ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616335

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616336

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616337

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractIsotactic polyvinyl isobutyl ether was obtained using chromium trioxide as catalyst at elevated temperatures, even at 80°C. Polymerization was carried out in a heterogeneous system. A stirring device to mill the catalyst is necessary to obtain polymer which has a high crystalline fraction. The crystalline fraction, whose melting point is over 140°C., was separated by extracting the amorphous portion with methyl ethyl ketone, and was between 20 and 30% weight of the total polymer. In this connection, other transition metal oxides were examined but chromium oxides of lower valence than 6 had little activity toward polymerization. Moreover, molybdenum trioxide, vanadium pentoxide, and nickel monoxide showed activity toward polymerization, but the polymers obtained with these catalysts had no crystalline fractio

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616304

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616338

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616339

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractDie Untersuchung der Richtungsabhängigkeit der Elektronenresonanzlinien von bestrahltem orientertem Polypropylen erlaubt eine relativ sichere Bestimmung der gebildeten Makroradikale. Es wurde festgestellt, dass bei 77°K bei der Bestrahlung vorwiegend ein Radikal der Formentsteht, während bei Zimmertemperatur vermutlich ein Radikal vom Allyltyp der Struktursich durch hohe Lebensdauer auszeichn

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616305

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616342

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractInvestigation of the polymerization process was carried out on emulsions placed in water‐thermostatted flasks. The temperatures of the central part of the flask and of the thermostat were measured with the aid of thermocouples. The heat balance of the reaction system under investigation is given by the differential equation:\documentclass{article}\pagestyle{empty}\begin{document}$$ {{dq} \mathord{\left/ {\vphantom {{dq} {d\tau = Cd{{(\Delta T)} \mathord{\left/ {\vphantom {{(\Delta T)} {d\tau + K\Delta T}}} \right. \kern-\nulldelimiterspace} {d\tau + K\Delta T}}}}} \right. \kern-\nulldelimiterspace} {d\tau = Cd{{(\Delta T)} \mathord{\left/ {\vphantom {{(\Delta T)} {d\tau + K\Delta T}}} \right. \kern-\nulldelimiterspace} {d\tau + K\Delta T}}}} $$\end{document}The quantity of heatdqevolved during the timedτ in the course of the reaction raises the temperature of the system byd(ΔT), part of the heat being removed by the cooling bath. The constantKexpresses the overall heat transfer, andCis the overall heat capacity of the polymerizing system. The left side of eq. (1) contains the time function of the reaction. We investigated the cases for zero‐, first‐, and second‐order reactions and derived the corresponding solution of the basic equation for ΔT=f(τ). For a zero‐order reaction:\documentclass{article}\pagestyle{empty}\begin{document}$$ {{\Delta T = (\Delta HK_0 } \mathord{\left/ {\vphantom {{\Delta T = (\Delta HK_0 } {K)(1 - e^{ - K\tau /C} ) + \Delta T_p e^{ - K\tau /C} }}} \right. \kern-\nulldelimiterspace} {K)(1 - e^{ - K\tau /C} ) + \Delta T_p e^{ - K\tau /C} }} $$\end{document}For a first‐order reaction:\documentclass{article}\pagestyle{empty}\begin{document}$$ {{\Delta T = [\Delta HK_1 M_p } \mathord{\left/ {\vphantom {{\Delta T = [\Delta HK_1 M_p } {(K - CK_1 )](e^{ - K_{1\tau } } - e^{ - K_\tau /C} ) + \Delta T_p e^{ - K_\tau /C} }}} \right. \kern-\nulldelimiterspace} {(K - CK_1 )](e^{ - K_{1\tau } } - e^{ - K_\tau /C} ) + \Delta T_p e^{ - K_\tau /C} }} $$\end{document}For a second‐order reaction:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \Delta T = \left( {{{\Delta HM_p } \mathord{\left/ {\vphantom {{\Delta HM_p } C}} \right. \kern-\nulldelimiterspace} C}} \right)\left[ {e^{ - K{\tau \mathord{\left/ {\vphantom {\tau C}} \right. \kern-\nulldelimiterspace} C}} - {1 \mathord{\left/ {\vphantom {1 {\left( {M_p K_{2\tau } + 1} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {M_p K_{2\tau } + 1} \right)}}} \right] + \Delta T_p e - K{\tau \mathord{\left/ {\vphantom {\tau C}} \right. \kern-\nulldelimiterspace} C} \\ + \left( {{{\Delta HK} \mathord{\left/ {\vphantom {{\Delta HK} C}} \right. \kern-\nulldelimiterspace} C}^2 K_2 } \right)e^{ - K\left[ {{{\left( {MpK_2^\tau + 1} \right)} \mathord{\left/ {\vphantom {{\left( {MpK_2^\tau + 1} \right)} {CMpK_2 }}} \right. \kern-\nulldelimiterspace} {CMpK_2 }}} \right]} \left\{ {\bar E_i \left[ {\left( {{K \mathord{\left/ {\vphantom {K {CMpK_2 }}} \right. \kern-\nulldelimiterspace} {CMpK_2 }}} \right)\left( {MpK_2 + 1} \right)} \right] - \bar E_i \left( {{K \mathord{\left/ {\vphantom {K {CMp\left( {K_2 } \right)}}} \right. \kern-\nulldelimiterspace} {CMp\left( {K_2 } \right)}}} \right)} \right\} \\ \end{array} $$\end{document}K0,K1, andK2in eqs. (2), (3), and (4) are the zero‐, first‐, and second‐order rate constants, respectively, ΔHis the heat of polymerization;Mpand ΔTp, the number of moles and the temperature difference at the start of the reaction, respectively; the difference\documentclass{article}\pagestyle{empty}\begin{document}$$ \bar E_i (x) = \smallint ^x - \infty ({{e^x } \mathord{\left/ {\vphantom {{e^x } {x)dx}}} \right. \kern-\nulldelimiterspace} {x)dx}} $$\end{document}is the so‐called reduced exponential integral. The constantsKandCmay be calculated from the experimental curve ΔT=f(τ) and from two–three value for the degree of conversion in the course of polymerization. From this any number of values may be obtained for the degrees of conversion with time. For such values we derived the relation\documentclass{article}\pagestyle{empty}\begin{document}$$ \log ({{\Delta p} \mathord{\left/ {\vphantom {{\Delta p} {\Delta \tau ) = i\log M + \log K_i }}} \right. \kern-\nulldelimiterspace} {\Delta \tau ) = i\log M + \log K_i }} $$\end{document}where Δp/Δτ is the overall reaction rate expressed by the increase with time of the amount of polymer. Expression (5) has a convenient linear plot, and from the slope and the intercept on the ordinate axis the reaction orderiand the rate constantKimay be determined directly. The theory was applied to a kinetic study of the emulsion polymerisation and styrene and chloroprene. An aqueous solution of potassion laurate served as emulsifier and potassium persulfate as initiator. The reaction was carried out at 40°C. The method permits accurate determination of the overall polymerization rate and of the monomer concentration in the latex particles. In a number of experiments the reaction rates and quantity of latex particles as function of initiator concentration were determined. The results were compared with conclusions following from the Smith‐Ewart quantitative theory of emulsion polymerization. The constants of chain growth of polystyren

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616306

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe diffusion of styrene vapor in ethyl cellulose film has been studied as a function of styrene solubility in the film at 50°C. Methods and data are presented for determining the equilibrium solubility of styrene in ethyl cellulose as a function of vapor pressure at 50°C. The permeation rates of styrene vapor through 3‐mil film were determined under steady state conditions for various pressures of pure styrene vapor on one side of the film and vacuum on the other side. From a plot of permeation rates versus styrene solubility the diffusion coefficient was calculated as a function of concentration. Measurements made over a concentration range of 0 to 0.7 g. styrene/cm.3of unswollen film show that the diffusion coefficient first increases rapidly with concentration, then goes through a maximum, and finally levels off at 10−7cm.2/sec. In the limited range of 0.06 to 0.10 g./cm.3the diffusion coefficient varies exponentially with concentration as has been reported for other systems in a similar range. However, such a functionality does not represent the present system over a broad concentration range. These results, if generally applicable to other systems, indicate that the nature of the diffusion process for organic vapors in polymers may be considerably more complicated than formerly sup

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616307

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY