A kinetic investigation of radiation induced bulk polymerization of acrylic acid

The kinetics of the γ-ray induced polymerization of acrylic acid in bulk is investigated in a temperature interval of 20–50°C and a dose rate of 2.8–24.6 Gy/min. The reaction rate was observed to increase with increasing temperature and dose rate. The order of the reaction α, with respect to initiation i.e. dose rate, changed between 1.51 and 0.79 in the temperature interval studied. The kinetic analysis of the conversion curves was made according to equations developed by Magat for nonsteady state polymerizations taking place in precipitating media. k_p/k_t ratio thus determined for bulk polymerization of acrylic acid increased with increasing temperature and decreased with dose rate at a given temperature. This behavior as well as the change in the molecular weights of the poly(acrylic acid)s were explained to be as due to the termination of growing chain radicals occluded in the precipitated polymer by primary radicals.     

A kinetic approach to homogeneous Ziegler type polymerization. Steady state

In this paper we present a kinetic approach to the analysis of steady-state homogeneous Ziegler-Natta polymerization activity data. The influence of the number of monomeric species that are coordinated to the active site on the apparent rate law is discussed and the equations are fitted to the experimental results.     

A kinetic approach to homogeneous Ziegler type polymerization. Transient state

In this paper we present a kinetic approach to the analysis of transient-state homogenous Ziegler-Natta polymerization activity data. The main features of the experimental data are discussed and fitted to transient kinetic models.     

Template molecular weight effects on the polymerization of acrylic acid

Acrylic acid was polymerized in dilute aqueous solution in the presence of a series of polyvinylpyrrolidones (PVP) of different molecular weight. Both inhibition time and rate of polymerization increased with PVP molecular weight. Purification of the PVP had no effect on these results. The complex produced by the polymerization was separated by methylation of the acrylic acid. The degree of polymerization ($\text{DP}$) of the polyacrylic acid formed in template polymerizaton was found to be remarkably similar to the $\text{DP}$ of the template PVP. A significant degree of isotacticity had also been induced in the PAA.     

A novel synthesis of acrylic acid containing polymers

A novel synthesis of linear acrylic acid containing polymers, poly(styrene-co-acrylic acid) and poly(acrylic acid), was accomplished through hydrolysis of the respective parent polymers, i.e. poly(styrene-co-methyl acrylate) and poly(methyl acrylate), with trimethylsilyl iodide under mild conditions. Combination of ¹H NMR, ¹³C NMR, FTIR, DSC and chemical titration confirms that the conversion from methoxycarbonyl to carboxyl is almost complete. This method is further successfully applied to synthesize poly-(ethyl methacrylate-co-acrylic acid) through selective hydrolysis of the methyl acrylate units in poly(ethyl methacrylate-co-methyl acrylate).     

The microwave radiation effect on the polymerization of styrene

Styrene was cured by microwave radiation at two different powers: 300 and 500 W. The temperature profile of the sample during the microwave curing process was determined to select a suitable temperature for comparison with the conventional method of cure. The results indicate a similar comparable temperature of about 80°C irrespective of the microwave power used. The percentage conversion of the cure was followed by Fourier transform infrared (FTIR) spectroscopy. The thermal polymerization at 79(±1)°C displayed a gradual increase in the rate of reaction at the gel effect from about 30 to 50% conversion of the reaction. The microwave cure at 300 and 500 W displayed a large and sharp gel effect from about 20 to 69 and 64% conversion of the reaction, respectively. The limiting conversion decreased with increase in microwave power which was also observed in the polymerization of methyl methacrylate (MMA). Based on similarity in temperature and reaction conditions, the 500 W cure was found to show a reaction rate enhancement of 190% and the 300 W cure 120%. A comparison of microwave induced reactions with thermal methods, therefore, must also specify the microwave power used. © 1996 John Wiley & Sons, Inc.     

The effect of ion energy upon plasma polymerization deposition rate for acrylic acid

A novel technique, which allows the importance of ion energy in plasma polymer film growth to be investigated, without perturbation of any other plasma parameter (particle densities or temperatures) or, in principle, perturbation of particle (neutral or ion) fluxes is applied in the plasma polymerisation of acrylic acid and new insight into polymer formation is gleaned.     

A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).     

Remarks on the relationship between isothermal and non-isothermal kinetic results. A new method for the kinetic analysis of isothermal data

Addition of 10mg/l of the haevy metal ions Zn⁺⁺, Cu⁺⁺, Pb⁺⁺, Cd⁺⁺ and Cr⁺⁺ to nongrowing E.coli cells shows a decrease in heat production by aerobic and anaerobic glycolysis up to 80 %. The heat production of cells incubated without glucose was decreased drastically too, after addition of 10mg/l of these heavy metal ions.The pattern of heat released during active transport of α MG was influenced by these haevy metal ions in a way, that there was a decrease in maximum heat flow, whereas the total heat production seemed to be constant.After increasing the metal ion concentration up to 100mg/l no endogenous heat production could be detected. The inhibition of heat production after addition of glucose was higher than 90 % in this case and there was a strong inhibition in α MG uptake.The results of these investigations indicate that the basic action of all tested metal ions is the energy metabolism and not the transport as stated earlier.     

掺稀土多孔硅中稀土光学活化的新方法: 微波热法

首次报道掺稀土多孔硅中稀土光学活化的一种新方法--微波热法.经微波加热处理后,掺稀土多孔硅样品外观均匀;室温下,分别观察到掺铒多孔硅在-1.5μm处、掺钕多孔硅在-1.06μm处强的光致发光.除起加热作用外,微波与样品之间的非热相互作用在稀土的光学活化方面与也起重要作用.     

Enhanced radiation crosslinking of acrylic acid and methacrylic acid to polymers: alkanes as model compounds for polyethylene

The crosslinking of polyethylene by irradiation is enhanced in the presence of acrylic acid. This process has been studied for model compounds; for ¹⁴C-labelled hexadecane, each molecule of polyacrylic acid is linked to an average of 47 hexadecane molecules; at the radiation dose used, this result implies a hitherto unexpected chain reaction. Evidence from ESR spectra indicates an ionic intermediate.     

A novel approach to phosphonic acids from hypophosphorous acid

A novel access to phosphonic acids via Pd-catalyzed tandem carbon-phosphorus bond formation-oxidation processes was developed. The procedures involve atom-economical and environmentally friendly functionalization reactions of hypophosphorous acid (H₃PO₂) and H-phosphinic acids [RP(O)(OH)(H)].     

A novel method for the synthesis of polysubstituted diaminobenzonitrile derivatives using controlled microwave heating

A novel, simple and efficient method for the synthesis of polysubstituted diaminobenzonitriles has been developed that involves reaction of 1,1,3-tricyano-2-aminopropionitrile with nitroolefins under controlled microwave irradiation conditions.     

Fast determination of reaction kinetic parameters with the use of microwave heating. Kinetics of decomposition of organic substances with nitric acid

A mathematical model for the kinetics of a chemical reaction under microwave irradiation in a close volume in the simplest approximation of the uniform temperature and pressure distribution in a system was proposed. The previously proposed dynamic method for determination of the activation energy of oxidation of organic substances with nitric acid was substantiated. According to this method, the activation energy is determined from the experimental exponential plot for the pressure in the nonisothermic system vs. inverse temperature of the reaction mixture. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1371–1375, June, 2005.     

Studying the effect of microwave heating on the digestion process and identification of proteins

The impact of microwave irradiation on the in‐solution digestion processes and the detection limit of proteins are systematically studied. Kinetic processes of many peptides produced through the trypsin digestion of various proteins under microwave heating at 50°C were investigated with MALDI‐MS. This study also examines the detection limits and digestion completeness of individual proteins under microwave heating at 50°C and at different time intervals (1, 5 and 30 min) using LC‐MS. We conclude that if the peptides without missed cleavage dictate the detection limit, conventional digestion will lead to a better detection limit. The detection limit may not differ between the microwave and conventional heating if the peptides with missed cleavage sites and strong intensity are formed at the very early stage (i.e., less than 1 min) and are not further digested throughout the entire digestion process. The digestion of Escherichia coli lysate was compared under conventional and short time (microwave) conditions. The number of proteins identified under conventional heating exceeded that obtained from microwave heating over heating periods less than 5 min. The overall results show that the microwave‐assisted digestion is not complete. Although the sequence coverage might be better, the detection limit might be worse than that under conventional heating.     

Preparation and polymerization of a diisocyanate from the Diels-Alder adduct of levopimaric acid and acrylic acid

Starting from tetrahydroabietic acid the model compounds tetrahydroabietoyl chloride, 2-aminoethyltetrahydroabietate hydrochloride, and 2-isocyanatoethyltetrahydroabietate have been prepared. Carbamate and urea derivatives of the isocyanate have been prepared. A Diels-Alder adduct of levopimaric acid and acrylic acid has been prepared and converted to its diacid chloride. The β-aminoethyl ester hydrochloride has been synthesized and converted to a diisocyanate which has been polymerized with poly(tetramethylene glycol) and also with p-phenylenediamine. Dimerex resin, a technical polymerized rosin, has been similarly converted to a diisocyanate. This isocyanate has not proven to be useful as a polymer-forming intermediate.     

A novel chiral phosphinediamine ligand and asymmetric hydrogenation of acrylic acid derivatives

A novel chiral phosphinediamine ligand (PN₂) was prepared from (S)-1-phenylethylamine and dichloroisopropylphosphine. The rhodium-PN₂ catalyst utilizing selective ligation of the amino unit and electrostatic interaction between the ligand and a substrate gave high enantioselectivities up to 92% ee in asymmetric hydrogenations of acrylic acid derivatives.     

Origins of the solvent effect on the propagation kinetics of acrylic acid and methacrylic acid

In this study, the relative rate of polymerization of acrylic acid (AA) versus methacrylic acid (MAA) and the effect of water on the polymerization kinetics are investigated within a combined static and molecular dynamics set of computational tools. Experimentally the relative rate of propagation of AA versus MAA is around 35 in bulk and 31 in water. Classical Molecular Dynamics calculations have been carried out to determine the location of the solvent molecules in the proximity of the dimeric poly(AA) and poly(MAA) units. A combined implicit/explicit solvent model was used for the evaluation of the kinetics of the dimeric polymer chains. We show that the rate acceleration of both polymers in water is mainly due to entropic rather than electrostatic effects and is in agreement with experimental findings. Moreover the slower propagation rate of MAA versus AA is ascribed to additional steric effects present in MAA due to the methyl group at the α position of the monomer. Among the functionals used, the M06‐2X/6‐311+G(3df,2p)//B3LYP/6‐31+G(d) methodology reproduces the experimental rate constants quantitatively the best. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013