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1965 Volume 7 Issue 5
1965, 7(5): 291-296
Abstract:
The temperature spectra of the dynamic mechanical properties of Nylon-6 monofila-ments of different draw ratios and with α，γ and γ+α forms of chain conformation in the crystalline region，were determined over a temperature range extending from一150°to + 170℃ by using the resonanting reed method in audio frequencies．In addition to the three internal friction peaks known in the literature，i.e. 一110℃(βα)，一40℃(β'α) and 50℃(αα)，a new loss peak at 130℃ was observed for Nylon-6 in γ-form containing monomer and oligomers．According tO the experimental results，the temperature of α-peak for samples in α-form is higher than those in γ-form，that means that chain segments in the γ-form have higher mobility than those in the a-form．The loss peak β'α was greatly enhanced when iodine was absorbed in the fibre．This supports the view that the β'α peak is connected with the motion of chain segments containing free amide groups．The β'α-peak also grows rapidly with orientation，indicating the possible breaking up of hydrogen bonds during the stret-ching process．The new internal friction peak ac was found in γ-forms only．The peak height decreased rapidly with increasing draw ratio and vanished at a draw ratio of 3.8. Experi-mental results indicate that the ac 1088 peak is due to molecular motions of the segments in the crystalline region in γ—conformation．
The temperature spectra of the dynamic mechanical properties of Nylon-6 monofila-ments of different draw ratios and with α，γ and γ+α forms of chain conformation in the crystalline region，were determined over a temperature range extending from一150°to + 170℃ by using the resonanting reed method in audio frequencies．In addition to the three internal friction peaks known in the literature，i.e. 一110℃(βα)，一40℃(β'α) and 50℃(αα)，a new loss peak at 130℃ was observed for Nylon-6 in γ-form containing monomer and oligomers．According tO the experimental results，the temperature of α-peak for samples in α-form is higher than those in γ-form，that means that chain segments in the γ-form have higher mobility than those in the a-form．The loss peak β'α was greatly enhanced when iodine was absorbed in the fibre．This supports the view that the β'α peak is connected with the motion of chain segments containing free amide groups．The β'α-peak also grows rapidly with orientation，indicating the possible breaking up of hydrogen bonds during the stret-ching process．The new internal friction peak ac was found in γ-forms only．The peak height decreased rapidly with increasing draw ratio and vanished at a draw ratio of 3.8. Experi-mental results indicate that the ac 1088 peak is due to molecular motions of the segments in the crystalline region in γ—conformation．
1965, 7(5): 297-303
Abstract:
The effects of temperature，rate of drawing，crystalline form，and the presence of oli-gomers and water in the polymer on the drawing characteristics of Nylon一6 have been studied．Experimental results indicate that the mechanism of cold drawing of Nylon一6 fibre is in agreement with Lazurkin’s relaxation theory．The authors suggest that cold ．drawing(under Tg) of polycrystalline polymer is a relaxation process of chain segments of the noncrystalline region．When the drawing temperature is higher than Tg，crystalli-zation and recrystallization begin，the relaxation process is mainly due to the segmental motion in the crystalline region．Tg and recrystallization temperature of Nylon-6 fibre are greatly reduced by the plasticizing effect of oligomer and water．Since the segmental motion is constrained by the crystalline region，the drawing characteristics of Nylon-6 fibre in a- and γ-forms are different．The effect of constraint of the more stable a-form is greater cban the meta—stable γ-form．ThUS the γ-form of Nylon-6 is favoured for the drawing of fibre．Time-temperature superposition is sucessfully applied to the drawing characteristics of Nylon-6 fibre. and the W．L．F．equation is satisfied：log aT=一43.3(T—Tg)／(374.8+T一Tg) The master curve SO obtained is valuable for the selection of technical conditions of fibre drawing．
The effects of temperature，rate of drawing，crystalline form，and the presence of oli-gomers and water in the polymer on the drawing characteristics of Nylon一6 have been studied．Experimental results indicate that the mechanism of cold drawing of Nylon一6 fibre is in agreement with Lazurkin’s relaxation theory．The authors suggest that cold ．drawing(under Tg) of polycrystalline polymer is a relaxation process of chain segments of the noncrystalline region．When the drawing temperature is higher than Tg，crystalli-zation and recrystallization begin，the relaxation process is mainly due to the segmental motion in the crystalline region．Tg and recrystallization temperature of Nylon-6 fibre are greatly reduced by the plasticizing effect of oligomer and water．Since the segmental motion is constrained by the crystalline region，the drawing characteristics of Nylon-6 fibre in a- and γ-forms are different．The effect of constraint of the more stable a-form is greater cban the meta—stable γ-form．ThUS the γ-form of Nylon-6 is favoured for the drawing of fibre．Time-temperature superposition is sucessfully applied to the drawing characteristics of Nylon-6 fibre. and the W．L．F．equation is satisfied：log aT=一43.3(T—Tg)／(374.8+T一Tg) The master curve SO obtained is valuable for the selection of technical conditions of fibre drawing．
1965, 7(5): 304-314
Abstract:
Copolyphenyl esters were prepared from tere-/iso-phthaloyl chloride and bisphenol-A by interfacial polycondensation. The interfacial saponification reaction during the course of reaction and various factors affecting the molecular weight and yield have been investigated. Based on the experimental data, some problems in connection with the reaction mechanism are discussed. The composition (tere-/iso-) of the copolyester prepared under different reaction conditions were determined by means of infrared spectra.
Copolyphenyl esters were prepared from tere-/iso-phthaloyl chloride and bisphenol-A by interfacial polycondensation. The interfacial saponification reaction during the course of reaction and various factors affecting the molecular weight and yield have been investigated. Based on the experimental data, some problems in connection with the reaction mechanism are discussed. The composition (tere-/iso-) of the copolyester prepared under different reaction conditions were determined by means of infrared spectra.
1965, 7(5): 315-321
Abstract:
A simplified method for calculating the composition of vinyl chloride—vinyl acetate copolymers has been proposed in this paper．The composition nomogram and the composi-tion distribution diagram of the copolymer containing 0.84—-0.96 mole fraction of vinyl chloride have been constructed．If strict uniformity in the composition of the copolymer ig not required，the copolymer containing 85—95％ vinyl chloride by weight may be manu-factured by the once-charge method．The simplified method may be extended to compute the composition of other copolymer systems with γ1>1，γ2M1 is the main component．
A simplified method for calculating the composition of vinyl chloride—vinyl acetate copolymers has been proposed in this paper．The composition nomogram and the composi-tion distribution diagram of the copolymer containing 0.84—-0.96 mole fraction of vinyl chloride have been constructed．If strict uniformity in the composition of the copolymer ig not required，the copolymer containing 85—95％ vinyl chloride by weight may be manu-factured by the once-charge method．The simplified method may be extended to compute the composition of other copolymer systems with γ1>1，γ2M1 is the main component．
1965, 7(5): 322-335
Abstract:
The kinetic aspects and chain transfer processes of the stereospecific polymerization of butadiene initiated by catalyst systems consisting of nickel acetylacetonate and dialkyl alu-minium chloride have been studied．It has been shown that the rate of polymerization is first order with respect to both monomer and nickel acetylacetonate concentrations，but second order with respect to the diisobutylaluminium chloride concentration．Thus the poly-merization rate with diisobutylaluminuim chloride system is expressed as 一dM一dt =k[M][NiA2][Al(i—C4H9)2Cl]2 When diethylaluminium chloride instead of diisobutylaluminium chloride is used．the rate of polymerization is 1/2 order in diethylaluminium chloride concentration，that is， 一dM一dt =[M][NiA2][Al(C2H5)2Cl]1/2, On the basis of these results，a possible polymerization mechanism of these two systems is proposed．The overall activation energy of polymerization has been determined to be 8.0±0.5 kcal／mole for the NiA2一Al(i-C4H9)2Cl system，and 8．9±0．5 kcal／mole for the NiA2-Al(C2H5)2Cl system．Effects of monomer concentration，catalyst concentration，con-version，solvent，and additive compounds on the polymer molecular weight were also studi-ed．Variation of temperature from O一35°has no significant effect on the molecular weight of polybutadiene obtained，indicating that the difference in activation energy，Ep一Et，is small．Values of chain transfer and termination constants are also presented． It appears that transfer to nickel-containing compound is the main chain transfer reaction in this system．
The kinetic aspects and chain transfer processes of the stereospecific polymerization of butadiene initiated by catalyst systems consisting of nickel acetylacetonate and dialkyl alu-minium chloride have been studied．It has been shown that the rate of polymerization is first order with respect to both monomer and nickel acetylacetonate concentrations，but second order with respect to the diisobutylaluminium chloride concentration．Thus the poly-merization rate with diisobutylaluminuim chloride system is expressed as 一dM一dt =k[M][NiA2][Al(i—C4H9)2Cl]2 When diethylaluminium chloride instead of diisobutylaluminium chloride is used．the rate of polymerization is 1/2 order in diethylaluminium chloride concentration，that is， 一dM一dt =[M][NiA2][Al(C2H5)2Cl]1/2, On the basis of these results，a possible polymerization mechanism of these two systems is proposed．The overall activation energy of polymerization has been determined to be 8.0±0.5 kcal／mole for the NiA2一Al(i-C4H9)2Cl system，and 8．9±0．5 kcal／mole for the NiA2-Al(C2H5)2Cl system．Effects of monomer concentration，catalyst concentration，con-version，solvent，and additive compounds on the polymer molecular weight were also studi-ed．Variation of temperature from O一35°has no significant effect on the molecular weight of polybutadiene obtained，indicating that the difference in activation energy，Ep一Et，is small．Values of chain transfer and termination constants are also presented． It appears that transfer to nickel-containing compound is the main chain transfer reaction in this system．
1965, 7(5): 336-344
Abstract:
A torsion pendulum with self-recording system designed for measuring dynamic mechanical properties of polymeric materials is described in detail. The apparatus can work well in the temperature range of -185° to 250℃ or over; the upper limit of its frequency range is 2 cps.Results obtained with cis-1,4 polybutadiene and low density polyethylene are given as illustrative examples.
A torsion pendulum with self-recording system designed for measuring dynamic mechanical properties of polymeric materials is described in detail. The apparatus can work well in the temperature range of -185° to 250℃ or over; the upper limit of its frequency range is 2 cps.Results obtained with cis-1,4 polybutadiene and low density polyethylene are given as illustrative examples.
1965, 7(5): 345-348
Abstract:
The intrinsic viscosities of twelve fractions of polydimethylsiloxane (Mη = 9.1×104-6.0×106) were determined in heptane and toluene solutions at 25℃. The values ofexpansion factor calculated from the Flory-Fox theory of intrinsic viscosity, α3 = [η]/[η]θ , givelinear plots of α5-α3 vs Mnnnnnnn1/2, and the molecular weight dependence of a is not in accord with the theory of Kurata-Stockmayer-Roig.
The intrinsic viscosities of twelve fractions of polydimethylsiloxane (Mη = 9.1×104-6.0×106) were determined in heptane and toluene solutions at 25℃. The values ofexpansion factor calculated from the Flory-Fox theory of intrinsic viscosity, α3 = [η]/[η]θ , givelinear plots of α5-α3 vs Mnnnnnnn1/2, and the molecular weight dependence of a is not in accord with the theory of Kurata-Stockmayer-Roig.
1965, 7(5): 349-354
Abstract:
A polydimethylsiloxane sample of an average molecular weight 450,000 was fractionated into eight fractions by the reprecipitation method. By determining their intrinsic viscosities and osmotic pressures in toluene solution, the [η]-M relation was established:[η] = 1.17×10-2 Mn 0.71 Toluene, 25℃And the KJθ values of polydimethylsiloxane were calculated by means of the Flory-Fox-Schaefgen method.Kθ= 7.45×10-2 Toluene, 25℃Kθ= 8.81×10-2 Toluene, 50℃Kθ= 2.89×10-2 Cyclohexane, 25℃These values show that the temper.
A polydimethylsiloxane sample of an average molecular weight 450,000 was fractionated into eight fractions by the reprecipitation method. By determining their intrinsic viscosities and osmotic pressures in toluene solution, the [η]-M relation was established:[η] = 1.17×10-2 Mn 0.71 Toluene, 25℃And the KJθ values of polydimethylsiloxane were calculated by means of the Flory-Fox-Schaefgen method.Kθ= 7.45×10-2 Toluene, 25℃Kθ= 8.81×10-2 Toluene, 50℃Kθ= 2.89×10-2 Cyclohexane, 25℃These values show that the temper.
