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1991 Volume 9 Issue 1
1991, 9(1): 1-13
Abstract:
1991, 9(1): 14-18
Abstract:
The phase transition kinetics of thennotropic liquid crystalline aromatic-aliphatic regular copolyester: were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.
The phase transition kinetics of thennotropic liquid crystalline aromatic-aliphatic regular copolyester: were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.
1991, 9(1): 19-23
Abstract:
The polymerization thermokinetics of pyrrole in the presence of iron trichloride art studied by using a Calvet microcalorimoter. The apparent activation energy, the pre-exponential constant and reaction order of this reaction in the temperature range of 25.2—37℃ are 34.5 KJ·mol-1, 10-1S2.74 and 1 respectively. The activation free-energies of this reaction at 25.2°, 30°and 37℃ are 91.8, 92.9 and 94.2 KJ·mol-1 respectively.
The polymerization thermokinetics of pyrrole in the presence of iron trichloride art studied by using a Calvet microcalorimoter. The apparent activation energy, the pre-exponential constant and reaction order of this reaction in the temperature range of 25.2—37℃ are 34.5 KJ·mol-1, 10-1S2.74 and 1 respectively. The activation free-energies of this reaction at 25.2°, 30°and 37℃ are 91.8, 92.9 and 94.2 KJ·mol-1 respectively.
1991, 9(1): 24-30
Abstract:
The kinetics of the photopolymerization of sensitized acrylamide (AM) system induced by He-Ne laser has been investigated. Using methylene blue (MB)-triethanolamine (TEOA) as the photosensitive system, the photopolymerization followed a nonsteady-state kinetic scheme in the initial period of polymerization (the monomer conversion C%C%>2%). Accirding to the steady-state hypothesis, the mechanism of photopolymerization was proposed. The deduced kinetic equation of the photopolymerization of AM is in good coincidence with the experimental results.
The kinetics of the photopolymerization of sensitized acrylamide (AM) system induced by He-Ne laser has been investigated. Using methylene blue (MB)-triethanolamine (TEOA) as the photosensitive system, the photopolymerization followed a nonsteady-state kinetic scheme in the initial period of polymerization (the monomer conversion C%C%>2%). Accirding to the steady-state hypothesis, the mechanism of photopolymerization was proposed. The deduced kinetic equation of the photopolymerization of AM is in good coincidence with the experimental results.
1991, 9(1): 31-38
Abstract:
Castor oil polyurethane/poly(methyl methacrylate) AB crosslinked polymers (ABCP) were synthesized by free radical copolymerization of MMA and vinyl-terminated castor oil polyurethane which was obtained from isocyanate-terminated castor oil polyurethane and hydroxyethyl methacrylate The mechanical properties, transition and relaxation, as well as compatibility and morphology of the ABCP were investigated by changing the component. The results show that the ABCP is a semicompatible system and the compatibility of the two components decreases with increasing content of the hard segment.The mechanical and damping properties of the ABCP are obviously superior to that of their homopolymers.The damping value is mainly controlled by crosslink density of the ABCP but Tg value by component.
Castor oil polyurethane/poly(methyl methacrylate) AB crosslinked polymers (ABCP) were synthesized by free radical copolymerization of MMA and vinyl-terminated castor oil polyurethane which was obtained from isocyanate-terminated castor oil polyurethane and hydroxyethyl methacrylate The mechanical properties, transition and relaxation, as well as compatibility and morphology of the ABCP were investigated by changing the component. The results show that the ABCP is a semicompatible system and the compatibility of the two components decreases with increasing content of the hard segment.The mechanical and damping properties of the ABCP are obviously superior to that of their homopolymers.The damping value is mainly controlled by crosslink density of the ABCP but Tg value by component.
1991, 9(1): 39-47
Abstract:
Six kinds of polymer ligands, supported on SiO2, containing coordinating atoms P, S and N respectively, have been synthesized. The Ru(Ⅲ)-Co(Ⅱ) bimetallic complexes of these polymer ligands have been obtained and examined as catalysts for the hydroformylation of cyclohexene. The effects of reaction temperature, pressure and Co/Ru ratio etc. on the activities of catalysts were investigated in detail. The catalysts are all polymer-noncarbonyl-metal complexes, easily to be prepared, active and stable. From the experimental results it can be suggested that under reaction conditions such polumer noncarbonyl-metal complexes convert"in situ" to polymer-carbonyl-metal complexes,thus be come active catalysts.The course of this conversion is supposed as a preliminary approach.
Six kinds of polymer ligands, supported on SiO2, containing coordinating atoms P, S and N respectively, have been synthesized. The Ru(Ⅲ)-Co(Ⅱ) bimetallic complexes of these polymer ligands have been obtained and examined as catalysts for the hydroformylation of cyclohexene. The effects of reaction temperature, pressure and Co/Ru ratio etc. on the activities of catalysts were investigated in detail. The catalysts are all polymer-noncarbonyl-metal complexes, easily to be prepared, active and stable. From the experimental results it can be suggested that under reaction conditions such polumer noncarbonyl-metal complexes convert"in situ" to polymer-carbonyl-metal complexes,thus be come active catalysts.The course of this conversion is supposed as a preliminary approach.
1991, 9(1): 48-54
Abstract:
Two types of the regular copolymer of poly (1, 4-phenyleneterephthalamide) were synthesized by the low temperature solution polycondensation in NMP-CaCl2 solvent system, using the piperazine or 2,5-dimethylpiperazine as the third components introduced in the main chain of poly (1, 4-phenyleneterephthalamide). The properties of copolymers were characterized by IR, SEM, X-RAY diffraction, polarizing microscopy, TGA and solubilities. Experimental results showed that the copolymers had good solubility and thermal stability,the concentrated sulfuric and (～98%) solution of regular PPTA copolymers had liquid crystalline properties.
Two types of the regular copolymer of poly (1, 4-phenyleneterephthalamide) were synthesized by the low temperature solution polycondensation in NMP-CaCl2 solvent system, using the piperazine or 2,5-dimethylpiperazine as the third components introduced in the main chain of poly (1, 4-phenyleneterephthalamide). The properties of copolymers were characterized by IR, SEM, X-RAY diffraction, polarizing microscopy, TGA and solubilities. Experimental results showed that the copolymers had good solubility and thermal stability,the concentrated sulfuric and (～98%) solution of regular PPTA copolymers had liquid crystalline properties.
1991, 9(1): 55-64
Abstract:
The dynamic mechanical modulus at 25℃ for blends of segmented polyurethanes with PVC was studied by using suitable mechanics models of multi-component systems. The analysis indicates that the blend morphology was mainly determined by soft segment structure of polyurethanes. The PPO-PU/PVC blends show typical two-phase morphology and their modulus-composition relations may be described by Halpin-Tsai model for domain-matrix two-phase systems.While the PCL-PU / PVC, PTMA-PU/PVC and PTMO-PU/PVC blends fit the Kerner's packed grain composite model.These results may imply that the modulus-composition relationship is packed grain composite model.These results may imply that the modulus-composition relationship is sensituve to the interaction between the components and the mixture morphology of the blends.
The dynamic mechanical modulus at 25℃ for blends of segmented polyurethanes with PVC was studied by using suitable mechanics models of multi-component systems. The analysis indicates that the blend morphology was mainly determined by soft segment structure of polyurethanes. The PPO-PU/PVC blends show typical two-phase morphology and their modulus-composition relations may be described by Halpin-Tsai model for domain-matrix two-phase systems.While the PCL-PU / PVC, PTMA-PU/PVC and PTMO-PU/PVC blends fit the Kerner's packed grain composite model.These results may imply that the modulus-composition relationship is packed grain composite model.These results may imply that the modulus-composition relationship is sensituve to the interaction between the components and the mixture morphology of the blends.
1991, 9(1): 65-70
Abstract:
The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd polymeric complex is characterized by IR and its catalytic activity, and the polymerization features have been investigated in comparison with that of the conventional Ziegler-Natta catalysts. When [Nd]=1×10-3 mol/L, [M]=5mol/L, Al/Nd=170(mol ratio) and CCl4/Nd=50(mol ratio), the polymerization conversion of styrene gets to 51.6% in six hours,and the catalytic activity reaches 1852 gPS/gNd,which is much higher than that of conventional rare earth catalysts.The polymerization reaction has an induction period and shows some characteristics of chain polymerization.The polymerization rate is the first order with respect to the concentration of styrene monomer.Addition of FeCl3 does not suppress the polymerization.
The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd polymeric complex is characterized by IR and its catalytic activity, and the polymerization features have been investigated in comparison with that of the conventional Ziegler-Natta catalysts. When [Nd]=1×10-3 mol/L, [M]=5mol/L, Al/Nd=170(mol ratio) and CCl4/Nd=50(mol ratio), the polymerization conversion of styrene gets to 51.6% in six hours,and the catalytic activity reaches 1852 gPS/gNd,which is much higher than that of conventional rare earth catalysts.The polymerization reaction has an induction period and shows some characteristics of chain polymerization.The polymerization rate is the first order with respect to the concentration of styrene monomer.Addition of FeCl3 does not suppress the polymerization.
1991, 9(1): 71-78
Abstract:
A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP). The complexation of copper ions with DKLCP greatly increases the phase transition temperature Tk from crystalline state to liquid crystalline state and Tcl from LC to isotropic state and makes the range of phase transition ΔT (ΔT=Tcl-Tk) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases.The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.
A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP). The complexation of copper ions with DKLCP greatly increases the phase transition temperature Tk from crystalline state to liquid crystalline state and Tcl from LC to isotropic state and makes the range of phase transition ΔT (ΔT=Tcl-Tk) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases.The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.
1991, 9(1): 79-85
Abstract:
A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.
A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.
1991, 9(1): 86-93
Abstract:
In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough and merge with each other with increasing concentration. The band-like texture is composed of parallel equidistant bright and dark alternative strips which are about 0.2-2.0 μm in width. In the band-like texture, the layers of ordered polymer chains are perpendicular to the solution film and the axes of helicoids are parallel to it.The width of the strips is different in different in different zones.Under the effect of an external magnetic field,the strips in the band-like texture first become wider and then narrower gradually.Moreover,the axes of helicoids in the (E-CE)C/DCA mesomorphic solution change from the direction normal to the magnetic field to the agreement with the magnetic field direction.
In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough and merge with each other with increasing concentration. The band-like texture is composed of parallel equidistant bright and dark alternative strips which are about 0.2-2.0 μm in width. In the band-like texture, the layers of ordered polymer chains are perpendicular to the solution film and the axes of helicoids are parallel to it.The width of the strips is different in different in different zones.Under the effect of an external magnetic field,the strips in the band-like texture first become wider and then narrower gradually.Moreover,the axes of helicoids in the (E-CE)C/DCA mesomorphic solution change from the direction normal to the magnetic field to the agreement with the magnetic field direction.
1991, 9(1): 94-100
Abstract:
The dependence of measured viscosity on NaCl concentration (0.1 to 3.0M), pH (range of 2—13) and cadoxen composition wcad (from 2% to 100%) for the lacquer polysaccharide in NaCl/cadoxen/H2O mixture containing HCl or without were obtained. All the viscosity exponents γ in the Mark-Houwink equations under three different solvent condition arc close to 0.5. The wcad dependence of reduced viscosity ηsp/c confirms the single strand chain of the polysaccharide. As the γ values close to 0.5 and values of unperturbed dimension S2>θ/M and [η] much smaller than those for usual linear polymers,these facts suggest that the polysaccharide chains in the aqueous solutions should be dense random coil owing to the highly branched structure.
The dependence of measured viscosity on NaCl concentration (0.1 to 3.0M), pH (range of 2—13) and cadoxen composition wcad (from 2% to 100%) for the lacquer polysaccharide in NaCl/cadoxen/H2O mixture containing HCl or without were obtained. All the viscosity exponents γ in the Mark-Houwink equations under three different solvent condition arc close to 0.5. The wcad dependence of reduced viscosity ηsp/c confirms the single strand chain of the polysaccharide. As the γ values close to 0.5 and values of unperturbed dimension S2>θ/M and [η] much smaller than those for usual linear polymers,these facts suggest that the polysaccharide chains in the aqueous solutions should be dense random coil owing to the highly branched structure.
