摘要:

AbstractPolymerization of acrylamide initiated with a pinacol–ceric ion redox system was investigated. The polymer obtained was found to contain one cerium atom in a polymer molecule. It was considered that the cerium atom was introduced into the polymer molecule by the termination reaction as there is no cerium atom in the initiating radical in the present system. A similar termination reaction was attained by ferric ion but not by cerous ion. The metal ion was considered to terminate the polymerization to form a stable polymer. Some considerations on the structure of the reaction product relating to the polymerization mechanism were discusse

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081001

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractContinuously uniform latices were applied in an experimental study of molecular weight development in constant‐rate styrene emulsion polymerization. The formulation around which this study centered exhibited Smith‐Ewart, case II kinetics from zero to about 60% conversion with a constant conversion rate of 13 ± 2%/hr and a final particle diameter of 2300 Å. By utilizing an inhibitor perturbation technique, we directly confirmed that free radicals are generated from K2S2O8by a first‐order process with 100% efficiency. We further confirmed that, in contrast to current theories for constant rate polymerization, both the instantaneous values ofM̄nandM̄vmay increase 6‐ to 9‐fold. Little or no chain branching is evidenced. We interpret these findings to mean that radicals are not utilized with 100% efficiency in emulsion p

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081002

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractA series of electron acceptor polyesters was prepared from 5‐nitroisophthalic, nitroterephthalic, and 4,6‐dinitroisophthalic acids. Those polymers prepared at high molecular weight were tough, soluble, linear materials of well‐defined structure. These materials were mixed with electron‐donor polymers based on aryliminodiethanols where the aryl group was phenyl,p‐anisyl, 2,5‐dimethoxyphenyl, and 3,4,5‐trimethoxyphenyl. The effects of the mixtures on the mechanical, spectral, viscometric, and conductive properties were studied and compared to the compo

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081003

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractPoly‐2‐oxazolidones were synthesized by the 1,3‐cycloaddition of bisglycidyl ethers to diisocyanates with the use ofN,N‐dimethylformamide and lithium chloride as solvent and catalyst, respectively. A variety of arylene and alkylene diisocyanates and coreactant bisepoxides were used in the polymer‐forming reaction. The polymers, obtained in high yield, were generally soluble in methylene dichloride, chloroform,N,N‐dimethylformamide, and dimethyl sulfoxide. They had intrinsie viscosities up to 0.42 dl/g and could be cast into films. In several cases molecular weights were determined by vapor pressure osmometry. The poly‐2‐oxazolidone based upon 1,6‐hexamethylene diisocyanate and the bisglycidyl ether of isopropylidene diphenol gave the highest molecular weight. Confirmation that the base unit of the polymers contains the 2‐oxazolidone ring was obtained by elemental analysis, infrared and NMR spectroscopy. The poly‐2‐oxazolidones synthesized were found to be amorphous by x‐ray diffraction. Thermogravimetric analyses indicated that a majority of the poly‐2‐oxazolidones were stable in dry air up to 300°C. In a number of casesTg's were also determined by using dif

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081004

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe polymerization of isobutyl vinyl ether by the VCln–AIR3system was carefully studied. The vanadium components were prepared by the reaction between VCl4and AlEt3orn‐BuLi as a reducing agent. VCl3·LiCl and VCl2·2LiCl are the effective catalysts for the stereospecific polymerization of isobutyl vinyl ether. When VCl3·LiCl is combined with AlR3, a new catalytic system is formed. The effect of the preparative conditions of the various vanadium component in the AlR3–VClnsystem shows that the effective vanadium component is trivalent. In the polymerization by VCl3·LiCl–Al (i‐Bu)3system, a change of the polymerization mechanism may occur at Al(i‐Bu)3/VCl3·LiCl ratio at around 5. When the ratio is lower than 5, a cationic polymerization by VCl3·LiCl takes place predominantly, while at ratios higher than 5, it is suggested that the polymerization proceeds by means of a VCl3·LiClA–Al(i‐Bu)3complex by a coordinated anionic mechanism. The polymers obtained by these catalysts are highly crystalline. Styrene was also polymerized by using the same catalysts. VCl3·LiCl and VCl3·LiCl–THF complex yielded amorphous polymer by cationic polymerization. When VCl3·LiCl was combined with 6 mole‐eq of Al(i‐Bu)3, the resulting polystyrene was highly crystalline and had an isotactic structure, while the VCl2·2LiCl–Al(i‐Bu)3(1:6) system yielded traces of polymer of extremely low stereoregularity. The results indicate that the effective vanadium component at Al/V ≧ 6 is trivalent and that the

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081005

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe addition reaction of styrene oxide (StO) with silk fibroin was studied in the presence of various salts in different solvents at 45–75°C. Some water was required to make StO react with silk padded with various salt solutions. The reaction rate increased with the salt concentration and reached a maximum value at a certain concentration of the salt. Padding with solutions of thiosulfate, cyanide, thiocyanate, bicarbonate, or carbonate resulted in high add‐ons (to 65 mole/105g) and low solubilities in HCl and NaOH aqueous solutions. The weight gains increased with the epoxide concentration and reached a constant value at a certain concentration of StO solution in ethanol, while they decreased slightly with epoxide concentration over 10% of StO solution inn‐hexane. Histidine, lysine, arginine, tyrosine, and aspartic and glutamic acids were found to react. The reaction rate decreased with increasing solubility parameter of the solvent used, reached a minimum value about at 10 or at the solubility parameter of the epoxide, and then increased with the parameter. The StO–silk reaction may depend on the distribution of StO between aqueous salt and an organic solvent phases, and on the swelling of silk fiber in different aqueous salt solutions or in various organic solvents. The mechanism for this epoxide‐silk reaction and the reactivity difference between StO and phenyl glycidyl ether toward silk fibroin are discussed in the light of the observed

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081006

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractMonolayer balance techniques have been used to study “two‐dimensional” polymerization of monomolecular films of octadecyl methacrylate and a divinyl ester. Polymerizations were initiated with ultraviolet radiation, and reaction rates and properties of the product evaluated from surface pressure–area isotherms. The polymerization rate of the acrylate in argon is linear up to 70% conversion; the product obtained in this way exhibits an isotherm which may reflect the packing and orientation of the starting monolayer. Rate data for the divinyl system—the product of which should be a sheet‐like, two‐dimensional analog of a network system—exhibit no u

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081007

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractIn copolymerization, Arlman's equation was modified to\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {1 + {{{\rm f}_1 } \mathord{\left/ {\vphantom {{{\rm f}_1 } {r_1 }}} \right. \kern-\nulldelimiterspace} {r_1 }}} \right)\left( {{{1 + 1} \mathord{\left/ {\vphantom {{1 + 1} {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}} \right){{k_{tab} } \mathord{\left/ {\vphantom {{k_{tab} } {\bar k_{tab} = {{K_1 + K_2 } \mathord{\left/ {\vphantom {{K_1 + K_2 } {r_1 r_2 + {{K_3 f_1 } \mathord{\left/ {\vphantom {{K_3 f_1 } {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}} \right. \kern-\nulldelimiterspace} {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}}}} \right. \kern-\nulldelimiterspace} {r_1 r_2 + {{K_3 f_1 } \mathord{\left/ {\vphantom {{K_3 f_1 } {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}} \right. \kern-\nulldelimiterspace} {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}}}}}} \right. \kern-\nulldelimiterspace} {\bar k_{tab} = {{K_1 + K_2 } \mathord{\left/ {\vphantom {{K_1 + K_2 } {r_1 r_2 + {{K_3 f_1 } \mathord{\left/ {\vphantom {{K_3 f_1 } {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}} \right. \kern-\nulldelimiterspace} {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}}}} \right. \kern-\nulldelimiterspace} {r_1 r_2 + {{K_3 f_1 } \mathord{\left/ {\vphantom {{K_3 f_1 } {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}} \right. \kern-\nulldelimiterspace} {r_1 + {{K_4 } \mathord{\left/ {\vphantom {{K_4 } {r_2 f_1 }}} \right. \kern-\nulldelimiterspace} {r_2 f_1 }}}}}}}} $$\end{document}wherektabis an apparent cross‐termination rate constant depending on a ratiof1= [A]/[B], andKz(x= 1, 2, 3, 4) is the ratio of each cross‐termination rate constant depending on the penultimate unit to the geometric meanK̄tabof two termination rate constants in homopolymerizations. The calculated values of (K1+K2/r1r2) by using this equation were related toK1+K2/r1r2= 18/

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081008

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractDiphenylsulfone (DPSO2) was found to react with an equimolar amount of potassium in tetrahydrofuran (THF), dimethoxyethane (DME), or diglyme (DG) at reflux or an elevated temperature to yield a reddish‐black solution, giving an electron spin resonance (ESR) signal. The signal was attributed to the formation of relatively labile DPSO2anion radical. The apparent effects of solvents on the reactivity of DPSO2with potassium depended on the polarities and the solvation powers: benzene ≅ toluene ≅ dioxane ≪ tetrahydrofuran

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081009

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe curing reaction of polyester fumarate with styrene was investigated with a differential scanning calorimeter (DSC) operated isothermally. The change in rate of cure was followed over the whole range of conversion. The rate of cure is accelerated by the gel effect to about ten to fifty times the rate of model copolymerization of diethyl fumarate with styrene. This autoacceleration is much enhanced for systems with higher crosslinking densities and at lower temperatures. The results confirm that both termination and propagation steps of the curing reaction are controlled by diffusion of polymeric segments and monomer molecules over almost the whole range of conversion. The final extent of conversion is short of completion for isothermal cure and even for postcure of polyester fumarate with styrene because of crosslink formation. The final conversion of isothermal cure decreases with increasing crosslinking density and shows a maximum with increasing reaction temperature. This temperature dependency of the final conversion is caused by the difference in the activation energies for two propagation rate constantskpfandkps, which were evaluated to be 7–10 and 5–8 kcal/mole, respectively, for the intermediate stage of the curing react

ISSN:0449-296X    

DOI:10.1002/pol.1970.150081010

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY