Terpolymerization was investigated by dilatometry for zincacrylate (ZnA2), acrylonitrile (AN), and styrene (St), radically initiated by a As2S3-styrene complex (I) in dimethyl sulphoxide (DMSO), at 90 ± 0.1°C for 1 h under inert atmosphere. The system follows non-ideal kinetics, due to primary radical termination as well as a degradative chain transfer reaction. The kinetic expression for the system is Rpα(I)0.27 (St)0.31 (AN) 0.22[ZnA2]0.12. The value for the activation energy and k/kt are 55 kJ mol?1 and 1.87 × 10?7 1 mol?1 s?1 respectively. The terpolymer has been characterized by IR and NMR spectroscopy. The thermal stability and solubility of the terpolymer have also been studied. 相似文献
The ylide-initiated radical copolymerization of 4-vinylpyridine (4-VP) with methyl methacrylate (MMA) at 60°C using carbon tetrachloride as inert solvent yields non-alternating copolymers. The kinetic parameters, average rate of polymerization (Rp) and orders of reaction with respect to monomers and initiator, have been evaluated and the kinetic equation is found to be Rpα[ylide]0.94 [MMA]1.0 [4-VP]1.5. The values of the energy of activation and kp2/kt are 48 kJ mol?1 and 6.6 × 10?5 litre mol?1s?1, respectively. The copolymers have been characterized by IR and NMR spectroscopy. 相似文献
Reactions of H atoms with COS, CS2, and H2S were studied behind reflected shock waves at temperatures between 1170 K and 1830 K and pressures around 1.0 bar by applying atomic resonance absorption spectroscopy (ARAS) for time-resolved measurements of H atoms at Lα. The thermal decomposition of a few ppm ethyl iodide (C2H5I) was used as a H-atom source. In the presence of a large excess of the molecular reactant COS, CS2, or H2S, a consumption of H was observed which follows a pseudo first-order rate law. Rate coefficients for the reactions: were determined to be: k1 = 2.4 × 1014exp(–3415 K/T) cm3mol−1s−1k2 = 1.4 × 1015exp(–9250 K/T) cm3mol−1s−1k3 = 2.5 × 1014exp(–2890 K/T) cm3mol−1s−1相似文献
In this study, nitroxide mediated polymerization of methacryloisobutyl POSS (POSSMA) and bio-sourced monomers: isobornyl methacrylate (IBOMA) and C13 methacrylate (C13MA, an alkyl methacrylate with an average chain length of 13 units) was conducted in solution (toluene) and miniemulsion. BlocBuilder-MA (with 10 mol% acrylonitrile [AN] controlling co-monomer, for the solvent-based system) and Dispolreg 007 (for the miniemulsion) were used as the alkoxyamine for initiation and controlling the polymerization. POSSMA/IBOMA/C13MA effective terpolymerization (having 10 mol% AN controlling co-monomer) with monomer conversion (X) <72% in toluene resulted in resins with Mn up to 21.3 kg mol−1 and Ð < 1.67. Next, terpolymerizations were conducted in dispersed aqueous media to completely remove the organic solvent, resulting in polymers with Mn up to 46.7 kg mol−1 and Ð < 1.65. The successful chain extension of poly(IBOMA/AN) with a mixture of POSSMA/C13MA/AN (Mn = 74.1 kg mol−1 and Ð = 1.55) showed high chain-end fidelity, exemplified by a clear, monomodal shift in the GPC chromatogram from the macroinitiator. Finally, it was shown that the addition of 20 mol% POSSMA improved the decomposition temperature of bio-based polymers of IBOMA/C13MA by 15%. 相似文献
The alternating copolymerization of methyl methacrylate (MMA) with styrene (S) using β-picolinium-p-chlorophenacylide (β-PCPY) as radical initiator at 55, 60, and 65°C for 3 h has been kinetically investigated. The copolymerization rate (Rp) is proportional to the square root of [β-PCPY] and indicates bimolecular termination. The average degree of polymerization decreases as [β-PCPY] increases. The values of kp2/kt and energy of activation have been evaluated as 1.43 · 10-3 l mol-1 s-1 and 87 kJ mol-1, respectively. The NMR spectroscopy has been used to determine the structure, composition, and stereochemistry of copolymers. 相似文献
Synthesis of a series of novel terpolymers, consisting of two electron-donating monomers, viz. N-vinyl pyrrolidone (N-VP) (heterocyclic polar monomer) and styrene (Sty) (non-polar monomer), with one electron-accepting polar monomer, i.e. acrylonitrile (AN), using α,α'-azobisisobutyronitrile as radical initiator and benzene as diluent at 60°C, has been extensively surveyed. Besides the synthesis, an attempt has been made to study the kinetics and various properties of the terpolymers, such as softening temperature and chemical resistance. The system follows non-ideal kinetics and the kinetic equation for the present system can be written as This non-ideality can be explained on the basis of significant initiator-dependent termination through primary radicals and degradative chain transfer to acrylonitrile monomer. The overall energy of activation is 72.4 kJ mol?1 and kp2/kt is 0.26 × 10?3 litre mol?1 s?1. The effects of various additives such as imidazolium-p-chlorophenacylide (ICPY) and ZnCl2 were also studied. ICPY functions as a chain transfer agent (Ctr = 0.43 × 10?4), whereas ZnCl2 accelerates the rate of reaction. IR spectroscopy was used to confirm the structure of the terpolymers. 相似文献
Rates of hydrogen atom attack on o-fluorotoluene (o-FTOL) and m-fluorotoluene (m-FTOL) at temperatures of 988–1144 K and pressures of 2–2.5 bar have been determined in a single-pulse shock tube study. Hydrogen atoms, generated from the decomposition of hexamethylethane, were allowed to react with the substrates and the characteristic products observed. Rate constants for two reaction channels, displacement of fluorine or methyl, were determined relative to displacement of methyl from 1, 3,5-trimethylbenzene (135TMB). Evidence is presented that abstraction of F is unimportant over the studied temperature range. With k(H + 135TMB → m-xylene + CH3) = 6.7 × 1013 exp(–3255/T) cm3 mol−1s−1, the following rate expressions have been derived: k(H + o-FTOL → C6H5CH3 + F) = 8.38 × 1013 exp(–6041/T) cm3 mol−1s−1; (1012–1142 K) k(H + o-FTOL → C6H5F + CH3) = 2.37 × 1013 exp(–2938/T) cm3 mol−1s−1; (988–1142 K) k(H + m-FTOL → C6H5CH3 + F) = 1.33 × 1014 exp(–6810/T) cm3 mol−1s−1; (1046–1144 K) k(H + m-FTOL → C6H5F + CH3) = 2.04 × 1013 exp(–3104/T) cm3 mol−1s−1; (1008–1144 K) Uncertainties in the relative rate constants are estimated to be factors of about 1.1, while the above absolute values have estimated expanded uncertainties of about a factor of 1.4 in rate, 10 kJ mol−1 in the activation energy, and a factor of 3 in the A-factor. The present data are compared with relevant literature data. From our data and the thermochemistry, a model of the elementary steps comprising displacement of F is developed. On the basis of the model fit to our data, rate constants for the addition of atomic fluorine to toluene at 1100 K are derived. Rate expressions for fluorination reactions of toluene are also determined. The significance of the present results is discussed in the context of the formation of fluorinated byproducts in high-temperature systems. 相似文献
The kinetics of the oxirane cleavage of epoxidized soybean oil (ESO) by methanol (Me) without a catalyst was studied at 50,
60, 65, 70 °C. The rate of oxirane ring opening is given by k[Ep][Me]2, where [Ep] and [Me] are the concentrations of oxiranes in ESO and methanol, respectively and k is a rate constant. From the temperature dependence of the kinetics thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), free energy of activation (ΔF) and activation energy (ΔEa) were found to be 76.08 (±1.06) kJ mol−1, −118.42 (±3.12) J mol−1 k−1, 111.39 (±2.86) kJ mol−1, and 78.56 (±1.63) kJ mol−1, respectively. The methoxylated polyols formed from the oxirane cleavage reaction , were liquid at room temperature and had
three low temperature melting peaks. The results of chemical analysis via titration for residual oxiranes in the reaction
system showed good agreement with IR spectroscopy especially the disappearance of epoxy groups at 825, 843 cm−1 and the emergence of hydroxy groups at the OH characteristic absorption peak from 3,100 to 3,800 cm−1. 相似文献
Solution terpolymerization of styrene (Sty), acrylonitrile (AN) and copper acrylate (CuA) has been carried out in dimethylformamide at 90°C for 4 h using p-acetyl benzylidene triphenylarsonium ylide as radical initiator. 1H nuclear magnetic resonance (NMR), IR and elemental analysis have been used to characterized the terpolymer. Analysis of kinetic data indicates the following rate equation: The overall activation energy is 38 kJ mol−1. The composition of terpolymer calculated from NMR and elemental analysis has been used to evaluate reactivity ratios as r1(Sty) = 5 ± 2 and r2(AN + CuA) = 0.4 ± 0.02 employing the Finemann–Ross method, which confirms its random origin. The terpolymer was thermally stable up to 2007deg;C. 相似文献
The asymmetric 1,4‐addition of phenylboronic acid to cyclohexenone were performed by using a low amount of rhodium/(R)‐(6,6′‐dimethoxybiphenyl‐2,2′‐diyl)bis[bis(3,4,5‐trifluorophenyl)phosphine] (MeO‐F12‐BIPHEP) catalyst. Because the catalyst shows thermal resistance at 100 °C, up to 0.00025 mol% Rh catalyst showed good catalytic activity. The highest turnover frequency (TOF) and turnover number (TON) observed were 53,000 h−1 and 320,000, respectively. The enantioselectivities of the products were maintained at a high level of 98% ee in these reactions. The Eyring plots gave the following kinetic parameters (ΔΔH≠=−4.0±0.1 kcal mol−1 and ΔΔS≠=−1.3±0.3 cal mol−1 K−1), indicating that the entropy contribution is relatively small. Both the result and consideration of the transition state in the insertion step at the B3LYP/6‐31G(d) [LANL2DZ for rhodium] levels indicated that the less σ‐donating electron‐poor (R)‐MeO‐F12‐BIPHEP could be creating a rigid chiral environment around the rhodium catalyst even at high temperature. 相似文献
Free-radical propagation rate coefficients (kp) at 30°C for the homopolymerization of cyclohexyl methacrylate (CHMA), 4-hydroxybutyl methacrylate (HBMA), 2-hydroxypropyl
methacrylate (HPMA), and 2-hydroxyethyl methacrylate (HEMA) were determined to be 1070, 917, 640, and 71.9 (L mol−1s−1), using the rotating-sector method. The kp value increases rapidly, and the value of life time of free radicals (τs) increases smoothly with increasing the alkyl chain length in the hydroxyalkyl pendant group of the monomer. Values for the
steady-illumination polymerization rate for CHMA, HBMA and HPMA are much larger than that for HEMA. Comparisons of kp values from different sources were also made. 相似文献
A series of low‐cost, pyridinium cation‐based hypergolic ionic liquids (HIL) containing amine, butyl, or allyl substituents with cyanoborohydride [BH3CN]− and dicyanamide [DCA]− anions were developed and characterized. The investigated physicochemical properties include melting and decomposition temperature, viscosity, density, heat of formation (ΔHf) and specific impulse (Isp). The ignition delay (ID) of all HILs was tested with the oxidizer RFNA. The HIL, 1‐allyl 4‐amino pyridinium dicyanamide, exhibited highest density (1.139 g cm−3) amongst the known pyridinium HILs. The heats of formation predicted on the basis of Gaussian 09 suit programs were within the range of − 30 to 356 kJ mol−1. The structure of HIL, 1‐butyl 4‐aminopyridinium cyanoborohydride, was examined by single‐crystal X‐ray diffraction, which revealed hydrogen bonding between anion and cation as N1−H1N ⋅⋅⋅ N3=2.07 Å, N1−H2N ⋅⋅⋅ H1B1=2.18 Å, and N1−H2N ⋅⋅⋅ H2B1=2.21 Å, respectively. HIL (1‐allyl 4‐aminopyridiniun cyanoborohydride) exhibited highest Isp of 228 s amongst the designed series. 相似文献