O₃ and SiO₂ which have strong acid properties were improved their catalytic activity with keeping of their selectivity for ammoxidation of isobutane to methacrylonitrile.     

Graft copolymerization of acrylonitrile and methacrylonitrile onto gelatin by mutual irradiation method

In order to improve upon certain properties of gelatin graft copolymerization of acrylonitrile (AN) and methacrylonitrile (MAN) onto gelatin has been studied in aqueous medium using γ rays as a source of initiation. Optimum conditions for affording maximum percentage of grafting have been evaluated as a function of various reaction parameters. The grafted polyacrylonitrile (PAN) was isolated from the graft copolymer by acid hydrolysis, and the average molecular weight (M_v) of the isolated polymer has been determined viscometrically. The graft copolymers were characterized by IR spectroscopic methods and thermogravimetric analysis (TGA). Acrylonitrile was found to be more reactive than methacrylonitrile toward graft copolymerization. © 1994 John Wiley & Sons, Inc.     

Effects of the chemical structure on the heat resistance of thermoplastic expandable microspheres

The effects of various additional non‐nitrile‐containing monomers on the heat resistance of thermoplastic expandable microspheres containing acrylonitrile and methacrylonitrile were investigated to determine the correlation between the chemical structure and expandable properties. Thermoplastic expandable microspheres were synthesized by suspension polymerization, with acrylonitrile and methacrylonitrile as the main ingredients and seven kinds of methacrylic acid derivatives, methacrylic acid, and acrylic acid as non‐nitrile‐containing monomers. The expandable properties, that is, the maximum expansion temperature, the expansion start temperature, and the maximum dimension change, were measured with thermomechanical analysis. For the development of heat‐resistant microspheres, polymer structures with smaller functional free volumes, higher glass‐transition temperatures, and higher cohesive energy densities, such as methyl acrylic acid, were applied as non‐nitrile‐containing monomers. Molecular structures such as ? COOH groups with strong electrostatic interactions and hydrogen‐bonding forces were found to be suitable for high heat resistance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1306–1312, 2005     

Observation of nitriles formed in the oxidative dehydrogenation of carboxylic acids over metal-oxygen cluster catalysts

At reaction temperatures of 300–350 °C isobutyronitrile and methacrylonitrile, in addition to the expected products of oxidative dehydrogenation, methacrylic acid, acetone, propene, CO and CO₂, are produced from isobutyric acid passed over ammonium salts of 12-molybdophosphoric acid.     

The formation of hydrogen cyanide during methacrylonitrile pyrolysis

This short note describes studies of the pyrolysis of methacrylonitrile over a wide range of temperatures under flowing nitrogen at atmospheric pressure. Hydrogen cyanide was not found to be a primary product, but several organic nitriles are formed which decompose at higher temperature (> 1100 K) to produce hydrogen cyanide almost quantitatively.     

The pyrolysis of organic nitriles

Detailed quantitative studies are reported on the kinetics of acetonitrile pyrolysis using an isothermal quartz tubular flow reactor at 720–1033 K and 1 atm. Pressure using flow rates, in nitrogen, of 2–200 ml min^?1. The pyrolysis of several other nitriles (acrylonitrile, propionitrile, methacrylonitrile and benzonitrile) has also been investigated qualitatively by pyrolysis-gas chromatography.     

Radiation-degradation susceptibility studies of vinyl terpolymers: Search for improved electron beam resists

To develop polymer systems with improved lithographic resist properties, terpolymers of methyl methacrylate/methacrylonitrile/methyl α-chloroacryate (MMA/MCN/MCA), methyl methacrylate/methacrylonitrile/α-chloroacrylonitrile (MMA/MCN/ACAN), and methyl methacrylate/methacrylonitrile/vinylidene chloride (MMA/MCN/VDC) were prepared by emulsion polymerization. Also one methyl methacrylate/ methyl α-chloroacylate/α-chloroacrylonitrile (MMA/MCA/ ACAN) terpolymer was prepared. The radiation susceptibilities of these terpolymers were measured using the ⁶⁰Coγ-irradiation method. Molecular weights were determined both by membrane osmometry and gel permeation chromatography. All terpolymers exhibited higher radiation-degradation susceptibilities than poly(methyl methacrylate). The Gs values did not follow the general trend, previously observed with MCN/MCA copolymers, of being directly proportional to the respective terpolymer compositions. In some cases, the addition of small quantities of α-chlorine-containing monomers caused Gx to increase. This observation greatly differs from those observed for copolymer systems such as MMA/MCA, MCN/MCA, MMA/ ACAN, etc. studied previously. Terpolymerization gives highly soluble polymers especially suitable for wet development by many solvents. This is an important consideration for polymers with high mole fractions of methacrylonitrile (MCN) or vinylidene chloride (VDC) which are rendered soluble in development solvents. The electron-beam sensitivities were obtained for samples of three classes of the terpolymers and they were higher than that of PMMA. For example, at 20Kev a 62/34/4 MMA/MCN/MCA terpolymer exhibited a sensitivity of 1.3 × 10^?5 coulombs cm^?2 at l/l_o = 1. The introduction of ACAN narrows the working range for positive resist behavior. For example MMA/MCN/ACAN(41/40/19) has a sensitivity of 8.3 × 10^?6 coulombs cm^?2 at l/l₀ = 0.6 but it crosslinks at 1 ? 1.3 × 10^? coulombs cm². The MMA/MCN/VDC(21/76/3) polymer was about 25 times more sensitive than PMMA (7 × 10^?6 C cm^?2 at l/l₀=1).     

Processing characteristics of alpha-methylstyrene–methacrylonitrile copolymer

Processing behavior of alpha-methylstyrene–methacrylonitrile copolymer has been studied in a Brabender Plasticorder and in a capillary rheometer. The copolymer is thermally unstable at a processing temperature of 230°C; however, addition of 2% ethyl acrylate to the copolymer composition enhances processing stability. The terpolymer is processable in the range of 210° to 250°C. However, it is limited by melt fracture at low shear rates.     

Catalytic synthesis of propionitrile from methanol and acetonitrile over activated carbon-supported sodium catalysts

Catalytic synthesis of propionitrile from methanol and acetonitrile was achieved by using activated-carbon-supported sodium catalysts. The activity of catalysts is determined by the precursor of the sodium; the catalysts prepared from sodium hydrogen carbonate show the highest activity. At high conversion of acetonitrile (70%), a propionitrile yield selectively exceeding 80% is achieved with a minor amount of methacrylonitrile as a secondary product. The order of catalytic activity of catalysts correlates well with the adsorption capacities for methanol and acetonitrile measured by the TPD method.     

Preparation,modification and characterisation of polymer-supported species

Techniques for the preparation of polymer supports are described. Details of suspension polymerisation reactions are given using novel resins based on poly(methacrylonitrile) as an example. The structure of supports is discussed, including both macroporous vinyl polymer based systems, and macroporous polysaccharide based species. Methods of derivatising supports are summarised with recent examples illustrating the ‘chemical modification’ approach, and the ‘functional monomer’ approach. Newer inert supports are introduced and the technique of γ-ray irradiation grafting described as one method of achieving derivatisation of these potentially very useful materials.     

单体配比对PMI泡沫塑料结构和性能的影响

探讨了四种不同单体配比(甲基丙烯酸/甲基丙烯腈)对PMI泡沫塑料结构和性能的影响.结果发现随着单体配比的增加PMI泡沫塑料的泡孔孔径先增大后减小,在单体配比为50/50时泡孔孔径最小.同时发现PMI的密度与泡孔孔径成反比,孔径越小,密度越大.PM1泡沫塑料的力学性能与耐热性能与其密度成正比,密度越大,其力学性能和耐热性...     

耐高温微细孔结构PMI泡沫的制备及研究

以甲基丙烯腈（MAN）、甲基丙烯酸（MAA）为单体、丙烯酰胺（AM）为第三单体、偶氮二异丁腈（AIBN）为引发剂、甲基丙烯酸烯丙酯为交联剂,并加入成核剂RHL-32,通过本体聚合,制备耐高温微细孔结构聚甲基丙烯酰亚胺（PMI）泡沫。借助FTIR、DSC、TG、光学显微镜等手段对于共聚物结构和发泡过程进行了分析。结果表明,聚合物在发泡和热处理中发生多种成环反应,除生成PMI泡沫需要的六元酰亚胺环,还生成酸酐环等。成核剂RHL-32的加入能有效降低PMI泡沫的孔径,通过调节RHL-32的量可得到合适的泡沫孔径。     

Transparent barrier resins with high nitrile content

The effect of 30–49 wt-% nitrile group content on the properties of copolymers is demonstrated. The nitrile is furnished by either acrylonitrile or methacrylonitrile. The exceptional resistance of such high nitrile content resins to the passage of gases and of solvents is shown and variations therein demonstrated for different comonomers. Transparent, tough, grafted polymers of good color are described which retain these properties. These qualities, combined with low second-order transition temperatures and adequate heat deflection temperatures, provide polymers of interest wherever containment and barrier are desired. Bottles, thermoformed containers, etc., could benefit from the use of some of the polymers described.     

The effect of replacing the α-hydrogen with a methyl group on the miscibility of systems containing styrene,methacrylonitrile and methyl methacrylate

Summary The phase boundaries as a function of copolymer composition have been established in one polymer/copolymer and two copolymer/copolymer blend systems involving the repeat unit methacrylonitrile. Using the critical conditions for miscibility according to the Flory-Huggins theory, and an overall blend interaction parameter (B_blend) expressed in terms of repeat unit interactions B_i-j, values of B_S-MAN and B_MMA-MAN have been determined. These are compared with the corresponding acrylonitrile interactions.     

Plasma-induced polymerization

Summary High molecular weight methacrylonitrile (M₁) — styrene (M₂) copolymers were obtained by plasma-induced bulk copolymerization. The reactivity ratios, determined by Kelen — Tüdös method, were shown to be r₁=0.21 and r₂=0.34 and indicate a radical mechanism of polymerization. Some microstructural aspects of the obtained copolymers are presented.     

Plasma Modifications to the Interface in Carbon Fiber Reinforced Thermoplastic Matrices

Radio frequency glow discharge oxygen plasma was used to modify the surfaces of PAN-based and mesophase pitch-based carbon fibers. Surface chemical changes to the fibers were monitored by X-ray photoelectron spectroscopy and by fiber wetting studies evaluated in terms of dispersive-polar components of surface energy and acid-base contribution to the work of adhesion. Physical changes to these fibers were monitored by scanning electron microscopy. Stress transferability of these fibers was evaluated by the embedded single fiber test in poly(methyl methacrylate), poly(ethyl methacrylate), poly(methacrylonitrile) and poly(vinyl chloride) as these matrices offered varying degrees of dispersive-polar and acid-base character. Experimentally determined critical aspect ratios were compared to the theoretical work of adhesion determined by dispersive-polar interactions and with the Lewis acid-base nature of the matrices.