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1987 Volume 5 Issue 3
1987, 5(3): 175-185
Abstract:
In this brief review article some aspects of the thermodynamics of polymer mixtures are discussed, mainly based on the author's research. The studies of poly (methyl methacrylate)/chlorinated polyethylene (CPE), poly (butyl acrylate)/CPE and CPE/CPE (different chlorine content) mixture verify the "dissimilarity" and "similarity" principles for predicting miscibility of polymer mixtures. The sign of heat of mixing of oligomeric analogues is not sufficient in predicting the miscibility. The Flory equation of state theory has been applied to simulate the phase boundaries of polymer mixtures.The empirical entropy parameter Q12 plays an important role in the calculation,this reduces the usefulness of the theory.With energy parameter X12 0 and Q12 0 the spinodals so calculated are reasonable compared to experiments.A hole model was suggested for the statistics of polymer mixtures.The new hole theory combines the features of both the Flory equation of state theory and the Sanchez lattice fluid theory and can be reduced to them under some conditions.
In this brief review article some aspects of the thermodynamics of polymer mixtures are discussed, mainly based on the author's research. The studies of poly (methyl methacrylate)/chlorinated polyethylene (CPE), poly (butyl acrylate)/CPE and CPE/CPE (different chlorine content) mixture verify the "dissimilarity" and "similarity" principles for predicting miscibility of polymer mixtures. The sign of heat of mixing of oligomeric analogues is not sufficient in predicting the miscibility. The Flory equation of state theory has been applied to simulate the phase boundaries of polymer mixtures.The empirical entropy parameter Q12 plays an important role in the calculation,this reduces the usefulness of the theory.With energy parameter X12 0 and Q12 0 the spinodals so calculated are reasonable compared to experiments.A hole model was suggested for the statistics of polymer mixtures.The new hole theory combines the features of both the Flory equation of state theory and the Sanchez lattice fluid theory and can be reduced to them under some conditions.
1987, 5(3): 186-190
Abstract:
Inverse gas chromatography(IGC) and Fourier-transform infrared (FT-IR) techniques were applied to determining the relative acid-base strength of polymers and coupling agents. The acid-base characteristics of fillers such as CaCO3 could be altered by treatment with different coupling agents. It was shown that some mechanical properties of filled polymers were obviously associated with acid-base interactions between polymers and fillers.
Inverse gas chromatography(IGC) and Fourier-transform infrared (FT-IR) techniques were applied to determining the relative acid-base strength of polymers and coupling agents. The acid-base characteristics of fillers such as CaCO3 could be altered by treatment with different coupling agents. It was shown that some mechanical properties of filled polymers were obviously associated with acid-base interactions between polymers and fillers.
1987, 5(3): 191-196
Abstract:
A series of liquid chloroprene-methacrylic acid copolymcr (CP--co-MAA) modified epoxy resin (ER)/poly (butyl methacrylate) (PBMA). semi-IPN were synthesized. Some physical properties were investigated. DSC diagrams showed two indistinct and inward endothermal transitions corresponding to the transitions of two networks in the semi-IPN system. By observing morphology with SEM technique it shows that there is a multiphase structure, in which CP-co-MAA's. domain sizes arc about 0.10--0.80μ. With increasing C/E ratio,the domain sizes are getting smaller,which is due to effect of mixing network of CP-co-MAA promoting entanglement and interpenetrating of PBMA and CP-co-MAA- ER network.In most of the semi-IPN's compositions,ER phase readily maintains its phase continuity while PBMA phase presents a band shape structure.Consequently,crosslinking network keeps in its continuous phase more readily than uncrosslinking one,thus it influences dominantly on the physical properties.
A series of liquid chloroprene-methacrylic acid copolymcr (CP--co-MAA) modified epoxy resin (ER)/poly (butyl methacrylate) (PBMA). semi-IPN were synthesized. Some physical properties were investigated. DSC diagrams showed two indistinct and inward endothermal transitions corresponding to the transitions of two networks in the semi-IPN system. By observing morphology with SEM technique it shows that there is a multiphase structure, in which CP-co-MAA's. domain sizes arc about 0.10--0.80μ. With increasing C/E ratio,the domain sizes are getting smaller,which is due to effect of mixing network of CP-co-MAA promoting entanglement and interpenetrating of PBMA and CP-co-MAA- ER network.In most of the semi-IPN's compositions,ER phase readily maintains its phase continuity while PBMA phase presents a band shape structure.Consequently,crosslinking network keeps in its continuous phase more readily than uncrosslinking one,thus it influences dominantly on the physical properties.
1987, 5(3): 197-204
Abstract:
Phenyltrichlorosilane was hydrolyzed both ifi. toluene and in ether from which two kinds of prepolymers were obtained with different structures, molecular weights, and molecular weight distributions. Polymers were prepared from the prepolymers in various polymerization conditions. The ladderlike, branched, and crosslinked structures formed under different polymerization conditions were characterized by means of FTIR, 1H and 29Si-NMR, and elemental analysis. Azeotropic distillation of solvents and H2O from the system and high molecular weight products with perfect ladderlike structure were obtained.
Phenyltrichlorosilane was hydrolyzed both ifi. toluene and in ether from which two kinds of prepolymers were obtained with different structures, molecular weights, and molecular weight distributions. Polymers were prepared from the prepolymers in various polymerization conditions. The ladderlike, branched, and crosslinked structures formed under different polymerization conditions were characterized by means of FTIR, 1H and 29Si-NMR, and elemental analysis. Azeotropic distillation of solvents and H2O from the system and high molecular weight products with perfect ladderlike structure were obtained.
1987, 5(3): 205-210
Abstract:
It was proposed that in the staining process allylamine diffuses into amorphous region of PET film, reacting slightly with ester bond on PET chain and connecting with it and remaining in the amorphous area, then OsO4 reacts with C=C group in allylamine, deposits in that region and hence, increases the contrast between amorphous and crystalline regions.
It was proposed that in the staining process allylamine diffuses into amorphous region of PET film, reacting slightly with ester bond on PET chain and connecting with it and remaining in the amorphous area, then OsO4 reacts with C=C group in allylamine, deposits in that region and hence, increases the contrast between amorphous and crystalline regions.
1987, 5(3): 211-219
Abstract:
A novel class of the liquid crystal polymers with mesogens laterally attached to flexible main chain backbones has been synthesized recently by us. While the flexible backbones tend to take configuration of maximum entropy the mesogenic side groups tend to orientate because of the anisotropie soft dispersion forces. A mean field theory is presented to describe the competition between these two trends which makes it possible for this class of polymers to show anisotropic (liquid crystal) phase within certain temperature range where the polymer main chains and the side chain mesogens will take approximately parellel arrangement,which is different from the mormal side chain liquid crystal polumers.The temperature range of the liquid crystal phase,its ordering and phase transition all depend on the flexibility of the backbone,the strength of the anisotropic forces of the side groups and the hinge elasticity.The results show that the liquid crystalisotropic phase transition is of the first order.The phase diagram,i.e.the dependence of the transition temperature on the structure of the polymers is also given.
A novel class of the liquid crystal polymers with mesogens laterally attached to flexible main chain backbones has been synthesized recently by us. While the flexible backbones tend to take configuration of maximum entropy the mesogenic side groups tend to orientate because of the anisotropie soft dispersion forces. A mean field theory is presented to describe the competition between these two trends which makes it possible for this class of polymers to show anisotropic (liquid crystal) phase within certain temperature range where the polymer main chains and the side chain mesogens will take approximately parellel arrangement,which is different from the mormal side chain liquid crystal polumers.The temperature range of the liquid crystal phase,its ordering and phase transition all depend on the flexibility of the backbone,the strength of the anisotropic forces of the side groups and the hinge elasticity.The results show that the liquid crystalisotropic phase transition is of the first order.The phase diagram,i.e.the dependence of the transition temperature on the structure of the polymers is also given.
SOLUBLE POLYACETYLENE OBTAINED WITH RARE-EARTH CATALYST AND SOME ASPECTS OF POLYMERIZATION MECHANISM
1987, 5(3): 221-227
Abstract:
Soluble polyacetylene (PA) with well--defined nature has been synthesized with catalyst system Nd(i-OPr)3/AIR3 (R=C2H5-, i-C4H9-) and characterized by IR, Raman and ESR Spectra etc. Number average molecular weight of the soluble specimen were determined by VPO to be about 500g/mol. or lower. The IR and NMR spectra and end group analysis of" the soluble polyacetylene fully demonstrate that polymerization of acetylene with rare-earth catalyst is realized through monomer insertion between the transition metal-carbon bond.
Soluble polyacetylene (PA) with well--defined nature has been synthesized with catalyst system Nd(i-OPr)3/AIR3 (R=C2H5-, i-C4H9-) and characterized by IR, Raman and ESR Spectra etc. Number average molecular weight of the soluble specimen were determined by VPO to be about 500g/mol. or lower. The IR and NMR spectra and end group analysis of" the soluble polyacetylene fully demonstrate that polymerization of acetylene with rare-earth catalyst is realized through monomer insertion between the transition metal-carbon bond.
1987, 5(3): 228-233
Abstract:
The transitions of bisphenol A and phenolphthalein o|igopolysulfones were investigated by DSC. It is found that both the oligomers have three transitions within the temperature range (230-550K) studied. Considering the strong dependence of the appearance of the two transitions, lower and higher than Tg, on the specimens' thermal history, i. e., temperature and time of heat-treatment, and their particular molecular strueture, it is proposed that these two transitions are morphological in origin arid are due to the disordering of relatively short range order of very small regions,and to the disordering of relatively well-ordered intra or/and intermolecular segments,respectively.Equations for linear relationship between Tg and 1/Mn for both the oligomers are given in the paper.
The transitions of bisphenol A and phenolphthalein o|igopolysulfones were investigated by DSC. It is found that both the oligomers have three transitions within the temperature range (230-550K) studied. Considering the strong dependence of the appearance of the two transitions, lower and higher than Tg, on the specimens' thermal history, i. e., temperature and time of heat-treatment, and their particular molecular strueture, it is proposed that these two transitions are morphological in origin arid are due to the disordering of relatively short range order of very small regions,and to the disordering of relatively well-ordered intra or/and intermolecular segments,respectively.Equations for linear relationship between Tg and 1/Mn for both the oligomers are given in the paper.
1987, 5(3): 234-2339
Abstract:
A kind of copolymer of acrylic acid and vinylpyridine was synthesized and the fluorescent properties of the complexes of the copolymer with Eu3+ or Tb3+ were studied. It was found that the fluorescence intensity of the complexes of the eopolymer with Eu3+ was 20 times as high as that of the complexes of polyaerylic acid with Eu3+ and twice as high as that of the complexes of polyvinylpyridine with Eu3+. The effects of the composition of the copolymer and the content of Eu3+ or Tb3+ in the complexes were studied.The fluorescence lifetime of the complexes was measured and it was found that two or more kinds of energy transfer mechanism existed.
A kind of copolymer of acrylic acid and vinylpyridine was synthesized and the fluorescent properties of the complexes of the copolymer with Eu3+ or Tb3+ were studied. It was found that the fluorescence intensity of the complexes of the eopolymer with Eu3+ was 20 times as high as that of the complexes of polyaerylic acid with Eu3+ and twice as high as that of the complexes of polyvinylpyridine with Eu3+. The effects of the composition of the copolymer and the content of Eu3+ or Tb3+ in the complexes were studied.The fluorescence lifetime of the complexes was measured and it was found that two or more kinds of energy transfer mechanism existed.
1987, 5(3): 240-253
Abstract:
Polysilane polymers which contain silicon hydride units in the chain were synthesized by sodium coupling of PhHSiCl2 with R1R2SiCl2 in toluene (R1 and R2 alkyl, aryl or aralkyl), followed by termination with a monochlorosilane and neutralization with sodium bicarbonate solution. These polymers are soluble in common solvents and can be formed into a variety of shapes by molding, casting, coating or potting. This class of polymers can be crosslinked by oxidation and irradiation, or by reaction with a multifunctional vinylsilane in th presence of platinum complexes.
Polysilane polymers which contain silicon hydride units in the chain were synthesized by sodium coupling of PhHSiCl2 with R1R2SiCl2 in toluene (R1 and R2 alkyl, aryl or aralkyl), followed by termination with a monochlorosilane and neutralization with sodium bicarbonate solution. These polymers are soluble in common solvents and can be formed into a variety of shapes by molding, casting, coating or potting. This class of polymers can be crosslinked by oxidation and irradiation, or by reaction with a multifunctional vinylsilane in th presence of platinum complexes.
1987, 5(3): 254-260
Abstract:
In order to study the effect ofalkyl chain length and the polymer effect on the photoreduction behavior of some viologens, a series of alkyl viologen, polyviologen and bisviologen compounds have been synthesized. In the presence of excess 2-propanol, the initial photoreduction of alkyl viologens and polyviologens follow the peudo--seeond--order reaction, the calculated rate constants are related to the alkyl chain length: In addition, the intramoleeular association of radical cations of polyviologens has been found even in dilute solution.Hoowever the extent of association is varied with the alkyl chain length.The observed polymer effect of polyviologens in the photoreduction is significant which can be explained in terms of the mature of second order reaction.
In order to study the effect ofalkyl chain length and the polymer effect on the photoreduction behavior of some viologens, a series of alkyl viologen, polyviologen and bisviologen compounds have been synthesized. In the presence of excess 2-propanol, the initial photoreduction of alkyl viologens and polyviologens follow the peudo--seeond--order reaction, the calculated rate constants are related to the alkyl chain length: In addition, the intramoleeular association of radical cations of polyviologens has been found even in dilute solution.Hoowever the extent of association is varied with the alkyl chain length.The observed polymer effect of polyviologens in the photoreduction is significant which can be explained in terms of the mature of second order reaction.
1987, 5(3): 261-264
Abstract:
A method for measuring moisture swelling of amorphous PET films by using Rayleigh interferometer is reported, Plots of the optical path of light transmission in the polymer vs. soaking time were obtained, and from the same curves, the dependence of time on the moisture swelling, saturated water absorption and diffusion coefficient of PET films were estimated. These results are in agreement with those obtained by weighing method. It is shown that optical interference method is a simple but sensitive method for the study of water absorption and swelling in transparent polymer films.
A method for measuring moisture swelling of amorphous PET films by using Rayleigh interferometer is reported, Plots of the optical path of light transmission in the polymer vs. soaking time were obtained, and from the same curves, the dependence of time on the moisture swelling, saturated water absorption and diffusion coefficient of PET films were estimated. These results are in agreement with those obtained by weighing method. It is shown that optical interference method is a simple but sensitive method for the study of water absorption and swelling in transparent polymer films.
1987, 5(3): 265-268
Abstract:
In this paper, calculating the molecular internal rotating steric factor of polymers by the radiation crosslinking method is studied and a relationship between the molecular internal rotating steric factor (σ) and crosslinking parameter β is established[1] by taking account of the effect of polymer chain flexibility on β value, σ value of polymer obtained by this method is in agreement with that given with other method.
In this paper, calculating the molecular internal rotating steric factor of polymers by the radiation crosslinking method is studied and a relationship between the molecular internal rotating steric factor (σ) and crosslinking parameter β is established[1] by taking account of the effect of polymer chain flexibility on β value, σ value of polymer obtained by this method is in agreement with that given with other method.
