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1.
Zhi‐Qi Cai Jianzhong Sun Daodeng Wang Qiyun Zhou 《Journal of polymer science. Part A, Polymer chemistry》2007,45(17):3922-3928
The curing kinetics of a novel liquid crystalline epoxy resin with combining biphenyl and aromatic ester‐type mesogenic unit, diglycidyl ether of 4,4′‐bis(4‐hydroxybenzoyloxy)‐3,3′,5,5′‐tetramethyl biphenyl (DGE‐BHBTMBP), and the curing agent diaminodiphenylsulfone (DDS) was studied using the advanced isoconvensional method (AICM). DGE‐BHBTMBP/DDS curing system was investigated the curing behavior by means of differential scanning calorimetry (DSC) during isothermal and nonisothermal processes. Only one exothermal peak appeared in isothermal DSC curves. A variation of the effective activation energy with the extent of conversion was obtained by AICM. Three different curing stages were confirmed. In the initial curing stage, the value of Ea is dramatically decreased from ~90 to ~20 kJ/mol in the conversion region 0–0.2 for the formation of LC phase. In the middle stage, the value of Ea keeps about ~80 kJ/mol for cooperative effect of reaction mechanism and diffusion control. In the final stage, a significant increase of Ea from 84 to 136 kJ/mol could be caused by the mobility of longer polymer chains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3922–3928, 2007 相似文献
2.
Starch belongs to the polyglucan group. This type of polysaccharide shows a broad β-relaxation process in dielectric spectra at low temperatures, which has its molecular origin in orientational motions of sugar rings via glucosidic linkages. This chain dynamic was investigated for α(1,4)-linked starch oligomers with well-defined chain lengths of 2, 3, 4, 6, and 7 anhydroglucose units (AGUs) and for α(1,4)-polyglucans with average degrees of polymerization of 5, 10, 56, 70, and so forth (up to 3000; calculated from the mean molecular weight). The activation energy (Ea) of the segmental chain motion was lowest for dimeric maltose (Ea = 49.4 ± 1.3 kJ/mol), and this was followed by passage through a maximum at a degree of polymerization of 6 (Ea = 60.8 ± 1.8 kJ/mol). Subsequently, Ea leveled off at a value of about 52 ± 1.5 kJ/mol for chains containing more than 100 repeating units. The results were compared with the values of cellulose-like oligomers and polymers bearing a β(1,4)-linkage. Interestingly, the shape of the Ea dependency on the chain length of the molecules was qualitatively the same for both systems, whereas quantitatively the starch-like substances generally showed higher Ea values. Additionally, and for comparison, three cyclodextrins were measured by dielectric relaxation spectroscopy. The ringlike molecules, with 6, 7, and 8 α(1,4)-linked AGUs, showed moderately different types of dielectric spectra. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 188–197, 2004 相似文献
3.
Bonding and singlet–triplet gap of silicon trimer: Effects of protonation and attachment of alkali metal cations
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Nguyen Minh Tam Tran Dieu Hang Hung Tan Pham Huyen Thi Nguyen My Phuong Pham‐Ho Pablo A. Denis Minh Tho Nguyen 《Journal of computational chemistry》2015,36(11):805-815
We revisit the singlet–triplet energy gap (ΔEST) of silicon trimer and evaluate the gaps of its derivatives by attachment of a cation (H+, Li+, Na+, and K+) using the wavefunction‐based methods including the composite G4, coupled‐cluster theory CCSD(T)/CBS, CCSDT and CCSDTQ, and CASSCF/CASPT2 (for Si3) computations. Both 1A1 and 3 states of Si3 are determined to be degenerate. An intersystem crossing between both states appears to be possible at a point having an apex bond angle of around α = 68 ± 2° which is 16 ± 4 kJ/mol above the ground state. The proton, Li+ and Na+ cations tend to favor the low‐spin state, whereas the K+ cation favors the high‐spin state. However, they do not modify significantly the ΔEST. The proton affinity of silicon trimer is determined as PA(Si3) = 830 ± 4 kJ/mol at 298 K. The metal cation affinities are also predicted to be LiCA(Si3) = 108 ± 8 kJ/mol, NaCA(Si3) = 79 ± 8 kJ/mol and KCA(Si3) = 44 ± 8 kJ/mol. The chemical bonding is probed using the electron localization function, and ring current analyses show that the singlet three‐membered ring Si3 is, at most, nonaromatic. Attachment of the proton and Li+ cation renders it anti‐aromatic. © 2015 Wiley Periodicals, Inc. 相似文献
4.
P. J. Oefner A. H. Lanziner G. Bonn O. Bobleter 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):547-556
Summary Chromatographic analysis of the degradation ofD-xylose either in plain water or aqueous sulfuric acid at temperatures ranging from 180 – 220°C gave up to 50 mol% of furfural. Activation energies did not differ significantly between reactions in plain water (E
a
=119.4 kJ/mol), 0.001M H2SO4 (E
a
=120.6 kJ/mol), 0.01M H2SO4 (E
a
=130.8 kJ/mol), and 0.1M H2SO4 (E
a
=120.7 kJ/mol). However, under alkaline conditions the activation energy was only 63.7 kJ/mol, indicating a different reaction mechanism. Isotachophoretic analyses revealed the formation of pyruvic, formic, glycolic, lactic, and acetic acid. While the relative yields of these acids ranged from 0.8 to 7% under hydrothermal and acidic conditions, 10 – 23% were obtained in alkaline degradation.
Quantitative Studien zur Bildung von Furfural und organischen Säuren während des hydrothermalen, sauren und alkalischen Abbaues vonD-Xylose
Zusammenfassung Die chromatographische Analyse des Abbaues vonD-Xylose in reinem Wasser und Schwefelsäure bei Temperaturen von 180 – 220°C ergab die Bildung von bis zu 50 mol% Furfural. In bezug auf die Aktivierungsenergie zeigten sich keine signifikanten Unterschiede zwischen dem Abbau vonD-Xylose in reinem Wasser (E a =119.4 kJ/mol), 0.001M H2SO4 (E a =120.6 kJ/mol), 0.01M H2SO4 (E a =130.8 kJ/mol), and 0.1M H2SO4 (E a =120.7 kJ/mol). Unter alkalischen Bedingungen hingegen betrug die Aktivierungsenergie nur 63.7 kJ/mol. Dies weist auf einen unterschiedlichen Reaktionsmechanismus hin. Ferner konnte mittels Isotachophorese die Bildung von Brenztraubensäure, Ameisensäure, Glycolsäure, Milchsäure und Essigsäure nachgewiesen werden. Während sich die relativen Ausbeuten in Wasser und Schwefelsäure zwischen 0.8 und 7% bewegten, betrugen sie unter alkalischen Bedingungen 10 bis 23%.相似文献
5.
运用密度泛函理论和半经验分子轨道方法,对一系列高能杂环硝胺—反式-1,4,5,8-四硝基-1,4,5,8-四氮杂萘烷异构体的热解机理和稳定性进行了系统地计算研究。在B3LYP/6-31G**和PM3水平上,分别计算了标题物的化学键离解能(BDE)和热解反应活化能(Ea),并根据BDE和Ea数值考察了硝胺取代基对化合物稳定性和热解机理的影响;同时,还详细考察了BDE与Ea、化学键重叠布居数、前线轨道能级以及能隙之间的相关性。结果表明,由BDE、Ea和静态电子结构参数推断的标题物热稳定性和热解机理的结论基本是一致的,N-NO2键均裂是标题物的热解引发步骤,间位取代异构体较对位取代异构体稳定,而邻位取代的异构体稳定性最差。 相似文献
6.
Polytriazole polyethylene oxide‐tetrahydrofuran (PTPET) is an energetic propellant elastomer that is prepared using glycidyl azide polymer and trifunctional alkynyl‐terminated polyethylene oxide‐tetrahydrofuran. Its thermal decomposition, determined using thermogravimetic analysis, showed two mass‐loss peaks largely related to the decomposition of azide groups and the main chain. Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose methods were deployed to obtain kinetic triplet parameters of PTPET thermal decomposition by the traditional model‐free method; the Coats‐Redfern approach was used as the model‐fitting method. Kinetics analysis indicated that the mechanism of the two‐step reactions were the primary‐reaction of first order and the power‐law phase reaction of the 2/3 order. The first decomposition stage of PTPET had an activation energy (Ea) of 113 to 116 kJ/mol while the second was 196 to 210 kJ/mol. The thermal decomposition of PTPET with different heating rates and mechanisms showed good kinetic compensation effects, the gas products being further studied with TG‐FTIR. 相似文献
7.
Yan Xiong Shuting Zhang Xuege Ling Xu Zhang Jinyue Wang 《International journal of quantum chemistry》2012,112(12):2475-2481
CCSD(T) calculations have been used for identically nucleophilic substitution reactions on N‐haloammonium cation, X? + NH3X+ (X = F, Cl, Br, and I), with comparison of classic anionic SN2 reactions, X? + CH3X. The described SN2 reactions are characterized to a double curve potential, and separated charged reactants proceed to form transition state through a stronger complexation and a charge neutralization process. For title reactions X? + NH3X+, charge distributions, geometries, energy barriers, and their correlations have been investigated. Central barriers ΔE for X? + NH3X+ are found to be lower and lie within a relatively narrow range, decreasing in the following order: Cl (21.1 kJ/mol) > F (19.7 kJ/mol) > Br (10.9 kJ/mol) > I (9.1 kJ/mol). The overall barriers ΔE relative to the reactants are negative for all halogens: ?626.0 kJ/mol (F), ?494.1 kJ/mol (Cl), ?484.9 kJ/mol (Br), and ?458.5 kJ/mol (I). Stability energies of the ion–ion complexes ΔEcomp decrease in the order F (645.6 kJ/mol) > Cl (515.2 kJ/mol) > Br (495.8 kJ/mol) > I (467.6 kJ/mol), and are found to correlate well with halogen Mulliken electronegativities (R2 = 0.972) and proton affinity of halogen anions X? (R2 = 0.996). Based on polarizable continuum model, solvent effects have investigated, which indicates solvents, especially polar and protic solvents lower the complexation energy dramatically, due to dually solvated reactant ions, and even character of double well potential in reactions X? + CH3X has disappeared. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
8.
Effect of nanosilica on the kinetics of cure reaction and thermal degradation of epoxy resin 总被引:1,自引:0,他引:1
Nanocomposites from nanoscale silica particles(NS),diglycidylether of bisphenol-A based epoxy(DGEBA),and 3,5-diamino-N-(4-(quinolin-8-yloxy) phenyl) benzamide(DQPB) as curing agent were obtained from direct blending of these materials.The effect of nanosilica(NS) particles as catalyst on the cure reaction of DGEBA/DQPB system was studied by using non-isothermal DSC technique.The activation energy(E_a) was obtained by using Kissinger and Ozawa equations. The E_a value of curing of DGEBA/DQPB/10%NS system showed a decrease of about 10 kJ/mol indicating the catalytic effect of NS particles on the cure reaction.The E_a values of thermal degradation of the cured samples of both systems were 148 kJ/mol and 160 kJ/mol,respectively.The addition of 10%of NS to the curing mixture did not have much effect on the initial decomposition temperature(T_i) but increased the char residues from 20%to 28%at 650℃. 相似文献
9.
The cure of a bismaleimide (BMI) neat resin modified with an aromatic diamine and a siloxane elastomer, has been studied by 13C solid state nuclear magnetic resonance. Two chemical reactions occur during the cure cycle; at a low temperature, Michael's reaction predominates, while at a high temperature the polymerization of the double bond maleimide creates the network. The degradation of this BMI material was characterized with isothermal and dynamic thermogravimetric analyses in air and in nitrogen. The BMI thermal stability is lower in nitrogen than in air. This behavior is an indication of oxygen participating in reactions at high temperatures. The activation energy (Ea) of thermal degradation was determined from isothermal data using an Arrhenius equation (In V vs. 1/T). The global Ea for the weight loss in air was found to be 91 kJ/mol. The nature and the evolution of the thermal degradation products were the combined analyzed by techniques of pyrolysis, gas chromatography and mass spectrometry. The major thermal decomposition products obtained in the temperature range of 300–700°C are identified as benzene, methyl formamide, aniline, toluene and isocyanate-derived products. 相似文献
10.
The superb heat resistance poly(lactic acid) (PLA) were prepared by blending PLA and poly(d ‐lactic acid) (PDLA) with various molecular weight (Mn). Formation of the stereocomplex in the blends was confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction. The results of the heat resistance implied it is possible that elevating the Vicat penetration temperature of PLA up to 150°C by blending with PDLA. The cold crystallization of homochiral crystallites is proven to be the critical factor affecting the heat resistance of PLA. While the PLA or PLA/PDLA blends were heated to cold crystallization temperature of samples, both the crystal content and the rigid amorphous region content are increased due to the cold crystallization and tethering effect, and the stiffness and heat resistance of the sample are improved. The cold crystallization homochiral crystallites kinetics of PLA and PLA/PDLA blends was also studied. The results showed the activation energy (?E) of cold crystallization increased from 120.30 kJ/mol to 144.66 kJ/mol with the increasing of PDLA content from 2% to 10%. 相似文献
11.
Mechanisms of syn-(Z)/anti-(E) isomerization of methyl 2-methoxy-N-methylbuta-2,3-dienimidothioate, including rotational, inversion, promoted by N-protonation, and nucleophile-catalyzed, were
studied by quantum-chemical methods, and the corresponding thermodynamic and kinetic parameters were calculated. The most
probable mechanisms of isomerization of buta-2,3-dienimidothioates were found to be inversion (E
a = 74.4 kJ/mol) and nucleophile-catalyzed (E
a = 61.6 kJ/mol).
Original Russian Text ? V.A. Shagun, N.A. Nedolya, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 11,
pp. 1591–1600.
For communication XII, see [1]. 相似文献
12.
Ian Hamerton Lisa T. McNamara Brendan J. Howlin Paul A. Smith Paul Cross Steven Ward 《Journal of polymer science. Part A, Polymer chemistry》2014,52(14):2068-2081
Three commercial bis‐benzoxazine monomers based on the aniline derivatives of bisphenol A (BA‐a), bisphenol F (BF‐a), and 3,3′‐thiodiphenol (BT‐a) are examined using a variety of spectroscopic, chromatographic, and thermomechanical techniques. The kinetics of the polymerization of BA‐a were found to be well described using an autocatalytic model for which values of n = 1.39 and m = 2.49 were obtained for the early and later stages of reaction respectively (activation energy = 81–88 kJ/mol.). Following recrystallization the same monomer yielded values of n = 1.80, m = 0.92, and Ea = 94–97 kJ/mol. BF‐a and BT‐a were also found to be well described using an autocatalytic model for which values of n = m = 2.11 (BF‐a) and n = 2.10, m = 1.47 (BT‐a) were obtained for the early and later stages of reaction (activation energy = 80–84 kJ/mol. for BF‐a and 88–95 kJ/mol. for BT‐a). The kinetic data are compared with parallel studies involving chemically initiated benzoxazine monomers. Molecular simulation is used to examine the rotational freedom of the central bridging units and this is related to the degree of conversion achieved. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2068–2081 相似文献
13.
Dana Meißner Lars Einfeldt Jürgen Einfeldt 《Journal of Polymer Science.Polymer Physics》2001,39(20):2491-2500
For all cellulose‐like oligo‐ and polyglucans, beginning with the dimer cellobiose, a broad relaxation process at low temperatures is observed using the dielectric relaxation spectroscopy method. This relaxation has its molecular origin in orientational motions of the sugar rings via the glucosidic linkages. We investigated the dynamics of this main chain motion for β(1‐4) oligoglucans with 2, 3, 4, or 5 anhydroglucose units (AGUs), as well as for β(1‐4) polyglucans having a degree of polymerization molecular weight averages (DPw) of 23, 37, 50, and 140 up to 3000. As a result we found that the activation energy (Ea) of the segmental chain motion has the lowest value (32 ± 1 kJ/mol) for cellobiose, followed by passing through a maximum for a DP between 7 and 15 with Ea = 51 ± 1 kJ/mol. Subsequently, the activation energy is decreased at a value around 44.8 ± 1.2 kJ/mol for chains containing more than 100 AGUs. Obviously, from a distinctly molecular dimension (DPw ~ 100) the mean number of AGUs that take part in the local chain motions and cross‐correlation between the motions of neighboring AGUs are nearly the same and the chain length has no influence on the segmental motion. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2491–2500, 2001 相似文献
14.
David K. Lewis Steven V. Hughes Justine D. Miller Jessica Schlier Kevin A. Wilkinson Sara R. Wilkinson Bansi L. Kalra 《国际化学动力学杂志》2006,38(8):475-482
The Arrhenius parameters for the gas phase, unimolecular structural isomerizations of 1,1,2‐trimethylcyclopropane to three isomeric methylpentenes and two dimethylbutenes have been determined over a wide range of temperatures, 688–1124 K, using both static and shock tube reactors. For the overall loss of reactant, Ea = 63.7 (± 0.5) kcal/mol and log10 A = 15.28 (± 0.12). These values are higher by 2.6 kcal/mol and 0.7–0.8 than previously reported from experimental work or predicted from thermochemical calculations. Ea for the formation of trans‐4‐methyl‐2‐pentene is 1.5 kcal/mol higher than Ea for the formation of the cis isomer, which is identical to the Ea difference previously reported for the formation of trans‐ and cis‐2‐butene from methylcyclopropane. Substitution of methyl groups for hydrogen atoms on the cyclopropane ring is expected to weaken the C? C ring bonds, and it has been reported previously that activation energies for structural isomerizations of methylcyclopropanes do decrease substantially over the series cyclopropane > methylcyclopropane > 1,1‐ or 1,2‐dimethylcyclopropane. However, the present study shows that the trend does not continue beyond dimethylcyclopropane isomerization. Besides reductions in C? C bond energy, steric interactions may be increasingly important in determining the energy surface and conformational restrictions near the transition state in isomerizations of the more highly substituted methylcyclopropanes. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 475–482, 2006 相似文献
15.
James E. Pickett Jonathan R. Sargent Nicole Babbie 《Polymer Degradation and Stability》2009,94(7):1085-1091
The lifetime of polycarbonate (PC) coated with silicone hardcoats containing UV absorber is shorter at elevated temperatures. The activation energy (Ea) for delamination was found to be 18 ± 2 kJ/mol (4.3 ± 0.5 kcal/mol) at the 95% confidence level in this study. This Ea is the consequence of the sensitivity of the substrate and the UV absorber to temperature. The Ea for PC photodegradation was previously found to be 17-21 kJ/mol (4-5 kcal/mol). The Ea for loss of absorbance in the second-generation silicone hardcoat was found to be 28.5 ± 5.4 kJ/mol (6.8 ± 1.3 kcal/mol) at the 95% confidence level. Results are consistent with experimental findings when these activation energies are used in published predictive models. Since the Ea for coating delamination depends on the Ea of UV absorber loss, coating systems different from the one in this study will need to be investigated separately. 相似文献
16.
The adsorption and dissociation of molecular oxygen on spinel CuCr2O4 (100) surface were carried out by first-principles calculations based on density functional theory (DFT). The calculated results indicate that the Cr site is most favorable for atomic oxygen adsorption, with an adsorption energy of 402.8 kJ/mol. For molecular oxygen adsorption, there are three types of favorable interaction modes: O2 forms bonds with the Cu site or O2 binds to two Cr sites or O2 interacts with both Cu and Cr sites simultaneously. The lowest activation energy (Ea = 35.4 kJ/mol) was found through exploring possible reaction pathways for O2 dissociation. The relationship between Ea and reaction enthalpy (ΔH) for O2 dissociation adsorption reactions fits Brønsted-Evans-Polanyi (BEP) behavior. 相似文献
17.
E. W. Meijer 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2199-2208
Using a model reaction we have studied the crosslinking chemistry of hydroxy-functional polymers and hexamethoxymethylmelamine. The transetherification of optically active monofunctional alcohols and hexamethoxymethylmelamine was monitored with polarimetry and 1H-NMR. The reaction rate constants for both the forward (k1) and the backward (k?1) reaction of the sulphonic-acid-catalyzed alcoholysis were determined. Primary and secondary alcohols showed the same reaction rate and activation energy (Ea = 96 kJ/mol) for the forward reaction. However, the backward reaction in the equilibrium is considerably slower for primary alcohols than for secondary alcohols, with activation energies of Ea = 96 and 79 kJ/mol, respectively. When amine salts of sulphonic acids are used as catalysts, the Ea is increased from 97 to 116 kJ/mol in the case of primary alcohols. In concentrated aprotic solutions the reaction order in acid is 2.5. The same order in acid is found for the alcoholysis of acetaldehyde diethyl acetal. All the results strongly support the statement that the crosslinking reaction proceeds by an Sn-1 mechanism. The results of this model study are compared with results obtained in network-forming reactions. The important role of the evaporation of the condensation product methanol is discussed. 相似文献
18.
Yuan‐Xin Wei Hai‐Bei Li Jian‐Bo Cheng Wen‐Zuo Li Qing‐Zhong Li 《International journal of quantum chemistry》2017,117(23)
The potential applications of tetrel bonds involving π‐molecules in crystal materials and biological systems have prompted a theoretical investigation of the strength of π···σ‐hole tetrel bond in the systems with acetylene and its derivatives of CH3, AuPH3, Li, and Na as well as benzene as the π electron donors. A weak tetrel bond (ΔE < 15 kJ/mol) is found between acetylene and tetrel donor molecule TH3F (T = C, Si, Ge, Sn, and Pb). All substituents strengthen the π tetrel bond, but the electron‐donating sodium atoms have the largest enhancing effect and the interaction energy is up to about 24 kJ/mol in C2Na2‐CH3F. The electron‐donating ability of the AuPH3 fragment is intermediate between the methyl group and alkali metal atom. The origin of the stability of the π tetrel‐bonded complex is dependent on the nature of the tetrel donor and acceptor molecules and can be regulated by the substituents. 相似文献
19.
Theoretical Study on Intermolecular Interactions and Thermodynamic Properties of Dimethylnitroamine Clusters 总被引:2,自引:0,他引:2
Ab initio SCF and Mφller-Plesset correlation correction methods in combination with counterpose procedure for BSSE correction have been applied to the theroetical studying of dimethylnitroamine and its dimers and trimers.Three optimized stable dimers and two trimers have been obtained.The corrected binding energies of the most stable dimer and trimer were predicted to be -24.68kJ/mol and -47.27kJ/mol,respectively at the MP2/6-31G^*//HF/6-31G^* level.The proportion of correlated interation energies to their total interaction energies for all clusters was at least 29.3 percent,and the BSSE of ΔE(MP2) was at least 10.0kJ/mol.Dispersion and/or electrostatic force were dominant in all clusters.There exist cooperative effects in both the chain and the cyclic trimers.The vibrational frequencies associated with N-O stretches or wags exhibit slight red shifts,but the modes associated with the motion of hydrogen atoms of the methyl group show somewhat blue shifts with respect to those of monomer.Thermodynamic properties of dimethylnitroamine and its clusters at different temperatures have been calculated on the basis of vibrational analyses.The changes of the Gibbs free energies for the aggregation from monomer to the most stable dimer and trimer were predicted to be 14.37kJ/mol and 30.40kJ/mol,respectively,at 1 atm and 298.15K. 相似文献
20.
Bart Dervaux Thomas Junkers Maria Schneider‐Baumann Filip E. Du Prez Christopher Barner‐Kowollik 《Journal of polymer science. Part A, Polymer chemistry》2009,47(23):6641-6654
Pulsed laser polymerization (PLP) coupled to size exclusion chromatography (SEC) is considered to be the most accurate and reliable technique for the determination of absolute propagation rate coefficients, kp. Herein, kp data as a function of temperature were determined via PLP‐SEC for three acrylate monomers that are of particular synthetic interest (e.g., for the generation of amphiphilic block copolymers). The high‐Tg monomer isobornyl acrylate (iBoA) as well as the precursor monomers for the synthesis of hydrophilic poly(acrylic acid), tert‐butyl acrylate (tBuA), and 1‐ethoxyethyl acrylate (EEA) were investigated with respect to their propagation rate coefficient in a wide temperature range. By application of a 500 Hz laser repetition rate, data could be obtained up to a temperature of 80 °C. To arrive at absolute values for kp, the Mark‐Houwink parameters of the polymers have been determined via on‐line light scattering and viscosimetry measurements. These read: K = 5.00 × 105 dL g−1, a = 0.75 (piBoA), K = 19.7 × 105 dL g−1, a = 0.66 (ptBA) and K = 1.53 × 105 dL g−1, a = 0.85 (pEEA). The bulky iBoA monomer shows the lowest propagation rate coefficient among the three monomers, while EEA is the fastest. The activation energies and Arrhenius factors read: (iBoA): log(A/L mol−1 s−1) = 7.05 and EA = 17.0 kJ mol−1; (tBuA): log(A/L mol−1 s−1) = 7.28 and EA = 17.5 kJ mol−1 and (EEA): log(A/L mol−1 s−1) = 6.80 and EA = 13.8 kJ mol−1. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6641–6654, 2009 相似文献