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1989 Volume 7 Issue 4
1989, 7(4): 289-298
Abstract:
A wide variety of different types of microorganisms are known to produce intracellular energy and carbon storage products, which have been generally described as being poly (β-hydroxybutyrate), PHB, but which are, more often than not, copolymers containing different alkyl groups at the β-position. Hence, PHB belongs to the family ofpoly (β-hydroxyalkanoastes), PHA, all of which are usually formed as intracellular inclusions in bacteria under unbalanced growth conditions. Recently, it became of industrial interest to evaluate these PHA polyesters as natural biodegradable and biocompatible plastics for a wide range of possible applications,such as surgical sutures or packaging containers.For industrial applications,the controlled incorporation of repeating units with different chain lengths into a series of copolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition.Such"made"copolymers can be produced under controlled growth conditions in that,if a defined mixture of substrates for a certain type of microorganisms is supplied,a welldefined and reproducible copolymer is formed.
A wide variety of different types of microorganisms are known to produce intracellular energy and carbon storage products, which have been generally described as being poly (β-hydroxybutyrate), PHB, but which are, more often than not, copolymers containing different alkyl groups at the β-position. Hence, PHB belongs to the family ofpoly (β-hydroxyalkanoastes), PHA, all of which are usually formed as intracellular inclusions in bacteria under unbalanced growth conditions. Recently, it became of industrial interest to evaluate these PHA polyesters as natural biodegradable and biocompatible plastics for a wide range of possible applications,such as surgical sutures or packaging containers.For industrial applications,the controlled incorporation of repeating units with different chain lengths into a series of copolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition.Such"made"copolymers can be produced under controlled growth conditions in that,if a defined mixture of substrates for a certain type of microorganisms is supplied,a welldefined and reproducible copolymer is formed.
1989, 7(4): 299-305
Abstract:
This paper reports the kinetics of group transfer polymerization (GTP)of ethyl acrylate (EA)with zinc iodide catalyst in 1,2-dichloroethane using dimethyl ketene methyl trimethylsilyl acetal (MTS) as initiator at 0℃ and above 0℃. The amount of catalyst used was studied. When zinc iodide catalyst used is more than 10mol% relative to monomer, the rate of polymerization is proportional to the concentration of monomer, whereas zinc iodide catalyst used is less than 10 mol% of the monomer, the rate of polymerization is independent of the monomer concentration.In the GTP of EA an induction period was observed when the zinc iodide contents are less than 10mol%.If the reaction temperature is over 0℃,living species become unstable and diminish,leading to incomplete weight distributions which are not changed as decreasing zinc iodide contents.The polydispersity is about 1.2.
This paper reports the kinetics of group transfer polymerization (GTP)of ethyl acrylate (EA)with zinc iodide catalyst in 1,2-dichloroethane using dimethyl ketene methyl trimethylsilyl acetal (MTS) as initiator at 0℃ and above 0℃. The amount of catalyst used was studied. When zinc iodide catalyst used is more than 10mol% relative to monomer, the rate of polymerization is proportional to the concentration of monomer, whereas zinc iodide catalyst used is less than 10 mol% of the monomer, the rate of polymerization is independent of the monomer concentration.In the GTP of EA an induction period was observed when the zinc iodide contents are less than 10mol%.If the reaction temperature is over 0℃,living species become unstable and diminish,leading to incomplete weight distributions which are not changed as decreasing zinc iodide contents.The polydispersity is about 1.2.
1989, 7(4): 306-314
Abstract:
The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C02, CH4 and N2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is found that P, D, and S of the membranes to all the three gases vary with the extent of bromination. S increases with the increase of the percent of bromine in each case, but D to CO2 increases remarkably only at higher degree of brominafion, and therefore, P to CO2 is increased by more than 100% over a wide range of pressure in the case.The solubility data are well described by the dual mode sorption model.It is found that the gas molecules sorbed by the Langmuir mode are relatively more immobilized and the contribution of the nonequilibrium character of the polymer to gas permeation increases obviously for CO2and is hardly changed for CH4 with increasing bromine content.These observetions are interpreted in terms of changes in specific free volume(SFV) and the cohesive energy density (EMD) of the polymers.
The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C02, CH4 and N2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is found that P, D, and S of the membranes to all the three gases vary with the extent of bromination. S increases with the increase of the percent of bromine in each case, but D to CO2 increases remarkably only at higher degree of brominafion, and therefore, P to CO2 is increased by more than 100% over a wide range of pressure in the case.The solubility data are well described by the dual mode sorption model.It is found that the gas molecules sorbed by the Langmuir mode are relatively more immobilized and the contribution of the nonequilibrium character of the polymer to gas permeation increases obviously for CO2and is hardly changed for CH4 with increasing bromine content.These observetions are interpreted in terms of changes in specific free volume(SFV) and the cohesive energy density (EMD) of the polymers.
1989, 7(4): 315-321
Abstract:
By means of the intensity theory of X-ray scattering and the two-phase concept of high polymer, the basic formula of the crystaUinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene-styrene)block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene-styrene ) block copolymers increases with the increase of the EO content and decreases in the order:PEO-PS-PEO-PS>PS-PEO-PS.
By means of the intensity theory of X-ray scattering and the two-phase concept of high polymer, the basic formula of the crystaUinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene-styrene)block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene-styrene ) block copolymers increases with the increase of the EO content and decreases in the order:PEO-PS-PEO-PS>PS-PEO-PS.
1989, 7(4): 322-329
Abstract:
Two series of interpenetrating sulfonic acid resins (ISAR), 10×n and n×10, were prepared by means of the wet method, and the physicochemical, thermodynamic and kinetic properties of the ISAR were measured. The results show: 10×n resins exhibit better properties than n×10 ones, mainly in higher apparent degree of crosslinking and larger conformational entropy effect, among which, 10×1 resin exhibits the best thermodynamic and kinetic properties. In the DTA graphs of n×10 resins, there are two Tg and two Tox,but in thpse of 10×n,only one Tg and one Tox.This result well supports the conclusion that 10×n resins have much better interpenetrating structural aspects.
Two series of interpenetrating sulfonic acid resins (ISAR), 10×n and n×10, were prepared by means of the wet method, and the physicochemical, thermodynamic and kinetic properties of the ISAR were measured. The results show: 10×n resins exhibit better properties than n×10 ones, mainly in higher apparent degree of crosslinking and larger conformational entropy effect, among which, 10×1 resin exhibits the best thermodynamic and kinetic properties. In the DTA graphs of n×10 resins, there are two Tg and two Tox,but in thpse of 10×n,only one Tg and one Tox.This result well supports the conclusion that 10×n resins have much better interpenetrating structural aspects.
1989, 7(4): 330-339
Abstract:
Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.
Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.
1989, 7(4): 340-345
Abstract:
Ethyl-cyanoethyl cellulose ((E-CE)C)/styrene solution could form anisotropic system when the concentration was high enough. The (E-CE)C/polystyrene(PS)multiphase polymer could be obtained by radical polymerization of the styrene in the solution. The (E-CE)C/PS multiphase polymer maintained both the crystalline structure of the (E-CE)C and the amorphous structure of the PS. In the multiphase polymer produced from the isotropic solution, however, the (E-CE)C formed spherulites and spread in the PS amorphous phase.While,in the multiphase polymer produced from the anisotropic solution,the(E-CE)formed cylinderic crystalline aggregates.Moreover,the ordered lamellar texture was also observed in the multiphase polymer produced from the anisotropic solution.
Ethyl-cyanoethyl cellulose ((E-CE)C)/styrene solution could form anisotropic system when the concentration was high enough. The (E-CE)C/polystyrene(PS)multiphase polymer could be obtained by radical polymerization of the styrene in the solution. The (E-CE)C/PS multiphase polymer maintained both the crystalline structure of the (E-CE)C and the amorphous structure of the PS. In the multiphase polymer produced from the isotropic solution, however, the (E-CE)C formed spherulites and spread in the PS amorphous phase.While,in the multiphase polymer produced from the anisotropic solution,the(E-CE)formed cylinderic crystalline aggregates.Moreover,the ordered lamellar texture was also observed in the multiphase polymer produced from the anisotropic solution.
1989, 7(4): 346-353
Abstract:
A novel polymer-bound 1,2-diol, 3-polystyrylsulfonyl-1,2-propanediol (6) had been prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3-chloro-1,2-propanediol in the presence of a phase transfer catalyst, n-tetrabutylammonium iodide. The capacity of resin 6 for terephthaidehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime(yield:89%)and p-formyl-benzalcohol(yield:734%),respectively.The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.
A novel polymer-bound 1,2-diol, 3-polystyrylsulfonyl-1,2-propanediol (6) had been prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3-chloro-1,2-propanediol in the presence of a phase transfer catalyst, n-tetrabutylammonium iodide. The capacity of resin 6 for terephthaidehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime(yield:89%)and p-formyl-benzalcohol(yield:734%),respectively.The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.
1989, 7(4): 354-359
Abstract:
The factors affecting particle size of reactive microgels formed during the self-emulsifying copolymerization of unsaturated polyester (UP)with butyl acrylate (BA)have been studied. The parameters discussed are: the proportion of the UP in the monomer mixture, the molecular weight and the carboxyl value of the UP, the phase ratio, the electrolyte concentration and the polar solvent additive. The seeding emulsion polymerization is discussed as well.It turned out that the particle size of the reactive microgels can be controlled in a definite range by changing the experimental conditions.However the particle size distribution becomes broader as the average diameter increases.It is suggested that the agglomeration of primary particles plays an important role during the growth of microgel particle.
The factors affecting particle size of reactive microgels formed during the self-emulsifying copolymerization of unsaturated polyester (UP)with butyl acrylate (BA)have been studied. The parameters discussed are: the proportion of the UP in the monomer mixture, the molecular weight and the carboxyl value of the UP, the phase ratio, the electrolyte concentration and the polar solvent additive. The seeding emulsion polymerization is discussed as well.It turned out that the particle size of the reactive microgels can be controlled in a definite range by changing the experimental conditions.However the particle size distribution becomes broader as the average diameter increases.It is suggested that the agglomeration of primary particles plays an important role during the growth of microgel particle.
1989, 7(4): 360-366
Abstract:
The polyquinolines with 2,2'-pyridylquinoline as bidentate and 2,6-diquinolylpyridine as tridentate ligand have been prepared from 4,4-dlamino- 3,3'-dibenzoyldiphenyl ether, 4,4'-diacetyldiphenyl ether and 1,4-bis (2-acetylpyridyl-6-oxy) benzene, 2,6-diacetylpyridine, respectively. These polyquinoline-supported ligands have been used in hydrogenation and hydroformylation of olefins with some transition metal complexes.
The polyquinolines with 2,2'-pyridylquinoline as bidentate and 2,6-diquinolylpyridine as tridentate ligand have been prepared from 4,4-dlamino- 3,3'-dibenzoyldiphenyl ether, 4,4'-diacetyldiphenyl ether and 1,4-bis (2-acetylpyridyl-6-oxy) benzene, 2,6-diacetylpyridine, respectively. These polyquinoline-supported ligands have been used in hydrogenation and hydroformylation of olefins with some transition metal complexes.
1989, 7(4): 367-378
Abstract:
Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated.The fractography of PSF,particle modified epoxy was examined in detail with SEM.The contribution of every possible energy absorption process has been discussed.Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.
Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated.The fractography of PSF,particle modified epoxy was examined in detail with SEM.The contribution of every possible energy absorption process has been discussed.Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.
1989, 7(4): 379-382
Abstract:
The kinetics of mesophase formation of a lyotropic aromatic polyamide from isotropic state has been studied by means of depolarized light intensity. Avrami type analysis of the data gives an exponent close to 1, which suggests the nucleation followed by one-dimensional growth. No influence of blending flexible chain from nylon 6 to the aromatic polyamide on the kinetics of mesophase formation was observed.
The kinetics of mesophase formation of a lyotropic aromatic polyamide from isotropic state has been studied by means of depolarized light intensity. Avrami type analysis of the data gives an exponent close to 1, which suggests the nucleation followed by one-dimensional growth. No influence of blending flexible chain from nylon 6 to the aromatic polyamide on the kinetics of mesophase formation was observed.
