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1964 Volume 6 Issue 6
1964, 6(6): 415-420
Abstract:
This paper presents the successful results obtained from redox initiated polymeriza-tion of acrylonitrile in concentrated aqueous solution of sodium thiocyanate．The redox systems studied were tertiary-butyl hydroperoxide (TBH) with triethanolamine (TEA)，di-ethanolamine (DEA)，mono-ethanolamine (MEA) and N，N’-dimethylaniline (DMA) res-pectively．In the case of TBH-TEA with mole ratio 1：1 in combination，conversion in one hour was around 90％ and the average molecular weight of the polymer obtained was around 85，000． It was found that the polymerization rate and conversion percentage for different redox systems were in the following order：TBH．TEA>TBH-DEA>TBH-MEA，and the order of average molecular weight of polymer obtained was just in the reverse．Both the rate of polymerization and the maximum conversion percentage increased with increase either in TBH or amine concentration． In the case of TBH-DMA，the maximum conversion obtained was around 60％，the rate of polymerization also jncreased with increase in the mole ratio of DMA／TBH，but the ultimate conver-sion percentage decreased in comparison with the case of the benzoyl peroxide (BPO)-DMA system for st3rrene as monomer．A possible reaction mechanism of TBH-amine system was then suggested．
This paper presents the successful results obtained from redox initiated polymeriza-tion of acrylonitrile in concentrated aqueous solution of sodium thiocyanate．The redox systems studied were tertiary-butyl hydroperoxide (TBH) with triethanolamine (TEA)，di-ethanolamine (DEA)，mono-ethanolamine (MEA) and N，N’-dimethylaniline (DMA) res-pectively．In the case of TBH-TEA with mole ratio 1：1 in combination，conversion in one hour was around 90％ and the average molecular weight of the polymer obtained was around 85，000． It was found that the polymerization rate and conversion percentage for different redox systems were in the following order：TBH．TEA>TBH-DEA>TBH-MEA，and the order of average molecular weight of polymer obtained was just in the reverse．Both the rate of polymerization and the maximum conversion percentage increased with increase either in TBH or amine concentration． In the case of TBH-DMA，the maximum conversion obtained was around 60％，the rate of polymerization also jncreased with increase in the mole ratio of DMA／TBH，but the ultimate conver-sion percentage decreased in comparison with the case of the benzoyl peroxide (BPO)-DMA system for st3rrene as monomer．A possible reaction mechanism of TBH-amine system was then suggested．
1964, 6(6): 421-427
Abstract:
1964, 6(6): 428-437
Abstract:
Samples of PAN were treated separately in vacuum and in atmospheres of ammonia and air，at each of the temperature，200°，250°，300°，350°，and 400℃，one after an-other for a definite length of time．Before and after each step of treatment，the weight of the sample，its infra-red spectrum，its solubilities in cone．sulphuric acid and in glacial acetic acid as well as the ultra—violet spectrum of its solution in cone．sulphuric acid were examined．The conditions of treatment are given in Table 1，and the results，in Figs．1—4．From a careful examination of these measurements, it was discovered that different schemes of mechanism have to be assigned for the reactions taking place in the different atmospheres and also at different temperatures．At lower temperatures，the first stage reactions taking place in vacuum(200°) and in atmospheres of ammonia (≤180°) and air (200℃) are considered to be the formation of the respective structure units：(Vlb)，(N1) and (O1)．After this，cyclization follows and it will proceed with tIle formation of (V2)，(N2) and (O2) one after another．But as soon as any two of the following groups：C—X，C=NH，C—NH2，C=O should come to meet at neighbouring positions，cyclization will be immediately stopped． Moreover，the different orientations of the CN groups with each other in atactic samples will also prevent cyclization to proceed further．With the increase of temperature，the rate of cyclization may be accelerated，and be-sides，additional cyclization may be obtained by the splitting of NH3 from the neighbour-ing C=NH，C-NH2 groups．But here again，the increased cyclization will be limited by the C—X and C=O groups．and by the atactic nature of the sample．Each of the molecules thus obtained will still be composed of a series of small units of polynuclear pyridine rings of different lengths and orientations，irregularly scattered along a carbon chain，[(V3) and (O3)]． The schemes of reaction mechanism suggested above agree nicely with all of the chief characteristics of our experimental facts given in Figs．1—4．and also with the low values of semiconductivity of the products。which are generally of the order of 10-9—10-7 Q-1 CM-1，obtained from measurements at 20°一300℃．From these, it will be seen that no large extended polynuclear pyridine systems of uniform composition and regular struc-ture could be formed as would be expected from the simple theories suggested by pre-vious authors．And hence the explanation made by some writers for the semiconductive properties of the products based on the formation of such an ideal structure is considered to be inadequate．
Samples of PAN were treated separately in vacuum and in atmospheres of ammonia and air，at each of the temperature，200°，250°，300°，350°，and 400℃，one after an-other for a definite length of time．Before and after each step of treatment，the weight of the sample，its infra-red spectrum，its solubilities in cone．sulphuric acid and in glacial acetic acid as well as the ultra—violet spectrum of its solution in cone．sulphuric acid were examined．The conditions of treatment are given in Table 1，and the results，in Figs．1—4．From a careful examination of these measurements, it was discovered that different schemes of mechanism have to be assigned for the reactions taking place in the different atmospheres and also at different temperatures．At lower temperatures，the first stage reactions taking place in vacuum(200°) and in atmospheres of ammonia (≤180°) and air (200℃) are considered to be the formation of the respective structure units：(Vlb)，(N1) and (O1)．After this，cyclization follows and it will proceed with tIle formation of (V2)，(N2) and (O2) one after another．But as soon as any two of the following groups：C—X，C=NH，C—NH2，C=O should come to meet at neighbouring positions，cyclization will be immediately stopped． Moreover，the different orientations of the CN groups with each other in atactic samples will also prevent cyclization to proceed further．With the increase of temperature，the rate of cyclization may be accelerated，and be-sides，additional cyclization may be obtained by the splitting of NH3 from the neighbour-ing C=NH，C-NH2 groups．But here again，the increased cyclization will be limited by the C—X and C=O groups．and by the atactic nature of the sample．Each of the molecules thus obtained will still be composed of a series of small units of polynuclear pyridine rings of different lengths and orientations，irregularly scattered along a carbon chain，[(V3) and (O3)]． The schemes of reaction mechanism suggested above agree nicely with all of the chief characteristics of our experimental facts given in Figs．1—4．and also with the low values of semiconductivity of the products。which are generally of the order of 10-9—10-7 Q-1 CM-1，obtained from measurements at 20°一300℃．From these, it will be seen that no large extended polynuclear pyridine systems of uniform composition and regular struc-ture could be formed as would be expected from the simple theories suggested by pre-vious authors．And hence the explanation made by some writers for the semiconductive properties of the products based on the formation of such an ideal structure is considered to be inadequate．
1964, 6(6): 438-445
Abstract:
Based on Kargin's simplified molecular model, a new linear relation between mole-cular weight and flow temperature is proposed, In M = AE/RTf.With fractionatedpolymethylmethacrylate as testing sample, both cold-molded and hot-molded, the experimental results are in accord with the above relation under different loading conditions. The effects of sample molding and loading weight on the temperature-deformation properties are discussed.
Based on Kargin's simplified molecular model, a new linear relation between mole-cular weight and flow temperature is proposed, In M = AE/RTf.With fractionatedpolymethylmethacrylate as testing sample, both cold-molded and hot-molded, the experimental results are in accord with the above relation under different loading conditions. The effects of sample molding and loading weight on the temperature-deformation properties are discussed.
1964, 6(6): 446-452
Abstract:
A study of the effect of temperature on the molecular weight of polyphenyl-acetylene in the thermal polymerization of phenylacetylene for 1．5，6 and 1 0 hours has been undertaken．The results obtained showed．in the temperature range between 150°and 500°，the average molecular weight of the polymer gradually decreased as the tem-perature increased，indicating that degradation of the polymer occurred at higher tempera-ture．The infrared spectra showed that the absorption bands of the polymer obtained at 400。were smaller than that of the polymer obtained at 200°，while the polymer ob-mined at 500°showed no noticeable absorption bands but rather a continuous absorption at an enhanced level(“background effect”)，The ratio of carbon and hydrogen content of the polymers also increased as the temperature of polymerization was raised．These results，in conjunction with the fact that the polymers obtained above 300°showed a dis-tinct fluorescence in solution，are taken to indicate that polyphenylacetylene underwent structural changes at higher temperature and there was，besides degradation to sinail frag-ments，probably also cyclizadon，dehydrogenation，and aromatization，thus converting the chain structure to condensed ring system and thence to three dimensional conjugated sys-tem．The determination of the electron spin resonance of the polymers showed that the concentration of free radicals in the polyphenylacetylene increased in the following order：300°polymer<400°polymer<500°polymer．
A study of the effect of temperature on the molecular weight of polyphenyl-acetylene in the thermal polymerization of phenylacetylene for 1．5，6 and 1 0 hours has been undertaken．The results obtained showed．in the temperature range between 150°and 500°，the average molecular weight of the polymer gradually decreased as the tem-perature increased，indicating that degradation of the polymer occurred at higher tempera-ture．The infrared spectra showed that the absorption bands of the polymer obtained at 400。were smaller than that of the polymer obtained at 200°，while the polymer ob-mined at 500°showed no noticeable absorption bands but rather a continuous absorption at an enhanced level(“background effect”)，The ratio of carbon and hydrogen content of the polymers also increased as the temperature of polymerization was raised．These results，in conjunction with the fact that the polymers obtained above 300°showed a dis-tinct fluorescence in solution，are taken to indicate that polyphenylacetylene underwent structural changes at higher temperature and there was，besides degradation to sinail frag-ments，probably also cyclizadon，dehydrogenation，and aromatization，thus converting the chain structure to condensed ring system and thence to three dimensional conjugated sys-tem．The determination of the electron spin resonance of the polymers showed that the concentration of free radicals in the polyphenylacetylene increased in the following order：300°polymer<400°polymer<500°polymer．
1964, 6(6): 453-458
Abstract:
Rates of emulsion polymerization of styrene and α，β，β-trifluorostvrene were measured dilatometrically in the presence of different emulsifiers．The following emulsifiers were used： fluorocarbon carboxylates，H(CF2)nCOOK，n=6，8，10 and F2CI(CFCICF2)3 COOK，and hydrocarbon carboxylates H(CH2)nCOOK，n=7， 11．Polymerization rates of α，β，β-trifluorostyrene are lower than that of styrene．With hydrocarbon carboxy-lates as emulsifiers，polymerization rates of styrene and α，β,β-trifluorostyrene are both greater than that with fluorocarbon carboxylates．In the ω-hydroperfluorocarboxylate series，H-(CF2)nCOOK n=6，8，10，the n=8 salt gave the best result．
Rates of emulsion polymerization of styrene and α，β，β-trifluorostvrene were measured dilatometrically in the presence of different emulsifiers．The following emulsifiers were used： fluorocarbon carboxylates，H(CF2)nCOOK，n=6，8，10 and F2CI(CFCICF2)3 COOK，and hydrocarbon carboxylates H(CH2)nCOOK，n=7， 11．Polymerization rates of α，β，β-trifluorostyrene are lower than that of styrene．With hydrocarbon carboxy-lates as emulsifiers，polymerization rates of styrene and α，β,β-trifluorostyrene are both greater than that with fluorocarbon carboxylates．In the ω-hydroperfluorocarboxylate series，H-(CF2)nCOOK n=6，8，10，the n=8 salt gave the best result．
1964, 6(6): 459-466
Abstract:
The molecular weight distribution by sedimentation velocity measurements and hydro-static pressure correction for the sedimentation coefficient of the floating system poly-dimethylsiloxane—bromocyclohexane at θ-temperature (28℃) have been studied．A new method for the experimental evaluation of the hydrostatic pressure correction of the sedi-mentation coefficient is proposed．By using different quantities of the solution added to the sedimentation cell，so as to give different heights of the liquid column，it is possible to determine the influence of the hydrostatic pressure on the sedimentation coefficient．Assuming a linear relation between the sedimentation coefficient and the hydrostatic pressure, the authors found that the pressure coefficient of the system studied is 1．44×10-3 (atm)-1 for hydrostatic pressures less than 200 atm．From the distribution of sedimentation coefficients，and the values of Mw [n]θ，and [n]toluene of a polydimethylsiloxane fraction the monodisperse relationships s-M，[n]θ-M，in the θ-solvent at 28℃ and [n]toluene 一M at 25℃ are obtained.
The molecular weight distribution by sedimentation velocity measurements and hydro-static pressure correction for the sedimentation coefficient of the floating system poly-dimethylsiloxane—bromocyclohexane at θ-temperature (28℃) have been studied．A new method for the experimental evaluation of the hydrostatic pressure correction of the sedi-mentation coefficient is proposed．By using different quantities of the solution added to the sedimentation cell，so as to give different heights of the liquid column，it is possible to determine the influence of the hydrostatic pressure on the sedimentation coefficient．Assuming a linear relation between the sedimentation coefficient and the hydrostatic pressure, the authors found that the pressure coefficient of the system studied is 1．44×10-3 (atm)-1 for hydrostatic pressures less than 200 atm．From the distribution of sedimentation coefficients，and the values of Mw [n]θ，and [n]toluene of a polydimethylsiloxane fraction the monodisperse relationships s-M，[n]θ-M，in the θ-solvent at 28℃ and [n]toluene 一M at 25℃ are obtained.
1964, 6(6): 467-473
Abstract:
The θ-compositions at 25℃ of polydimethylsiloxane for the binary solvent systems：ethyl benzene-diethyl phthalate and heptane-dioxane were determined by the precipitation threshold method of Elias．They were further confirmed by light scattering measurements to give A2=O and by the intrinsic viscosity-molecular weight relationships to give a=1／2．Weight average molecular weights of eight fractions of polydimethylsiloxane were deter-mined by light scattering in toluene and intrinsic viscosities of these fractions were mea-sured in the above mentioned θ-solvents at 25℃．The data fit the following equations.
The θ-compositions at 25℃ of polydimethylsiloxane for the binary solvent systems：ethyl benzene-diethyl phthalate and heptane-dioxane were determined by the precipitation threshold method of Elias．They were further confirmed by light scattering measurements to give A2=O and by the intrinsic viscosity-molecular weight relationships to give a=1／2．Weight average molecular weights of eight fractions of polydimethylsiloxane were deter-mined by light scattering in toluene and intrinsic viscosities of these fractions were mea-sured in the above mentioned θ-solvents at 25℃．The data fit the following equations.
1964, 6(6): 474-476
Abstract:
1964, 6(6): 477-480
Abstract:
In the presence of catalyst composed of n-butyl lithium and titanium tetrachloride in n-hexane solution in a nitrogen atmosphere the polymerization of phenylacetylene took place readily producing polyphenylacetylene in moderate yields．The polymers were partly soluble in benzene and the soluble fraction had an average molecular weight around 1100．The infrared spectra of the polymers showed that they probably have the linear conjugated polyene structure．Electrical measurements of the benzenesoluble fraction indicate a conductivity around 10-11 ohm-1·cm-1 at room temperature and a resistance-temperature relationship which is typical of semiconductors．Magnetic measurements of the same fraction show a paramagnetism of 0.2×10-6 cgs unit．
In the presence of catalyst composed of n-butyl lithium and titanium tetrachloride in n-hexane solution in a nitrogen atmosphere the polymerization of phenylacetylene took place readily producing polyphenylacetylene in moderate yields．The polymers were partly soluble in benzene and the soluble fraction had an average molecular weight around 1100．The infrared spectra of the polymers showed that they probably have the linear conjugated polyene structure．Electrical measurements of the benzenesoluble fraction indicate a conductivity around 10-11 ohm-1·cm-1 at room temperature and a resistance-temperature relationship which is typical of semiconductors．Magnetic measurements of the same fraction show a paramagnetism of 0.2×10-6 cgs unit．
1964, 6(6): 481-484
Abstract:
In this paper a new type of polymerization of benzonitrile with boron trifluoride-anisole complex catalyst system is reported．It was found that when benzonitrile was heated with boron trifluoride-anisole complex at 350°for 7 hours, trimerization and polymerization of benzonitrile took place simultanously，producing the cyclic trimer and the polymer of benzonitrile respectively．The influence of the amount of boron tri-fluoride-anisole complex used relative tO benzonitrile upon the trend of trimerization and polymerization has been studied．The infrared spectrum of the polymer of benzonitrile shows no absorption band chracteristic of the —C三N group，but absorption bands at 6.0--6.1 μand 6.3—6.4 μ，which are indicative of acyclic conjugated—C=N—linkage．This shows that the poly-met may contain the following chain structure which is a new type of conjugated polymer．
In this paper a new type of polymerization of benzonitrile with boron trifluoride-anisole complex catalyst system is reported．It was found that when benzonitrile was heated with boron trifluoride-anisole complex at 350°for 7 hours, trimerization and polymerization of benzonitrile took place simultanously，producing the cyclic trimer and the polymer of benzonitrile respectively．The influence of the amount of boron tri-fluoride-anisole complex used relative tO benzonitrile upon the trend of trimerization and polymerization has been studied．The infrared spectrum of the polymer of benzonitrile shows no absorption band chracteristic of the —C三N group，but absorption bands at 6.0--6.1 μand 6.3—6.4 μ，which are indicative of acyclic conjugated—C=N—linkage．This shows that the poly-met may contain the following chain structure which is a new type of conjugated polymer．
1964, 6(6): 485-486
Abstract:
The circuit for the excitation of longitudinal vibration of a fibre which was described in a previous paper is simplified. A multivibrator circuit triggered by line voltage is used so that the pulse generator is not necessary.
The circuit for the excitation of longitudinal vibration of a fibre which was described in a previous paper is simplified. A multivibrator circuit triggered by line voltage is used so that the pulse generator is not necessary.
1964, 6(6): 487-488
Abstract:
Di-(α-chloroallyl)-dimethylsilane, a new silicon-containing α-ω-diene monomer, was synthesized through coupling of dimethylsilicondichloride with α-chloroallyl-magnesium chloride in tetrahydrofuran with 84 % yield. It was then polymerized with ABN, but not with BPO, at rather low temperature (60? to a white powder polymer with softening range of 80-100°. The structure of polymer was elucidated primarily through IR spectra to be the ladder type cyclo-polymer.
Di-(α-chloroallyl)-dimethylsilane, a new silicon-containing α-ω-diene monomer, was synthesized through coupling of dimethylsilicondichloride with α-chloroallyl-magnesium chloride in tetrahydrofuran with 84 % yield. It was then polymerized with ABN, but not with BPO, at rather low temperature (60? to a white powder polymer with softening range of 80-100°. The structure of polymer was elucidated primarily through IR spectra to be the ladder type cyclo-polymer.
